I think your theory of the head gasket is correct Brian. Thanks for your honest and very detailed way of sharing your progress. Keep it going, we will be here.
Combustion pressure leaking into the cooling system causes all kinds of problems. Glad you didn't severely overheat that first engine while testing. It will be interesting to see what the mechanic finds inside. See if he will take some photos of the damage as he tears it down. We'd love to see.
Very useful film, and glad you were able to bounce back so quickly! Re: two channels or not, my understanding is the more people not clicking on a thumbnail the less the algorithm likes you, therefore anyone not interested in bikes is going to have negative impact on your flying channel, which would be a shame.
I really appreciate the effort you put into being thorough in both your analysis and explanation of the airplane and the issue with the engine. I agree with your take on what happened with engine #1 It might be worth the $ and effort to send a few oil samples from this engine and the freshened one to Blackstone Labs for a workup on the oil. I've done it with several engines over the years and was always happy with the peace of mind the numbers give me, and, once a pattern is established if a change happens the odds are you'll see it in the oil before it goes south on ya. Just a thought...
Thank you for being transparent with your issues. I think you are correct in your assessment of your engine problem that it was an unknown issue from the beginning. I think you are sincerely giving the Yamaha engine an honest review. I am a fan on this engine. Keep going with the videos we are all enjoying your journey. I hope to be there one day with my own plane with a Yamaha.
Thanks for sharing. Love the video. The head gasket makes so much sense. I think it is smart to have two engines. You are crossing new grounds with that engine and learning so much. Love it.
Good update. I have used a product called Mend Tite by Zecol and Bars Leak with some success on older vehicles. I haven't seen any detrimental effects from either other than sometimes they don't stop the leak. I have it in an old truck that had a slight head gasket leak that it worked pretty well on, but I had to add more stop leak from time to time. All stop leaks are temporary at best in my opinion. Ultimately if you have a leak it's best to fix it correctly. I don't think I would put any of them in an airplane.
Interesting to say the least. I'm really wanting to know what the TBO numbers will look like. And the bright side is, you can get the rebuild done at your local sled & bike shop.
Sorry you’ve had this problem with your engine. I really appreciate your analytical approach to discovering the issue and being able to fix it. I sure hope the new engine will give you the results you are looking for.
It sounds to me like you most likely had a slight head gasket leak in the first place that over pressured the cooling system and caused the weeping leak at the radiator weak spot.When you added the stop leak, it did plug the weeping leak but wouldn't stop the head gasket leak which injects compressed air into the cooling system. Unlike the radiator leak which released excess pressure out of the cooling system. That's how stop leak products are designed to work from the inside out not outside in, as was head gasket leak. In the end the water system failed because of over pressure. I write this as you have discovered. Any how I see that problem all the time with high performance diesel engines in my fleet. Beautiful plane b y the way! Thoroughly enjoyed watching your vids of your building of it. Keep it going!
I've had coolant additive completely ruin a heater core. It flowed coolant, but inlet and outlet temps were almost identical after the client added the additive. There was little or no heat transfer any longer. Not sure how much damage it did inside the radiator. Any film on the interior surfaces of the passages in a heat exchanger, severely lessens the heat conductivity of that component. We found the leak, repaired it properly, flushed the system with a chemical that would dissolve the additive, then with distilled water before filling with coolant and returning the machine to service.
Great breakdown of engine choices!Thanks for keeping the information objective. Sorry to see your engine having problems, but you’ve saved the next guy many many headaches. Loved every minute of this video. Thanks Bryan!
Thanks Brian, be sure to share what you think of your engine rebuilder. What is your thoughts on ECM or battery redundancy? Definitely will go with Brian D's ACM ECM/harness setup. Thanks as always for sharing your experiences.
I put 1300 trouble free hours on a EA-81 Soob conversion in my first RANS S-7, and loved rubbing that number (as it grew to the total) in the noses of people who would at first diss such a relatively unusual engine choice! More recently, after reaching TBO and beyond on my current 912S, with zero issues, when talking to a die hard legacy engine pilot the numbers kind of put an end to any dissing of the Rotax. Point being, build those hours big time, nothing succeeds like success, 10 hours is a blip, 500+ hours and up will really prove the concept. Looking good!
Great video! You are likely correct that the leaking head gasket issue was there from the beginning. Most likely cause is lack of proper/timely coolant changes by the previous owner. As a professional mechanic, I can definitely say, that a large part of the motoring public are totally lame when it comes to maintenance. Oil changes are about all a lot of them do. Any time work is done that opens the cooling system, after the first engine run up to operating temperature, let the engine cool down completely. Then open the system and add coolant as needed. Often, you have an air pocket in the system. This air pocket will work itself out after a good run. Failure to do this, may lead you to later think that you have a leak.
Thanks, Bryan. I really appreciate the time you put into this video series, and I'm sure I'll be referring back to your videos as I work through the rest of my build (a Series 5). I too considered a lot of alternative engines, but in the end I wanted a reliable, proven package so I could just fly and not be faced with problems I don't know how to solve. I spoke to John at Kitfox and learned that their firewall forward kit for the Rotax 912iS is extremely complete, since that's the engine they use on their S-LSA product. So, I've got that engine on order and my prop is arriving any day now. Maybe by the time I wear out the Rotax, the Apex will be a mature option and I can make the upgrade!
Just came across my feed with this video. Vary impressed. Went through some of the same issues many years ago with a Subaru engine on a Kolb Mark IV. After a little work and time , it ended up being a fantastic flyer, for many years. Good luck to you, I really enjoyed watching your video and I will go back and catch the others.
Great channel and conent! Viking has the 1.5L Honda 130 Hp (no turbo) and they also have a 1.8L Honda 150 Hp (no turbo)... some Rans S-21s are now running the 1.8L 150 Hp engine. The Viking 1.5L Turbo at 195 Hp is probably not a good choice for the Kitfox but matches up exceptionally well for the CH750 SD or a Rans S-21 Outbound.
Agree. On our car, I had bad experience with those bottled head gasket repair. Damaged the water pump seals. Only sealed the combustion leak for a month. It's negative utility, it is not a fix.
Great videos, so informative…. and (for what it’s worth) I think you made the right choice on engine. Good decision to get a second Yammy motor for a spare: there’s little worse than a sunny day at the airport with your aircraft grounded / in bits! Several people have commented on getting the oil analysed regularly: I spent 20+ year racing old cars, mostly early 911s, and we found that you often got early warning of problems from the oil check. In fact we ended up using the oil check & compression check to decide when to do a rebuild - if the race engine passed both tests, keep going & save the money for later! It might be interesting to try a flight-adjustable prop on that motor: if it has a sweet-spot around 8k you might be able to optimise cruise performance with higher throttle setting & ‘pulling it down’ to 8k with the prop setting (of course I might be missing something…). I believe that someone will soon try to put an adjustable prop with ‘beta’ reverse thrust setting as a way of shortening the STOL Comp landing phase ( rather like Mike Patey’s Draco ) Anyhow, many thanks for your videos: great to see someone ready to share so much detail. Fly safe! Peter / England
There is a guy that's flying an adjustable prop. Check out oshkosh stol videos. Juan Brown and Corey Robbins both show this guy. Sorry I can't remember his name off the top. He does hit reverse prop on stol landings.
We have data logging on our liquid cooled drag cars and I run a water pressure channel in the system. It clearly shows pressure events (if/when they occur)... spike from cylinder pressure is super clear (I was fighting a problem when I decided this would be a good channel to add). I would be tempted to do the same on a liquid cooled kitfox .... which I hope to build one day.
I am looking at engine choices for my S-21 since the Titan 340 is basically Chinese unobtainium now. I am leaning 915, but the cost is nosebleed territory for sure, but then so is the Titan now … if you can get one. One thing about the Yamaha is that you mention it is designed for 200 HP and you are derating it to 160. Well, very few auto or Motorsport engines are designed to run at a significant percentage of their max HP for extended periods. They will make high HP for short times, but many won’t last long when running at high outputs for long periods of time as in aircraft or marine use. So, while the motorcycle and sled engines may be rated for 200 peak HP, but will seldom make more than 50% of that for more than a few seconds or minutes at time. Most of their life will be spent making 20-40% of their peak output. So, if you run at even 100 HP for long periods, you are running the engine far harder than it is typically run in a bike or sled. It will be interesting to see how the engine does after 2,000 hours in an airplane. Do you know of any that have run even close to that long?
your instincts are right with the additives. I have only used it on vehicles that were not worth repairing or customers did not have the funds and wanted to roll the dice. If leaks were tiny like 12-8 oz over the course of a 4 or 5 hours it seems to work and only for head gaskets or cracked heads. Another thing i learned over the years is if you have a bad head gasket/cracked head . The time it takes for the engine to heat up and for the silicate to glass up in the additive it usually makes it way to the oil and your oil analysis will show extra silicate which is not advantageous for engine wear. which Im sure you know.
I think the Yamaha is a great solution. Being an early adopter is always going to be extra work. Thank you for sharing, your experiences will help the next guy. I’m planning a super light Yamaha Phazer build in the near future, also great power to weight.
a quick fix coolant is a really bad idea, a CO2 test in the coolant tank is an assurance test, but ya they get beat up by the snowmobile guy that's why I wanted to go true mine before installation. that would be the right time to get the crack welded and balance and to put the 10/1 ratio GP piston for eventual turbo boost.
I've been riding motorcycle for 40 yrs and I'm quite accustomed to hi-revving engines. However, I don't know if I could ever get used to seeing a constant 8000+ RPM as my "cruise" setting. I have no doubt the Yam engine can handle it but it would just feel "busy" to me!!!
Rotax four cycle engines where and are WAY expensive compared to any experimental versions in the market. the reduction gear mechanism is a piece of concern. No Rotax for me. I am really happy about what aí hear from Yamaha users. Thanks for your feedback.
Great episode and outcome. I learned about coolant additives as a poor college student. No way would I try it again. Also, I've had a car with a tiny head gasket leak which was not visible on the outside of the engine, but it was pumping combustion gases into the cooling system - which caused the cap to vent. It was a broken head bolt in my situation but that is unlikely with the Yamaha. Thanks for sharing your experiences.
Thank you for being honest you don't have to share this info and you do I've had Yamaha street bikes with similar engines and never had a problem they've always been great I used head gasket sealer in the coolant 1time to get me home and I regretted it bad what a mess it seems the Yamaha is the best choice after listening to you break it down I heard Yamaha is now going to start making aircraft engines for lightsport probably going to be expensive lol great vlog as always thanks brother
Thanks for sharing, and especially the head gasket issues on a used sled engine. It goes with what I posted on the FB yamaha page. Best of luck with the new engine. Love your videos. Very detailed. You are very thorough!
Based on my experiences with rebuilding motorcycle engines I suspect that anyone with the mechanical aptitude to build an ENTIRE AIRPLANE can easily overhaul their own Yamaha engine. Granted you would need to pay a machine shop for any needed reconditioning (bore/hone cylinders....resurface head) but the assembly part isn't rocket surgery. I'm also amazed that even one single person is willing to install an engine that was run in a snowmobile without rebuilding it and then bet their life that it will probably run alright.
Would you be able to bypass the air to oil cooler to see if the water to oil cooler is adequate now? Keep up the great testing and diagnostics, youre helping a lot of people!!!
I’m 12 mins in. Who needs an interviewer when you are answering all the good questions. Thanks mate. 22 mins in, do these engines get stripped and rebuilt before putting it in?
it's possible the green gunk is what is supposed to stop leaks, and it may have worked too well. if there was an exhaust leak into the block from a bad head gasket the green gunk may well have blocked the overflow valve too causing an enormous coolant system pressure problem resulting in, among other things, the blown water pump gasket. i wouldn't be surprised if that coolant leak company defends their product in such a way. like you, i don't like the stuff... it's just a wrong-headed way to approach a fix. it may be useful for diagnosing a problem. which may have been, ironically, what happened it your case. IDK. good luck on the new engine, and like many others, i'm anxious to see what was up with the old one.
Fantastic video Brian, very entertaining and educational. There are another couple of Apex options you did not discuss, although I’m certain you must have at least a ‘view’ on. An ‘Edge’ modified Yamaha and a ‘turbo’ Apex. Would appreciate any thoughts you have on these, yes I appreciate that either/both are expensive. Cheers.
That is the issue I have with them, they are expensive. I also think the 300hp version is total overkill unless your sole purpose is to compete. 160hp is so much more than the Rotax 912, it has amazing performance. The turbo could be used to normalize the hp at higher altitude, and that is what I will be working on next. Edge makes nice stuff, but too expensive when you can run a 160hp BD turnkey engine Yamaha for less than half the cost.
I appreciate such an objective and in depth review of this particular option. The power/weight/cost certainly seems like a no brainer! What is the TBO that guys recommend with these engines? What is it like cruising at 7900-8800 rpm compared to 200-2200? Keep the videos coming whether it's fly or bike adventures, it's all great content!
TBO is yet to be determined, time will tell on that, but we are collecting oil sample data and monitoring things like compression at intervals. It should give us signs when it is time. Cruising at 7900-8800 is no big deal, you get used to it.
Leak checking - one can get (or fabricate - that's what I ended up doing for my Rotax) an adapter to replace the radiator cap and pressure test the cooling system without draining / removing anything. In my case, I ended up finding that the water pump was weeping, but I ended up leaving it pressurized overnight before I found it since the leak was very slow with the engine not turning. Leak stop stuff - no thank you...
Thanks for telling the whole story as usual! Where is the design engineer when you need one? Also, I wonder if the head can be modified for better cooling since it was designed for cold climates.
I’m really drooling over the potential of the Higgs Diesel engine line. Their Falcon engine would be a totally awesome option for the Kitfox, and a great option for bigger aircraft in the nominal 180 to 200 hp range (the Cozy MkIV, for example). Nothing but promises and pamphlets right now; hopefully they don’t go the way of the Gemini.
lets hope they stick around..IMHO diesel is teh way to go and God knows there are enough of them around somebody should be able to adapt one to aircraft use
What's the estimated weight? Diesels are typically heavy engines. Peter just crash landed his Audi diesel powered Raptor into a corn field due to engine failure. That was his second engine failure during flight.
@@stonevalleyozark475 165 lbs (75 kgs) for the 210 hp version. They compare themselves to Rotax, so they probably leave off accessories and leave out oil qty ready to fly, just like Rotax does in all their pamphlets. They also don’t include the weight of the liquid cooling system. www.ac-aero.com/falcon-fl200/
I’m amazed how pithy people get when somebody doesn’t stay within the lines!! Omg what happened to the American spirit!! It’s people like this that give us other options I guarantee rotax didn’t start in the air!! 40,000 grand for an engine i’d rather use a Honda engine! !! And I’ve rebuilt plenty of engines! The 915 is stupid. In its cost 60,000 grand for an engine!!!!!
Get a borescope and leak down compression tester. Can look at pistons, cylinder walls, valves with cheap borescope for any used engine (and for tge engine u fly to see if overhaul is due). With leakdown compression set up can blow air into cylinder and listen to oil pan, exhaust and intake to see where engine is losing compression (foe used
👍🔥Awesome review, appreciate your unbiased honesty and objective approach to the compromises, thank you. Recently took notice of UL Power Aero engines. My initial impression so far is it’s a top contender with little compromises, especially in the direct drive segment. Very interested in a head head to head comparison with the Yamaha in this exact mission and aircraft type. 😉🔥❤️😎
in 2003 I was riding an R1 at around 130mph on the freeway on a long straight 5 hr 550km journey late afternoon around 22oC. It had 8,000kms on the clock. Bought it new. My baby. I was lying down as one does chin on tank. I smelt coolant and a split second later as i was thinking is that coolant smell I saw green spots of it hit the screen. I hit the engine kill switch immediately, pulled the clutch and coasted to a stop. Called for a tow. The temp gauge was definitely on the normal mark. Yamaha dealer found the tiny stone hole with stone embedded in radiator and repaired the radiator. They started the bike and test drove it and same symptom as yours. Was blowing coolant out. No water oil mix etc. They had to do head gasket. They explained that in that split second in a 1-2mm section in that part of the gasket the lack of coolant had caused the heat to melt and damaged the gasket. They checked the head. No need for a skim. Known issue... I'm non mechanical and didn't see gasket. Dealer mechanic is trusted old mate and used him for years. At cooler "speed" running temp you loose coolant it'll do head gasket in 3 secs or less it seems.... Hope that helps in the future bro. Love yr videos
They do a big bore and weld the crank and add oil squirters, also offer turbo and fuel injection, but I wouldn't consider it heavily beefed up. Still a 100 hp design engine.
Did you consider the Yamaha 988T at all when you were deciding on engines? I saw the @Project 2 Aero guy who's putting one in his rans 21. Very cool looking project. Skytrax built him a gearbox for it. Would love to do something like this just not sure if I'll want to do it on my first build.
Almost all new engines come from the factory with sealant in the coolant, only a problem when a head gasket fails, exposes the chemical to air and it congeales the coolant inside rather than on the outside.
Sounds like urban legend? Evidence this is true? I’ve never heard or read this anywhere and I’ve been an engineer and worked on cars, trucks and motorcycles for 50 years.
The succes and adoption on the Apex is based on one proprietary PSRU. Suzuki would be my choice , Arctic Cat has used them for years, but no PSRU available for them.
I suspect swapping engines was probably more work than pulling the head off would have been. If the head was warped there was likely a local machine shop that could have decked it too. Even if you were interested in a major rebuild, I can tell by your videos (as if just being able to build a kitplane with significant mods wasn't enough) that you could likely teardown and reassemble the engine with fresh parts too. As with everything though, there is obviously a tradeoff between paying an expert to do a job versus taking the time to do it yourself. Not to mention if you are more comfortable trusting the work of an expert, versus perhaps another person thinking nobody will take more care with an aircraft's engine than they would themselves.
So can the engine be equipped with a constant speed or even a ground adjustable prop that could give you that cross country performance. Seems like a ground adjustable would be the simplest and most economical option.
hi ive thoroughly enjoyed your content from start to finish. I am at the very beginning and plan on doing the same as you. could you please answer the following question. what is the overall length and height of the plane? i am trying to determine if my garage will work as the spot as to where to build it. thanks
It’s just so hard to imagine a Japanese in-line 4 having such an issue. I have had so many sport bikes of various years conditions and milage with zero engine issues. I wonder it it’s the full throttle high rpm nature of it being in a snowmobile and then continuously run at 8K plus in a aircraft to be the culprit? Can you buy a factory new factory replacement engine from Yamaha?
No you can't unfortunately. I truly believe that this issue was present before it went into the engine, so I don't think it running at 8000rpm continuous or at higher rpms for takeoff had anything to do with it. In the sled world, a head gasket leak is very rare unless it has been over heated and the head warps. I have also heard of the head to case having corrosion build up if the engine sits for long periods of time, like this one did, which can lead to a leak. I will know more when I tear down the engine.
@@BowenAero yes sir, looks like we all agree these engines are not known for those issues. Shoot the one litre race bikes go wide open at what, up to 200 mph for 200 laps and the whole pack usually finishes the race.
Old japanese bike guy here. Having used Yamaha, Honda, Kawasaki, Suzuki, here is my thought. If you ever use a Suzuki, especially tear one down and look at it from a durability standpoint.....ohh, I see now. That Slime tubeless tire sealer, disguised as coolant stop-leak is clever...and useless. Horse manure was in the old pellet style Bar's stop leak. It's a no-no in anything you care about. Sir, your learning curve is quick. Let me know if you fit a Suzuki in there. Not only will you win, you'll do it again next year on the same engine.
What is the gearbox that you're using? I would say probably the biggest downside from listening to your plane, is the noise of 8000 rpm, I love it but I'm not sure my wife would.
Great video, What is your opinion on the desser tires compared to the Alaska bush tires in performance only. Not weight or ware. Also how much psi are in the desser tires. Thanks
I’m loving them. Running 8psi. I have been out on the river bars in pretty big rocks and the are hardly any different than the ABW. I highly recommend them.
Great analysis, $2k for an overhaul is not bad considering an overhaul on a Lycoming can be $14k. Just makes the Yamaha that much more attractive. I'm assuming a rotax overhaul is over $10k as well, but not sure on that
Yep, and IMO a good builder will give you an engine that is better than a factory engine. I know I trusted the builder on my race bikes as he was fanatical about his builds.
I would want a dyno break in and some dyno pulls confirm everything is good a few extra grand for a dyno still way under what an aviation engine would cost. I wonder if engine builder knows your using it in an aircraft engine might not be so inclined to do the work. Then again likely small shop wouldn't care they have no clue about aviation litigation won't turn away business.
Did you consider any of the options from UL Power? Just wondering. I heard one running at a fly in, and it was super smooth and quiet. I wasn’t able to ask the guy about it, though. I looked up and he’d left.
@@BowenAero kind of the same thing Rans said. I was just curious. It’s been interesting and fun watching you build this one. Thanks for sharing it with us.
@@BowenAero It’s a shame there is’t anything more on the UL power. Both Vans and Kitfox have not embraced them with good reviews across Zenith and Just for example. A UL350iS would seem a good engine for the Kitfox along with an Airmaster prop!? Thanks for the review. Enjoyed watching your build.
Wonder if Yamaha will market an aircraft engine I'm guessing it will cost the same as a Rotax we do need more competition that would drive prices down. I think in a bush plane like this where it has such a low stall speed, and short landing capability, wings fold easily if have an engine out likely it will be easy landing. Aircraft like RV's cruse at 200, stall at 60 probably better idea to go with typical aircraft engine. That jelled stuff in your coolant looks like when you mix IAT with OAT or HOAT coolant get that jelly stuff eventually clogs it all up big job cleaning it all out of a vehicle the block being low have to pull the drain plugs and flush.
@@GrizzAxxemann And now, 5 months later, Yamaha has announced a partnership with aircraft part manufacturer to make and test aircraft engines. A test bed has already been purchased.
@@GrizzAxxemann If you were, I would start screaming that you are one of the knuckle draggers that is holding GA back, and thus killing people because of it. Man how I hate people holding back progress, if you can't tell ^^
Very rare these days to finds someone who is as honest and open as you are Bryan, keep up the great work
I think your theory of the head gasket is correct Brian. Thanks for your honest and very detailed way of sharing your progress. Keep it going, we will be here.
Combustion pressure leaking into the cooling system causes all kinds of problems. Glad you didn't severely overheat that first engine while testing. It will be interesting to see what the mechanic finds inside. See if he will take some photos of the damage as he tears it down. We'd love to see.
Yes, Please update on what was found !!
Very useful film, and glad you were able to bounce back so quickly! Re: two channels or not, my understanding is the more people not clicking on a thumbnail the less the algorithm likes you, therefore anyone not interested in bikes is going to have negative impact on your flying channel, which would be a shame.
I really appreciate the effort you put into being thorough in both your analysis and explanation of the airplane and the issue with the engine. I agree with your take on what happened with engine #1
It might be worth the $ and effort to send a few oil samples from this engine and the freshened one to Blackstone Labs for a workup on the oil. I've done it with several engines over the years and was always happy with the peace of mind the numbers give me, and, once a pattern is established if a change happens the odds are you'll see it in the oil before it goes south on ya. Just a thought...
Absolutely. For both the gear box and the engine.
Thank you for being transparent with your issues. I think you are correct in your assessment of your engine problem that it was an unknown issue from the beginning. I think you are sincerely giving the Yamaha engine an honest review. I am a fan on this engine. Keep going with the videos we are all enjoying your journey. I hope to be there one day with my own plane with a Yamaha.
Thanks for sharing. Love the video. The head gasket makes so much sense. I think it is smart to have two engines. You are crossing new grounds with that engine and learning so much. Love it.
And still miles less money than the 915is
Good update.
I have used a product called Mend Tite by Zecol and Bars Leak with some success on older vehicles. I haven't seen any detrimental effects from either other than sometimes they don't stop the leak. I have it in an old truck that had a slight head gasket leak that it worked pretty well on, but I had to add more stop leak from time to time. All stop leaks are temporary at best in my opinion. Ultimately if you have a leak it's best to fix it correctly. I don't think I would put any of them in an airplane.
Interesting to say the least. I'm really wanting to know what the TBO numbers will look like.
And the bright side is, you can get the rebuild done at your local sled & bike shop.
Sorry you’ve had this problem with your engine. I really appreciate your analytical approach to discovering the issue and being able to fix it. I sure hope the new engine will give you the results you are looking for.
10 hours on it now and it runs perfectly. Since the change I have had zero issues and I am loving the airplane.
It sounds to me like you most likely had a slight head gasket leak in the first place that over pressured the cooling system and caused the weeping leak at the radiator weak spot.When you added the stop leak, it did plug the weeping leak but wouldn't stop the head gasket leak which injects compressed air into the cooling system. Unlike the radiator leak which released excess pressure out of the cooling system. That's how stop leak products are designed to work from the inside out not outside in, as was head gasket leak. In the end the water system failed because of over pressure. I write this as you have discovered. Any how I see that problem all the time with high performance diesel engines in my fleet. Beautiful plane b y the way! Thoroughly enjoyed watching your vids of your building of it. Keep it going!
I've had coolant additive completely ruin a heater core. It flowed coolant, but inlet and outlet temps were almost identical after the client added the additive. There was little or no heat transfer any longer. Not sure how much damage it did inside the radiator. Any film on the interior surfaces of the passages in a heat exchanger, severely lessens the heat conductivity of that component. We found the leak, repaired it properly, flushed the system with a chemical that would dissolve the additive, then with distilled water before filling with coolant and returning the machine to service.
Great breakdown of engine choices!Thanks for keeping the information objective. Sorry to see your engine having problems, but you’ve saved the next guy many many headaches. Loved every minute of this video. Thanks Bryan!
This was an epic episode!
Feel like viewers should receive technical education credit fot watching.
Thanks Brian, be sure to share what you think of your engine rebuilder. What is your thoughts on ECM or battery redundancy? Definitely will go with Brian D's ACM ECM/harness setup. Thanks as always for sharing your experiences.
Just watching this again and enjoying it as much as the last time.
Solid gold Bryan!
Best airplane/engine option video ever!
Thank you!
Mike Fitzgerald
Calgary Canada 🇨🇦
I put 1300 trouble free hours on a EA-81 Soob conversion in my first RANS S-7, and loved rubbing that number (as it grew to the total) in the noses of people who would at first diss such a relatively unusual engine choice! More recently, after reaching TBO and beyond on my current 912S, with zero issues, when talking to a die hard legacy engine pilot the numbers kind of put an end to any dissing of the Rotax. Point being, build those hours big time, nothing succeeds like success, 10 hours is a blip, 500+ hours and up will really prove the concept. Looking good!
as a non flyer I totally enjoyed your description in an easy to understand way. Loved it. Look forward to the follow up on the engine "autopsy"
Great video! You are likely correct that the leaking head gasket issue was there from the beginning. Most likely cause is lack of proper/timely coolant changes by the previous owner. As a professional mechanic, I can definitely say, that a large part of the motoring public are totally lame when it comes to maintenance. Oil changes are about all a lot of them do. Any time work is done that opens the cooling system, after the first engine run up to operating temperature, let the engine cool down completely. Then open the system and add coolant as needed. Often, you have an air pocket in the system. This air pocket will work itself out after a good run. Failure to do this, may lead you to later think that you have a leak.
Thanks, Bryan. I really appreciate the time you put into this video series, and I'm sure I'll be referring back to your videos as I work through the rest of my build (a Series 5). I too considered a lot of alternative engines, but in the end I wanted a reliable, proven package so I could just fly and not be faced with problems I don't know how to solve. I spoke to John at Kitfox and learned that their firewall forward kit for the Rotax 912iS is extremely complete, since that's the engine they use on their S-LSA product. So, I've got that engine on order and my prop is arriving any day now. Maybe by the time I wear out the Rotax, the Apex will be a mature option and I can make the upgrade!
Pretty cool stuff actually; Like the way you just calmly work through it
I edited out all the bad words.
Just came across my feed with this video. Vary impressed. Went through some of the same issues many years ago with a Subaru engine on a Kolb Mark IV. After a little work and time , it ended up being a fantastic flyer, for many years. Good luck to you, I really enjoyed watching your video and I will go back and catch the others.
Great channel and conent!
Viking has the 1.5L Honda 130 Hp (no turbo) and they also have a 1.8L Honda 150 Hp (no turbo)... some Rans S-21s are now running the 1.8L 150 Hp engine. The Viking 1.5L Turbo at 195 Hp is probably not a good choice for the Kitfox but matches up exceptionally well for the CH750 SD or a Rans S-21 Outbound.
Agree. On our car, I had bad experience with those bottled head gasket repair. Damaged the water pump seals. Only sealed the combustion leak for a month.
It's negative utility, it is not a fix.
Great videos, so informative…. and (for what it’s worth) I think you made the right choice on engine. Good decision to get a second Yammy motor for a spare: there’s little worse than a sunny day at the airport with your aircraft grounded / in bits!
Several people have commented on getting the oil analysed regularly: I spent 20+ year racing old cars, mostly early 911s, and we found that you often got early warning of problems from the oil check. In fact we ended up using the oil check & compression check to decide when to do a rebuild - if the race engine passed both tests, keep going & save the money for later!
It might be interesting to try a flight-adjustable prop on that motor: if it has a sweet-spot around 8k you might be able to optimise cruise performance with higher throttle setting & ‘pulling it down’ to 8k with the prop setting (of course I might be missing something…). I believe that someone will soon try to put an adjustable prop with ‘beta’ reverse thrust setting as a way of shortening the STOL Comp landing phase ( rather like Mike Patey’s Draco )
Anyhow, many thanks for your videos: great to see someone ready to share so much detail. Fly safe!
Peter / England
There is a guy that's flying an adjustable prop. Check out oshkosh stol videos. Juan Brown and Corey Robbins both show this guy. Sorry I can't remember his name off the top. He does hit reverse prop on stol landings.
Absolutely awesome awesome awesome episode. I like how you dissect every aspect of your decisions and thoroughly explain why.
We have data logging on our liquid cooled drag cars and I run a water pressure channel in the system. It clearly shows pressure events (if/when they occur)... spike from cylinder pressure is super clear (I was fighting a problem when I decided this would be a good channel to add). I would be tempted to do the same on a liquid cooled kitfox .... which I hope to build one day.
What was causing the spike?
I am looking at engine choices for my S-21 since the Titan 340 is basically Chinese unobtainium now. I am leaning 915, but the cost is nosebleed territory for sure, but then so is the Titan now … if you can get one. One thing about the Yamaha is that you mention it is designed for 200 HP and you are derating it to 160. Well, very few auto or Motorsport engines are designed to run at a significant percentage of their max HP for extended periods. They will make high HP for short times, but many won’t last long when running at high outputs for long periods of time as in aircraft or marine use. So, while the motorcycle and sled engines may be rated for 200 peak HP, but will seldom make more than 50% of that for more than a few seconds or minutes at time. Most of their life will be spent making 20-40% of their peak output. So, if you run at even 100 HP for long periods, you are running the engine far harder than it is typically run in a bike or sled. It will be interesting to see how the engine does after 2,000 hours in an airplane. Do you know of any that have run even close to that long?
Love the overhead view from the cockpit.
Like in a Wonderwoman jet.
your instincts are right with the additives. I have only used it on vehicles that were not worth repairing or customers did not have the funds and wanted to roll the dice. If leaks were tiny like 12-8 oz over the course of a 4 or 5 hours it seems to work and only for head gaskets or cracked heads. Another thing i learned over the years is if you have a bad head gasket/cracked head . The time it takes for the engine to heat up and for the silicate to glass up in the additive it usually makes it way to the oil and your oil analysis will show extra silicate which is not advantageous for engine wear. which Im sure you know.
I think the Yamaha is a great solution. Being an early adopter is always going to be extra work. Thank you for sharing, your experiences will help the next guy. I’m planning a super light Yamaha Phazer build in the near future, also great power to weight.
One of your best videos ever
a quick fix coolant is a really bad idea, a CO2 test in the coolant tank is an assurance test, but ya they get beat up by the snowmobile guy that's why I wanted to go true mine before installation.
that would be the right time to get the crack welded and balance and to put the 10/1 ratio GP piston for eventual turbo boost.
I've been riding motorcycle for 40 yrs and I'm quite accustomed to hi-revving engines. However, I don't know if I could ever get used to seeing a constant 8000+ RPM as my "cruise" setting. I have no doubt the Yam engine can handle it but it would just feel "busy" to me!!!
Great video Brian will consider the Yamaha in my Dakota Hawk.
This was a great episode, and I as well appreciate all of your honesty. I think the Yam is a contender..
Rotax four cycle engines where and are WAY expensive compared to any experimental versions in the market. the reduction gear mechanism is a piece of concern. No Rotax for me. I am really happy about what aí hear from Yamaha users. Thanks for your feedback.
Sorry for the troubles but thank you for thiscsuperb, detailed, well thought out and articulate video.
Dam that’s a beautiful plane. I live in Boise can’t wait to build mine
Very nice piece, It shows that you are a talented "Engineer" "root cause comes to mind
I was going to ask about the oil in the floor, if it was from the Yamaha.
Five grand for a high-confidence engine seems reasonable.
Loving your content. Big fan of Trent as well but your stuff makes me want to grab a kitfox and do an apex build. Thank you.
Great episode and outcome. I learned about coolant additives as a poor college student. No way would I try it again. Also, I've had a car with a tiny head gasket leak which was not visible on the outside of the engine, but it was pumping combustion gases into the cooling system - which caused the cap to vent. It was a broken head bolt in my situation but that is unlikely with the Yamaha. Thanks for sharing your experiences.
I have a hunch that original engine possibly got pretty hot at some point when it was still in the sled chassis.
Thank you for being honest you don't have to share this info and you do I've had Yamaha street bikes with similar engines and never had a problem they've always been great I used head gasket sealer in the coolant 1time to get me home and I regretted it bad what a mess it seems the Yamaha is the best choice after listening to you break it down I heard Yamaha is now going to start making aircraft engines for lightsport probably going to be expensive lol great vlog as always thanks brother
Thanks for sharing, and especially the head gasket issues on a used sled engine. It goes with what I posted on the FB yamaha page. Best of luck with the new engine. Love your videos. Very detailed. You are very thorough!
I think you should try and
Make it go fast. Be interesting to see the envelop and what it takes to go to both extremes.
Electric constant speed prop I think. Fixed pitch ,,, you have to fiddle to get the envelope you want. Speed? , climb, stol???
Looks like you recently posted a follow-up video so need to watch that now.
Based on my experiences with rebuilding motorcycle engines I suspect that anyone with the mechanical aptitude to build an ENTIRE AIRPLANE can easily overhaul their own Yamaha engine. Granted you would need to pay a machine shop for any needed reconditioning (bore/hone cylinders....resurface head) but the assembly part isn't rocket surgery. I'm also amazed that even one single person is willing to install an engine that was run in a snowmobile without rebuilding it and then bet their life that it will probably run alright.
Thanks for that video. It's good info for any experimental aircraft
Nice video. I hope we get to see some photos and measurements of anything out of specs from the repair shop.
Would you be able to bypass the air to oil cooler to see if the water to oil cooler is adequate now? Keep up the great testing and diagnostics, youre helping a lot of people!!!
We will be eliminating the heat exchanger all together with Bryan Dacus’s oil cooler thermostat set up.
I wonder if a turbo would reduce RPM for Cruise an adjustable prop would be handy typically boost will bring power curve to lower RPM.
I’m 12 mins in.
Who needs an interviewer when you are answering all the good questions.
Thanks mate.
22 mins in, do these engines get stripped and rebuilt before putting it in?
They should
it's possible the green gunk is what is supposed to stop leaks, and it may have worked too well. if there was an exhaust leak into the block from a bad head gasket the green gunk may well have blocked the overflow valve too causing an enormous coolant system pressure problem resulting in, among other things, the blown water pump gasket.
i wouldn't be surprised if that coolant leak company defends their product in such a way. like you, i don't like the stuff... it's just a wrong-headed way to approach a fix. it may be useful for diagnosing a problem. which may have been, ironically, what happened it your case. IDK.
good luck on the new engine, and like many others, i'm anxious to see what was up with the old one.
Great video! Thanks for sharing.
Fantastic video Brian, very entertaining and educational. There are another couple of Apex options you did not discuss, although I’m certain you must have at least a ‘view’ on. An ‘Edge’ modified Yamaha and a ‘turbo’ Apex. Would appreciate any thoughts you have on these, yes I appreciate that either/both are expensive. Cheers.
That is the issue I have with them, they are expensive. I also think the 300hp version is total overkill unless your sole purpose is to compete. 160hp is so much more than the Rotax 912, it has amazing performance. The turbo could be used to normalize the hp at higher altitude, and that is what I will be working on next. Edge makes nice stuff, but too expensive when you can run a 160hp BD turnkey engine Yamaha for less than half the cost.
Excellent discussion. Thanks for sharing your experience and thoughts.
I appreciate such an objective and in depth review of this particular option.
The power/weight/cost certainly seems like a no brainer! What is the TBO that guys recommend with these engines? What is it like cruising at 7900-8800 rpm compared to 200-2200?
Keep the videos coming whether it's fly or bike adventures, it's all great content!
TBO is yet to be determined, time will tell on that, but we are collecting oil sample data and monitoring things like compression at intervals. It should give us signs when it is time. Cruising at 7900-8800 is no big deal, you get used to it.
Leak checking - one can get (or fabricate - that's what I ended up doing for my Rotax) an adapter to replace the radiator cap and pressure test the cooling system without draining / removing anything. In my case, I ended up finding that the water pump was weeping, but I ended up leaving it pressurized overnight before I found it since the leak was very slow with the engine not turning.
Leak stop stuff - no thank you...
The newer coolants can have problems even with other coolants, gelling, etc.. Worth looking into.
Thanks for telling the whole story as usual! Where is the design engineer when you need one? Also, I wonder if the head can be modified for better cooling since it was designed for cold climates.
I’m really drooling over the potential of the Higgs Diesel engine line. Their Falcon engine would be a totally awesome option for the Kitfox, and a great option for bigger aircraft in the nominal 180 to 200 hp range (the Cozy MkIV, for example). Nothing but promises and pamphlets right now; hopefully they don’t go the way of the Gemini.
lets hope they stick around..IMHO diesel is teh way to go and God knows there are enough of them around somebody should be able to adapt one to aircraft use
What's the estimated weight? Diesels are typically heavy engines.
Peter just crash landed his Audi diesel powered Raptor into a corn field due to engine failure. That was his second engine failure during flight.
@@stonevalleyozark475 165 lbs (75 kgs) for the 210 hp version. They compare themselves to Rotax, so they probably leave off accessories and leave out oil qty ready to fly, just like Rotax does in all their pamphlets. They also don’t include the weight of the liquid cooling system. www.ac-aero.com/falcon-fl200/
oh by the way, the engine has some very very small cooling passages between the exhaust valves which are now likely plugged .
I’m amazed how pithy people get when somebody doesn’t stay within the lines!! Omg what happened to the American spirit!! It’s people like this that give us other options I guarantee rotax didn’t start in the air!! 40,000 grand for an engine i’d rather use a Honda engine! !! And I’ve rebuilt plenty of engines! The 915 is stupid. In its cost 60,000 grand for an engine!!!!!
Get a borescope and leak down compression tester. Can look at pistons, cylinder walls, valves with cheap borescope for any used engine (and for tge engine u fly to see if overhaul is due). With leakdown compression set up can blow air into cylinder and listen to oil pan, exhaust and intake to see where engine is losing compression (foe used
and tge engine your flying).
👍🔥Awesome review, appreciate your unbiased honesty and objective approach to the compromises, thank you.
Recently took notice of UL Power Aero engines. My initial impression so far is it’s a top contender with little compromises, especially in the direct drive segment. Very interested in a head head to head comparison with the Yamaha in this exact mission and aircraft type. 😉🔥❤️😎
in 2003 I was riding an R1 at around 130mph on the freeway on a long straight 5 hr 550km journey late afternoon around 22oC. It had 8,000kms on the clock. Bought it new. My baby. I was lying down as one does chin on tank. I smelt coolant and a split second later as i was thinking is that coolant smell I saw green spots of it hit the screen. I hit the engine kill switch immediately, pulled the clutch and coasted to a stop. Called for a tow. The temp gauge was definitely on the normal mark. Yamaha dealer found the tiny stone hole with stone embedded in radiator and repaired the radiator. They started the bike and test drove it and same symptom as yours. Was blowing coolant out. No water oil mix etc. They had to do head gasket. They explained that in that split second in a 1-2mm section in that part of the gasket the lack of coolant had caused the heat to melt and damaged the gasket. They checked the head. No need for a skim. Known issue... I'm non mechanical and didn't see gasket. Dealer mechanic is trusted old mate and used him for years. At cooler "speed" running temp you loose coolant it'll do head gasket in 3 secs or less it seems.... Hope that helps in the future bro. Love yr videos
Thanks for that. Explains the symptoms
Edge Performance engines are not stock Rotax anymore. They are heavily beefed up to handle the extra ponys.
They do a big bore and weld the crank and add oil squirters, also offer turbo and fuel injection, but I wouldn't consider it heavily beefed up. Still a 100 hp design engine.
Great!! I was loving the 915 just based on reputation but the cost is ridiculous. This Yamaha conversion might be the best option. Thank you
Did you consider the Yamaha 988T at all when you were deciding on engines? I saw the @Project 2 Aero guy who's putting one in his rans 21. Very cool looking project. Skytrax built him a gearbox for it. Would love to do something like this just not sure if I'll want to do it on my first build.
Thank you for the update!
Almost all new engines come from the factory with sealant in the coolant, only a problem when a head gasket fails, exposes the chemical to air and it congeales the coolant inside rather than on the outside.
Sounds like urban legend? Evidence this is true? I’ve never heard or read this anywhere and I’ve been an engineer and worked on cars, trucks and motorcycles for 50 years.
Looking forward to a longevity report. Sending oil out for contamination tests?
Several of us are tracking oil samples and comparing data for longevity. I will certainly share as we go.
The succes and adoption on the Apex is based on one proprietary PSRU. Suzuki would be my choice , Arctic Cat has used them for years, but no PSRU available for them.
Love all the commentary and info on Yamaha Apex. Need to do more homework.
Watched this series. As we say in England. This was ACE.
I suspect swapping engines was probably more work than pulling the head off would have been. If the head was warped there was likely a local machine shop that could have decked it too.
Even if you were interested in a major rebuild, I can tell by your videos (as if just being able to build a kitplane with significant mods wasn't enough) that you could likely teardown and reassemble the engine with fresh parts too. As with everything though, there is obviously a tradeoff between paying an expert to do a job versus taking the time to do it yourself. Not to mention if you are more comfortable trusting the work of an expert, versus perhaps another person thinking nobody will take more care with an aircraft's engine than they would themselves.
Awesome video, I’m a new subscriber, Thanks for the detailed information. I am interested in your opinion about why naturally aspirated and not turbo?
So can the engine be equipped with a constant speed or even a ground adjustable prop that could give you that cross country performance. Seems like a ground adjustable would be the simplest and most economical option.
Teal has a way to mount an Airmaster on the gearbox. Could be an option
hi ive thoroughly enjoyed your content from start to finish. I am at the very beginning and plan on doing the same as you. could you please answer the following question. what is the overall length and height of the plane? i am trying to determine if my garage will work as the spot as to where to build it. thanks
I was really curious about the Viking Company Haven’t found a UA-cam video of an owner making one yet
You are looking in the wrong places.
It’s just so hard to imagine a Japanese in-line 4 having such an issue. I have had so many sport bikes of various years conditions and milage with zero engine issues. I wonder it it’s the full throttle high rpm nature of it being in a snowmobile and then continuously run at 8K plus in a aircraft to be the culprit? Can you buy a factory new factory replacement engine from Yamaha?
I have a hunch the original engine got pretty hot at some time in the sled chassis maybe.
No you can't unfortunately. I truly believe that this issue was present before it went into the engine, so I don't think it running at 8000rpm continuous or at higher rpms for takeoff had anything to do with it. In the sled world, a head gasket leak is very rare unless it has been over heated and the head warps. I have also heard of the head to case having corrosion build up if the engine sits for long periods of time, like this one did, which can lead to a leak. I will know more when I tear down the engine.
@@BowenAero yes sir, looks like we all agree these engines are not known for those issues. Shoot the one litre race bikes go wide open at what, up to 200 mph for 200 laps and the whole pack usually finishes the race.
Still being able to get a factory new engine so you don’t have to guess about the condition would certainly be a benefit of the sidewinder…
Old japanese bike guy here. Having used Yamaha, Honda, Kawasaki, Suzuki, here is my thought. If you ever use a Suzuki, especially tear one down and look at it from a durability standpoint.....ohh, I see now.
That Slime tubeless tire sealer, disguised as coolant stop-leak is clever...and useless. Horse manure was in the old pellet style Bar's stop leak. It's a no-no in anything you care about.
Sir, your learning curve is quick.
Let me know if you fit a Suzuki in there. Not only will you win, you'll do it again next year on the same engine.
Hi Brian as usual great videos so much useful information thank you
very much
What is the gearbox that you're using? I would say probably the biggest downside from listening to your plane, is the noise of 8000 rpm, I love it but I'm not sure my wife would.
Great explanation thank you.
Thank you for the update. Where are you sourcing the engines?
Just watching the classifieds.
Thanks for all the engine info !
Grinding the head will fix the head leak but what about the cam bearing surfaces, they will be out of line!
It will be rebuilt
Very nice video appreciate all the info and thanks for sharing.
What about UL engines, do any Kit Fox owners use them, they're suppose to be really light weight for the horsepower they produce
Yes, but at the wrong RPM, most at 3300 prop rpm.
Great video, What is your opinion on the desser tires compared to the Alaska bush tires in performance only. Not weight or ware. Also how much psi are in the desser tires. Thanks
I’m loving them. Running 8psi. I have been out on the river bars in pretty big rocks and the are hardly any different than the ABW. I highly recommend them.
Did your rebuild on the first engine go good? I have an Apex I just bought and I am thinking about getting it rebuilt before I install it. Thanks
Great analysis, $2k for an overhaul is not bad considering an overhaul on a Lycoming can be $14k. Just makes the Yamaha that much more attractive. I'm assuming a rotax overhaul is over $10k as well, but not sure on that
Yep, and IMO a good builder will give you an engine that is better than a factory engine. I know I trusted the builder on my race bikes as he was fanatical about his builds.
I would want a dyno break in and some dyno pulls confirm everything is good a few extra grand for a dyno still way under what an aviation engine would cost. I wonder if engine builder knows your using it in an aircraft engine might not be so inclined to do the work. Then again likely small shop wouldn't care they have no clue about aviation litigation won't turn away business.
Who built your Yamaha motor? Did you just pull it out of and throw it in or did a shop get it prior and soup it up?
Did you consider any of the options from UL Power? Just wondering. I heard one running at a fly in, and it was super smooth and quiet. I wasn’t able to ask the guy about it, though. I looked up and he’d left.
Kitfox said they looked at them but decided not to support them.
@@BowenAero kind of the same thing Rans said. I was just curious. It’s been interesting and fun watching you build this one. Thanks for sharing it with us.
@@BowenAero It’s a shame there is’t anything more on the UL power. Both Vans and Kitfox have not embraced them with good reviews across Zenith and Just for example. A UL350iS would seem a good engine for the Kitfox along with an Airmaster prop!? Thanks for the review. Enjoyed watching your build.
Wonder if Yamaha will market an aircraft engine I'm guessing it will cost the same as a Rotax we do need more competition that would drive prices down. I think in a bush plane like this where it has such a low stall speed, and short landing capability, wings fold easily if have an engine out likely it will be easy landing. Aircraft like RV's cruse at 200, stall at 60 probably better idea to go with typical aircraft engine. That jelled stuff in your coolant looks like when you mix IAT with OAT or HOAT coolant get that jelly stuff eventually clogs it all up big job cleaning it all out of a vehicle the block being low have to pull the drain plugs and flush.
Yep, definitely a coolant mix mismatch that forms that gel.Shit job cleaning it all out.
Don't count on Yamaha building aircraft engines.
@@GrizzAxxemann And now, 5 months later, Yamaha has announced a partnership with aircraft part manufacturer to make and test aircraft engines. A test bed has already been purchased.
@@benghazi4216 I'm not mad about being wrong on this!
@@GrizzAxxemann If you were, I would start screaming that you are one of the knuckle draggers that is holding GA back, and thus killing people because of it.
Man how I hate people holding back progress, if you can't tell ^^
Great info, appreciate the honesty and time.