Also gapping the ring in the cylinder when installed; making sure the piston has correct clearance, and measuring the top of the piston in the cylinder where it meets the head aka "squish clearance" but these are all technical things that are taken into account when you put it together
if there isn't enough piston to wall clearance or squish clearance that will seize the bike in the first ride tho, and the piston ends up super beat up. and too little gap will break the ring in the first few hours as well. but if I heard him correctly this bike was at its hour limit and didn't have broken rings and the piston was in one piece so it couldn't be that. I think it's either just a plating defect from factory, or the previous owner honed it and introduced cracks that made it let go.
Just found this channel, awesome content! As an experienced YZ250 owner and general stroke motorcycle fanatic, a few tips: Warming up two stroke engines isn't as much about the transmission as it is about piston to cylinder clearance, when the bike isn't warmed up sufficiently the piston expands faster than the cylinder and thus can have excessive wear and even may seize (this is known as cold-seizure). Given how your old piston has significant visible wear and scoring on the exhaust (hotter) side and you had a fractured exhaust port, insufficient warm up was almost certainly the cause of your cylinder damage. On the subject of premix/oil, 40:1 is perfectly adequate with a well made high performance oil. That said, select the proper oil for your application. Motul 710 is excellent for woods/enduro riding as it has both low viscosity and a very low flashpoint. If, however, you ride motocross, desert, or any discipline with lots of sustained high RPM's, a higher viscosity and higher flashpoint oil (such as Motul 800) is recommended as it will resist fully burning off/combusting at the higher associated engine temperatures. I highly recommend you NOT use the Yamalube 2-S as that is specifically formulated injector oil and is very low viscosity, Yamalube 2-R is what is recommended for the YZ250 and would be a much better choice. Don't use exhaust sponge/oil as an indicator of engine oiling, sponge is just unburned fuel/oil exiting the engine and is present due to overly rich jetting, not due to excess oil. Hope this is helpful to any new two stroke owners!
Finally someone with actual experience! A rare breed in UA-cam comments section. I have an old Yamaha RX100. It has one of those pesky oil injectors that almost always throws a hissy fit if I even look at it the wrong way. I always have to calibrate that damn thing but 2-strokes are crazy fun!
When you oil a foam filter, it should not have oil beads or drop on the filter. I have tested this on a dyno and over oiled filters reduce intake air flow and makes your bike run richer. Once the filter is oiled, put it inside a clean plastic bag and massage the oil into the foam itself. The plastic bag will remove the excess oil that forms beads on the filter and also keep your hands clean. A filter that was massaged in a plastic bag also flows more air and let your bike run at the right air fuel ratio. You can also gain a horsepower or two more when doing this, and not running an over oiled filter.
If you have oil or black spooge coming out of your exhaust your bike is running rich not lean. And its fine as long as your bike responds at all throttle positions.
Put grease on the part of the air filter that sits on the air box. Around the orange lip. It will create a seal around there allowing no dirt in. How I’ve done it my whole life.
Piston size relative to bore dimension is key. Piston skirt slap is a killer. Use the factory carb tuning settings plus butt dyno and you'll generally be ok
Everybody says they run a good oil, and if they are not having problems and get good lubricity, all is good. But I know some guys in North CA. who had problems with their race engines lower rod bearings, and they ended up doing some great durability dyno testing, for the best oil. Motul Kart GP 2-t oil won their half hour, wide open at peak power dyno tests. Klotz Supertechniplate (Klotz uses 20% caster mixed with their synthetic), was right there with it too, but runs a bit dirtier if the jetting is not crisp. Motul is way more expensive, but I use it now because I know how sharp those guys are, and testing like that is very rare.
A great idea is to add a small amount of seafoam in your fuel to stop your piston rings from sticking. Also adding seafoam in your spark plug hole at top dead center when storing the bike keeps it running perfectly. You can extend your riding times before top end jobs.
You can use aerospace 303 protectant on your carburetor gaskets to condition them. This will make sure your carb runs consistently. You can also use 303 on your tires to extend the life. It is water based so it wont affect the tire traction.
A chip in the cylinder like that would probably have corresponding piston damage which suggests that it was the previous owner and he changed the piston.
Warming up the bike is also a process of heat expansion in the cylinder. Since the pistons walls are much thinner and there is no cooling on the piston like the cylinder has water cooling, the piston heats up way faster than the cylinder if you go all out right away so thats means the piston expands lore than the cylinder. The piston will expand too much so the clearance between the piston and the cylinder walls are much tighter and it may lose all clearance and it will seize.
in our 700cc zabel we run 1:70 putoline mx7 and its the best one we used, no carbon buildup, and after 22 mth the motor is even oiled too much ( going almost full gas all the time)
I have a ? For you. I recently bought a yz250x just had fresh piston and rings. Compression was great for a little while (probably has 8-10hrs on it) and I feel like it lost some compression.. just when I kick it over though. The bike still runs amazing. (I am just curious what would have caused it so quickly. I checked out the cylinder before the install and it didn’t seem to have any scratches or any bad imperfections in it.
I’m going to get a compression tester and see what it’s at. And if it’s at below average then I’m going to tear it down and see if something’s not right in it now or what’s up with it.
@@weston5146 I mean it still starts first kick. But it just seems low.. I have to tear into my engine now anyways.. because the crank seals are bad. It’s burning motor oil. 🙄
probably just a casting or plating defect, leading to a crack ejecting the piece. it sounds like you are doing everything right, and I know I have treated my bikes far worse without chipping my nicaseal. ie I've blown up a lot of pistons, few seizures, and a water pump failure and never chipped, but have worn out the plating. or the previous owner ported it without replanting it because it will chip easily in that process. or honed the plating for a rebuild that will cause cracks and chips too. the plateing is hard but brittle and doesn't like to be scratched.
I think you have a good handle on what to watch out for. I can't say I would do much differently. The only thing I will add is when replacing a piston I tend to think some aftermarket may lack the proper expansion properties so I may consider a yammi piston or do research at l ast. I think your damage was probably a defect in casting from the beginning. I would run 32 to 1 because I feel companies push the limits due to emissions standards. Longevity is loosing that battle. Same with what the EPA has done to Diesel engines. They can't meet standards and last as long as they did a decade ago.
Typically severe engine failure is from cold seizures, to include 4 corner cold seizure. Normal ware would reduce compression, resulting in performance loss and running poorly. Clutch less shifts are ok on dirt bikes, the force is absorbed through chain, then ultimately rear tire is able to slip. If you had 100% traction similar to street bike there is no loss of traction, so gears ⚙️ take the abuse.
No visible damage to the ring or piston. all you need to know. with "75h" on it when sold, should not have needed to be disassembled by then. spotting OE gaskets or signs of intrusion, shiny loosen corners on bolts, sealant. etc could point at prior owner deception, but that's moot as it "ran brilliant" i'd suspect mfgr defect, and thank you for taking the full repair path, before it became serious. besides compression records, piston inspection through the exhaust port, i heard no reason for a full teardown inspection. i'll leave you with this one point to ponder, examining piston wash, clean area size by the transfers is one of the proven low tech ways to check combustion. 3:36 shows the crown with no clean areas, suggesting the piston was getting hot enough the incoming charge could not keep it from baking on oil. confirmation would be a matching carbon area on the underside of the crown. enjoy your ride.
The previous owner could have had the throttle cable too tight. This may cause the little nub at the end of the cable that attaches to the slide to get torn off and ingested by the bike due to the force of the handle bars. It would explain the perfect size hole. Just check your cable tension in your manual
to me that doesn't look like oil issue. might have been small crack from the factory and it just chipped off during a ride. also that didn't look that bad. surely would have been ok to ride
Oil ratio doesn't determine rich or lean Ness. Jetting does. You can run 100:1 and be super rich, or 10:1 and be lean. Also you need to put grease around your air filter. As far as warming up, wait until the radiators are hot. But you need to keep revving the bike to clear it out and warm everything up even. Also play with your clutch as it's warming up, to help separate the plates with the cold thick oil holding them together. As far as the myth about pulling clutch in after high rpm. You don't really need to. Just blip your throttle. I promise it's not hurting the motor one bit. Have you ever seen a pro racer pull their clutch in back in the day? Not really. On the motocross track it's such a short amount of time before you have to get back on the throttle again there's no point. Shoot I'll go from 5th tapped to 2nd or 3rd to get the maximum engine breaking, never had a issue... For jetting. You do not want to run to rich as you can do just as much damage as to lean. You want your spakr plug dark paper bag brown. Oil out your silencer isn't a good thing. You need to repack your silencer and lean your bike out a little. That oil is unburnt fuel which isn't good.
@@okerhrh4139 need to repack your silencer. Go to stock jetting. And then you need to figure out your elevation, and temp and jet your bike accordingly. I would suggest 40:1 with redline. I run my 125 to the ground and done 100 mile desert races/rides and never once had a issue. If you can afford it. Run AV gas.
I wouldn’t trust the amount of spooge out of the tail pipe as an indicator that the bike is properly lubricated. Excessive spooge could mean that you’re getting blow by past the rings on the downstroke. In other words, fuel/oil is not getting into the cylinder through the ports and is not completely combusting.
True but I've never seen a 2stroke bike that didnt have oil coming out of the exhaust. Some more then others and even on bran new bikes. My riding backpack has a million black tiny spots on it after years of riding. I usually mix around 40:1 43:1 and I've always ran castor 927. Ive have heard alot of the time it's the type of oil a person uses, that makes that black spooge, or obviously If your running to heavy on your oil mix.
2 stroke engine braking is an interesting one. Like you say with a set up like yours when you shut off the throttle you reduce fuel and therefore lubrication but there are 2 strokes with auto lube systems consisting of an oil tank and pump. Now some of these systems just pump the oil into the carb to mix with the fuel which gives the same issue of less lube when shutting off the throttle but some have a system where the pump runs off a gear on the crank and inject the oil directly into the intake port (after the carb) On these bikes/scooters the system will be providing oil based on engine speed regardless of the throttle position and fuel input which should mean shutting of the throttle at high rpm is not an issue. At least that’s how I see it, could be wrong. I have this system on a scooter but that’s an auto so no clutch to pull anyway. Good your still loving the 2 stroke they are great fun
Most vintage Japanese 2 strokes from the mid 60's onwards do this too. Yamaha's autolube is a great system and very reliable. Only problem is if the pump decides to suddenly stop working...
Ive engine braked all of my 2-strokes, and continue to do so to this day and have never had an engine failure. If there is enough fuel for the engine to run, there is sufficient oil for lubrication, unless your jetting is way out of line. Been using Sunico Silver 100 octane race gas and Klotz castor for over 30 years with absolutely no problems whatsoever.
idk but running motorex cross power at 60:1 with no issues on anything over multiple years has been pretty good with no rebuilds just normal maintenance and cleaning
Either on my 450 or my 250 two stroke, I always ride the track below 50% for the first lap or two, depending on the size of the track, to get the bike up to operating temperature.
adding oil to fuel dosen't make it run rich it actually leans the bike out, you can run whatever the oil manufacturers recommend as long as you jet according ! bikes run on fuel not oil, the more oil in the fuel the less fuel rich the mixture
The engine braking thing is BS I rode raced bikes 2-stroke bikes for years and even ran flat track with them shutting the throttle off going into the turns in both situations never never had a problem. I had more problems cold seizing an engine from not letting it warm up or not breaking it in long enough
@@wilco300674 ye say if your going down a very steep hill for about 20 seconds that’s when it probably starts fucking up the moter because there will still be oil in the cylinder it won’t dry up that quickly it’s like wheelies people say it isn’t good for them as the oil is at the back and the engine isn’t being lubricated.say if you were all the way back constant for about 5 minutes then yes it problay would be shit for the bike but your always going up and down so the oil finds it’s way around still but that’s a similar kind of thing to 2 stroke engine breaking cause everyone thinks your starving the bike u are are fine unless it’s a really excessive amount
@@luixzzzz who is they lol. I've only owned 2 strokes. I have never ever seen one sieze or blow from engine braking. There is constent air flow + fuel flow while engine braking. If youre scared pull the clutch in blip the throttle here and there while going down hill. I "engine brake" really hard on my bikes when im riding the track, im more worried about me blowing my gear box vs piston frying off or something. If youre bike is jetted good or even if it aint it is completely okay.
Defective casting or damage from machining, but there would be evidence on the piston, rings or skirt. PS: AND Where the chip was, wasn't affecting a damn thing! Not exhaust timing anywhere, I'd have put a 10°taper on it top and bottom chip area, checked ring gap, and sent it! Zero harm done. But Like someone below said- (piston may have already been changed-good call,) but its a non issue - unless *** it hints at more casting defects. In which case only Time will tell OR you get the barrel tested. Sonic? X ray? NDI? Idk. Jmho. Good luck. Might be worth getting checked. GOOD LUCK!
Ok, a couple things. One, Motul is aweful. Switch to Amsoil. You absolutely will not regret it. I know 2 people that switched, and they both testify to getting 40% more life out of their top end. Two, Try a hotter spark plug to burn off that excess coming out the pipe, or look into repacking the silencer, thats cheap and easy, and will soak up a lot before that starts happening again. Three, Check out Project Farm's comparison on oil. He did a great job at testing several oil brands, including motul and amsoil. Not 2 stroke oil test, but you can expect same quality. Ill link that video for you.
With modern engines and oils, you can go even further : 1/50 ... ou 1/60. No joke, my 582 Rotax was very happy this way, while giving it's 65hp full power for hours in a row. Using too much oil it is really worse than too little... too much oil ends up in much faster rings / cylinder wear. A good way to sieze a two stroke is to cool it too fast...however, your is water cooled so no risk of cooling schoke. Too lean is a bad plan because it overheat the exhaust ports edges. But on you type of bike, you probably don't ride with throttle full open for very long period of time in continuous. One more idea, something was sucked in the cylinder end did not pass the port fast enough...and get caugth by the piston edge....and it can actually be anything from sparkplugs to casting burs, not mentionning piece of gaskets, anything falling in the air filter during maintenance... Don't be too anxious : two strokes are usually VERY reliable and 100 hours at YOUR pace is not going to wear it a lot...
Dirt bikes suck dirt into the air cleaner, and if it makes it past the filter, it lands on the piston ports, scores the pistons, then drops into the crank case, making your main bearings grind while wiping out the crank seals. Take care of your filter, and it will take care of you.
I use the maxima air filter oil and cleaner. You definitely want to use the cleaner outside, what ever is in that stuff has a pungent chemical smell that lingers!
if my cylinder has a ridge at the top (presumably where the ring/ piston wasnt reaching) do i need to have it honed down? i know it was there during my last top end rebuild and nothing went wrong after 50-100 hours of riding. but i am doing a full rebuild of this bike (3rd gear was slipping) so i dont want to risk anything. at a guess it probably sticks out like a quarter or half a millimeter or so. i guess ill take it to a shop and see what they think.
Uuuhhhhmm that oil out of the muffler Shure looks like a right side crank seal! You should probably check that also your trans oil will just disappear if it is bad. Also great video! 👍. Don't forget to check the crank play bc sometimes the crank bearings explode into the cylinder
I often wonder why modern off road 2T bikes can't last very long. Maybe because they are so highly tuned? Saying that though the old Aprilia RS125 was highly tuned but didn't need a rebuild so often (5k miles for rings for example). mmm, anyone help me with this one?
Yz yamalube 2S is not made for the race bikes like yz250. The correct oil to run is yamalube 2R, for their race series bikes. And this is actually some of the highest quality oil. A lot of pro racers run this oil in their bike, some who ride other brands besides Yamaha as well
He couldn't be more wrong about the Yamaha brand oil. Yamaha does not make that oil. It's made in a oil refinery where all the other ones are made, just because you run Yama Lube, doesn't mean you're going to prevent damage. All 2 strokes will need new piston & rings after so many hours of run time, that's just the nature of 2 strokes. Yes, good quality oil is important, as are many other things, brand however, is the least of importance.
Such damage is probably caused by the piston hitting the side of sylinder. Nothing major can come through the airfilter and not letting the bike heat up would simply be bad for any gaskets.
@@NirHason Well it's nothing else than the piston that can hit the sylinder walls, the question is rather why and how the edge got hit by the piston. Furthermore I know nothing about previous ownership and such, so it's hard to know
Ok, yes, I have a history of riding dirt bikes and maintaining my friends racing dirt bike. I'm a tad confused though. Was there anything going on that made you look ? From what I heard there wasnt. So to me that so called damage is or was not an issue. My friends dirt bike, rode every weekend for hours and then raced on weekends twice a month never had any issues. Granted not the same bike as his was a yz250 back in the mid to late 70s. But the only thing I ever did was replace the rings between motos. Otherwise just normal maintenance. Sooo, did you actually have a real issue ?
Yeah, that damage was not caused with that piston. there is only one thing that can chip the cyllinder like that, and thats the piston. and it had no damage. good call ;-)
Seeing that I think you are JHB which is at 6000ft altitude make sure that it’s jetted for that High altitude Particularly if the bike came from Natal or somewhere closer to sea level
Spooge isn't the result of too much oil in your gas mixing, if anything it'd be the opposite. Also your point about the engine not getting enough lubrification when closing the throttle at high RPMs is kind of a debunked myth, there's usually plenty of lubrification left and still happening in the cylinder, as the spark plug isn't getting to burn all that's left, because of the closed throttle, usually, if you aren't doing more than a mile of engine braking, your engine should be fine. In conclusion, adding more oil in your mixture can result in less spooge, more lubrification, and some also say more power, as the oil will help seal the piston better, there are actually a couple of experiments on this topic.
About the carburetor/FI debate, carburetors are mechanical, Fi is electric. There's next to no difference in performance when it comes to motorcycles. It's impossible to make a 2-stroke engine clean. so there's always going to be oil build-up on your exhaust. Whether your engine is running lean, rich or stoichiometric can only be told by a mechanic with a lot of experience with carburetors. I only work with very small 2-stroke engines and the way I'm setting up a carb is by listening to the sounds the engine's making and how it responds to my inputs.
my top end blew on my 2 stroke atv and now i've rebuilt it completely. Im running into countless problems trying to start it but the main one is sometimes the piston gets caught due to lack of lubrication.
I dont get how pulling clutch would help "lubricate"... Its damn same if you just shut off throttle. Pulling clutch doesnt magicly stop your engine, it just doesnt provide power to your rear wheel, rpms, fuel consumtion doesnt change
@@331moto lol true that I only ride a old honda xr 500 lol 😆 It's not like the most raw badass bike 😎 I have nothing against 2 strokes do that fun I just prefer having the ability to have power on tap all the th refers range thay are fun and easy engines to work on so positive
@@activelygaming1786 dude you are riding a 40 year old motorcycle.. a 2-stroke has all the power "on tap" if you know how to ride one. One finger on the clutch will immediately get a 2-stroke screaming
@@331moto yup and 40 year old bike still shows all the other newer dirt bike lol, To be fair I have only ride a few 2 strokes so hay maybe there is something, My one downside to 2 strokes in my opinion is not been able to really keep them pinned for long times so yea maybe for just riding dirt although I live in SouthAfrica you know I take my dirtbike in the highway 😆 🤣 😂
Because it’s stupid to do this. I’ve had 8 years on a couple of engines still very good compression over 200 hours. I’ve done crank seals before the top end lol 😂 if the compression is good way bother with it. Maybe 70 to 80 to 1 on mix I could see 30 hours and it be junk it just plane stupid to run that high of mix. You making less power. More engine wear. It’s stupid
Always use one oil only. If u made your mind to use motul keep your head strong and use it for ever. And I would say u should have asked the previous owner what did he used. Coz my mechanic always says this to me "Your bike is just like you if today i give you water from a lake you will fall sick coz u are use to the RO water, but think about those living in there drinking lake water, so always use one oil in your bike and if possible try to fill feul from one station this will give your bike more life". So please don't try yamalubes for once just to feel if it any different or not
You are right on the mixing different oils part, however if your tank is empty you can change the oil and let it warm up for 10-15 minutes so it gets used to the new oil.
The only reason you shouldn't change oil is because there is some oil that will react to another type, it is perfectly fine to change oil brands, just drain the tank and carby of the old stuff and fill it all up with the new, and she'll be right
A rider that admit he makes mistakes and still has alot to learn..,,
A rare breed...
For real! Don’t see that enough in the sport, especially with younger dudes like myself.
A good old saying: "The day you think you know it all, is the day you have a lot to learn." Know anybody like that? :)
Also gapping the ring in the cylinder when installed; making sure the piston has correct clearance, and measuring the top of the piston in the cylinder where it meets the head aka "squish clearance" but these are all technical things that are taken into account when you put it together
if there isn't enough piston to wall clearance or squish clearance that will seize the bike in the first ride tho, and the piston ends up super beat up. and too little gap will break the ring in the first few hours as well. but if I heard him correctly this bike was at its hour limit and didn't have broken rings and the piston was in one piece so it couldn't be that.
I think it's either just a plating defect from factory, or the previous owner honed it and introduced cracks that made it let go.
U blip the throttle when your slowing down on a 2 stroke you never engine break a 2 stroke
@@akthethotboi9711u do if u premix
Just found this channel, awesome content! As an experienced YZ250 owner and general stroke motorcycle fanatic, a few tips:
Warming up two stroke engines isn't as much about the transmission as it is about piston to cylinder clearance, when the bike isn't warmed up sufficiently the piston expands faster than the cylinder and thus can have excessive wear and even may seize (this is known as cold-seizure). Given how your old piston has significant visible wear and scoring on the exhaust (hotter) side and you had a fractured exhaust port, insufficient warm up was almost certainly the cause of your cylinder damage.
On the subject of premix/oil, 40:1 is perfectly adequate with a well made high performance oil. That said, select the proper oil for your application. Motul 710 is excellent for woods/enduro riding as it has both low viscosity and a very low flashpoint. If, however, you ride motocross, desert, or any discipline with lots of sustained high RPM's, a higher viscosity and higher flashpoint oil (such as Motul 800) is recommended as it will resist fully burning off/combusting at the higher associated engine temperatures. I highly recommend you NOT use the Yamalube 2-S as that is specifically formulated injector oil and is very low viscosity, Yamalube 2-R is what is recommended for the YZ250 and would be a much better choice.
Don't use exhaust sponge/oil as an indicator of engine oiling, sponge is just unburned fuel/oil exiting the engine and is present due to overly rich jetting, not due to excess oil.
Hope this is helpful to any new two stroke owners!
Finally someone with actual experience! A rare breed in UA-cam comments section. I have an old Yamaha RX100. It has one of those pesky oil injectors that almost always throws a hissy fit if I even look at it the wrong way. I always have to calibrate that damn thing but 2-strokes are crazy fun!
When you oil a foam filter, it should not have oil beads or drop on the filter. I have tested this on a dyno and over oiled filters reduce intake air flow and makes your bike run richer. Once the filter is oiled, put it inside a clean plastic bag and massage the oil into the foam itself. The plastic bag will remove the excess oil that forms beads on the filter and also keep your hands clean. A filter that was massaged in a plastic bag also flows more air and let your bike run at the right air fuel ratio. You can also gain a horsepower or two more when doing this, and not running an over oiled filter.
If you have oil or black spooge coming out of your exhaust your bike is running rich not lean. And its fine as long as your bike responds at all throttle positions.
Put grease on the part of the air filter that sits on the air box. Around the orange lip. It will create a seal around there allowing no dirt in. How I’ve done it my whole life.
Especially if riding in sand. Seen many engines go down because they sucked in sand.
@@bcwingit I’m a service tech, I can’t tell you how many people have brought in dusted Motors because they don’t clean or oil the filter
Piston size relative to bore dimension is key. Piston skirt slap is a killer. Use the factory carb tuning settings plus butt dyno and you'll generally be ok
Great vid man! Keep up the good work. I have literally been obsessed with your vids recently.
I usually run my Gasgas EC 300 with a mix ratio of 1:50 and it still spits a bit oil out the exhaust and smokes a bit too.
What mixture you use? Amsoil?
It should be in my opinion. Rather be spitting oil and smoking then not spitting oil and smoking
Thats cause your supposed to run 50:1
Everybody says they run a good oil, and if they are not having problems and get good lubricity, all is good. But I know some guys in North CA. who had problems with their race engines lower rod bearings, and they ended up doing some great durability dyno testing, for the best oil. Motul Kart GP 2-t oil won their half hour, wide open at peak power dyno tests. Klotz Supertechniplate (Klotz uses 20% caster mixed with their synthetic), was right there with it too, but runs a bit dirtier if the jetting is not crisp. Motul is way more expensive, but I use it now because I know how sharp those guys are, and testing like that is very rare.
A great idea is to add a small amount of seafoam in your fuel to stop your piston rings from sticking. Also adding seafoam in your spark plug hole at top dead center when storing the bike keeps it running perfectly. You can extend your riding times before top end jobs.
You can use aerospace 303 protectant on your carburetor gaskets to condition them. This will make sure your carb runs consistently. You can also use 303 on your tires to extend the life. It is water based so it wont affect the tire traction.
Repack your silencer. The packing is saturated with oil. Your neighbors will thank you too.
I did mine and it didn’t make a difference for sound
A chip in the cylinder like that would probably have corresponding piston damage which suggests that it was the previous owner and he changed the piston.
Warming up the bike is also a process of heat expansion in the cylinder. Since the pistons walls are much thinner and there is no cooling on the piston like the cylinder has water cooling, the piston heats up way faster than the cylinder if you go all out right away so thats means the piston expands lore than the cylinder. The piston will expand too much so the clearance between the piston and the cylinder walls are much tighter and it may lose all clearance and it will seize.
in our 700cc zabel we run 1:70 putoline mx7 and its the best one we used, no carbon buildup, and after 22 mth the motor is even oiled too much ( going almost full gas all the time)
Great video and breakdown. All us dirtbike owners need to pay attention to protect our investments and toys. 💪🔥
I have a ? For you.
I recently bought a yz250x just had fresh piston and rings. Compression was great for a little while (probably has 8-10hrs on it) and I feel like it lost some compression.. just when I kick it over though. The bike still runs amazing. (I am just curious what would have caused it so quickly. I checked out the cylinder before the install and it didn’t seem to have any scratches or any bad imperfections in it.
I’m going to get a compression tester and see what it’s at. And if it’s at below average then I’m going to tear it down and see if something’s not right in it now or what’s up with it.
@@jaredbaker5510 my yz125 did the exact same thing, I think its normal and it is running fine, Im not 100% tho
@@weston5146 I mean it still starts first kick. But it just seems low.. I have to tear into my engine now anyways.. because the crank seals are bad. It’s burning motor oil. 🙄
probably just a casting or plating defect, leading to a crack ejecting the piece. it sounds like you are doing everything right, and I know I have treated my bikes far worse without chipping my nicaseal. ie I've blown up a lot of pistons, few seizures, and a water pump failure and never chipped, but have worn out the plating.
or the previous owner ported it without replanting it because it will chip easily in that process. or honed the plating for a rebuild that will cause cracks and chips too. the plateing is hard but brittle and doesn't like to be scratched.
Engine braking is bs, it has plenty of residual oil to lubricate the cylinders
I think you have a good handle on what to watch out for. I can't say I would do much differently. The only thing I will add is when replacing a piston I tend to think some aftermarket may lack the proper expansion properties so I may consider a yammi piston or do research at l ast. I think your damage was probably a defect in casting from the beginning. I would run 32 to 1 because I feel companies push the limits due to emissions standards. Longevity is loosing that battle. Same with what the EPA has done to Diesel engines. They can't meet standards and last as long as they did a decade ago.
Typically severe engine failure is from cold seizures, to include 4 corner cold seizure.
Normal ware would reduce compression, resulting in performance loss and running poorly.
Clutch less shifts are ok on dirt bikes, the force is absorbed through chain, then ultimately rear tire is able to slip. If you had 100% traction similar to street bike there is no loss of traction, so gears ⚙️ take the abuse.
No visible damage to the ring or piston. all you need to know. with "75h" on it when sold, should not have needed to be disassembled by then. spotting OE gaskets or signs of intrusion, shiny loosen corners on bolts, sealant. etc could point at prior owner deception, but that's moot as it "ran brilliant"
i'd suspect mfgr defect, and thank you for taking the full repair path, before it became serious.
besides compression records, piston inspection through the exhaust port, i heard no reason for a full teardown inspection.
i'll leave you with this one point to ponder, examining piston wash, clean area size by the transfers is one of the proven low tech ways to check combustion.
3:36 shows the crown with no clean areas, suggesting the piston was getting hot enough the incoming charge could not keep it from baking on oil.
confirmation would be a matching carbon area on the underside of the crown.
enjoy your ride.
Welcome to the world of second hand dirtbikes. Previous owners know when to sell.
The previous owner could have had the throttle cable too tight. This may cause the little nub at the end of the cable that attaches to the slide to get torn off and ingested by the bike due to the force of the handle bars. It would explain the perfect size hole. Just check your cable tension in your manual
to me that doesn't look like oil issue. might have been small crack from the factory and it just chipped off during a ride. also that didn't look that bad. surely would have been ok to ride
Invest in a twin air wash cover. It'll keep water out of the carburetor and engine!
Oil ratio doesn't determine rich or lean Ness. Jetting does. You can run 100:1 and be super rich, or 10:1 and be lean. Also you need to put grease around your air filter.
As far as warming up, wait until the radiators are hot. But you need to keep revving the bike to clear it out and warm everything up even. Also play with your clutch as it's warming up, to help separate the plates with the cold thick oil holding them together.
As far as the myth about pulling clutch in after high rpm. You don't really need to. Just blip your throttle. I promise it's not hurting the motor one bit. Have you ever seen a pro racer pull their clutch in back in the day? Not really. On the motocross track it's such a short amount of time before you have to get back on the throttle again there's no point. Shoot I'll go from 5th tapped to 2nd or 3rd to get the maximum engine breaking, never had a issue...
For jetting. You do not want to run to rich as you can do just as much damage as to lean. You want your spakr plug dark paper bag brown. Oil out your silencer isn't a good thing. You need to repack your silencer and lean your bike out a little. That oil is unburnt fuel which isn't good.
My yz125 runs ok but drips a lot of oil from the exhaust, so I just change the main fuel jet in the carb to a size smaller ?
@@okerhrh4139 need to repack your silencer. Go to stock jetting. And then you need to figure out your elevation, and temp and jet your bike accordingly. I would suggest 40:1 with redline. I run my 125 to the ground and done 100 mile desert races/rides and never once had a issue. If you can afford it. Run AV gas.
Love 2 bangers. Can run till they can’t no more
I wouldn’t trust the amount of spooge out of the tail pipe as an indicator that the bike is properly lubricated. Excessive spooge could mean that you’re getting blow by past the rings on the downstroke. In other words, fuel/oil is not getting into the cylinder through the ports and is not completely combusting.
True but I've never seen a 2stroke bike that didnt have oil coming out of the exhaust. Some more then others and even on bran new bikes. My riding backpack has a million black tiny spots on it after years of riding. I usually mix around 40:1 43:1 and I've always ran castor 927. Ive have heard alot of the time it's the type of oil a person uses, that makes that black spooge, or obviously If your running to heavy on your oil mix.
Would love to see you ride Wild West enduro track. It’s one of my favourites. Keep up the great work.
2 stroke engine braking is an interesting one. Like you say with a set up like yours when you shut off the throttle you reduce fuel and therefore lubrication but there are 2 strokes with auto lube systems consisting of an oil tank and pump. Now some of these systems just pump the oil into the carb to mix with the fuel which gives the same issue of less lube when shutting off the throttle but some have a system where the pump runs off a gear on the crank and inject the oil directly into the intake port (after the carb) On these bikes/scooters the system will be providing oil based on engine speed regardless of the throttle position and fuel input which should mean shutting of the throttle at high rpm is not an issue. At least that’s how I see it, could be wrong. I have this system on a scooter but that’s an auto so no clutch to pull anyway. Good your still loving the 2 stroke they are great fun
Most vintage Japanese 2 strokes from the mid 60's onwards do this too. Yamaha's autolube is a great system and very reliable. Only problem is if the pump decides to suddenly stop working...
Ive engine braked all of my 2-strokes, and continue to do so to this day and have never had an engine failure. If there is enough fuel for the engine to run, there is sufficient oil for lubrication, unless your jetting is way out of line. Been using Sunico Silver 100 octane race gas and Klotz castor for over 30 years with absolutely no problems whatsoever.
Je maakt leuke video's met interessante onderwerpen. Dankje!
Alsje
idk but running motorex cross power at 60:1 with no issues on anything over multiple years has been pretty good with no rebuilds just normal maintenance and cleaning
Either on my 450 or my 250 two stroke, I always ride the track below 50% for the first lap or two, depending on the size of the track, to get the bike up to operating temperature.
adding oil to fuel dosen't make it run rich it actually leans the bike out, you can run whatever the oil manufacturers recommend as long as you jet according ! bikes run on fuel not oil, the more oil in the fuel the less fuel rich the mixture
The engine braking thing is BS I rode raced bikes 2-stroke bikes for years and even ran flat track with them shutting the throttle off going into the turns in both situations never never had a problem. I had more problems cold seizing an engine from not letting it warm up or not breaking it in long enough
short doesn't harm a 2 stroke, but going from a long hill only braking on the engine might cause damage as the engine does not get fuel and so no oil.
@@wilco300674 ye say if your going down a very steep hill for about 20 seconds that’s when it probably starts fucking up the moter because there will still be oil in the cylinder it won’t dry up that quickly it’s like wheelies people say it isn’t good for them as the oil is at the back and the engine isn’t being lubricated.say if you were all the way back constant for about 5 minutes then yes it problay would be shit for the bike but your always going up and down so the oil finds it’s way around still but that’s a similar kind of thing to 2 stroke engine breaking cause everyone thinks your starving the bike u are are fine unless it’s a really excessive amount
@@luixzzzz nah ive engine braked for miles and miles of down hill. No issues. You still gey FUEL when you are engine braking.
@@richlee7047 then why do people say it does Fuck the engine ?
@@luixzzzz who is they lol. I've only owned 2 strokes. I have never ever seen one sieze or blow from engine braking. There is constent air flow + fuel flow while engine braking. If youre scared pull the clutch in blip the throttle here and there while going down hill. I "engine brake" really hard on my bikes when im riding the track, im more worried about me blowing my gear box vs piston frying off or something. If youre bike is jetted good or even if it aint it is completely okay.
Defective casting or damage from machining, but there would be evidence on the piston, rings or skirt. PS: AND Where the chip was, wasn't affecting a damn thing! Not exhaust timing anywhere, I'd have put a 10°taper on it top and bottom chip area, checked ring gap, and sent it! Zero harm done. But Like someone below said- (piston may have already been changed-good call,) but its a non issue - unless *** it hints at more casting defects. In which case only Time will tell OR you get the barrel tested. Sonic? X ray? NDI? Idk. Jmho. Good luck. Might be worth getting checked. GOOD LUCK!
more of this this is awesome thanks
Ok, a couple things. One, Motul is aweful. Switch to Amsoil. You absolutely will not regret it. I know 2 people that switched, and they both testify to getting 40% more life out of their top end. Two, Try a hotter spark plug to burn off that excess coming out the pipe, or look into repacking the silencer, thats cheap and easy, and will soak up a lot before that starts happening again. Three, Check out Project Farm's comparison on oil. He did a great job at testing several oil brands, including motul and amsoil. Not 2 stroke oil test, but you can expect same quality. Ill link that video for you.
silencer leaking oil could be the packing or perhaps crank seals
With modern engines and oils, you can go even further : 1/50 ... ou 1/60. No joke, my 582 Rotax was very happy this way, while giving it's 65hp full power for hours in a row.
Using too much oil it is really worse than too little... too much oil ends up in much faster rings / cylinder wear.
A good way to sieze a two stroke is to cool it too fast...however, your is water cooled so no risk of cooling schoke.
Too lean is a bad plan because it overheat the exhaust ports edges. But on you type of bike, you probably don't ride with throttle full open for very long period of time in continuous.
One more idea, something was sucked in the cylinder end did not pass the port fast enough...and get caugth by the piston edge....and it can actually be anything from sparkplugs to casting burs, not mentionning piece of gaskets, anything falling in the air filter during maintenance...
Don't be too anxious : two strokes are usually VERY reliable and 100 hours at YOUR pace is not going to wear it a lot...
Dirt bikes suck dirt into the air cleaner, and if it makes it past the filter, it lands on the piston ports, scores the pistons, then drops into the crank case, making your main bearings grind while wiping out the crank seals. Take care of your filter, and it will take care of you.
I use the maxima air filter oil and cleaner. You definitely want to use the cleaner outside, what ever is in that stuff has a pungent chemical smell that lingers!
I mean, your channels name is the answer to this question
Brilliant video man
if my cylinder has a ridge at the top (presumably where the ring/ piston wasnt reaching) do i need to have it honed down? i know it was there during my last top end rebuild and nothing went wrong after 50-100 hours of riding. but i am doing a full rebuild of this bike (3rd gear was slipping) so i dont want to risk anything. at a guess it probably sticks out like a quarter or half a millimeter or so. i guess ill take it to a shop and see what they think.
Uuuhhhhmm that oil out of the muffler Shure looks like a right side crank seal! You should probably check that also your trans oil will just disappear if it is bad. Also great video! 👍. Don't forget to check the crank play bc sometimes the crank bearings explode into the cylinder
Question:what causes damage to 2stroke enjine
Awnser:choas causes damage to 2 stroke enjine😂
Bad fuel can cause detonation. Just a few carb adjustments on the lean side can ruin your engine.
check the spark plug to figure out if its runing rich
I tried Honda's HP2 premix in my 03 CR250R. I had so much spooge and the bike loaded up.... I switched back to klotz
Klotz is the best! And that smell, oh yes!
I often wonder why modern off road 2T bikes can't last very long. Maybe because they are so highly tuned? Saying that though the old Aprilia RS125 was highly tuned but didn't need a rebuild so often (5k miles for rings for example). mmm, anyone help me with this one?
Improper jetting, bad air filters, improper ring gap, shitty aftermarket pistons…the list goes on and on 😂
Yz yamalube 2S is not made for the race bikes like yz250. The correct oil to run is yamalube 2R, for their race series bikes. And this is actually some of the highest quality oil. A lot of pro racers run this oil in their bike, some who ride other brands besides Yamaha as well
U want yamalube 2r.... that 2s is formulated for lower power / reving 2 strokes
30:1 it’s 4.27 oz vs 4 oz 32:1 not a huge difference but I think it makes a difference
He couldn't be more wrong about the Yamaha brand oil. Yamaha does not make that oil. It's made in a oil refinery where all the other ones are made, just because you run Yama Lube, doesn't mean you're going to prevent damage. All 2 strokes will need new piston & rings after so many hours of run time, that's just the nature of 2 strokes. Yes, good quality oil is important, as are many other things, brand however, is the least of importance.
NEW SUBSCRIBER HERE .
I GOT THIS TOO
WHEN MY COOLANT GET EMTY BOOM 💕💕💕💕
Such damage is probably caused by the piston hitting the side of sylinder. Nothing major can come through the airfilter and not letting the bike heat up would simply be bad for any gaskets.
What can cuse that hit?
@@NirHason Well it's nothing else than the piston that can hit the sylinder walls, the question is rather why and how the edge got hit by the piston. Furthermore I know nothing about previous ownership and such, so it's hard to know
Ok, yes, I have a history of riding dirt bikes and maintaining my friends racing dirt bike. I'm a tad confused though. Was there anything going on that made you look ? From what I heard there wasnt. So to me that so called damage is or was not an issue. My friends dirt bike, rode every weekend for hours and then raced on weekends twice a month never had any issues. Granted not the same bike as his was a yz250 back in the mid to late 70s. But the only thing I ever did was replace the rings between motos. Otherwise just normal maintenance. Sooo, did you actually have a real issue ?
There is a chance the engine got a catasrophic failure and someone just changed the piston and sold it to you
Yeah, that damage was not caused with that piston. there is only one thing that can chip the cyllinder like that, and thats the piston. and it had no damage. good call ;-)
@@MC-Racing yup sellers do everything to get rid of their bikes
Seeing that I think you are JHB which is at 6000ft altitude make sure that it’s jetted for that High altitude
Particularly if the bike came from Natal or somewhere closer to sea level
Damage was caused by the bike catching you looking at another four stroke.
Spooge isn't the result of too much oil in your gas mixing, if anything it'd be the opposite.
Also your point about the engine not getting enough lubrification when closing the throttle at high RPMs is kind of a debunked myth, there's usually plenty of lubrification left and still happening in the cylinder, as the spark plug isn't getting to burn all that's left, because of the closed throttle, usually, if you aren't doing more than a mile of engine braking, your engine should be fine.
In conclusion, adding more oil in your mixture can result in less spooge, more lubrification, and some also say more power, as the oil will help seal the piston better, there are actually a couple of experiments on this topic.
What about the fuel filter that’s important
7:58 a tad lean ? Wtf😂
It's what 2 stroke moto crosser's do ! High strung engines wear themselves out .
just general wear after multiple top ends will chip the nikasil nothing new its a classic, or by piston slap
i miss your R6
Bruh change the insulator in your canister lol
Reverb! :D Get some foams on them walls dude
ua-cam.com/video/Sowki1N_YeY/v-deo.html
2 stroke engine braking is a myth. if so then it would seize under idle. if it’s getting fuel, it’s getting oil
I think the issue is prolonged breaking at high revs. Mine blew up after multiple descents from a 500 foot hill climb. I think it starved the top end.
About the carburetor/FI debate, carburetors are mechanical, Fi is electric. There's next to no difference in performance when it comes to motorcycles.
It's impossible to make a 2-stroke engine clean. so there's always going to be oil build-up on your exhaust. Whether your engine is running lean, rich or stoichiometric can only be told by a mechanic with a lot of experience with carburetors. I only work with very small 2-stroke engines and the way I'm setting up a carb is by listening to the sounds the engine's making and how it responds to my inputs.
my top end blew on my 2 stroke atv and now i've rebuilt it completely. Im running into countless problems trying to start it but the main one is sometimes the piston gets caught due to lack of lubrication.
Trottle off choke pulled every time its easy
I just reuse my air filter i use petrol to clean my filter and the rest
Yamalube 2s is meant for injector bikes
I dont get how pulling clutch would help "lubricate"... Its damn same if you just shut off throttle. Pulling clutch doesnt magicly stop your engine, it just doesnt provide power to your rear wheel, rpms, fuel consumtion doesnt change
Try engine breaking your 2stroke and I promise you dont have it anymore
well pulling your clutch in with no throttle just drops it to idle so
Youneed a freewheel so engine braking becomes impossible
4 stroke for the win bro, 2 trokies werk nie met my nie 😆 🤣
You obviously don't know how to ride a dirtbike....
@@331moto lol true that I only ride a old honda xr 500 lol 😆 It's not like the most raw badass bike 😎 I have nothing against 2 strokes do that fun I just prefer having the ability to have power on tap all the th refers range thay are fun and easy engines to work on so positive
@@activelygaming1786 dude you are riding a 40 year old motorcycle.. a 2-stroke has all the power "on tap" if you know how to ride one. One finger on the clutch will immediately get a 2-stroke screaming
@@331moto yup and 40 year old bike still shows all the other newer dirt bike lol, To be fair I have only ride a few 2 strokes so hay maybe there is something, My one downside to 2 strokes in my opinion is not been able to really keep them pinned for long times so yea maybe for just riding dirt although I live in SouthAfrica you know I take my dirtbike in the highway 😆 🤣 😂
it could be because it runns too rich that it became too hot
I want 8 mins of my life back, sorry but I though this was going to be informative.
Arrogant
it must be the other owner
yamalube is trash amsoil dominator for the win
@@BaronvonOldenBiker def not a sales rep yamalube is just bad
Are you south african?
Yzeee not yzed lmao
I believe Yamaha recommends a top end overhaul every 30 hours.
Check your manual.
The manual says replace the rings at 7.5 hours, replace the piston at 12.5 hours.
I’m sure 0.0 people do that.
Because it’s stupid to do this. I’ve had 8 years on a couple of engines still very good compression over 200 hours. I’ve done crank seals before the top end lol 😂 if the compression is good way bother with it. Maybe 70 to 80 to 1 on mix I could see 30 hours and it be junk it just plane stupid to run that high of mix. You making less power. More engine wear. It’s stupid
First
why?
Second I guess 🤷♂️😆
@@juliusju9145 cause I’m the goat
Always use one oil only. If u made your mind to use motul keep your head strong and use it for ever. And I would say u should have asked the previous owner what did he used. Coz my mechanic always says this to me "Your bike is just like you if today i give you water from a lake you will fall sick coz u are use to the RO water, but think about those living in there drinking lake water, so always use one oil in your bike and if possible try to fill feul from one station this will give your bike more life". So please don't try yamalubes for once just to feel if it any different or not
I’m gonna call bs on your mechanic. Microbes, minerals and bacteria in water is nothing like oil in an engine.
You are right on the mixing different oils part, however if your tank is empty you can change the oil and let it warm up for 10-15 minutes so it gets used to the new oil.
The only reason you shouldn't change oil is because there is some oil that will react to another type, it is perfectly fine to change oil brands, just drain the tank and carby of the old stuff and fill it all up with the new, and she'll be right
What a lot of nonsense
2 stroke just needs to be serviced every 20 hours. It is how they work. Put on a new cilinder and piston every 20 hours.
No
maybe if you ride a 125cc at WOT all the time, otherwise no.
just switch to 4 stroke. 2 stroke sucks anyway
That just looks like the cylinder had bad metal in it from the factory to me
Bad fuel can cause detonation. Just a few carb adjustments on the lean side can ruin your engine.