I ported the heads to match the diameter of factory manifold. Replaced the filter airbox with a K&N air filter. Put in a high lift cam ,new valve springs, retimed the cam, bored it out to 650, rejetted the carbs. Had a Kerker header. Ran low 12s. Faster than my CBX. My favorite bike. Did 100,000 miles
What cam did you use? And where did you get the valve springs? I just picked up one recently that's been cafed out and I'm looking to eventually make it into a real performer. Only thing is I can find practicality nothing in the way of performance parts for it other than carbs. Haven't heard of any performance cams for it. Only thing I'm thinking might possibly work is putting an earlier SOHC CB750 cam in, but it's just a shot in the dark if it would fit or not. Looking forward to your response, any help is greatly appreciated!👍
@@danraymond1253 I'm sorry. I did this in the 80s when I was working in the Honda dealerships in San Diego. I'm sure none of these parts are available. I have trouble finding parts for my 95 VFR750 nowadays. Love my VFR and miss my CBX but the CB 500/550's were my first love. Good luck.
@@markwilkes4318 your fine. Thanks for the reply. This bike is quite new to me. I was raised on old Harley's and Indians so a 1980 CB650 is kinda outta left field lol. I'm looking to make my dream cafe racer out of it, and to learn how to properly build a performance engine along the way. We'll see where it takes me.
@@markwilkes4318 Hi Mark, I was lent a Cb550K3 for a season whilst in college back in the late 70‘s in South London. Interestingly enough, I also ride a Vfr750f, the Rc36b from 97, me now living and riding in Germany. Managed to get everything through eBay over here as mega loads were sold in Europe and, according to what I‘ve read there’s supposedly still over 100k of these active on European roads in their various years and forms. Wear and tear parts are literally available over the counter here but when it came to spares, I‘ve received parts not just from Germany, but France and England also. Wish you success and good luck in your hunting Mark, Best greetings from Düsseldorf;-)
My dad had one he never rode. I snuck it out & rode it to high-school a handfull of times. No license, no tags, no insurance. 14 miles each way. My dad woulda killed me
It would be great to see a comparison between the mikuni and a rebuild stock carb. To really be able to judge. Thanks for showing these mikunis though!
I agree that would be a great side by side comparison. Looks like I need to find another cb550! 😂 if my wife asks, I am going to blame it on you. 😂Thanks for watching.
It is interesting to see that you were able to evaluate the motor characteristics (so much more power, etc.) within your neighborhood in just over a mile of riding with tires that needed air… 😉
While just a backyard mechanic I rejetted the 4 carbs (with K&N filters), installed a 4 into 2 Jardine pipes. Increased the motor sprocket by 1 tooth and decreased the rear sprocket by 2. Installed a Barnett clutch. Found out I could swap the stock 550 tank for a 750 tank, this required narrowing the rubber grommets (that mount to the frame) and moving the fuel lines to the other side. This gave me an extra gallon of gas. I also went up 1 size on both tires. Even with the Windjammer II fairing I could do 110mph, but that was top speed. I could ride 90 miles to work then put in 8-10 hrs. heavy construction work, and drive another 90 miles home.
@@motorcyclerewind It was. A friend and I (him on his big Harley) rode together on the highway about 30 miles hitting 90mph. He commented, the next day on how surprised he was that my 550 kept up with his. He didn't think it had any power. I put about 60,000 miles on that bike. Only stopped riding because a work injury to my hands made it impossible to ride long distances. Ride Safe!
@@motorcyclerewind Honda issued a recall on the gas tank latch. Due to the possibility of a rider pressing the release tab accidentally the fix was to replace the tab with a key activated release.
Friend of mine did this conversion on a CB750F2 1980 model and the difference was amazing..much easier to keep vacuum balanced and with better delivery..once set up right you'd wish you did it earlier ..
The 1980 CB750 was a four valve DOHC with completely different original carbs almost impossible to set up without stock intake system. This would be a great conversion for any of the late models
I have worked with a Canadian vintage road racer and have achieved very close to 75 RWHP with 592cc displacement. The bike has been a dominant vintage force over the past 10 years. A lot of effort in the cylinder head, parts and assembly (setting squish etc). The Megacycle 126-20 is the cam to use.
That's damn cool. I did a set of CB 750 pistons a few years ago to my spec for a vintage racer, changed a few angles on piston crown to get better squish and burn. 75 at wheel is pretty impressive, Honda only rated 550 - 50bhp at crank
I'm interested in knowing how well the idle tunes on this setup? The four carb setup is notoriously tricky to get that perfect idle tune.. I want to hear a sweet, stutter free 1000rpm idle!!! Even a crap set of carbs sound good when you burp the throttle and hear that awesome CB-four tone!!
Doug the bike is running great. Been on a few rides in the neighborhood. Just finished the battery box mod to be able to fit the filters. will have ab update video coming out in the coming weeks.
I never had issues with mine, but I did have genuine Honda vacuum gauge set. The center carbs are not set same as outside ones with OEM gauges, aftermarket will put all the slides at same level.
Since I've now watched several of your video's, I subscribed. I've had my 550F1 since new, June 1977. It's been 'retired' a while since it has over 106,000miles, 70,000+ with big bore kit. Always much preferred the smaller bike over CB750 which is too wide and too heavy to handle really well. Best conversion in my opinion is actually the 591cc mod (plus, the dual carb conversion didn't exist back then). The stock carbs are quite difficult to set up without stock air-box, (particularly if you have a later 550K which that appears to be - alternator cover has exposed screws with Honda cast in). I would figure out some sort of bracket for rear of carbs, they will droop over time and cause rich running if not supported Normal tuning doesn't seem to work so well, bigger main jets and raise needle just uses even more fuel but no improvement in running. Dropping needles one extra notch works better than raising them. I did mine 1979 or 80, modified CB750 K0 pistons (not to 1974 Cycle World 'Gentleman's Express' spec though) I still have way too many projects started but watch far too much You Tube to get much done (being hurt doesn't help, painkillers only do so much) Who would have thought teaching was more dangerous than riding motorcycles? (12 years at MMI) Oh, didn't know you had XS 650, I was really into them and did long rod conversions (Honda CR500 rods) with XV750 pistons to get 800cc motors. You need to fit oversize liners to cylinder though. Only saw Alfa at end, had a bunch of Alfa Sud, flat four is awesome motor. It was designed by a former Porsche engineer who told Porsche they were doing it wrong 😁
Thanks for the subscribe. Really appreciate it. I sure would love to chat with you someday. I always say, the motorcycles are cool but the stories are way better. Thanks for watching.
Do they have those kits for a 72CB 750? I’ve got a tip though take some 0000 steel wool and some mothers aluminum polish to the forks and the aluminum engine and you can get that bike looking shinier than chrome. then wipe off with a Terry cloth towel
I thought about it for a while.Thinking about all the times I had them on and off to have it not run well, helped me make the decision. Wish I would have made it sooner. It sat parked waiting for over a year.
Going from 4 to 2 seems a bit counter-intuitive, was there something wrong with the stock carbs. Is it an issue that the new carbs weight is cantlivering off an extended intake manifold with no support from the air box.
Lee haven't done anything to it but adjust the idle. Starts and runs great. Here is a link to a quick clip I posted on instagram. instagram.com/p/CcZDACKLeoa/
I know this is a few months out by now. But I have a few questions. I just got the Murray's kit for my cb750. It started up but idling really high, routing of cable seems ok, but honestly sounding kind of similar to how your bike started up. I've been messing with it but haven't touched any of of the adjustments screws. It starts but idle is too high, but also a bit erratic and unpredictable 1. I notice when you give it a rev it does a like a 1-2 rev (22:02) was that a cable issue or an adjustment issue? I saw in your "its so good" video that it was revving/ riding great 2. Did you do much other than tweak air fuel screw? I've honestly only ever messed around with the cb750 round tops and I'm always worried about messing with carbs, I know it's a bit irrational but I'm always worried I'm going to do something irreparable
Hey Joseph, Thanks for watching. #1. cable was hanging up. #2. I did very little tweaking and only to the air screw. Know where you are starting, so you can always go back. Do the same thing to both sides. I like to save carb tweaking for last. Do standard maintenance first. Cam chain tensioner, valves, timing, then carbs. Hope this helps.
If both stock carbs and this swap are tuned properly, does this actually make more power? I can't imagine that the four-carb setup from the factory would produce less performance than these carbs, even if these are a little bigger. I have a 650 cafe racer that I just picked up. I'm not doing anything major yet, but down the road I plan to make it into a real screamer. Hopefully it'll be easier than I'm thinking it's gonna be, but probably not lol. There is almost nothing in the way of performance parts I can find for it besides Keihin CR29 carbs, so it looks like I'm gonna have to do a lot of work. 👍
It honestly isn't even close. This kit definitely has some issues you have to be ok living with, it runs super rich just off idle up to 1/8 throttle, to the point where you will hear it running on 3 cylinders. I've moved the clip on the needle, tried larger needles, smaller needle jet and different throttle valves to no avail. But, if you shift to a higher gear the load increases enough that you need more throttle and get out of that range. Other than that issue, these things are sooo much quicker everywhere, fire up immediately and idle well. They are also quite a bit lighter and make the bike a lot easier to work on.
@@travisshrey6720 what was the air mixture screw at? Less than 1 turn out? I've had the same issue, including having to blip the throttle. Murray said it was the throttle cables. And I rerouted them with his assistance and it made no change. I took pods of and watch the slides there's no sticking in the cables.
@@jacob14163 my entire issue was the original Murray manifolds. There must have been some kind of leak between them and the stock manifolds. I checked them half a dozen times and never found a leak, but as soon as I put the new manifolds on that bolt directly to the head it was a different bike. I put all my changes back to his original settings and it just ripped.
When I ordered it a few weeks ago it did not say it, but noticed it when I went back later. I am really impressed with the kit. Only wish they were labeled left & right and top.
new carb kit and now it don't run rite, that ain't no damn Rocketship where i come from, plus where you going 2 put the pod filters,, there supposed 2 be on the outside of the frame, looks like 2 me you got it on ass backwards, but what do i know...
Guy goes out of his way to film the set up, makes a follow up video after fine tuning and you feel the need to comment negative shit. UA-cam Douche bag award goes to you @jamesbanjomanjohnson ! Ass...
Doubt you much more horse power than the standard carbs with a re-jet and high flow air filters for the cost of new carbs . Devalues the bike as well .
I ported the heads to match the diameter of factory manifold. Replaced the filter airbox with a K&N air filter. Put in a high lift cam ,new valve springs, retimed the cam, bored it out to 650, rejetted the carbs. Had a Kerker header. Ran low 12s. Faster than my CBX. My favorite bike. Did 100,000 miles
I was being cheeky with my video title. You really turned yours into a ROCKETSHIP!!!!
What cam did you use? And where did you get the valve springs? I just picked up one recently that's been cafed out and I'm looking to eventually make it into a real performer. Only thing is I can find practicality nothing in the way of performance parts for it other than carbs. Haven't heard of any performance cams for it. Only thing I'm thinking might possibly work is putting an earlier SOHC CB750 cam in, but it's just a shot in the dark if it would fit or not. Looking forward to your response, any help is greatly appreciated!👍
@@danraymond1253 I'm sorry. I did this in the 80s when I was working in the Honda dealerships in San Diego. I'm sure none of these parts are available. I have trouble finding parts for my 95 VFR750 nowadays. Love my VFR and miss my CBX but the CB 500/550's were my first love. Good luck.
@@markwilkes4318 your fine. Thanks for the reply. This bike is quite new to me. I was raised on old Harley's and Indians so a 1980 CB650 is kinda outta left field lol. I'm looking to make my dream cafe racer out of it, and to learn how to properly build a performance engine along the way. We'll see where it takes me.
@@markwilkes4318 Hi Mark,
I was lent a Cb550K3 for a season whilst in college back in the late 70‘s in South London.
Interestingly enough, I also ride a Vfr750f, the Rc36b from 97, me now living and riding in Germany. Managed to get everything through eBay over here as mega loads were sold in Europe and, according to what I‘ve read there’s supposedly still over 100k of these active on European roads in their various years and forms.
Wear and tear parts are literally available over the counter here but when it came to spares, I‘ve received parts not just from Germany, but France and England also.
Wish you success and good luck in your hunting Mark,
Best greetings from Düsseldorf;-)
My dad had one he never rode.
I snuck it out & rode it to high-school a handfull of times.
No license, no tags, no insurance.
14 miles each way.
My dad woulda killed me
That’s awesome. Living in the edge. Thanks for watching.
Honda CB550 - unsung hero award.
I agree.
Had this CB 550 for a long time,then my son rode it for a few years same color.
This is an amazing motorcycle. Really like the 550 size.
It would be great to see a comparison between the mikuni and a rebuild stock carb. To really be able to judge.
Thanks for showing these mikunis though!
I agree that would be a great side by side comparison. Looks like I need to find another cb550! 😂 if my wife asks, I am going to blame it on you. 😂Thanks for watching.
😂😂
It is interesting to see that you were able to evaluate the motor characteristics (so much more power, etc.) within your neighborhood in just over a mile of riding with tires that needed air… 😉
Thanks for watching.
Great point!
While just a backyard mechanic I rejetted the 4 carbs (with K&N filters), installed a 4 into 2 Jardine pipes. Increased the motor sprocket by 1 tooth and decreased the rear sprocket by 2. Installed a Barnett clutch. Found out I could swap the stock 550 tank for a 750 tank, this required narrowing the rubber grommets (that mount to the frame) and moving the fuel lines to the other side. This gave me an extra gallon of gas. I also went up 1 size on both tires. Even with the Windjammer II fairing I could do 110mph, but that was top speed. I could ride 90 miles to work then put in 8-10 hrs. heavy construction work, and drive another 90 miles home.
WOW!!! Bet it was fun to ride. The 550 is my favorite size.
@@motorcyclerewind It was. A friend and I (him on his big Harley) rode together on the highway about 30 miles hitting 90mph. He commented, the next day on how surprised he was that my 550 kept up with his. He didn't think it had any power. I put about 60,000 miles on that bike. Only stopped riding because a work injury to my hands made it impossible to ride long distances. Ride Safe!
@@richardkawucha1232 My favorite thing about these old motorcycles. are the stories. Thanks for sharing yours with me.
@@motorcyclerewind Honda issued a recall on the gas tank latch. Due to the possibility of a rider pressing the release tab accidentally the fix was to replace the tab with a key activated release.
Friend of mine did this conversion on a CB750F2 1980 model and the difference was amazing..much easier to keep vacuum balanced and with better delivery..once set up right you'd wish you did it earlier ..
I am waiting on a set to come in for my 1979 Honda CB750K.
The 1980 CB750 was a four valve DOHC with completely different original carbs almost impossible to set up without stock intake system.
This would be a great conversion for any of the late models
I have worked with a Canadian vintage road racer and have achieved very close to 75 RWHP with 592cc displacement. The bike has been a dominant vintage force over the past 10 years. A lot of effort in the cylinder head, parts and assembly (setting squish etc). The Megacycle 126-20 is the cam to use.
WOW! that was really a rocket ship.
That's damn cool.
I did a set of CB 750 pistons a few years ago to my spec for a vintage racer, changed a few angles on piston crown to get better squish and burn.
75 at wheel is pretty impressive, Honda only rated 550 - 50bhp at crank
Dude this was a revelation for me!!! Thank you for posting, I had no idea the vm 34 could be adapted to the Cb- amazing 🤙
Glad I could help! Thanks for watching.
Learning a lot. Thanks for showing the whole process!
I'm going to comment on all the videos I watch just to help your analytics. I hope that is cool.
That’s awesome. Like, comment, share. Thanks so much.
I replaced the carbs on mine with cb750 carbs.
That’s a good idea.
Nice, does it change something ?
I'm interested in knowing how well the idle tunes on this setup? The four carb setup is notoriously tricky to get that perfect idle tune..
I want to hear a sweet, stutter free 1000rpm idle!!! Even a crap set of carbs sound good when you burp the throttle and hear that awesome CB-four tone!!
Doug the bike is running great. Been on a few rides in the neighborhood. Just finished the battery box mod to be able to fit the filters. will have ab update video coming out in the coming weeks.
I never had issues with mine, but I did have genuine Honda vacuum gauge set.
The center carbs are not set same as outside ones with OEM gauges, aftermarket will put all the slides at same level.
Old Hondas and fords I love it !!
Thanks Tommy! The funny thing is I traded a Yamaha xs650 for the truck.
Since I've now watched several of your video's, I subscribed.
I've had my 550F1 since new, June 1977.
It's been 'retired' a while since it has over 106,000miles, 70,000+ with big bore kit.
Always much preferred the smaller bike over CB750 which is too wide and too heavy to handle really well.
Best conversion in my opinion is actually the 591cc mod (plus, the dual carb conversion didn't exist back then).
The stock carbs are quite difficult to set up without stock air-box, (particularly if you have a later 550K which that appears to be - alternator cover has exposed screws with Honda cast in).
I would figure out some sort of bracket for rear of carbs, they will droop over time and cause rich running if not supported
Normal tuning doesn't seem to work so well, bigger main jets and raise needle just uses even more fuel but no improvement in running.
Dropping needles one extra notch works better than raising them.
I did mine 1979 or 80, modified CB750 K0 pistons (not to 1974 Cycle World 'Gentleman's Express' spec though)
I still have way too many projects started but watch far too much You Tube to get much done (being hurt doesn't help, painkillers only do so much)
Who would have thought teaching was more dangerous than riding motorcycles? (12 years at MMI)
Oh, didn't know you had XS 650, I was really into them and did long rod conversions (Honda CR500 rods) with XV750 pistons to get 800cc motors.
You need to fit oversize liners to cylinder though.
Only saw Alfa at end, had a bunch of Alfa Sud, flat four is awesome motor.
It was designed by a former Porsche engineer who told Porsche they were doing it wrong 😁
Thanks for the subscribe. Really appreciate it. I sure would love to chat with you someday. I always say, the motorcycles are cool but the stories are way better. Thanks for watching.
damn sounds great with the new carb!!!
It does. You should check out the follow up video ua-cam.com/video/7B0dUYMhLLM/v-deo.html thanks for watching.
Great Headline!! Even I had to see what you were going to do. Hope you are doing awesome!
Thank you! Would love to catch up.
Buddy just threw on some carbs out the box and the damn bike started up. where can i get this voodoo?
I got them from speedmotoco.com
Do they have those kits for a 72CB 750? I’ve got a tip though take some 0000 steel wool and some mothers aluminum polish to the forks and the aluminum engine and you can get that bike looking shinier than chrome. then wipe off with a Terry cloth towel
SpeedmotoCo has kits for a cb750
Really considering this for my 550 Four
I thought about it for a while.Thinking about all the times I had them on and off to have it not run well, helped me make the decision. Wish I would have made it sooner. It sat parked waiting for over a year.
Is that an American truck, European roadster and Japanese bike? This guy is cool!
I have been telling my wife for years, "I am cool" not I have confirmation.
Rub a little washing up liqiud on the rubber boots first it will fit easier and quicker.
That’s a good trick. Thanks for sharing. Thanks for watching.
Going from 4 to 2 seems a bit counter-intuitive, was there something wrong with the stock carbs. Is it an issue that the new carbs weight is cantlivering off an extended intake manifold with no support from the air box.
I thought about the weight of the carbs and filters. No issue yet. Maybe I should make a bracket to support it.
Those had good bottom end torque, I could go round traffic islands in top
So much fun to ride. Thanks for watching.
have you got it dialled in yet? and have you noticed much diffrence in fuel useage? cheers
Lee haven't done anything to it but adjust the idle. Starts and runs great. Here is a link to a quick clip I posted on instagram. instagram.com/p/CcZDACKLeoa/
Just got the speedo drive in. So soon I will be able to answer your question!
I know this is a few months out by now. But I have a few questions.
I just got the Murray's kit for my cb750. It started up but idling really high, routing of cable seems ok, but honestly sounding kind of similar to how your bike started up. I've been messing with it but haven't touched any of of the adjustments screws. It starts but idle is too high, but also a bit erratic and unpredictable
1. I notice when you give it a rev it does a like a 1-2 rev (22:02) was that a cable issue or an adjustment issue? I saw in your "its so good" video that it was revving/ riding great
2. Did you do much other than tweak air fuel screw? I've honestly only ever messed around with the cb750 round tops and I'm always worried about messing with carbs, I know it's a bit irrational but I'm always worried I'm going to do something irreparable
Hey Joseph,
Thanks for watching. #1. cable was hanging up. #2. I did very little tweaking and only to the air screw. Know where you are starting, so you can always go back. Do the same thing to both sides. I like to save carb tweaking for last. Do standard maintenance first. Cam chain tensioner, valves, timing, then carbs. Hope this helps.
If both stock carbs and this swap are tuned properly, does this actually make more power? I can't imagine that the four-carb setup from the factory would produce less performance than these carbs, even if these are a little bigger. I have a 650 cafe racer that I just picked up. I'm not doing anything major yet, but down the road I plan to make it into a real screamer. Hopefully it'll be easier than I'm thinking it's gonna be, but probably not lol. There is almost nothing in the way of performance parts I can find for it besides Keihin CR29 carbs, so it looks like I'm gonna have to do a lot of work. 👍
It honestly isn't even close. This kit definitely has some issues you have to be ok living with, it runs super rich just off idle up to 1/8 throttle, to the point where you will hear it running on 3 cylinders. I've moved the clip on the needle, tried larger needles, smaller needle jet and different throttle valves to no avail. But, if you shift to a higher gear the load increases enough that you need more throttle and get out of that range. Other than that issue, these things are sooo much quicker everywhere, fire up immediately and idle well. They are also quite a bit lighter and make the bike a lot easier to work on.
Thanks for watching!
@@travisshrey6720 what was the air mixture screw at? Less than 1 turn out? I've had the same issue, including having to blip the throttle. Murray said it was the throttle cables. And I rerouted them with his assistance and it made no change. I took pods of and watch the slides there's no sticking in the cables.
@@jacob14163 my entire issue was the original Murray manifolds. There must have been some kind of leak between them and the stock manifolds. I checked them half a dozen times and never found a leak, but as soon as I put the new manifolds on that bolt directly to the head it was a different bike. I put all my changes back to his original settings and it just ripped.
@@travisshrey6720 Interesting I will have to test that out. It took the whole issue away?
Im sick of chasing down issues on a very rough set of 78 carbs def getting a VM34 kit asap
I was having the same issues. Here is a link to a quick clip of it running. instagram.com/p/CcZDACKLeoa/
goodness im there too. these bikes are becoming so expensive to own
@@lemoncarrot7068 Yeah but riding them is worth it....
@@motorcyclerewind totally, what a sound
@@lemoncarrot7068 I thought these bikes were reliable?
Hey I noticed the cb550 kit says coming soon. Is this the cb509 kit?
Look up Murray carbs
let's see the "rocket" that sounded pretty rough. No timing check?
thanks for watching
I'm doing this with my 78 gs550
Wish I would have done it sooner!
I have a video coming out tomorrow on how ai modified the battery box.
@@motorcyclerewind I just got a battery tray yesterday my bike didn't come with one.
I noticed the 550 kit for the carbs says coming soon. Is this the 500 kit
When I ordered it a few weeks ago it did not say it, but noticed it when I went back later. I am really impressed with the kit. Only wish they were labeled left & right and top.
@@motorcyclerewind awesome ty! Looking Fiqar's to future vids
good job
Thanks.. Please Subscribe.
Running rich and check your advance unit for sticking
Thanks
new carb kit and now it don't run rite, that ain't no damn Rocketship where i come from, plus where you going 2 put the pod filters,, there supposed 2 be on the outside of the frame, looks like 2 me you got it on ass backwards, but what do i know...
Thanks for watching.
Guy goes out of his way to film the set up, makes a follow up video after fine tuning and you feel the need to comment negative shit. UA-cam Douche bag award goes to you @jamesbanjomanjohnson ! Ass...
Doubt you much more horse power than the standard carbs with a re-jet and high flow air filters for the cost of new carbs . Devalues the bike as well .
Thanks for watching
The easiest way to turn a CB550 into a rocketship is, sell it & buy a Hayabusa
🤣🤣🤣🤣🤣🤣 That would be the quickest way to the Hospital for me!!!!
😂
what a crock...the bike was clearly running so much worse than even a worn out stocker. Put the tools away....or the camera...or tell the truth
Thanks for watching.