adapting a CVT to a motorcycle engine

[odypilots]

There has been talk of this before, so when I stumbled across this, I thought some may like to see it. It involves using the motorcycle engine in a snowmobile, but the info could be adapted to a buggy.

http://www.mtukrc.org/download/mtu/m...paper_2005.pdf

[jumpin jellybean]

wow good info there too bad didn't go thru gearbox

[LiveWire]

I have read that article before. I found the way they built a custom muffler interesting as well.

[PilotHawK]

I've got one that I'll snap a few pictures of for you sometime in the next couple of days.

[grant_wt]

You need to find a Yamaha 4 stroke sled. They are crazy fast, especially when turboed. They push a +550lb sled just as fast as a 800 2 stroke pushes a 450lb sled. It would be way less work than trying to adapt a bike engine. The actual sled would cost more, but it probably would cost less than all the custom machining and work required to do it the other way.

When they turbo the Yamaha's though, they are getting hp numbers comparable with a turboed Hayabusa.

[Bugpac]

Its still a rare find to get a yamaha sled motor, a turbod bike motor will make serious hp to...It all boils down to cash, Im pretty confident a gixxer 1000 etc, would smoke an apex with a cvt drive....And a good aaen driven clutch or something that can spin 13 grand....cant even imagine a turbo busa cvt drive...

[grant_wt]

Originally Posted by Bugpac

Its still a rare find to get a yamaha sled motor, a turbod bike motor will make serious hp to...It all boils down to cash, Im pretty confident a gixxer 1000 etc, would smoke an apex with a cvt drive....And a good aaen driven clutch or something that can spin 13 grand....cant even imagine a turbo busa cvt drive...

You may be right. I don't know. I know that my 800 polaris XC with 150hp before the high compression head, aftermarket single pipe with lightweight jackshaft and gears, etc, about equal with an apex. And an apex is 100lbs heavier than mine! And guys are getting +330hp out of them when turboed.

I just think even if you had to put out $4-5000 for a complete but wrecked Yamaha you still would be better off than buying a Gixxer, a cvt, the machining, etc.

[nutz4sand]

I keep having trouble trying to see the file in the first post but will try again.

I still think what would be a good idea is to have a shaft like a jackshaft that is long with a bearing at each end. Then have a sprocket mount on it and the end of it tapered to fit common CVT's

This could be mounted right at the back of your buggy so the chain from the motor was longer and no overheating issues and with the clutch right at the back it would be easy to clean and "tune" Then run the belt off it forward to the driven.

Some have said that they think that the gear you left the bike motor in would wear to much but I cannot see why. With good lube many bikes are run in the same gear for great distances.

Its likely you would even make use of two gears. One with the motor in the mid of its powerband for casual cruising and another when you were putting the hammer down. Each would spin the clutch similiar speeds if setup right but be at different points in the motors powerband. (i.e. more power available)

I think a shaft setup like that would be a great seller as then you could use it behind a Hayabusa and not have to shift (except for high to low range) for about or less than the cost of a good Yamaha RX1 or APEX motor unless you score a deal. Bill

[Bugpac]

you run bikes down the highway in the same gear for long periods correct? I dont see that being an issue either...

[nutz4sand]

I finally got to see the whole file on the Sled/bike motor (I hate dialup...). Not to bad but they sure seem to take the long way to Nicks house (The "scenic route")

Personnally I would be a bit leary of the crank end with the flywheel holding all the power. I know on the sled motors I have had apart the flywheel end was half the size of the clutch end. Maybe bike motors are bigger now days on the flywheel end to handle heavy flywheels and clutch dumps??

As for the Scenic route above. For all the work and machining etc. It seems to me like it would have been a bit better to replace the bike motors tranny guts with two custom shafts and leave just one gearset to send power. Then where the sprocket was the second custom shaft coming out of the motor would allow the CVT to bolt right on. Or just a CVT adaptor on the crank with a support bearing be easy if they managed all that.

With the sled motors today though there is no reason to go thru all this trouble. I can see why they did WHEN they did. Even if the sled motors are hard to find they are not impossible and for the average Joe who wished it the shaft behind the bike motor as in my above post still seems the way to lay out ANY bike motor into a buggy with CVT shifting.


I am sure K-fab will likely chime in here but I do recall him saying he has seen RX1 sled motor machines running with Hayabusa powered machines in some cases. (Its posted here on MBN but I will have to look to find it. He likely remembers where) But I do not know if either was built of if the rides were close in weight and all the other factors that need to be weighed in before it can be compared more. He likely might.

I know they are taking the Yamaha sled motors up and up in the power ranges. I do not know if they are at high end like the Hayabusa but they are impressive. But for the average buggier 300 horse out of a Yamaha motor is not to hard to achieve. With no shifting thats gonna be hard to catch if the machine was not very heavy. I wonder if Yamaha has a 1300cc sled motor in the skunk werkz. That would help even the oddz. No doubt aftermarket is working on it. Bill