Diesel/Veggie oil motorcycle

[euromodder]

Originally Posted by Christ

I think this efficiency loss with CVT is a bit blown out of proportion, though.

When it is only cruising, shouldn't it be about as efficient as a basic belt drive of the same ratio?

No, it's less efficient, even at fixed rpm when cruising.
It is a friction-based system, rather than a direct mechanical linkage, so you'll have some slippage.

[dcb]

Originally Posted by Christ

That one has a model that comet doesn't make any more, but it seems to me that 75% wouldn't allow that klr diesel to get up to 60mph+ with a 10hp motor... Let alone 120+mpg.

Yah that wouldn't make sense. But 60mph cruise (8.5hp) doesn't quite add up either. My cb125 says it has 12hp and a top speed of 65 (though I need to fix the front brake and true up the front wheel before I can get close to that). Honda CB125 - Wikipedia, the free encyclopedia

[Christ]

Originally Posted by euromodder

No, it's less efficient, even at fixed rpm when cruising.
It is a friction-based system, rather than a direct mechanical linkage, so you'll have some slippage.

The comet is a spring/weight cvt with a drive and driven pulley, like snowmobiles use...in fact, identical to snow mobile drives, not a friction drive.

Did I misunderstand?

[Frank Lee]

CVTs on sleds eat up a lot of power. Even sleds with wheel kits for summer get awful fe.

[Christ]

Numbers?

[dcb]

just googling, nothing real scientific:
CVT efficiency
Manual - 97%
Automatic - 86%
CVT belt - 88%
CVT torroidal - 93%

[Frank Lee]

Only credible thing I found said 80% for the rubber belt.

That 88% is probably for an automotive steel belt.

[euromodder]

Originally Posted by Christ

The comet is a spring/weight cvt with a drive and driven pulley, like snowmobiles use...in fact, identical to snow mobile drives, not a friction drive.
Did I misunderstand?

Maybe we're talking different things

Spring/weight : are you referring to the automatic centrifugal transmissions used in mopeds / scooters and the like ?

To me CVT is the pulley / belt system - the more advanced version of the antique Daf Variomatic .

[dcb]

to me the scooter transmission IS the belt-pully variator, like in the changzuki.

http://ecomodder.com/forum/showthrea...tml#post244431 , I believe that is the "comet" transmission there.

The appeal of the variator with a diesel motorcycle conversion is clear, they are readily available and not too expensive and there are plenty of working examples. But I have been researching suitable gearboxes as well, and personally would rather go through the effort to have a clutch and gears. I can get over 100mpg on my 250 without the conversion (and with plenty of available acceleration and top speed), I have to aim a lot higher than 104MPG to make it worth the effort for me, and I think gears would help, but it is a notably more challenging path at current and not for everyone.

[PeterS]

Originally Posted by dcb

Some of the conversions have transmissions, and obviously that would be preferable if it fits your budget and bike. But the torque curves on these is very flat once you are rolling, so you can "get away" without one, by making the same compromises as the no-transmission electric vehicles do.

I would love to see some transmission options, I know the old BSA and any divorced transmissions route, retro-direct doesn't work on a diesel, some folks have converted 2 and 4 stroke bike transmissions (would love to see a build thread on that) by sawing off the cylinders,etc, others have made custom gearboxes...

Here you are DieselBike.net • View topic - Jawa / yanmar clone .