Diesel motorcycles. Me want, me shall have.

[Christ]

I'm thinking for the sake of quick gearing changes, and simple service, I'm going to connect the engine to the trans using either a toothed belt or a 4 rib serpentine.

4 rib serpentine its the most likely candidate, for price, availability, range of pulleys available, etc. They surely can handle running alternator, a/c, power steering pump, etc., so my 10hp engine shouldn't have a problem with it.

Transmission to wheel, standard chain.

Clutch, I'm still thinking about. Considering ways to use a standard motorcycle clutch basket setup.

[Christ]

Available chassis choices:

1980 Kawasaki KZ250
1978 Honda CM185T
1988 Suzuki Katana GSX600F

The only one I currently have a title for is the Katana, but the others can be obtained, for the most part, easily enough.

[Varn]

If you use a japanese transmission make sure your get one with a chain drive primary. Otherwise you will have a motorcycle that runs backward. The Japanese usually use a design that the output shaft is not on the same as the input shaft.

Older british and american use the same shaft for input and output.

[theycallmeebryan]

The Ninja 250 motor puts out about 35hp.... much more than 14!

I'm not so sure how a 10hp diesel motor will do in a enduro/motocross style frame. Since you are siting upright, the frontal area will be very high.

If i were doing this, i would look for a bike that will give the lowest possible frontal area.... perhaps a Honda Rebel 250 frame or something similar.

[redneck]

I'm thinking for the sake of quick gearing changes, and simple service, I'm going to connect the engine to the trans using either a toothed belt or a 4 rib serpentine.

4 rib serpentine its the most likely candidate, for price, availability, range of pulleys available, etc. They surely can handle running alternator, a/c, power steering pump, etc., so my 10hp engine shouldn't have a problem with it.

Transmission to wheel, standard chain.

Clutch, I'm still thinking about. Considering ways to use a standard motorcycle clutch basket setup.[/

You can use a 2-stroke motorcycle engine. Just remove the crank, piston,cylinder and head. Replace the crank with a straight shaft machined to fit the primary gear on one end and a pully on the other (rotation will be correct). Block off the cyl. opening with a plate. Stand engine up vertical to reduce room needed. Belt the two together just like a HD.

This way you can use the existing clutch and shifter.


I would suggest using a 80cc - 125cc with a 6 speed transmission. (more compact)

This is a lot cheaper than HD tranny or Comet. Comet went out of business and it is hard to get the correct parts and or springs for adjusting engagment RPM.

This is the setup I'm going to use in my build.

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[Christ]

Anyone have any comments on the possible use of a belt-driven set of cvt pulleys instead of a transmission?

I have a bunch of snowmobile parts available to me, so this is something I'm looking at as a viable option.

[redneck]

In trying to use a snowmobile CVT you would probably run into the problem that I eluded to earlier, that being clutch engagement RPM. Typically, snowmobiles begin initial clutch engagement at a relatively high RPM (3000-5000), then advance to to full engagement over several more thousand RPM.

Finding springs and roller kits that would allow engagement at a 1000 rpm or less would be a challenge, if not impossible.

Another problem would be the physical size of the clutch and driven pulley, also the distance between the pulleys needed due to the length of the average belt used on a snowmobile.

Here are some links that may help you.

Comet FAQs (Frequently Asked Questions) & Definitions

500 Series Engagement Chart

Comet 500 Series Torque Converter System (Symmetrical)


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[kawboyCAFE]

use the KZ250 bike as your donor. they look so cool.

[dcb]

the kz does look good, but keeping a low profile will help the top speed (needs all the help it can get w/10 hp ).

[Christ]

The snow mobile parts, I didn't intendon using the clutch pulley.. I have drive/driven pulleys that never let go of the belt they dive completely, but I'm not sure if they operate with load or just rpm.. Probably not a great idea in the end, anyway.

For the majority of the riding I'll be doing, 3 gears should be plenty, if high is direct drive. Just an observation, really.

The more I think about it, the more I want to restore the KZ to it's small bike glory and use the katana or the twinstar chassis I have, instead. The twinstar is destined for a junkyard anyway, so it may be the best candidate, having already been stripped of many of the unnecessary parts.