2 stroke trans idea

[bubby-joe]

With any small engine assembly the crankshaft is a balanced assembly. So here is the idea, remove the piston, cylinder and the con rod from the donor engine assembly, add 1/4 to 1/2 cup oil to splash lubricate the low end bearings and cap the cylinder opening with a gasket and a metal plate. On the alternator end of the crankshaft install a 4-5 inch serpentine belt pulley. On the engine use an 8 to 10 inch pulley this gives between 1.5 to 2 times overdrive to the existing 2 stroke crankshaft, puts it into the right RPM band. Use a serpentine belt adjuster to keep everything tight.
The gain here should be four fold, the clutch, transmission, alternator as well as the kick starter but it's just a thought. I'm looking at a 125 cc Yamaha dirt bike engine and trans assembly basically stood engine up and transmission down behind a Yanmar generator engine to shorten the assembly as short as possible. Later I will mock this idea up with some junk parts I have around here and take pictures for others to add Ideas and comments to.

[Diesel Dave]

Like my old granpa used to say....There's nowt new in this world.

Take a look at Sam Bumby's Ruggerini powered VFR Honda and zoom in on the gearbox...

RD350 (RZ350 in the States) with the cylinders lopped off and a triple belt drive.

Cheers
Dave

[bubby-joe]

The point of using a 2 stroke as the base transmission in a diesel build is for those that don't have access to an aluminium welder to close the 4 stroke transmission that in most cases uses the same oil supply for the engine and transmission. In the 2 stroke engine the lower chamber below the piston is sealed or it won't work, if it leaks the engine won't build primary compression to move the fuel charge to the secondary compression area above the piston very poor top end performance, just add a small amount of oil for the crankshaft webs to splash around and the lower end oil needs are covered and close the cylinder base with a plate and gasket, no cutting and welding except for the plate...and just look at the number of potential conversion transmissions available for the most case free for the asking.
There is the point of my original post.
There is after all a very limited number of pre-unit transmissions available in the world any more and most are very over priced, the use of a 2 stroke engine transmission could fill a void at little to no cost to the builder.

[bubby-joe]

Like my old granpa used to say....There's nowt new in this world.

Take a look at Sam Bumby's Ruggerini powered VFR Honda and zoom in on the gearbox...

RD350 (RZ350 in the States) with the cylinders lopped off and a triple belt drive.

Cheers
Dave

Thanks Diesel Dave
I couldn't find that one please point the way I'm still not up on the search tool here. I did find a CB350 with a lopped off engine but no real closeups of how it was done.

[Sphere]

I'm not sure there are any; haven't seen them here (dieselbike.net) or on dieselkrad.info.

[Stuart]

Here's a close-up

[sbrumby]

Thanks for the pic Stu its a better one than I can find. A word of warning, allways take lots of pics when creating, this is hard as its not high priority. On mine which was not too hard, split the engine and get rid of all the bits you dont need, kickstart, oil pump etc. remove crank, 4 bearings on crank remove outer two, to use again, bearings were 30mm ID, so had a length of 30mm stainless machined with thread on one end with woodruff key slot, these were same as original crank so original drive cog and nut fitted. On other end another key slot to take taper lock pulley. Blank plate fitted to where cylinders were. Plug made for kickstart hole.Whole engine mounted 90deg, crank at top. Breather which is now at the bottom I connected small pipe too and this is now oil level sight tube. Place where oil pump was is now at top so now is the breather.
Bit of oil in crankcase just to keep two bearings happy, away you go 6 speed box and oil filled clutch. Hope this helps.

[bubby-joe]

That's a very good written description of how you did it and will help a lot thanks, I have access to a small lathe 3X12 and lots of metal practice material , I also have a small milling table for the lathe bed so key ways are no problem, the picture was very dark and not easy to see clearly between the engine and transmission but It looks like the same idea. Where you go through the engine where the crankshaft was did you install anything to splash feed the oil so the bearings are lubed properly or how do you lube the shaft bearings in your install. And the other entry is right pictures are a low priority during a build but pictures are able to describe far better than my red-neck written thoughts. This is a great site and after talking to a few local friends have a few others interested in similar projects, one wants a diesel quad to go with his diesel truck. But it does spark the imagination. Thanks everyone now it's off to gather more potential parts to modify. My point in what I plan to build is HOW CHEAP CAN I GO and make it all legal and work...

[sbrumby]

No nothing to spash feed oil. But the space where the crankshaft was is half full of oil, so the bearings are half submerged.
Dont forget they used to work with just a mist of oil now they have plenty.

[bubby-joe]

No nothing to spash feed oil. But the space where the crankshaft was is half full of oil, so the bearings are half submerged.
Dont forget they used to work with just a mist of oil now they have plenty.

Good to know. I suppose some kind of baffled vent wouldn't hurt either.