XR350R: 1983-84 Transmission In 1985 Engine. Is This Possible?

I am working on a 1985 XR350R , and I was wondering if anybody in the forum with experience with those bikes could help me out with a question I have. The bike has a broken transmission countershaft which is very difficult to find since it is only available for that particular year.

The 1983-84 bikes use the same transmission set while 1985 bikes have a different design according to their parts diagram. I believe it was because the bike was modified from a wet sump engine to a dry sump engine. I am wondering if I could retrofit an entire transmission set from a 1983-84 engine into a 1985 engine. It would have to be an entire transmission since they have a different design. In fact I would have to replace the bearings that support the shafts as well. Shift forks, shift drum and gearshift spindle are all the same on all 3 year models.

Does anybody have any thoughts on that? If that cannot be done, my options are to let go of this project or replace the entire engine with one from a 1983-84 bike or oven a different size engine.

It is possible. About 20 years ago, I installed a transmission from an '84 XR350R into an '85. Unfortunately, my alleged memory is hazy and I did not keep notes so I have no specific info. I remember that I had to mix and match a couple of gears and had to buy a couple of bearings. Bring up the parts fiches for both years and compare part #s of the various components, that will be a start.

It is possible. About 20 years ago, I installed a transmission from an '84 XR350R into an '85. Unfortunately, my alleged memory is hazy and I did not keep notes so I have no specific info. I remember that I had to mix and match a couple of gears and had to buy a couple of bearings. Bring up the parts fiches for both years and compare part #s of the various components, that will be a start.

+1

That's what I do when I want to check the interchange of parts; print out both part fiche and compare line by line.

I know the crankshafts are different but the trans likely share at least some of the gears. I just picked up an 83 for nearly nothing. A guy needed a disc brake front wheel, some supertrapp discs and a front master cylinder/lever for an 83 XR500 and he was happy to trade the whole 350 for them. Good engine and suspension but bent frame.

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