Quote:
Originally Posted by mister c
Thanks for the comments. I think that I'm going to have to rebuild the engine again. I thought that I was lucky that she ran with such an old crankshaft in, but have been having problems with carburation.
The bike ticks over fine & runs great after 6000 rpm, but is really fluffy up to 6k. The only thing I can put it down to is the crankshaft oil seals as I've set the carbs as per the manual, then set them as well as I could to no avail. The way finances are at the moment & with Winter on its way soon, I dont think it will be done until next year  |
What a pity, it is a very nice bike, indeed you have made such a nice job of it that you have to fix it properly.
Have you pressure tested the crankcase yet? You are a very competent mechanic, so I’m guessing you know how. It would not take long to rig up some bungs, a pump and a gauge to check out each side with the bike still in the frame. That won’t help fix the issue, but you will know what and where it is. At the very least you will be able to identify whether the issue is with an outer seal or (I suppose much more likely) an inner seal.
I rather assume you changed the outer seals on both cylinders as you were building up the motor, but depending on the results of the pressure test I wonder whether it might be worth changing both again. I don’t know that particular engine, but it looks like it is piston ported (well, no disc valves anyway) so the outer seals will be a really simple (and cheap) job.
Good fortune.
A
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