QuestionHello fellow expert! I'm Bill forster, an expert in the auto body repair section. Anyhow, my 82 Kaw CSR 750 twin has a pretty major running problem, it backfires thru the exhaust, and the carbs. I cleaned, even replaced the carbs with KZ750 carbs, to little avail, I've cleaned dozens of cycle carbs over the years, and I really don't think the carbs are the prob. I also took off the stock electronic ignition, and put on a points plate and advance from a kz750, but with little result. It seems better, but it still isn't right. I took the cam cover off, but I can't really determine if the cams and crank are lined up properly. The fact that you can adjust timing with a points plate as opposed to an electronic ignition leads me to believe that it's jumped time. That would possibly explain why it runs better with points. I don't know what else to try. I bought the bike non running for a song, but it would be great to get it to run properly. The cam gears look good, and what I can see of the crank gear looks good, also. Do you know how to line the timing up on a kz twin? Or do you have something else I could try? I'm normally a good wrench with a bike, and have had several motors completely down, and assembled them again- and they ran! Why won't this one cooperate? Thanks, Bill
AnswerHi Bill.
If the crank jumped timing, then the bike wouldn't even run. What could be the issue is the valve gap or valve seals. If those are overdue for adjustment or the seals are no good or worn, then you could be looking at the cause for the backfiring.
Now if it has managed to jump timing and still run, no matter how poorly, then it is probably only a tooth or two. There is normally a mark on the cam gear which will match to one on the cam chain. If that bike has one, then you should be able to match them and correct the issue.
I would refer to the repair manual for the specifics on that.
I wish I could help you more on that.
Good luck and ride safe.
FALCON
