carb spitting

Can anyone give some input for an Xr 600 (97) which is hard starting, bad idle, will idle for 3-5 revolutions then seems to backfire through the Carb, (brand New), recently rebuilt engine, would like to know if anyone is familiar with where the impulse setting should be, I'd assume that it goes right on the mark, my book doesn't mention anything (Clymer) any advice would be appreciated

well, diagnosis by text is a sketchy science but, I think if I had this problem, first I would make sure valves are not too tight,sure has the symptoms.

next the multi meter comes out, (I hate this part) and check all electrics.

I am curious though, did this thing run before the rebuild or was this the reason for it?

I don't think it's a spark timing issue, I don't think you can change that, at least on my '86 you can't and I can't see honda changing that it would cost money to re-tool.

I can see the pulse coil going bad and sending a bad signal, or a bad stator, but this is a usually warm engine thing,and a few rev.s isn't long enough to get warm.

Yes,,check those valve/tappet gaps,,and of course plug gap..Surprising how a bad gap on the plug can affect a 600..Something so simple but if it's wrong the bike goes but not very well as I learnt when trying to use a feeler gauge with too many or too few zeros and dots,,

Please lets have standardization..

Edited by Horri

Sounds like and air leak some where maybe the intake O-ring is bad or boot is cracked.

Pop's

Sounds like and air leak some where maybe the intake O-ring is bad or boot is cracked.

Pop's

certainly,,that pop and stop through the carb/air intake is a difficult one,,Multi choice.

certainly,,that pop and stop through the carb/air intake is a difficult one,,Multi choice.

I agree witcha Horri........:smirk:

It could be a multiple of things.

If the cam chain is worn, the cam gear can jump a tooth out of correct time. The intake valves then open at the wrong time and allow cylinder pressure to escape backward through the intake.

A similar effect can be cause by an intake valve which doesn't seal well.

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