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What causing po-po-po-poppng on decel?

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Just resinstalled head after seat cutting and valve and spring replacement (OEM). I know, there are much better options, but I went the cheap route-consider me a guinea pig. Anyway, pulls as hard as ever and revs out like brand new. 2 questions...

How soon should I recheck the clearances?

What the hell causes the rapid popping on decel? It does'nt seem to be a performance issue, I just don't recall it doing it like that before. Maybe it's just me, maybe it has something to do with the FMF Factory 4 w/Power bomb? I did change the copper exhaust ring and the exhuast is "tighter" than it was before valve job. I went up on the ex. valve shims (obviousy) and one clearance was a tight .11 the other a tight .12. Doubt that's the prob. :thumbsup:

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Turn the fuel screw out a little. If that doesn't clear it up go up a size on the pilot (slow) jet.

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it's either lean or exhaust leak ... sounds to me like an exhaust leak

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Its your fuel screw and jetting. Get FMF's jet kit and adjust the fuel screw to what the jet kit instructions say.

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is it all the time on decel or after a good hard rev. I know when i race theres one corner u go flying in to on the track and coast through about half of it then square off and come flying out of it. When my bike and a couple other 4 strokes go into that corner it sounds like popcorn like none other but its just a lil unspent gas in ur head pipe going out. Its perfectly fine for high performance machines. It probably also did it why u had it all stock but when u put the pipe on u just became self conscience of urself and starting asking questions like "did i do something wrong" or " is the jet not rite"

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Its your fuel screw and jetting. Get FMF's jet kit and adjust the fuel screw to what the jet kit instructions say.

why would it be his jetting ? if it didn't do it before and now it does it after he had the top end apart that wouldn't affect jetting ... maybe if he did a Hicomp piston or big bore but not just because he did his valves

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why would it be his jetting ? if it didn't do it before and now it does it after he had the top end apart that wouldn't affect jetting ... maybe if he did a Hicomp piston or big bore but not just because he did his valves

I said it was the jetting because I thought he said he just put a new pipe on but after re-reading his post it sounds like he already had the pipe. Anyway if he is going to run a fmf pipe or any other after market pipe his bike will probably run better if he jets it per the pipe manufacturers recommendations. Remember they are the ones that put the $1000's of dollars into R&D not the average rider or weekend superstar.

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Go figure.... :ride: I went out for a ride after dinner, and it didn't pop at all. It ran perfectly quite frankly. I didn't touch anything. Stronger than ever, no popping. Don't get it.

Thanks for all the responses though. Still learned some things :thumbsup:

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