still popping on decel - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 6 (permalink) Old 04-22-2009, 05:30 PM Thread Starter
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still popping on decel

I've had popping (afterfire) on decel since I owned the bike - about 2months). I've already coastered. The carb boots are all tight and not leaking. I've sprayed carb cleaner around the exhaust manifold while engine running with no apparent response.

My pilot screw is out 2 1/4 turns on both carbs and have had it out as much as 3.5 turns and still have popping.

What's the next step for me?

He who whittles himself down to please everyone will soon have no legs to stand on.

99 750
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K&N filters
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post #2 of 6 (permalink) Old 04-22-2009, 07:34 PM
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Looking at what you have done already, with coastering,K+N filters and costom pipes, I would say you are running lean. Look in threads about rejeting the carbs, when others have done what you did they had to do the Carbs also.

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post #3 of 6 (permalink) Old 04-23-2009, 06:50 PM Thread Starter
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I think you're right. I've double checked exhaust headers for leak/draw. Doesn't seem to be a problem there. So this evening I backed the pilot needle out farther than I've ever tried it...to 4 turns. And it helped immensley. Most of the popping is gone.

Is it okay to have the pilot screws out that far?

He who whittles himself down to please everyone will soon have no legs to stand on.

99 750
18K
Coastered
K&N filters
Custom pipes
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post #4 of 6 (permalink) Old 04-23-2009, 07:29 PM
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What color are your plugs? White/lean Black/rich Tan/Good


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post #5 of 6 (permalink) Old 04-23-2009, 07:38 PM Thread Starter
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Last week I pulled the plugs (they're pretty new) and there was a lot of black. But I had a big problem going on with the vacuum line off the tee from the carbs was blocked and causing some real problems.

I'll recheck the plugs now that its been running good for about a week.

He who whittles himself down to please everyone will soon have no legs to stand on.

99 750
18K
Coastered
K&N filters
Custom pipes
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post #6 of 6 (permalink) Old 04-25-2009, 08:24 PM
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try this...

an old school method of adjusting the carbs is to attach a pressure guage to the vacuum line of the carb. screw the mixture screws all the way in and out until it sounds like its running correctly. just pay attention to pressure guage and the noise from the exhaust. doing this to each carb will give better synched carbs
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