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Old 22-11-2016, 14:52   #1
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idle richness Yamaha 15 4 stroke

I just replaced the carb on my engine. It starts great, runs great I am ramping up the throttle slowly, just before the main jet starts working, the engine boggs down just a bit and then accelerates to the main jet.

I am guessing this is a idle richness issue, but I can't seem to dial it in.

The last carb was old and original and had been apart so many times I decided up for a new one.

New plugs, oil, and gas...It is annoying and it doesn't die, just runs rough at that one very small twist of the grip. I'd like to get rid of that spot. It starts from dead cold first pull.

Anything ideas?
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Old 22-11-2016, 17:15   #2
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idle richness Yamaha 15 4 stroke

Find the idle air screw if there is one, may be under a plug that you have to remove.
What you describe is classic lean mixture to meet emissions testing, and yes there is of course a point where the carb comes off of the idle circuit and onto the main, of course the idle mixture adjustment will not have much of an effect at all on the main circuit.
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4 stroke

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