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2003 Nissan 9.9 HP 4-Stroke missing at higher RPM's

mills

Contributing Member
Picked up a Nissan 9.9 HP 4-Stroke. Carb is absolutely clean, new spark plugs. Took the carb apart and made sure all the small orifices are clean. Starts right up on first or second pull. Idles great. BUT misses badly at higher RPM. Changed out the coil with another one. Same issue. Pulled the flywheel to be sure all is well. Plugs look black and sooty after running at higher RPM's. CDI unit???
 

mills

Contributing Member
Sounds too rich. What main jet is installed?
Paul,
You are right on! Sorry about the delayed response but we were gone for 2 weeks. I had 2 carbs for this motor. They had different size main and secondary jets. I installed the jets with the smaller size and it now runs GREAT. THANKS for your help.
 
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