Yamaha 115 carb 2 stroke surges

prolineez

Cadet
Joined
Aug 19, 2005
Messages
17
The motor is a 115 hp 2004 carb 2 stroke. A dealer that, in my experience, has little ability to diagnose and fix a problem rebuilt my carbs because the motor was hard to start. That did not solve the problem and I went to another mechanic who fixed the starting problem with a simple ajustment to the choke plate. Now I have a surging problem. At about 4000 rpm and above the motor surges. It idles fine but above 4000 it will go from 4800 to 4000 then back up again. It does this for the first 20 to 30 minutes and after that I can run all day no problem. What could the dealer have done while rebuilding the carbs to cause this problem?
 

rodbolt

Supreme Mariner
Joined
Sep 1, 2003
Messages
20,066
Re: Yamaha 115 carb 2 stroke surges

have another tech open up the carbs for a look, you may wish to run a fuel system vacum test first.
 
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