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Engine Won't Idle Down

S

Swagonmaster

Regular Contributor
OK, I'm going to take another stab at this idle speed problem. It's a '79 merc 140 2 stroke that won't idle any lower than about 1500 rpm and this is even with linkages taken loose. The carbs have been overhauled and taken apart and rechecked and I've shot carb cleaner all around the carbs and manifold without finding any air leaks. I can live with it but my wife is having fits getting the boat on the trailer at times because she can't approach the trailer with the engine in gear. Any ideas would be appreciated.
 
Step #1 is always a compression test.----Post the numbers.----Test for spark on all leads that jumps a gap of 3/8" or better.---How did the motor run last year for you ?
 
Idle speed with the carbs fully closed is 3,000 rpm at full spark advance. The ONLY way the motor runs lower rpm is by retarding the spark. There's a stop that needs to be adjusted--that's why it won't idle any lower.

Jeff
 
That makes sense as a repair, I had tried pushing the timing advance rod back and it finally slowed down a little so I guess I just need to pull some more timing out of it.
 
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