Yamaha runs rough 950-1150 rpms

Z

zappaddles

Recruit
Joined
Mar 26, 2011
Messages
4
2002 TLRB 70 hp 2 stroke Yamaha runs rough from 950-1150 rpms. Had the carbs removed, cleaned and rebuilt. Twice. No change. Mechanic says it must be a cracked, bent or debris laden situation in the reed valves. Other than that RPM range the engine runs beautifully. Any thoughts as to the possible problem? BTW: The mechanic gave me a full refund. Zap
 
C

CharlieN

Cadet
Joined
Sep 21, 2011
Messages
7
Re: Yamaha runs rough 950-1150 rpms

If it is spitting back through one or more carbs you more than likely have a bad check valve on the side of the intake in the drain hoses that go up to the transfer ports.
 
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robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
Re: Yamaha runs rough 950-1150 rpms

Did your carb mechanic linq and synch the carbs after cleaning/rebuilding? If not, might cause rough idle.
 
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