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1982 ITyamaha 125 wont rev up.

6K views 2 replies 2 participants last post by  MXLord327 
#1 ·
hi my bike wont rev up when it is under load if you ride it nice and easy and not to much gas its fine the second you give it gas to take off it bogs out .but it will sit there and idle all fricken day please can someone help me .
 
#3 ·
There could be a lot of different things causing this - the carb jetting could be either way too rich or lean, each will cause a bog when wacking the throttle wide open from idle. There could be water in the carb, or the jets could be plugged from crud collecting in the float bowl. The top end could be completely worn out - a distinct possibility for a 27 year old 125. The pipe or silencer (spark arrestor) could be plugged with carbon, the air filter could be completely covered in dirt, the ignition timing could be way off. I would start with the simplest things first, clean the air filter, check the spark plug for color, take the pipe and silencer off and make sure they are not plugged, pull the carb apart and blow out all the jets with compressed air, and do a compression test on the motor.
 
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