Question about 1987 Yamaha SDR
After riding for a short while my 1991 bravo begins to lose power and the idle gets rough
Are you turning off the choke after its warmed up? bike will not run right if the choke is left on and will seem like its losing power. if its off, then read on.
pull the spark plug and take a look at it. does it look like light brown toast (as it should) at the end that goes into the cylinder or does it look like it is brand new (still white)? if it looks brand new, then its indicating a lean condition and will run very hot (you may see evidence [blueing] on the exhaust pipe where it exits the cylinder head) and stop running. hopefully damage was not done to the piston (usually a lean condition will put a hole in the top of the piston). if its a lean condition, then read on.
so what's causing the lean condition? have you recently added a high flow air cleaner or after market exhaust pipes without rejetting the carb? or maybe you had to rebuild the carb, bought a kit from a dealer and the size of the jets were not correct? if you can return things to the "before" condition one at a time, then you can determine what change caused the problem.
Posted on Jan 18, 2009
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