Went into Mongoose but when they looked at the sleeve and piston they think I have a detonation problem which I need to fix before getting the the work done. Anyone have any ideas where to start looking for that??
yea, check what gas your running and what spark plug you have. check your owners manuel and make sure your running the right plug....if both the gas are good and spark plug is right, its prolly in the ignition somwhere
Odds are that your timming is not the problem....what has been done to the bike??? any jet changes....I need a bit of history....a shot in the dark would lead me to start looking at the jetting...weather plugged or changed....basically a 125 is a high reving engine and to get detonation it has to be running lean or the timming is out...but the timming on most MX bikes has limited adjustments...unless the back plate screws came loose or the flywheel came loose and sheared the key...that can be easily checked with a little screwdriver in the plug hole and turn the crank by hand until you feel top dead center and there will be 2 lines on the ignition back plate that should be close to the line on the crank/flywheel...i doubt you have a dial indicator so this should get you close...to rule out the timming issue....
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