Question My grandfater bought this new and it means alot to me. the problem i am having is it seems to run fine when ideling but bogs down when i try to take off. Almost like trying to take off in a higher gear or something. I have had the carburator off 3 times cleaned and rebuilt but it doesnt help.
AnswerJosh, I'll assume it is the Enduro MT125 and not the MT125R roadracer! :>)
Carb specs: 24.00mm float level, #98 main jet, #200 main air jet, #50 slow (idle) jet. Timing spec is 20.5mm (1.96mm from TDC, using a dial indicator).
Point gap should be .012"-.016" B8ES plug at around .025" gap. Clip on the slide needle is set at middle of the 5 positions.
When dealing with 2 strokes, you have to consider that they have crankseals on both ends, one behind the ignition and the other one off the transmission side. If either are leaking then you can have either a lean condition or a oily rich condition, depending on which side is bad. You have to use a 2 stroke vacuum draw system to determine if there are crankcase leaks at either end of the crank.
After 31 years, the crankseals could well be worn/leaking which requires a full motor teardown and crankshaft rebuild.
Being that you didn't mention adjusting the timing or cleaning the points, I suspect that the point gap has reduced itself down to where there is insufficient spark timing to allow the bike to make decent power. If you are sure that the carb is to specs, the petcock is clean, the tank gas cap is venting and the motor has good compression and no vacuum leaks, then the spark timing is probably the main culprit at this time. The spark timing is fixed at 20.5 degrees, but could slip backwards 5 or 10 degrees with worn points, still giving a good idle, but no power under load.
Bill Silver
