K1 RM125 sounds bad.No idea why.

May 13, 2018
It sounds like running rich, but the spark plug is nice brown, and i have just replaced my crank seals. My ignition is retarded a bit. Running on 95octane, not better with 100 octane. Premixing with motul710 1:40. The bike pulls great, but sounds bad for me. The bike was rebuilt and I ran 10hours since rebuild. Stock nicasil cylinder, Vertex piston (C size),new bearings(Prox(ntn)),and seals. Please help me why it doesnt sound well! Heres a video where i pushing it, but its not clear sound.

i cleaned the carb several times. it was running with 460 main jet, the spark was black.I replaced with 430 and its nice brown, and the sound of the bike is better, but still not clear.I dont want to go smaller main jet because it would be too lean, i dont want to seize it. pilot 25(stock 40), Main 430(stock 460), needle in the middle, air screw 0.5 out(if 1,5 out it bogs when i pull the throttle at low rpm.)Spark brown.(at full throttle i cut out the engine and i screw out and check the spark plug.)
Reed seemed OK.(no gap)



Dec 31, 1969
Dallas, Texas
Couple of things ... maybe it's the video, but it sounds fine to me? What was the procedure you used to read the plug? Removing the plug after just "riding around" won't allow an accurate read. I'll let the jetting guru's comment further, I'm not one of them.

@Rich Rohrich
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