I have a 64 CC Stihl chainsaw motor that came out of a old 039 Chainsaw. I had to install a Transil Products ignition system on it to make it run. I have the timing set at 28 degrees and I have one of those C & H timing modules in it. The motor always ran pretty good but would backfire, or pop at full trottle. No matter where I set the timing or needle valves it always popped. The last time I bought gas, I mixed up some 24 to 1 instead of the 40 to 1 that I had run for years. Guess What? The backfiring and poppping went away. Also I'm just using 10 W 30 motor oil, not synthic oil. I think the extra oil content provides a better seal for the rings which ups the compression ratio.
It's a fantastic motor now. I have a Auto-cad drawing of all the parts I needed to make if anyone is intrested. Free!!!
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