I've gotta Stihl 180. Too bad the carb is self adjusting, so no tinkering screws anywhere. It's been working allright in stock shape, but lack of screws worries me if I do any port job on it.
I timed the ports several times over on this 180. The stock timing sets new standards for word "conservative". I did check and recheck for errors in timing. None that I can find. Figures are here:
EXH. DUR. 140º
TRANSFER DUR. 96º
BLOW DOWN 22º
Local Stihl dealer told me the unloaded max rpm for 180 model is 15 000rpm, and cutting is at 10 000rpm.
I'm surprised the thing can actually cut at 10 000rpm with those timings.
I guess I'll try straight on with a pipe before anything else. I'm hoping that'll give some more oomph.
Theory behind this approach is that I'm dumping precious air/fuel mixture straight outta exhaust. Having design pipe to take care of that, my cylinder's volumetric efficiency should get better, hence more power with somewhat same fuel consumption (and I most likely don't have to worry about readjusting the carb, which cannot be readjusted anyways).
I have bought a 2-stroke pipe design software. That makes design job for the pipe a piece of cake.