Thanks for reporting back on that Micky. It validates what the workshop manual says, and agrees with a good proportion of the various internet reports too: it is a good, smooth running engine that has the misfortune to have a carburetor that is difficult to clean properly. However, I don't recall personally hearing of a "problem engine" Suzuki M120 that was not due to a simple carburetor fouling issue, or at least might have been (in many cases the owner never did really clean the carburetor the right way, so we don't know if it would have fixed it).
You've given us a clearly documented case now on Outdoorking. I think we had one before that was carburetor, and one where the member put the job aside when simple maintenance didn't fix it. I don't recall any more than those two cases. So, yours is a really useful addition to our archives. And congratulations on sticking with it until you found the answer.
