Originally Posted by Hicksy
I'm running in my 66cc beastie, it's only got 80km on the clock at the moment.
She fires up easily enough using choke, within 2-3 mins runs well with choke off.
Low range pulling is fantastic but when I get the speed up it sounds like it's faultering. Almost like it's only firing every second stroke.
The plug has no residue on it, still shiny silver, running 20:1 mix, blue smoke at mid throttle to WOT.
Break-in is best accomplished with the use of various throttle positions and engine speeds- don't be afraid to run it up once in awhuile, it's not going to grenade just because it's new. Baby-ing a new engine will not help in any way.
Now, these engines are piston ported crude old school engines. You are a little rich in the mid range from the sounds of it. These engines will break into a four cycle when they are not loaded (going up hill/speeding up/ect) if they are set right. If you are trying to speed up from mid range and it still is four cycling, you are too rich. If it breaks into a clean two cycle with application of throttle, you are in pretty good shape.
In my experience at least, if you get these things to run in a nice clean two cycle all the time, they are too lean and suffer not only in power, but engine longevity. (wristpin, bottom end bearings).