I boomeranged back to mopeds and have been playing with a cheapo kstar. The silly thing struggles to rev past 7500k unless I have gravity helping me out.
- unported kit, B- case matching job (it's just mild), thick enough base gasket to just let exhaust fully clear
- za50, have tried both 20x40 and 18x40, same RPM ceiling basically
- pretty mostly confident it's buttoned up tight with no leaks
- 15mm bing with a 78 jet, richest needle setting
- MLM peoples sidebleed (troubleshot this by putting it on a TCCD kit I also have, rips right up to 9k)
- high comp O ring head
- some mystery CDI that starts at about 25 degrees and retards down to 15 or so (works lovely on that aforementioned TCCD)
SO, the one thing that is pretty glaring is that the piston crown is 1-2mm short of hitting the top of the cylinder. Certainly no measurable squish using a 1.5mm thick piece of solder (I should probably get a bigger gauge solder). This issue has been covered a little bit before on here - most notably this thread - but it didn't seem like there was any good solution. Kinda feel like probably everyone has this kit so maybe I'm missing something.
Roffman already advised me to just sell it, haha, but I like torturing myself. Is there any reason that I couldn't just manually lap the top of the cylinder down 1-2mm? I'm using an O-ring head, so maybe it would be forgiving? Do I just need to throw a bigger carb on it? That doesn't seem to equate with the expectations I'd had reading other people's results with the kit.