Could be a exuast pipe. Just so happened that I match ported the flange a little to much cutting just close enough to let it hang on until I modified it with a thermal jug, a aluminum no trespassing sign, a AZ licence plate, some strips of rubber inner tube tire, hose clamps, screws, 2pt epoxy puddy. Ultimately birthing it into your broke, I wanna tuned pipe now.
Soo... Much more power.. you need the expansion chamber and tuned to your motor. My flow bench meter worked great for me
Anyways while going to get tubes for my next build, I needed to put one of the original exhausts pipes back on. Night an day, went super snail away.
Soo try your pipes. Drill out the center tube inside it. Let"r breath. Or just order the pro pipe and know it's a belt you can be change to the next brand new rebuilt motor you get.
Safe to say it's a $50.⁰⁰investmentand that usually doesn't fail.. and or your ports could be casted halfway closed. Mine was just waiting to crumble off before slapping around and letting alumi cast take it all out.
Did check the eco screw located around the other side of the crank cqse. ? Could also be that it or you just need to let the solar fins around the cylinder jug continue to charge up the spark for just a bit longer. No one ever talks about that very much.
Chain could be binding, tires could be low or lil more on the flat side, could have to much oil an need to burn it hot, try giving it that. She likes that after I fill her up from the pump and just dump in a old 99grape shot bottle full of 2stroke oil into her tank. Shaking it up sometimes doesn't work and it all drops down into the carb. She bogs out. So I choke her to the point of her pop pa pop bopbopbaba vroom when she's been getting thick and couple times being cold outside with these storms I've even just left it in the ¼/almost mid range choke.
it's motors 1st rule of law...