Hello to you all, I have searched a lot with no luck at all bit here I saw many that know about this engines, my engine is not from a minibike but from a genset, I got an AllPower 3500watts genset model APG3002D was working perfect, this Saturday I heard it was running out of gas so I went turned OFF the breaker and finally turned the genset OFF, took the opportunity waited for the engine to cool off changed the sparkplug with factory specs NGK BP6ES gap it to specs, when I tried to start the engine it turned a bit and then I almost brake the pull string because the engine stopped like it had something on top of the piston, . I thought maybe there was something around the sparkplug and when I removed the sparkplug it fell inside the combustion chamber, removed the engine head and all was good, with engine head removed tried to pull the string and still very hard, turns if I use ratchet with a 22MM socket but very hard, removed the generator so I can try to turn engine with nothing bolted to it and nope still hard, I now got no clue what is the problem, wondering if the crankshaft ball bearings can cause this, but I will really like any ideas or opinions from experts on this type of engine before opening it, have no problem to open this engine I have rebuilt a few B&S, Tecumseh back in the day, forgot to mention I removed the flywheel just in case something was there blocking but nothing, the flywheel key is also in perfect shape, removed the oil and no particles of anything, I can upload photos if you need, the engine has info being made in China by JD, 6.5HP OHC, thanks in advance TP