Alright so I bought my friends pitbike, i believe its a 2004 ssr 125cc four stroke, yesterday I paid $500 and i was riding it in the yard this morning and the chain fell off and i put it back on and got it going again, then once again it fell off i put it back on the second time, then I was riding down the road in 3rd gear and shifted into 4th and the chain flew off wound up around the gear and this is my outcome, pics below. Is this fixable or should i just throw a new moter in it, the bike already smokes bad when i start it up so im guessing its either the valve seals or the piston ring. so should i just pick up another motor or what? Here are some pics to help justify what I should do.



