I have a 1989 250 moto4, the other day i went to start it and it didn't sound like it was turning over.(it made a clunk when i hit the start button) but it was, it had no compression. i took off the valve cover to see if the valves were moving, they were not. so i took off the cam cover to see if the cam and cam chain were turning, i found out they were not turning either.

Does anyone know what happened? have any suggestions?

 

The timing chain probably jumped off the gear on the crankshaft.

 

how would i get it back on? would i have to take the motor apart?

 

well if it jumped off its prolly shot, they stretch over time, just find out what side of the engine the chain is on, pull that cover off and the stator and whatever else so you can see it around the gear on the crank, and you might have to pull the cylinder head off to get the chain back up onto the cam gear, make sure your bike is on top dead center and your cam gear is lined up with the index mark when you put it back on

 

okay, i got a mechanic so he should know what to do