Motorcycle Repair: Locking Tire, yamaha 125, bill silver

Question
Hi Chris, I have a problem with my Yamaha 125 dirtbike. It's a 1981 which generally runs great, but last time I had it out, I did something to it. First off let me tell you about how I start it. The kickstart does not work any more so I run start it. Anyway, when I run and jump on it, then hit it down into 1st gear, the tire locks up and it dosent start or even try to start, it just locks up and skids. I thought it had something to do with the carb sticking, but I took that apart and cleaned it so it works good now. If you could help me with this and hopefully tell me I didin't blow the engine again it I would be very thankfull.


Thanks, Chris


Answer
Chris, if the kickstarter doesn't work and it doesn't turn over when you bump start it then the engine is seized....
Either the crankshaft is damaged or the piston is stuck in the cylinder.

Pull the exhaust pipe and look up inside the port to see the condition of the piston. Take the crankshaft cover off and see if you can turn the motor over with a wrench.

If it doesn't turn over, then you have some big repairs to do.

Take the cylinder head and cylinder off next to see where the damage is.

The only other possibility is a damaged transmission gear that is locking up the whole power train. If the bike will roll with the clutch in then it is probably the motor, not the trans.

Bill Silver