siezed yz engine

[shooter114]

:yikes: hey all just seized my yz125 engine on the weekend and was wondering what was the easiest way to free the piston from the barrel without causing to much damage to the barrel? i removed the head and had a look into the barrel and it looks like the piston is at the bottom of its stroke so going down to free it might not be an option!

 

[2strokerfun]

Generally, you unbolt the cylinder from the case and lift it off the piston. I've never had one seize so bad I couldn't get the cylinder off of it. I've heard that pouring a little ATF on top of the piston and letting it soak for a while will help loosen a piston, but the only time I had to do that was an old engine where the rings were rusted to the cast iron cylinder. You should have a Nikasil-coated cylinder. Once apart check it closely and inspect your main bearing and lower rod bearing.

 

[_JOE_]

Chances are slim that the plating in the bore is still useable. I would be more concerned with trying to reduce stress on the lower end while disassembling. You can get two peices of wood and slide them in under the cylinder after you unbolt it, then use another piece of wood on top of the piston and a hammer to gently drive it out. Good luck!!!

 

[rmc_olderthandirt]

When mine was stuck I sprayed a lot of WD-40 in the spark plug hole and then shifted up to 6th gear and rocked the bike back and forth until it broke free.

Rod

 

[shooter114]

thanks guys, im going to have a crack at it this weekend so ill let u know how i go !