Seized piston?

[420J]

Hello everyone, This is my 1st post. wooohooo :aj: . Anyways I have an 88' RM250

I am new to 2 strokes. I rebuilt the top-end last wwek and it started up fine. Took it to a friends house to tune it in and of course I don't know what I am doing. So were making adjustment to the exh valve deal and topend screw and I am heavy on the gass. I keep it pinned open for about 3 seconds and when I let off the throttle the engine came to an abrupt hault. I try to kick it over but it seems the pistons seized up in the CYL. Just GREAT :|. I just got a LA sleeve instaleed and I put a new weiso piston in. I havent pulled the cyl yet. I was gonna post here to see what you guys think. Is it goona be bad? Do you think I could just replace the ring or is there more probably damaged. I am going to open it up soon. I just hate to think I blew $500 bucks. Thanks for any help guys.
Jason

 

[RM_guy]

I hate to say it but but you did just blow some bucks. :( It sounds like you seized due to not breaking it in properly. The Weisco pistons are forged (which makes them very strong) and need to be broken in the right way or it will seize. There are several threads in the Maintanance Forum on how to break them in corretly.

You may get away with just a new piston and rings. Make sure you check the cylinder over well to make sure it doesn't need to be bored out.

Good luck

 

[420J]

I pulled the cyl off today and well its pretty bad. The piston rubbed the cly wall very hard. Both piston and cyl wall are scored. DANG IT! :( . I am going to take it back to the local shop to get it bored and honed. Also got to get a new Wisco poston :| . THanks for the insight Rm_Guy. All will be well when I learn about these deadgum 2 smokes. ;) Thanks

 

[TFR]

Make sure whoever does the boring also chamfers the ports and relieves the exhaust bridge. Your exhaust bridge was probably not relieved last time. This along with not breaking it in properly caused your seizure. GOOD LUCK. JIM-2-fastracing.