Cascade Crew

nonsensekid20 · Posted: Fri Feb 11, 2011 4:14 pm Post subject: Boring a cylinder

How much material can be taken off when boring a cylinder? FYI this is on my 2-stroke YZ250

Twilightoptics · Posted: Fri Feb 11, 2011 4:39 pm Post subject:

Depends on the engine specifically.

You bore the engine to the piston size.

If you "bore" and engine, you need oversized pistons.

If you "hone" an engine, and the bore diameter is still within specifications, you can reuse the old piston/stock piston.

Though it sounds like your piston is junk anyway.

nonsensekid20 · Posted: Fri Feb 11, 2011 4:43 pm Post subject:

This goes back to the other post.

The cylinder is all messed up. So I need to bore it out. YZ250.

Twilightoptics · Posted: Fri Feb 11, 2011 6:06 pm Post subject:

Means you take it to the machine shop. And talk it over with them how indepth you want to/need to go to rebuild the motor.

nonsensekid20 · Posted: Fri Feb 11, 2011 6:19 pm Post subject:

I know that. I'm wondering how much material they can take off.

chevymad · Posted: Fri Feb 11, 2011 6:21 pm Post subject:

nonsensekid20 · Posted: Fri Feb 11, 2011 7:59 pm Post subject:

Is there a maximum amount?

Dewey316 · Posted: Fri Feb 11, 2011 8:06 pm Post subject:

nonsensekid20 · Posted: Fri Feb 11, 2011 8:19 pm Post subject:

Alright fair enough. It's been resleeved once. Hopefully I don't have to do it again. The cuts didn't seem that deep. That's why I wanted to know how much they could take off so I could measure it and not waste my time goin into the machine shop if I didn't have to.

Twilightoptics · Posted: Sat Feb 12, 2011 1:29 am Post subject:

They might tell you the "cuts" are normal.

Piston rings score the cylinders in nature. How much is okay.... is subjective.

blue89 · Posted: Sat Feb 12, 2011 6:01 pm Post subject:

I would also check to see if over bore pistons are available for your engine and what sizes.

nonsensekid20 · Posted: Sat Feb 12, 2011 7:27 pm Post subject:

Cylinder

Piston

Cylinder head

BigDaddyVu · Posted: Sat Feb 12, 2011 10:08 pm Post subject:

thats really bad might need a new head. take a pic of the piston ring grove and include the ring pin. rings on 2 stroke pistons have to be stationary. looked like you broke the pin and the ring rotated and the end gap caught the intake or exhaust port.