125 rebuild

[weebles]

how do I find out if my head needs to be bored out or if I just need rings and how do I find out if I need a new piston

[dklassen]

First of all you don't bore the cylinder head. The head can be machined to raise compression but that's not what your dealing with here. The cylinder is what wears as do the piston and rings. If your bike has a coated cylinder like most modern MX'ers then the cylinder can't be bored like the old steel ones. There is lots of discussion on this site regarding re-sleeving vs re-chroming on this board. I suggest that you take the cylinder, piston, rings and cylider head into a dealer and have them look at it. They can tell you what it needs.

[yamahammer01]

get a compression tester and twist the throdle wide open and get it 5 good hard full kicks and see what the compression is in the cylinder. that will get u started in the right direction.