how can I tell if my crank is bad?

[Quadboy14]

I have a 95' blaster that I want to rebuild soon (topend), but it has a "wirring" sound by the base of the cylinder. Someone told me that this means my crank is bad, I also have heard this is normal. I don't want to rebuild my topend, then have to do it again because of my crank. Please let me know what you think, don't post unless you have experience please.
Thanks in advance, Ethan:cool:

[underpowered]

grab teh piston rod. try to pull straight up and down on it. it should have a little side to side play it in, but no up and down paly at all. if it moves up and down at all it needs replaced. also roll it over by hand to see if it has any tight spots in the bearings or anything just b slowly turning the crank by hand.

[Quadboy14]

thanks, does anybody have any way to tell without taking the head off.

[250X_project]

You can turn it by hand with the kicker to feel for the main bearings. Then again you said you want to rebuild the top end anyway. ;)