rebuilt 250r engine squeaking?

[jaykup]

I just finished rebuilding my '81 250r. I had it bored, honed, and ports chamfered from Eric Gorr, in Madison WI. He bored it using a 1mm over OEM cast piston for specs. I replaced everything, base gasket, head studs, head and base nuts, reed cage bolts, the works. I installed everything with a healthy amount of Motor Oil. The only hacked part, was the previous piston was a Wiseco, and I re-used the wrist pin. I checked it against the manual, and the OD specs OK. I had to shorten it using a grinder on one end because the stock OEM piston's cir-clip positions are closer in than the Wiseco. This shouldn't have affected anything. When I kick over the assembled engine, it squeaks. Think of a dog chewing on a squeaky toy. Every time it passes the compression stroke, it squeaks!

I thought, maybe it will go away once it starts. So I started it, and it still squeaks, loudly, and much much faster. It also seems to be lacking power (just idling with 16:1 fuel mixture for break in) when I rev it, until it hits the powerband. This is probably just due to the rich fuel mixture though.

It moves freely, when you kick it with the spark plug out.

I started taking off parts to see if it changed. When I kick it, it squeaks fully assembled, with the carb off, then with the exhaust off, then with the head off. When I remove the cylinder and piston, and spin the crank by pushing up and down on the connecting rod really fast, it does not squeak at all.

I guess the only thing I didn't check was if the reed cage has any effect on the squeak when it is removed. I'm going to try to check that now.

Any ideas??? This is totally weird, and I have never had this problem, nor can I find anything on google about it.

[qwvwvwvq]

it sounds like air or combustion air is leaking out the cases . possible crack in cases or a bad seal. with the motor fully assembled the upper and lower of the engine is pressurized. I had a seal leak in my cr500. I heard it come from the oil fill cap. squeak. I took off the cap and put my thumb over the hole and at the end of the stroke at it highest compression it would leak and with the cap on it squeaked. good luck!

[Paulie B]

Definitely sounds like an air pressure leak. Check the easiest parts first- the head gasket then the other stuff like the base gasket and then the cases.