250r rebuilt 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.

[Daddio]

It sounds like a leaking head gasket to me but Ive been wrong before.

[jaykup]

I wish that was the case...

I removed the head completely and kicked it over. It still makes a very loud squeaking. :(

[Erics350x]

wrist pin bearing

[lndy650]

^it could be the wrist pin bearing.

try a wiseco wrist pin

[jaykup]

I have a wrist pin and bearing that is wiseco. The piston is stock OEM.

I found the problem though.

When I remove the reed cage, no squeaking. WHen it is on, tons of it. Reeds are probably bad.

They are slightly bent (metal) inwards, and I tried to bend them straight, but it didn't affect the squeaking at all.

It is not the gaskets or the gasket surface. All has been cleaned and sealed.

Anything I can do with the reeds to make them work? I really wanted this running tomorrow.

[Erics350x]

try fliping the over on the cage, also make sure you piston isn't backwards

[jaykup]

flipping the reed cage didn't help

the piston has an IN stamped on it, which is facing towards the intake manifold

I hope that is right.

I bent the reeds enough now so it squeaks on kicking and low low low idle, but as soon as you rev it goes away (or I just can't hear it)

Before it was overpowering the exhaust/engine

I hope it is OK for tomorrow.

Thanks for the input

[toocheaptosmoke]

the piston has an IN stamped on it, which is facing towards the intake manifold

I hope that is right.



You just have to make sure the ring ends are not on the exhaust port side, they won't last long like that.

[jaykup]

Ok, after being out on the trails, I actually figured it out. The reed cage was just causing a pressure build up, making the base gasket leak.

When I removed the old gasket, I left small amounts of it by the studs (idiot!) They acted like spacers to hold the base gasket up. With the reed cage in, air was escaping. This was very noticeable after riding, and seeing exhaust / fuel air mixture shooting out of the side.

I completely removed the rest of the old base gasket, put some RTV down, and it ran great for hours on the trail after that.

As for the ring position, there are notches in the OEM piston that I made sure the rings were set at. They were both on the intake side.

Thanks for the input, you guys were right in the beginning about a leaking gasket, head or base.