Fresh topend, Chirping sound?

[fishx65]

Got the topend done this weekend and fired her up! Fresh valve job and cylinder bore. It made a chirping or squeaking sound for the first 20 miles. This sound was easy to hear at idle. Seemed like it was gone when I ran it today for a little while. I was kinda worried that it was the cam bearings because it was definitely coming from the motor. Any ideas or is this normal with a fresh topend? Other then that she seems to be running great.

Thanks, FishX

 

[ratchracing]

Did you check for oil pressure at the small set screw on the right side of the head?
What was the ring gap with the new piston/rings? Did you bore or hone the cylinder?

 

[jasonp]

That sounds like a head gasket leaking or exhaust gasket donut.

 

[fishx65]

I went with a bore and hone. New 84mm piston. I did not check the ring end gaps before I put it together. I assumed the shop checked everything since they had the new piston and rings before the hone (OOPS!). Should I have checked the end gab of the rings? Head gasket does not seem to be leaking at all. Talked to a mechanic who thought the sound might have been the new valves seating. The shop I had the valve job done at told me that they do not lap new valve seats. Sounded kinda strange to me but I went along with this since I don't know much about cutting fresh valve seats. I would hate to pull it apart again but I'll do it if I missed something. The end gap thing is kinda freaking me out!

 

[ratchracing]

You should always check ring gap, that said I've gotten away without checking it on lawnmowers and mini bikes which all ran fine.

Is the engine still making the sound or has it stopped?

 

[fishx65]

Thanks for all the responses guys! After the first 20 miles it was still chirping when I shut it down for the night. The next morning it still chirped when I started it. I then put about 1/4 mile on it and let it idle for a while and didn't here anymore noise. I've got it at my northern Michigan cabin so I have not run it since. One thing I forgot to mention is that I didn't oil up the valve springs and new valves before I first started it. I'm thinking that I should have. Do you guys think I should just run it now if I'm no longer getting any crazy noises out of her.

One more question, this machine has always been really easy to start. Are they a little harder to start for a while with a fresh topend? Are things a little tight for a while?

 

[hatfield44]

Can't the valves not being in proper adjustment cause one to be hard to start?

 

[jasonp]

Yeah out of adjustment valve would make it hard to start. Could cause that type of noise. I believe you want to lap as it will help seat the valve. If the valve is not seating then you can burn a valve as it uses the seat to cool.
You should put a little oil up on the valve springs but I wouldn't worry to much about that.
The engine will start to loosen up a little bit as rings are like 45 percent of friction in an engine and much more when new but really should start right up and have no problems turning over or anything like that.

 

[fishx65]

Sounds like I might be cool. Not gonna be up at my place for about 3 more weeks but I'll let you guys know how it turns out. Hope she runs strong for another 10 years!

Thanks, FishX

 

[fishx65]

Well, she runs strong but still has that darn chirping sound. Put about 20 more miles on. From idle, if I bring up the RPMs just a little and let off, I get a very slight backfire.

 

[jasonp]

Well, she runs strong but still has that darn chirping sound. Put about 20 more miles on. From idle, if I bring up the RPMs just a little and let off, I get a very slight backfire.

Sounds like it is lean on the pilot jet/fuel screw.

Could be head gasket or exhaust leak.

 

[fishx65]

The bore is now 84mm. Would this bore size require rejetting? Besides cleaning, nothing in the carb has ever been changed. I can't find any head gasket leaks and I just put a new exhaust gasket in. Wouldn't I see a head gasket leak?

 

[fishx65]

Just a quick update: Got about 200 miles on her now and she's still chirping up a storm at idle. A little more difficult to start then it was before but runs very strong with no more smoke. Any chance at all that the cam bearings could cause the chirp?