This dosen't look good! What do you think?

[Josh]

I've been having some misfiring and detination at low rpm's for a while know removed heads and this is part of what I saw. The carbon build up is up to 1mm tall on the edges.

[pete roper]

This looks like oil burn to me. Note how the rear/anti-thrust side of the piston is washed clean? This indicates to me that too muh oil is getting past the rings and burning. The burning oil creates the deposits, the washed area is where it's *spurting*, (To use the pornographic phrase.) up past the rings on the induction stroke.

 

Causes?

 

a.) a broken or won oil control ring on that cylinder.

 

b.) a glazed bore caused by the use of the wrong oil or an incorrect break-in proceedure.

 

c.) buggered valve guides, especially the inlet on that side.

 

and yes, you'll be hearing a horrible noise. It may be detonation, (Oil polluted charge detonates real easy!) or it may be pre-ignition caused by hot spots in the carbon.

 

Either way it needs to be addressed.

 

Take the heads to a decent head shop and follow their advice on what needs to be rebuilt. De-Glaze the bores with 1200 wet 'n' dry but clean THOUROUGHLY afterwards with a good wash. Re-Ring it and check the gaps on the new rings.

 

Pete

[Josh]

The problem seems to be worn valve and valve guide, found .03mm of wear on intake valve stem. This is probably a case of the soft valve issue as the bike only has about 12k miles on it. The seat face of the exhaust valve also had some light pitting. Thanks for your comments Pete!