Kawi2strokes.com Forum

Been chasing a loud ping only at idle. Besides the ping that seemed to get louder over the past several months the bike ran great, very good throttle response, nice idle, no pinging that i could hear above idle.
Removed the heads today and see a few things that I would appreciate your expertise. The left cylinder one of the head bolts was oiled up pretty good and at that corner the head gasket appeared to not be sealing completely, the left head was the only one with some built up carbon that can't easily be wiped clean. The right cylinder has a fair amount of pitting. What are the key features to inspect?

Thanks

Pretty much what you're doing, plus look for scoring or any unusual wear on the cylinder walls, and look for signs of loose rod bearings (crank turns a little without moving piston). It would have been good to post a recording of the noise you're hearing. Often a clanking sound at idle is piston slap, caused by excessive piston-cylinder clearance. Pinging usually refers to detonation of the air-fuel mix, and isn't likely to happen at idle.

A cylinder being oilier than the others may mean that one is running rich. Was the right head's pitting there when the engine was assembled, or has id happened since then?

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If it surges, that's normal, upshift.

I purchased the bike a year ago and don't have an idea of the engines condition. I'm assuming the pitting was there when previously assembled. Head bolts look great, almost new, the plating on the bolts and washers appears new. I'm assuming it was refreshed not too long or many miles before I purchased. I guess the sound can be defined as clanking. Just past idle the noise can't be heard.

The center and right piston tops are fairly oily and a bit black, the left is much lighter in color, almost grayish and fairly dry. The center and right head gaskets have a clear 100% contact marks.

Jim, I would be thrilled to post a video, but I haven't figured out how. I appreciate your comments and questions.

To post a video, upload it to YouTube and post a link to it here.

From your description, one or more pistons are a little loose in the bore(s). That doesn't mean the clearance is out of spec, just somewhat bigger than the minimum.

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If it surges, that's normal, upshift.

That's not just normal piston slap. Something is wrong, and you should take off the cylinders and do a good inspection, including piston clearances and connecting rod radial bearing play to start.

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If it surges, that's normal, upshift.

Totally agree Jim! I pulled the heads which you've seen the photos. Pulled the cylinders and lastly the pistons. Starting with the left I removed the wrist pin clip, and the pin only slides as far as the clip groove. I may have a small burr that I'll clean up in the morning or use a makeshift tool to remove. With that sound I'm guessing I may be able to feel slop somewhere either at the piston to pin or pin to bearing. Very curious. Thanks for your help!
Another question, the head gasket and cylinder gasket are copper. I've found new head gaskets but not the cylinder. Are the paper gaskets now preferred over copper for the cylinder? In my opinion the gaskets look very good. Can I clean them up gently with emery cloth and reuse? Not trying to save a buck I just haven't found replacements as of now.

Copper base gaskets are fine, as well as the stock type. Copper gaskets are used to space the cylinder up for port timing modifications. They're available in various thicknesses and are custom made by companies like Cometic.

To reuse a copper gasket, clean it and then heat it red hot to anneal it. You can let it air cool or drop it in a pan of water. The water method tends to flake off the black oxide that forms from the heat. Then avoid bending or otherwise work hardening the now soft gasket.

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If it surges, that's normal, upshift.

Thank You Jim

A few pics of the left cylinder. Happy to see its std size. checking the fit between the pin to the piston, required a puller to remove and it came out nice and smooth. The fit between the pin and the bearing feels pretty good, no signs of wear on the pin or bearings. The fit between the bearing and the rod felt a bit loose but until I measure all I can't say I found the culprit. We'll see how the center and rights cylinders check out.