"Ticking" sound when engine is warm

[marshall]

Ever since I checked and set the valve clearances on my '80 XS a while ago, I've noticed a pretty loud ticking noise (one tick per engine revolution) coming from somewhere around the upper right side of the engine. I hadn't noticed the sound before I changed the shims, but it certainly could have been happening and I just wasn't listening for it. My first thought was that I must have miscalculated the required shim thickness at one valve there, so what I'm hearing is the cam lobe slamming into the shim. For a while I was sure this was the case, because when I set the valve clearances I made the mistake of shooting for the large side of the gap tolerance, after misreading a comment here. Then, I found out my #4 spark plug hole was stripped, which led me to think I was just hearing air shooting out around the plug on ignition. Did the Helicoil fix (which was great by the way, glad I didn't have to take the head off), but the sound is unchanged.

The reason I've become skeptical that it's the valve clearance, is that the noise only happens when the engine is warm. I don't know for sure how it works, but doesn't the gap between a cam and shim get smaller as the engine warms up, because the valve stem is getting longer? If that's correct, then you would think the noise would happen when the engine's cold, then get quieter or go away once it's warmed up. Which is the opposite of what's happening.

Of course, I could just take off the valve cover and recheck clearances, but I cringe at the thought of re-cleaning the gasket surfaces and making a new gasket - figured I'd check here first.

Any thoughts?

Thanks a lot,

Marshall

[marshall]

Oops, let me add that when I say "one tick per engine revolution," I mean "on the order of one tick per engine revolution" - so it could be 1/2 click per rev. I suppose if it was 1 click per 2 revolutions, I would know for sure it was cam/shim contact. Hey, maybe I can pull the timing cover and check that tomorrow...

[bikerphil]

Make sure your cam chain is adjusted properly and check for loose header bolts. These will contribute to lifter noise. Also a misfiring cylinder can cause a valve to make noise. I have a similar problem, but in reverse. Ticks a little when cold, but fine after 1 minute of warm up.

[TopCatGr58]

Hey Marshall,

SHooting for the large side of the valve clearance gap isn't bad, because as the engine wears, the valves do tend to seat further into the head seat, and this will narrow the clearances, along with like you mentioned, as the engine warms up, clearances get closer!

Have you checked your exhaust pipe head gaskets??

You can take a piece of wood dowel or such and use it as a stethoscope to check to see/hear where the sound is really coming from, head, crankcase, etc., put it on several places around the engine to better hear the ticking while the engine is running.
T.C.

[tarzan]

The reason the noise gets louder when the engine warms up is that the oil is thinner when hot.

[marshall]

Hey Marshall,

SHooting for the large side of the valve clearance gap isn't bad, because as the engine wears, the valves do tend to seat further into the head seat, and this will narrow the clearances, along with like you mentioned, as the engine warms up, clearances get closer!

T.C.

So I had it right after all - that's a relief.

Tomorrow I'll try the wood dowel stethoscope, and pay special attention to the header gasket area. I'll also reset cam chain tension and report back with any news. Thanks guys,

Marshall