Possible Valve seat Issue?

[rpgoerlich]

Took the time today to go through the 80G. Last couple rides been hearing a valve tapping. Pulled the valve cover and checked clearances. Had 2 intakes at .10, had 1 exhaust at .30 and one at .45. I was able to swap shims on both intakes to bring them to spec along with .30 exhaust. But the one that was tapping, the .45 had a 2.90 shim in it. To bring that one just into spec, I'd need a 3.10. Kinda strange it would be that far out, and loose at that.

I'm thinking I may need to pull the head and check that valve/seat. Cam looks good, no abnormal wear. Whatcha all think?

Thanks,

[mack]

Not good news

I wouldn't pull the head yet. Pull the plugs and drop the headers and have a look inside. Shine a light in the plug hole and have someone rotate the engine by hand.(don't touch the cam chain tension at all!!!) If you see light around the valve shoulder it's not seating. Should be able to determine what's causing it. Could be just a build up of carbon. Did the bike sit for a long time? If it looks pretty clean for carbon but still see light,odds are, your going to wind up pulling the head, pay particular attention to the valve spring lengths for those cylinders.Good news is that pulling the head isn't a big deal and 290 is the original shim I believe. So while it's apart clean and lap all the ones that need it and you have lots of sizes left to drop to and mesure all the springs. They're probably the originals as well. How many miles BTW

[rpgoerlich]

It sat a while before I got it just over a year ago. It has 5,248mi on it now. I've put just over 1kmi on it since I've had it. Ran great on the trip up to MOM last year.

I adjusted the cam chain tensioner today right after running the valves before putting it back together. Ran fine today putting 50 miles on it.

Gonna find a 3.10 shim this week. Install it, then watch it for a month. I'll probably pull the pipes as you suggested and take a look.

[mro]

Compression Test


mro

[mro]

If there seems to be a problem with the compresion then a leak down test would help pin point the problem.
All much easier than pulling the head.

mro

[mack]

wierd

The impression I got was that it ran fine up till a couple rides ago. Just sounds like there is an obstruction of some kind in the valve train. Possibly at the seat. Could be something got knocked in the plug hole and before it could get exhausted it go mashed between the shoulder and the seat. Certainly nothing could come through the carbs, and the oil galleries are well above the chamber so oil could not have carried anything in there. Compression test would certainly confirm a seating problem but a physical look wouldn't hurt. However, after having said all that. I'm afraid the head will likely have to come off in any event.

[kirmit77]

I have some 300 Shims if you need those but no 310

[TADracer]

Like MRO says, do a leakdown test. That will tell you without a doubt if its valve seats or perhaps a sticking valve, or not. Valve seat going bad is unusual unless something else is going on to cause it.

If all its doing is tapping and not missing, spitting or backfiring then I think your situation is more at the upper end of the valve.