Cause of Burnt Valve 1995 R 1100 R ?

I just had to replace two valves at 63,000 miles. When I asked the mechanic what would cause this problem he stated as long as good maintenance was practiced it was hard to tell, someinmes a lot of stop and go driving will cause it.
I have taken the bike in every 6,000 miles to be profesionally serviced since I purchased it used ( 6500 miles when I pruchased the bike over 4 years ago) and my main riding is weekends in rural areas around Richmond Va. , usually 40 to 100 miles each outing.

well, it is almost 20 years old.
Somebody before you messed with something, or missed something.

valves

intake or exhaust valves? left or right cylinder? Jon

intake and exhaust, left side

Might want to check the injector out for that side. If it was slightly clogged and causing that cylinder to run way too lean ...

valves

do you have access to an infra red thermometer? Get your up to operating temperature then check the exhaust header next to the head on both cylinders. It should be about the same. If not, the problem is still there.

DarkCloud said:

do you have access to an infra red thermometer? Get your up to operating temperature then check the exhaust header next to the head on both cylinders. It should be about the same. If not, the problem is still there.

Click to expand...

good idea!
I'm always looking for an excuse to buy a new tool.
I need one of those.

It's been theorized that carbon builds up on the piston face, then breaks off and keeps the valve from sealing. A few cycles with a partially opened valve causes the damage.

It's also been theorized that spending time at high rpm keeps carbon from building up. My oilheads have all spent a lot of time above 6000 rpm, and recieve several full-throttle excursions to the rev limiter on a daily basis. YMMV, but it's worked for me for over 250,000 miles.

Both intake and exhaust valves? Likely culprit is lack of clearance on valve adjustment. They could easily have been too tight and as the engine heated up lost full seating on both valves. Carbon build up is normally more on the exhaust side than the intake otherwise.

Running too lean is also a good possibility. Can you get the exhaust examined? When I say that, I mean several states do an exhaust "sniff test" for particulates and such. If you can get to a shop that has the equipment they can tell you if one side is running too lean. It's a better test than simply checking for temperature differences between the jugs.

All of the above, with "Too Tight" being my first thought also.

There are also cases appearing now where too much alcohol in the gas (15%, or just a poor - or possibly more profitable - mix) is burning up our engines.