White Exhaust Valve

[AnnapolisAirhead]

During routine maintenance/cleanup of my '83 R100, I removed the exhaust and decided to take a peek at the valves. Left side looks good, nice darkish brown color. The right side, however is snow white on the stem and up to the edges (looking through the exhaust spigot on the head). As I manually spin the engine and watch the valve open, I can see a bit of white on the valve seat as well, not much but a faint trace. The bike has 64,000 miles on it.

The bike is dual plugged running Bosch W6DC top and W6BC bottom. All 4 plugs look very clean and nicely tanned. I've pulled both carbs and just rebuilt them with new o-rings and diaphragms, stock jets, stock settings listed in the Bing manual. Both were in similar condition, nothing unusual between the left and the right carbs. It doesn't use any (noticeable) amount of oil between changes (2-2500 mile changes) and has been a fairly reliable regular ride when I commuted about 50 miles each way yo work. I don't commute any longer and my rides are 100-200 mile days when I go. I'm careful not to lug or over rev the engine. I try to maintain between 4-4500 RPM as much as possible usually cruising at 4400.

I also run premium fuel in the bike, if that matters. I know I don't need to, but my opinion is that a small amount more $$ to run fuel that burns hotter and more completely should keep the engine cleaner--the plugs agree, but I know not everyone here does. Dual plugging would indicate I can run pretty much any fuel, but I've been using premium since I got the bike (about 1 year and ~5,000 miles ago).

Is it possible that at some point it ran too lean on the right side and this happened? If that's the case and the lean condition were corrected, shouldn't the white go away or is it baked on like porcelain?

How can I assess if damage has been done? There are not shiny flakes of metal on the white valve, nor in the oil or drain plug. Everything 'seems' to be running ok, I just want to know what others think. Is this normal (I don't think so...)? Common? Catastrophic?

Thanks,
Tony

[RecycledRS]

If all four plugs look good I suspect the problem is with the exhaust valve and seat recession. 81 through 84 were prone to valve recession. Are you still running the exhaust air system? This will contribute to the problem with hotter exhaust valve temperatures. Have the exhaust valves needed adjustment more often?

[AnnapolisAirhead]

If all four plugs look good I suspect the problem is with the exhaust valve and seat recession. 81 through 84 were prone to valve recession. Are you still running the exhaust air system? This will contribute to the problem with hotter exhaust valve temperatures. Have the exhaust valves needed adjustment more often?

If you mean the emissions gear, I removed that a year ago when I got the bike (old enough to be exempt in my state anyway).

As far as the valve adjustments go, I have not needed to adjust them except for one time in the middle of Winter the left side tightened up. Plenty of thread left and from what I can tell, I can see both angles on the valve itself. Is there a way to check the valve seat without removing the heads?

[RecycledRS]

If you can find a bore scope you look inside but I believe the wear will occur on the valve stem itself. If you can see the valve backside and the seat area looks good you should be OK

[AnnapolisAirhead]

If you can find a bore scope you look inside but I believe the wear will occur on the valve stem itself. If you can see the valve backside and the seat area looks good you should be OK

I have to admit, I am always looking or a reason to buy more tools and a scope would be a great one. Never cheap though.

I know that '81-84 bikes had a different valve seat to handle unleaded fuels, While it handled the unleaded fuel, it did not dissipate heat very well and that cause premature seat recession. This bike came to me already dual plugged, and I am hoping new valve seats were put in at that time. I have plenty of room to adjust the valves and they seem to hold their setting--so I am concluding that they are 'probably' ok.

I'll see if I can't find someone with a scope.
Thanks.

[AnnapolisAirhead]

If you can find a bore scope you look inside but I believe the wear will occur on the valve stem itself. If you can see the valve backside and the seat area looks good you should be OK

I have to admit, I am always looking or a reason to buy more tools and a scope would be a great one. Never cheap though.

I know that '81-84 bikes had a different valve seat to handle unleaded fuels, While it handled the unleaded fuel, it did not dissipate heat very well and that cause premature seat recession. This bike came to me already dual plugged, and I am hoping new valve seats were put in at that time. I have plenty of room to adjust the valves and they seem to hold their setting--so I am concluding that they are 'probably' ok.

I'll see if I can't find someone with a scope.
Thanks.

[RecycledRS]

If you want to acquire one Mikes has an inexpensive one. Don't know about the quality though. http://www.mikesxs.net/products-7.html?category_id=7.1