bluecycle3
New member
I would like to know what time frame were the valve seats suspect on the airheads? What was the fix? cost? etc... thanks greg
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airhead valve problem what years?
- Thread starter bluecycle3
- Start date
Well, technically, valve seats were a problem from 1970 thru 1984. Eventually, likely, all valve seats are going to be a problem, but less so after 1984.
From 1970 to 1980, the problem was the old seats would slowly wear away. From 1981 to 1984, the seats were poor conductors of heat...they didn't wear away as much as they transferred that heat back to the valve. This heat in the valve face ended up warping it. And the problem was more noticeable in the 1000cc engines because of more heat generated. Any bike could have the problem sooner rather than later if you really wring the bike out.
Net result for both time periods was the lost of valve clearance over time. The fix is all cases is new seats and depending on the rest of the top end, new valves and guides.
From 1970 to 1980, the problem was the old seats would slowly wear away. From 1981 to 1984, the seats were poor conductors of heat...they didn't wear away as much as they transferred that heat back to the valve. This heat in the valve face ended up warping it. And the problem was more noticeable in the 1000cc engines because of more heat generated. Any bike could have the problem sooner rather than later if you really wring the bike out.
Net result for both time periods was the lost of valve clearance over time. The fix is all cases is new seats and depending on the rest of the top end, new valves and guides.
bluecycle3
New member
airhead valve problems
thanks
thanks
ebeeby
Member
Depending of course on your resources, you would do the valves and guides at the same time as the seats. Ted Porter gets $650 for a pair of heads with all new parts (springs, guides, valves, seats). He has thought this through very completely and his choice of valves is based on years of experience (call and ask him about it)
J
James.A
Guest
I'd recommend that you not let anyone talk you into saving $150 by using aftermarket 1 piece, hardened stainless steel valves. For best results, use OEM only.
lkchris
Active member
Oh, it will be new exhaust valves for sure on the early '80s models.
This from my '84 RS at ~60K miles
The risk was that the knife edge of the exhaust valve would eventually collapse, the valve would be sucked up by spring until keepers fell off and the remainder of the valve then could collide with piston.
This bike was properly maintained and clearance increased to .020 as recommended.
This condition can be inspected through the exhaust port with headers removed.
Polarbear
Polarbear
Here's an option;
CD2, a fake lead additive has very nearly stopped all valve recession in my R100/7'78 model year for 10 years now
. I have some remarkable proof in an engine with way over 300000 miles with the stock valves still in it!!! I found this stuff about 10 years ago in an auto parts store and its concentrated, using only a half ounce per 9 gallons of gas. I have a 9g Heinrich tank. ALL said is true about valve recession, so beware of it. My suggestion above has worked too, for mine. This is an exceptional case, with all these miles and stock parts still in the engine. I bought the bike new. Randy
CD2, a fake lead additive has very nearly stopped all valve recession in my R100/7'78 model year for 10 years now
. I have some remarkable proof in an engine with way over 300000 miles with the stock valves still in it!!! I found this stuff about 10 years ago in an auto parts store and its concentrated, using only a half ounce per 9 gallons of gas. I have a 9g Heinrich tank. ALL said is true about valve recession, so beware of it. My suggestion above has worked too, for mine. This is an exceptional case, with all these miles and stock parts still in the engine. I bought the bike new. RandyHi, Polarbear,
It's nice to know the non-lead additive works. Your engine was designed for leaded premium. The '81-'84 engines were designed for UNleaded. In these, it was a metallurgical problem. So while your engine benefits from a lead-substitute additive, the '81-'84 heads will only benefit from replacement of the valve seats and, probably, valves and valve guides. You are postponing the necessity to replace your valve seats by using the additive. Maybe it works so well you will never have to replace the valve seats. Unfortunately, those with the '81-'84 bikes should replace the valve seats sooner rather than later.
It's nice to know the non-lead additive works. Your engine was designed for leaded premium. The '81-'84 engines were designed for UNleaded. In these, it was a metallurgical problem. So while your engine benefits from a lead-substitute additive, the '81-'84 heads will only benefit from replacement of the valve seats and, probably, valves and valve guides. You are postponing the necessity to replace your valve seats by using the additive. Maybe it works so well you will never have to replace the valve seats. Unfortunately, those with the '81-'84 bikes should replace the valve seats sooner rather than later.
ebeeby
Member
CD2, a fake lead additive has very nearly stopped all valve recession in my R100/7'78 model year for 10 years now
I picked up some CD2 last year based on Polarbear mentioning it in a post and hoping it would solve my exhaust valve recession in my 1973 R75/5. It did not and the exhaust valves continued to close. I bit the bullet and sent the heads to Ted Porter.
However, I think that CD2 is a worthwhile additive and I plan to continue to use it for its lubricating properties .
Last, CD2 has an amazing similarity of appearance to Marvel Mystery Oil. Coincidentally, my 4 cylinder airhead guru (with 52 years experience) had suggested adding a Marvel Mystery oil to the gas tank some time ago....
RonKMiller
New member
CD2, a fake lead additive has very nearly stopped all valve recession in my R100/7'78 model year for 10 years now
Nothing succeeds like success.
With only 21,000 miles on my new to me R80/7 that is a must in my book.
I did buy some Gunk brand lead substitute, and a couple of pony shots will be in my first tank of gas when she gets back on the road in a week or two.
FUNCTION AND APPLICATION: Allows older engines designed for use with "leaded" gasolineÔÇÖs to
run safely with low lead or unleaded fuels when used as directed.
OUTSTANDING PROPERTIES: Prevents valve damage and upper cylinder wear in older engines
with "soft" valves by coating with a protective metallic film designed to prevent valve recession.
USE DIRECTIONS: Add to fuel tank before refilling. Use one bottle of M50-12 for up to 20 gallons,
M50-32 treat at the rate of 4 oz for 10 gallons.
and some interesting stuff from the EPA:
Lead has been blended with gasoline, primarily to boost octane levels, since the early 1920s. EPA began working to reduce lead emissions soon after its inception, issuing the first reduction standards in 1973, which called for a gradual phasedown of lead to one tenth of a gram per gallon by 1986. The average lead content in gasoline in 1973 was 2-3 grams per gallon or about 200,000 tons of lead a year. In 1975, passenger cars and light trucks were manufactured with a more elaborate emission control system which included a catalytic converter that required lead-free fuel. In 1995 leaded fuel accounted for only 0.6 percent of total gasoline sales and less than 2,000 tons of lead per year. Effective January 1, 1996, the Clean Air Act banned the sale of the small amount of leaded fuel that was still available in some parts of the country for use in on-road vehicles. EPA said fuel containing lead may continue to be sold for off-road uses, including aircraft, racing cars, farm equipment, and marine engines.
In addition to increasing the octane of gasoline, leaded gasoline also protected exhaust valve seats (in vehicles designed to operate on leaded gasoline) from excessive wear. Both of these objectives are now accomplished without the use of leaded gasoline. Owners of older vehicles with engines designed for leaded fuel may use an unleaded gasoline of comparable octane. For vehicles operating under higher loads, a lead substitute additive may be used, but owners should check with vehicle manufacturers as to which lead substitute additives are appropriate.
Oh, it will be new exhaust valves for sure on the early '80s models.
This from my '84 RS at ~60K miles
The risk was that the knife edge of the exhaust valve would eventually collapse, the valve would be sucked up by spring until keepers fell off and the remainder of the valve then could collide with piston.
This bike was properly maintained and clearance increased to .020 as recommended.
This condition can be inspected through the exhaust port with headers removed.
Thank you Kent. I was thinking about pulling the heads to take a look but now I'll just pull the headers (exhaust nuts are already off anyway ).
T
TGHSMITH
Guest
you can also rotate the crank untill the ex. valve is fully open and look through the spark plug hole...
lkchris
Active member
Lead is and always was a scam and was never required to "protect" anything.
http://www.thenation.com/doc/20000320/kitman
Y
Yarddog
Guest
What would be your thoughts on top cylinder lubricant, like Marvel Mystery Oil, in the gasoline? I've used it for years in my pickups, but never in my motorcycle... I've used Rocket Fuel in my Harley for years to help with pinging in hot weather... it works well, also... But you've been around these Beemers a LOT longer than I!
Thanks...
Thanks, Kent. That was really interesting. I had no idea of this history.
Kitman has written (very well, I think) for Automobile Magazine for many years.
RonKMiller
New member
I've always liked The Nation. I'm a big fan of Democracy Now as well.
Vewwy interesting..
paulfinney2
New member
Isn't Marvel Mystery oil like kerosene?
Anyname
Active member
That would surprise the engineers who used it to produce the first high octane gasoline. I believe it was one of he few good things to come out of WWI.
J
James.A
Guest
I would also respectfully dis-agree with Kent regarding tetra-ethyl lead as a fuel additive. Of course, eliminating lead is now known to be a good thing, environmentally. However, the lead was a a useful component of the atomized fuel for the effect of lubricating the valve to seat contact point. Additionally, lead free fuel was/is known to produce hotter exhaust flow. Why else would BMW go thru the effort to change valve seat composition to accomodate the absence of lead in fuel?
Y
Yarddog
Guest
Naw...MMO is a bona fide lubricant, although I reckon kerosene might have some sort of lubrication ability...you might be confusing Gunk for diesel though...they smell and act the same...
