Krauser Heads

Are they any good? My mechanic believes in them and says they add something like 25 HP to the power :huh

I read somewhere of early wear on the valve guides , but have never actually met anyone who had them on a bike and could confirm the accuracy of this .

It may just be that bikes with the Krauser heads get run a bit harder than their two valve cousins.

I think all the spares are availible , so even if it is true I would just get used to changing the guides frequently - horsepower rarely comes cheap!

Yuo could try a search on the Boxerworks forum , some of the guys there post pics of four valve bikes they claim to own.

I saw a pair of "new in box", never used heads on ebay go for over $3000. It led to a very spirited discussion on the airheads list. The old timers who remember actually trying them, seem to really hate them. Of course, they also hate 2-1 exhaust and pretty much anything that you do that contravenes the work of Der Vaterland. It seems like a great idea to me. Obviously that is the direction that BMW chose for the oilheads. I suppose it was just poorly executed by Krauser. Four-valve heads seem like something that might really improve an airhead's performance.

My mechanic also says that to set the valve clearance properly, the heads need to be at operating temp! He's had a lot of burned fingers doing clearances on these heads.

$3K seems a bit too much for them. I know a used pair in my location for roughly $500.

i would love to have them if you decide you don't want them.

The number of people who claim to have a pair on the shelf seems to far exceed the number running them on the road.... Hmmm - maybe that should tell you something. Anyhow, I would think that the historical value to a collector would far exceed $500. If they are complete, snap them up! I certainly would.

Purely guessing here - but I would imagine that you would have to do a lot of fiddling about with carbs and exhaust to get the best from those heads. Probably cams and other stuff too. Even then, I seriously doubt you'd see more than 10 or 15 HP without some big compromises. If you could truly expect 25HP simply by adding Krauser heads to an airhead, then BMW screwed up by not exactly copying the Krauser design for the oilheads because there is much less than 25 Hp difference between comparable-sized early oilheads and late model airheads.

I've got a Classic Bike magazine at home with a Krauser equipped R100RS in it.

Dyno output is 65hp with, I believe a 336 cam.

Barring mechanical issues with the heads themselves, it would seem that you would have to do a lot of fiddling to get it right(as was mentioned previously). I suppose that may be one of the things people don't like. Everybody wants to bolt on a new part and have it work perfectly. I think in a case like this one, that option goes out the window pretty fast. Don't expect a lot of help from the standard group of airhead owners (oak, et al). Hell, for $500, buy em. If you don't like them, I'm sure you could get your money back out of them.

This little shop in the Netherlands bought both right as molds. They sell most of the parts/stuff:
http://http://hobbyist.nl/krauser.php
17.000 valves on stock, so replacing won't be a problem
Send them a mail in english if wanted, they will answer it properly.

And if you dislike them, I'll take them any given day for 500 plus shipping

I want to be next in line at $500. How many you got?

I have a 1983 Cycle World test of the Krauser head kit installed on an R100. The original kit included 10.5:1 pistons and assorted gaskets and pushrods. The bike made 52.3 bhp & 49.05 ft-lbs stock on a dyno and 62.01 & 55.09 with the Krauser kit. The staffers liked the fact that the torque curve was 12-15% better between 3500 and 6500 rpm where the roll-on performance was much improved over stock. It was 8 mph quicker in the 1/4 mile too. The Krauser heads had a 40mm exhaust outlet and USA bikes had 38mm pipes. There was a special insert required to sleeve the outlet down to 38mm for USA bikes.

That is a correct statement. It is a kit. Pistons, pushrods, cam etc. Stock parts won't work. There where a few early missteps, valve guides, seats etc. growing pains and quality control. The later, the better.

Mixed blessings

The Good:

Probably a little better combustion chamber shape, which is good if you bump the CR

Lighter valves will be easier to control

Smaller individual valves might result in a better port shape and better flow

Trick-Race looking.....wow your mates

The Bad:

The intake port still looks like a Dog's Hind Leg, and all the valves in the world ain't going to change that

247's are not limited by valve size

You do have the special pistons required......right?

Air-cooled 4-valve designs are problematical. Cooling the area between the exhaust seats is a bitch. The Boxer design probably is the best at this however.

Money could be better spent on a "total package" (ported 2V heads, carbs, cam, pipes, light flywheel, etc, etc) for the same $$$ or less.

JMHO, YMMV - PS - Here is the Manual for the 4V Heads*


No matter what we do to an airhead....it ain't going to look like this:
(A proper induction system....go ahead and drool)




PS - OK, Sod the heads. But the Krauser MKM 1000 "Birdcage" frame is the Dog's Balls




* I have no bloody idea if this is copyrighted material or not. But then, I am not selling these (nor is the original source). Let your conscience be your guide. The OS has a statement where it is OK to have a gander for "the purpose of private study, research, criticism, review". If the mods want to delete the link they will get no grief from me.....but the OS states direct linking is "OK"

Sounds more complicated than I thought. Thought it was a plug and play thing. The heads in question are actually those pictured. They're installed on an R100S which is being sold. There is a chance that the owner will sell the bike with the original heads to make a few more bucks selling the Krausers to someone else.

The owner never mentioned any special mods when installing the Krausers. OTOH, neither is he that mechanically-inclined :huh

I took the 25 HP claim of my mechanic with a grain of salt. The bike was never dyno'd so it's just a wild claim. But he was the one who made the installation and the owner appears to be happy (a relative term...). I should talk to the mechanic some more.

If the owner is willing to sell them separately, and has the original parts to put back on, I'd offer to help him make the swap so you can take the pistons, etc. as well.

It might be worth getting the whole bike to get the heads. I bought a whole bike to get the gas tank.

talk about desperate! and you also now want to buy a whole frame to get the steering stops!

No, I DON'T want to buy a WHOLE frame for the steering stop. :huh I just want the steering head to scavenge the steering lock boss. Steering stops are easy to make, but that boss is a bit trickier. I missed out on one by 2 hours - the guy had just cut it up and took it to the scrap yard!

I did buy an 83 R80ST recently for $2K because it has the R80G/S tank on it. Do you know how hard those tanks are to find? You wouldn't laugh if you knew!

Didn't you tell me you wanted an older airhead to fix up? A Krauser headed 100S would be a great candidate!

Buy the whole bike to get the heads. Sell the heads on ebay, you'll be plesantly surprised how much people are willing to offset the purchase price of the bike for you. These heads disapperared from sight long enough ago that a lot of new airhead owners are looking to reinvent the wheel and they are willing to pay for their folly.

Ain't that the truth. I bought a 76 r75/6 a year or two ago to fix up. Buy the time I sold the stuff I didn't want, ugly seat, electronic ignition, ugly bags, bar backs, ugly fairing etc., I had $95 in the bike. I did put about $600 cash back into it but I was amazed at what the crap sold for.