Darryl.Richman's picture

As mentioned already, we were unsure of what the best route and most expedicious fix for the leaking head gaskets might be. I decided not to try machining these complicated and, in our timescale, irreplaceable parts. The other choice at hand was to use some high temp copper RTV goop. One problem with it is that it wants 24 hours to set up, but we didn't even have 12...

The next day was a long, hot trip (279 miles) to Spirit Lake, IA, home of (the latest incarnation of) Indian Motorcycles, which was recently purchased by Victory/Polaris. In the morning, the bike fired up easily and sounded good, with no detectable leaks around the head/cylinder joint. Off we went!

...for seven miles. On the far side of Anamosa, I could already hear, through my helmet and earplugs, the death rattle coming from the left cylinder (the right seemed to continue on just fine). Before I could find a nice, paved parking lot to pull into, the left head gasket really let go, and I felt something on my left shin. I looked down, and what I saw was FIRE! It was coming out from the head/cylinder joint!

I stopped the engine and got off onto a dirt shoulder. I opened my tail bag and got out my "magic" wrench. (It has a 60 degree cranked head and allows one to almost always remove the bottom head nut from its stud without also removing the exhaust system and the floorboard.) I checked the tightness of all the nuts, but they were snug. The head had to come off, so I also got out a tire iron.

The tire iron allows wiggling the head, which must be done as the nuts are backed out a little at a time. I was able to get the head off before it was cool enough to hold. I scraped off the remnants of the RTV and the burned gasket. By this time, most of the bikes had passed and the checkpoint crew came by. Then the sag wagon, known as The Reaper, pulled up. I spent another 45 minutes with an emery board trying to clean up the head's surface and then installing another gasket, but when I fired it up, it was already leaking badly... So the bike and I ended up on the wagon.

There are a couple advantages to being towed home. Air conditioning is one of them. Another is company and conversation. We even got to the Mason HD Dealer in time to have some lunch. BTW, apparently, it is bad luck to mention the word lunch before actually arriving and getting it. We were nearly there when I mentioned that we might be in time for it, and was immediately shushed, but not five seconds later did we have to stop for a bike on the side of the road. (We still all made it in time for a burger or hot dog.)

Needless to say, that hardly replaced the disapointment of not finishing out the day on two wheels.


Daryl, I can't imagine your

Bengt Phorqs's picture

Daryl, I can't imagine your disappointment. Well, I kinda sorta can but I don't have near the time and effort invested in this worthy endeavor. So what's next? Can you get to Sturgis and do a full on 24 hour repair? What's causing the overheating? Possibly a blocked oil gallery? Keep us in the loop, we're behind you all the way and cheering for your success! -Mike

flatmotors and head gaskets

R66RODENT's picture

Damn-what a bummer after all your hard work. I was looking at the photo of the blown gasket and the inside of the head, and I had some thoughts: the gasket area doesn't look very wide-compared to what is common on English and American flatheads I've worked on. The head is secured by studs in alloy, rather than having through-bolts from the outside threaded into the iron barrel. Also, the finning of the head may be inadequate-not for heat disappation, but for the rigidity of the head.If these heads have been planed at any time, this could be another factor contributing to head gasket failure. I think this 500cc bike is at the limit at what it can do anyway in that heat, day after day. Even big flatties have problems with it. On the first Cannonball, Pete Young was on his third crankpin at the end of the run-he had two made by local machinists where he broke down-so soldier on, and good luck. You'll figure this out!


Good luck!

K100's picture

As a Harley rider turned BMW rider I am rooting for Daryl and his bike. Hopefully he can get the problem sorted out and back on the road for the duration.

Head Gaskets

Jim Hansen's picture

The head gaskets are blowing so quickly, there has to be something wrong. The obvious, of course, would be a warped head or uneven cylinder surface. Another possibility is that the head has been surfaced in the past, leaving the compression ratio too high (in relation to the head's marginal sealing capability). A fix would require a shim to increase the combustion chamber volume. Peak combustion pressures could be reduced by retarding the ignition timing a little, although this could cause the engine and exhaust valves to run hotter .

Anyway, bravo to you! I hope that, despite the great difficulties, you are enjoying the adventure. And there always is another day.


Drew Grant's picture


The gaskets are blowing at the junction between the valvechest and the bore, suggesting the need of a greater sealing pressure at that point.

Would it be possible to fit a strongback over the head bearing down on the head just over those pointsand pulling down possibly on the lower studs for the exhaust and inlet manifold?.

Drew Grant

Head studs, torque, and good gasket seal

oligee7275's picture

Daryl, I feel your pain. Having had this very issue on old race bikes ( and modern ones as well) I have some thoughts that haven't been brought up thus far. (My wife says I can't stop myself) Sometimes in the heat of frustration we tend to not look at obscure possibilities. The fact that there are muliple burn throughs in the gaskets and that now you seem to be losing them sooner and sooner leads me to think that you are loosing torque force, hence sealing ability.
Could the studs be stretched in the head threads causing loss of torque and seal? Could the head nuts be bottoming on the stud threads under torque before the gasket is fully sealed? Are you not applying enough torque for fear of pulling the studs out of the heads?
Someone else here mentioned the gaskets themselves could be suspect (those kind usually are). A solid copper gasket with sealant would work much better.
Running the old bikes at speeds near their limits puts tremendous pressure on the head studs due to the constant pounding of the pistons.
Stay with it man, we're rootin' for you.

Blowing Head Gaskets

Pat Tobin's picture

I first place the head, sealing surface down, on a precision flat block or other very flat surface. Then go around the sealing surface with a .002" feeler gauge strip. If it will slip under the sealing surface anywhere, that's a leak.

More correctly, that's a spot which will put less pressure on the gasket, making that spot more prone to a gasket blowout.

Only rarely is it necessary to remove metal by machining, which does, as mentioned, run the risk of upping the CR. If it's not more than, say, .010", a workover with a precision flat block and abrasive paper will usually be enough. All you have to do is get it so that you can't slip a .002" feeler strip under the mounting surface at any place.

Pullin' for you, Bro.

Pat Tobin

I do really appreciate all of your inputs

Darryl.Richman's picture

Just got in to Sturgis less than an hour ago, after a successful, but not uneventful, run.

The head gaskets are burning through at the same location on both cylinders. You need to know that on these motors, there's only one cylinder and one head casting, and even though they are far from symmetrical, the intake on the left is the exhaust on the right.

I am certain I can beat the flat rate manual for replacing a cylinder head on a 1928-29 BMW. I did it this morning in ~25 minutes in someone's dirt driveway. I ran one of Vech's heads the rest of the day on the right cylinder, and the double gasket mess on the left cylinder.

I can answer a few questions from the comments above:

  • I'm not bottoming on the studs with the nuts, and belice me that I'm not holding back torqueing them. I am limited only by my hand wrench.
  • None of the studs are coming out of the heads
  • Typically, after installing a head and torqueing down on it good, and then running it for about 25-50 miles, I can put another quarter turn on the nuts. After that, it stays completely tight.
  • You can't do normal tests or machining on these heads. There's a "heel" that protrudes above the sealing surface that fits into the piston area to increase compression and, I am told, add swirl to the mixture. This, and the studs, prevent easy surfacing of the sealing surface. I'm sure that a good machinist could remove the studs and fixture the head, then measure and remove what's needed.

I'm fairly convinced that my heads are both warped. Not that it matters at this point. When I get home, I can have these machined flat and make some solid copper gaskets, that should be a pleasant way to spend an afternoon.

--Darryl Richman
"Bling is not made in Germany" --OTL, 12/05

Sounds like a plan

oligee7275's picture

Sounds like the Vech on the right and the mess on the left got you by. Hope it gets you to the end of the rally.
Still pullin' for you.

blowing headgaskets

R66RODENT's picture

It's good to hear that you've made it through the day with only 'minor' head gasket adventures. When you get to Sturgis, you may be able to find a local machinist who can make you a set of .062" solid copper gaskets. Forget about flashing unless you're confident that the mating surfaces of the head and block are straight. It doesn't sound like they are. I know it'll be your day off...but. Keep on truckin'


Head Gaskets

Jim Hansen's picture

If Vech's head and the double head gaskets fail, trying copper gaskets sounds interesting. But if the head is warped, the copper gaskets will probably leak. People have mentioned the use of copper wire as a gasket. I like the idea of a copper sheet gasket with copper wire on it. The thickness of the copper sheet would reduce the compression ratio a little, and the wire would compensate for the head warpage. (I don't have any personal experience with this).

It sounds like you have become so incredibly proficient at changing head gaskets that you could simply incorporate gasket replacement as part of your daily mechanical maintenace scheme, along with changing the oil. The $64 question is, do you have enough gaskets? The fact that the failure rate of the head gaskets seems to have slowed (or maybe stopped?) is encouraging.

If you run out of head gaskets, just buy a roll of copper wire!

Pulling for you, Darryl

Monte Miller's picture

When faced with the challenges you are dealing with, Darryl, lesser men may have quit by now, pulled up tent stakes and gone home. Press on, amigo. Gotta feeling you're going to see that Golden Gate from the seat your R52.

Proclivity (!) For Blowing Head Gaskets

Pat Tobin's picture

Darryl, If you are you sure you have the aluminum alloy sealing surface flat and it still blows after a few miles, I would then begin to suspect too much heat entering the head at that spot.

We know about hearing the air squeek through a broken gasket. But have you listened closely to the exhaust at idle? Better yet, to a non-running kick-over.

My next stop would be at Radio Shack. WHAT? They don't sell motorcycle parts.

No, but they sell a dandy hand-held IR Temp Reader. They have two stock numbers

55039404 $40

55039405 $45

The instrument is made by HAWK;

Model Q31 - TH220, Cat. No. 55039404 $40

Model Q31 - TH420 Cat. No. 5503905 $45

More info on Hawk's site:


One of these can be aimed at the head from a foot away (non-critical) and will give a quick, accurate IR reading of temp.

If the heat peak is from the are of the exhaust valve, it probably means the exh valve can't get rid of its heat efficiently enough. That would be an expected case on an engine of that era. Here are several things to do: Some may be too much for a road repair; try your brain trust on these:

If the valve is not seating completely around the head or if the sealing surface is not pristine, the valve can't get rid of its heat.

If it were me, I would hie me to a RS and buy one of the handy pocket IR sensors. The web site hints that not every store stocks them, however.

First and foremost, is there enough valve stem clearance when the engine is hot? Things swell with heat and if excessive, the valve will be held slightly off its seat when the engine is pulling hard.

If the valve stem bore is worn, the valve can't get rid of the remainder of what heat passes from from the valve head. Here we have to dream of exh valves with sodium-cooled stems; for another day.

If the valve stem guide is simply a bore in the cast iron block material, as most of that era are, it might help to have modern valve guides installed. A silicon - alloy is often used; probably it will conduct heat better than cast iron. And it will definitively reduce stem-to-guide wear, substantially increasing heat transfer.

Remove the exh. valves for exam. The dimensions of the sealing surface are critical, yet often overlooked in 'valve jobs.'

Basically, it's a compromise: Seat contact area must be as wide as possible to enable better heat removal from the valve,

But not too wide or the sealing surface won't have enough pressure (force divided by area) to make a good seal. (If the sealing width is too wide, there's good heat transfer but not enough pressure on the valve to make a metal-to-metal good seal, which reqjuires a tiny bit of crush of the metsl. I would guesstimate that your engine should have a seating surface contact area of about 20% ~ 25% of the total seat width. This dimension is effected by doing a 'three angle' grinding of the seat.

Last but certainly not least, if none of the above is practical for the present time, You might try to reduce combustion temp by any of several means:

Retard max advance 3 ~ 4 degrees. Might be VERY helpful.

Add grain (wood) alcohol to the gasoline, if legal. That should reduce combustion temp.

Add some additive (not known to me) which might stand a chance of reducing combustion temp a little. You're in a position where it might be smart to sacrifice a little speed and fuel mileage.

Pullin' for you, Bro!

Pat Tobin

head gaskets

guest's picture

Darryl, I don't think they're the same, but if you need me to FedEx out my R12 cylinder heads to a specific location, let me know You have my card from the send-off at Motorcyclepedia.
Shawn M.

Head gasket failure

Buddy Vitt's picture

When an air cooled engine is going through high heat combustion stress, it is going to get warped . If I may suggest something to do in tandem with the copper head gaskets or you may want to try with the original gaskets and that is o-ringing the cylinder head gasket surface with .025 or .032 copper wire, you can use a wood plane with the blade sides ground down to the width of the wire and adjust to half that for the depth, a machine shop mill would make things easier but it can be done by hand in a parking lot and if the head is really warped badly go to thicker wire and make adjustments in the depth and width. Cutting the groove 1/4 to 5/16 out from the cylinder bore will work ok (that's where I put them on both normally aspirated and turbo charged @20psi race and street engines with zero failures) but in the case of your alloy head it may be better to run the groove near the studs /bolts to get better compression of the copper wire . I have done this to a lot of Triumph's , BSA's Norton's with great success. There was one BSA that blew the cylinder off the cases, the flange of the cylinder was still there and the head gasket was still intact.

I like Dean's suggestion that

Pat Tobin's picture

I like Dean's suggestion that the heads may already have been machined down (some way or another). Mindless raising of the CR was, for decades, the first step in coaxing more horses out of an engine.

Darryl, you may not need or want this info, but I'm trying to cover all the bases in case something, not necessarily an idea of mine, will suddenly give you a "EUREKA!" moment.

So here's my method for checking CR. It depends on the spark plug bore being vertical, which may be damned inconvenient. Anyhow, here goes:

Put the piston at TDC. Pour a solution of light oil (further thinned with gasoline) into the combustion chamber through the spark plug hole. (Sometimes it is convenient to fill clear to the top of the spark plug threads; in that case subtract 1.0 cc from the measured quantity poured in.) I use a cheap plastic vial calibrated in CC's. You can get them at any serious photography store; that is, any which still support chemical darkrooms.) And often larger pharmacy departments in drug stores.

When you have the chamber volume, then calculate the swept volume of the cylinder, using the standard formula for the volume of a cylinder given diameter and length. (I'd write the formula but I'm a little shaky about the memory, and am trying to hurry this.)

Then calculate the CR as (V1 + V2) / V2
where V1 is the calculated swept volume, V2 is the chamber volume.

I'm pullin' for you, Bro!

Pat Tobin

head gaskets

R66RODENT's picture

The rear head on my 11-50 JAP was planed so many times that I had to make a copper gasket 1/8" to restore the original compression ratio (5:1). The front required 1/16". I cc'd the engine on the bench. Even that wasn't easy. Hope you get some well deserved rest in Sturgis. Sounds like you're closing in on the gasket problem anyway.

Soldier on, old horse!

Martin Lodahl's picture

We're pulling for you! And just think of the bright career ahead of you, changing head gaskets on R52's! Customers will be lining up ... -Martin

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