Cylinder Head Gasket Weeping Oil? Here's A .32 Cent Bandaid

[cafeman]

I've been tweaking, adjusting, detailing, etc my just purchased 01 Bullet and noticed I have some weeping of oil at the head gasket. I've been getting some oil spatter on the coil, carb, and sides of the toolboxes after longer rides, and while I have the gaskets on the way to fix it, I'm not wanting to tear things down just yet after having just gotten it. It's more of a nuisance rather than a serious problem, having to wipe things down after every ride. So in the meantime, I gave some thought on what would work to stop oil from getting all over the place. I figured some cotton rope pushed tight around the perimeter, wedged between the fins might do the trick, would be very absorbant, and be easily replacable if it really got soaked. Went up to Hobby Lobby, found the right thickness and bought a yard of the stuff. Was hoping they had black cotton so it would'nt show as much, but no go. Out the door cost was .32 cents! Went for a good hour ride and there's no oil anywhere like before. Might be a good bandaid until gaskets and time are available, or maybe even leave it as is until next de-coking service. Obviously want to make sure compression is good, and watch the oil level before forgetting about it... 

[AgentX]

Did you re-torque the head?  That often stops leaks around the gasket.

[cafeman]

Checking the bolts would be the obvious first thing to do, but if after assembling things it still weeps, I'd have to tear it apart again to replace the gasket(s) when I get them (I'm getting the composite version from Hitchcocks) This is just a case of oil weeping vs. oil getting into the cylinder or compression leakage.....like I said, it's  just a bandaid for me until I get the parts and time, and most likely will wait until it's time to de-coke. I may even do some porting when the head is off!

[ace.cafe]

Most of the time the oil leakage around the head gasket joint is because the barrel spigot is too tall, and prevents the head from seating down on the head gasket sufficiently to seal the oil around the pushrod tunnels.
In cases like that, no amount of re-torquing will fix the leak. However, a little measuring of the gasket gap between the head and barrel, and a gasket that is .010" thicker than the gap, will fix it. Or, if you turn down the spigot enough so that the gasket gap is .010" thinner than the gasket you plan to use, then it will seal.

As for the porting, the port is already big enough for 6000 rpm, and all the gains for that port will be in the valve seat, unless you go to bigger valves and know how to re-shape the bowl properly to get gains from it.
Take it from a guy who has a LOT of Bullet cylinder head work under his belt.
And if you plan to ever have it ported professionally, like by us, then leave it alone until you want to send it in, because sometimes we can't get the best results if metal is removed where it wasn't supposed to be removed.

This port retains the 32mm entry, but has 1.84" intake valve with narrower stem, with re-shaped bowl and special 5-angle valve job done on a Serdi machine, with custom guides, and will receive a custom hand-matched and flowed inlet manifold stub pinned on those pin-holes you see in the photo.

[cafeman]

Most of the time the oil leakage around the head gasket joint is because the barrel spigot is too tall, and prevents the head from seating down on the head gasket sufficiently to seal the oil around the pushrod tunnels.
In cases like that, no amount of re-torquing will fix the leak. However, a little measuring of the gasket gap between the head and barrel, and a gasket that is .010" thicker than the gap, will fix it. Or, if you turn down the spigot enough so that the gasket gap is .010" thinner than the gasket you plan to use, then it will seal.

As for the porting, the port is already big enough for 6000 rpm, and all the gains for that port will be in the valve seat, unless you go to bigger valves and know how to re-shape the bowl properly to get gains from it.
Take it from a guy who has a LOT of Bullet cylinder head work under his belt.
And if you plan to ever have it ported professionally, like by us, then leave it alone until you want to send it in, because sometimes we can't get the best results if metal is removed where it wasn't supposed to be removed.

This port retains the 32mm entry, but has 1.84" intake valve with narrower stem, with re-shaped bowl and special 5-angle valve job done on a Serdi machine, with custom guides, and will receive a custom hand-matched and flowed inlet manifold stub pinned on those pin-holes you see in the photo.

I've read somewhere about what you recommend doing as far as measuring the gap and possibly fitting a thicker gasket, I will do that for sure, and definately agree with the porting advice. Nothing like messing up flow and velocity by ham handed hogging out of the ports with no idea what ones doing.
All I ever do when backyard porting (cleanup) is remove any globs, irregularities, sharp edges, maybe contour the guide bosses a smidge and work on the throat, or just below the last angle cut, without getting into the bowl area, and spend some time smoothing the short side radius....all without really enlarging anything or getting into serious removal of material. I stick to basic port cleanup. I worked on the head of my 2007 Benelli Cafe Racer (it had two guides where oil was leaking between the guide and head) it was blowing a cloud of blue smoke at start-up after sitting and when getting on it, removed the head, diagnosed, fixed, and while I was at it, did the above porting. It was as cast with major sharp edges, casting globs in the intake port, had sharp edges on the intake and (really bad) exhaust short side radius's, as well as the throats. I spent lots of time smoothing (not polishing) and cleaning things up.
I could see sourcing one of those reworked heads you have perfected one day though, maybe for a cafe style Bullet I still fancy building!

[ace.cafe]

Most factory engines suffer from similar flow problems because they can't take the time to do that kind of hand work on the assembly line.

In many cases, just a really good valve job with the correct angles for the application can do wonders for a factory bike.

[Blltrdr]

Checking the mating of the spigot to the mating surface on the head is essential. Ace has gone over this many times before. If you do a forum search on this site or Tom's (Ace) site you will find the info needed to properly check and mate the surfaces. Most mating surfaces are suspect on newly assembled iron barrel motors from the RE factory. The spigot top should be parallel to the machined surface on the barrel top. Many times it isn't. The spigot and head should be lapped. Ultimately you want a perfect seal mating barrel spigot to head and parallel surfaces barrel to head for the best gasket seal.

I would say that a complete blueprinting of an iron barreled Bullet motor would be a must when finally deciding to do a complete tear down. From the factory the varied tolerances and poor metallurgy make engine survival a real crapshoot. There are a few who have a jillion miles on their Bullets. The word few is the real problem because it should really be the opposite when talking longevity of a product that has been in production as long as the Bullet has been. If you love your Bullet as much as most of us do you will one day have to pony up the cash and time to make it right. Thanks to Tom and Chumma's meticulously thought out parts testing and rebuilding process a new foundation has been laid to build a practically bulletproof Bullet iron barrel motor. For many this may not be monetarily feasible but could be a basis to use when rebuildling to stock specifications. Thankfully Tom and Chumma have really gone to great lengths to offer a kit for every level of price point and performance along with the knowledge and support to help everyone along through their build. This shows great dedication and discipline between the two which can be attributed to their love of these motorcycles and they're passion for innovation. I am looking forward to what they have in the works for this new year.

[Chuck D]

Checking the mating of the spigot to the mating surface on the head is essential. Ace has gone over this many times before. If you do a forum search on this site or Tom's (Ace) site you will find the info needed to properly check and mate the surfaces. Most mating surfaces are suspect on newly assembled iron barrel motors from the RE factory. The spigot top should be parallel to the machined surface on the barrel top. Many times it isn't. The spigot and head should be lapped. Ultimately you want a perfect seal mating barrel spigot to head and parallel surfaces barrel to head for the best gasket seal.

I would say that a complete blueprinting of an iron barreled Bullet motor would be a must when finally deciding to do a complete tear down. From the factory the varied tolerances and poor metallurgy make engine survival a real crapshoot. There are a few who have a jillion miles on their Bullets. The word few is the real problem because it should really be the opposite when talking longevity of a product that has been in production as long as the Bullet has been. If you love your Bullet as much as most of us do you will one day have to pony up the cash and time to make it right. Thanks to Tom and Chumma's meticulously thought out parts testing and rebuilding process a new foundation has been laid to build a practically bulletproof Bullet iron barrel motor. For many this may not be monetarily feasible but could be a basis to use when rebuildling to stock specifications. Thankfully Tom and Chumma have really gone to great lengths to offer a kit for every level of price point and performance along with the knowledge and support to help everyone along through their build. This shows great dedication and discipline between the two which can be attributed to their love of these motorcycles and they're passion for innovation. I am looking forward to what they have in the works for this new year.

What he said.

[cafeman]

I agree with checking the mating surfaces of the cylinder head and barrel. I've lapped a few heads in the past, mostly vintage Husqvarna dirtbikes as standard practice during rebuilds, but specifically an old school S&S stroked 1974 Sportster with massively reworked heads, big cams etc that I had quite a few years back. Was using copper gaskets, and was getting oil sucked into the bores from the integrated oil return passages in the barrel. So I lapped, used copper gaskets and a thin coating of Yamabond 4 (I believe it was, this on the recommendation of a Harley dragbikeracer/builder) Solved the problem. Lapping probably did it, the sealant was for good measure I reckon.
I'll be leaving the bandaid for now, and when it comes time to service the topend I'll let the fun begin. 

[ace.cafe]

You can still use a gasket if you want to, as long as the surfaces are straight, and the spigot height sets the gasket gap properly.
I use gaskets more often than not.

But whatever method you use to seal the oil, the spigot height must be set properly for the method you are going to use.
This is because the spigot mating into the head recess is what seals the compression in this engine. The head gasket only seals the oil around the pushrod tunnels. They both have to be in the correct relationships with their respective mating surfaces at the same time, when you put the head on.

[cyrusb]

In addition to the above info you may want to have a look at the stud near the spark plug. It communicates with the crankcase and is a direct line to the outside world. Mine actually bubbled oil. When it's tore down a little sealant on the case side threads does the trick. BTW, my spigot does not contact the head, and the gasket holds the tremendous compression quite nicely.

[Blltrdr]

BTW, my spigot does not contact the head, and the gasket holds the tremendous compression quite nicely.

If that is the case, wouldn't the characteristics of your combustion chamber change if the spigot does not contact the recessed surface. That can't be right or good in my opinion.

[ace.cafe]

If that is the case, wouldn't the characteristics of your combustion chamber change if the spigot does not contact the recessed surface. That can't be right or good in my opinion.

Stock Bullets with their low compression can survive a bad fit at the spigot, and often do.
It becomes much more of an issue when the compression is raised, and pressures and temps go up, which can cause some damage if the compression seal at the spigot is not correct.

[cyrusb]

If that is the case, wouldn't the characteristics of your combustion chamber change if the spigot does not contact the recessed surface. That can't be right or good in my opinion.

How many other engines do you have that have that requirement? I can tell you that of the many air cooled high performance engines I have had (and have) the bullet is the only one to have this need. At 6.5 to one no less. I have to own up that my old beetles were built that way. But in their case they allowed for the problem of getting an absolutley tight head and get your pushrods to seal by making them collapsable.

[cafeman]

How about surfacing the head and barrel as well as machining the raised ring to a point where it does not contact the head, yet still acts as a fire ring, locating ring, but then fitting an MLS type gasket, which would do "all" the sealing, and in a superior manner? I know MLS head gaskets are the latest technology for autos, as well as most motorcycles. After all the head work Ace Performance has done/is doing using the latest tecnnology, it would seem to me that the above scenario would be at the same level as what they have already come up with, perhaps something worth looking into....if not already?

[ace.cafe]

There are times when things need to be changed, and other times which just require things to be put together the way it was intended.

This is one of those times when it just needs to be put together as it was intended.

[cyrusb]

Ace, not trying to be an ass pain, but, where does it actually say that? I have never seen a real (not snidal's) RE engine manual. Does anyone have one? It just seems like an engineering "don't" to make two surfaces seal perfectly in that manner. And certainly not a 3rd world process.

[ace.cafe]

Ace, not trying to be an ass pain, but, where does it actually say that? I have never seen a real (not snidal's) RE engine manual. Does anyone have one? It just seems like an engineering "don't" to make two surfaces seal perfectly in that manner. And certainly not a 3rd world process.

I'm just discussing the head gasket sealing procedure, not the "lapping the head to eliminate the head gasket" procedure.

With the spigot too high, it's apparent that the gasket can never seal, so we know that has to be short enough to let the head crush the head gasket to seal the oil.

With the spigot too short, the gap above the spigot in the recess around the combustion chamber permits hot combustion gases under pressure to get into that area. The only place that spigot can seal is at the top, against the head.
If that doesn't seal at the top, these hot gases can, and often do, go over the top of the spigot and down to the head gasket itself. As this happens, flame cutting takes place and erodes the head recess and spigot until the area of cutting gets big enough to compromise the integrity of the head gasket and the head gasket blows. If any detonation is happening, it happens even worse. When it does this, it often blows to the pushrod tunnel, and causes very high crankcase pressure, which is often the first indication to the owner that something is amiss. Upon disassembly and examination, this flame cutting damage has been seen to be the cause.

The higher the compression in the engine, or the worse the detonation problems, the more likely we are to see this problem. However, it is even seen on stock engines from time to time.
So, the answer is to fit the parts so that the seals work properly, and no problems.
We have a "hard surface seal" on top of the spigot, and a "soft crushable seal" on the head gasket. All that's needed is to set the height of the spigot to handle both seals at the same time. It's simple, really. We do it on every engine we build, and if we don't do it ourselves, we instruct our clients how to do it themselves. I have instructed people in India how to do it, by email.


Additionally, just looking at a combustion efficiency point-of-view, the crevice that might be left above the spigot on a non-sealing spigot/head interface would be included in "parasitic crevice volume" problems that should be avoided in combustion chambers. Areas like that which can get the fuel pushed into them and not have room to properly ignite can cause poor combustion because that fuel which is intended to mix with a certain amount of air is pushed into that crevice by compression pressure, and then the remaining mixture in the chamber has lean spots because that fuel is hiding in that crevice volume. This causes poorer combustion, excess heat, loss of power and fuel economy, etc. The same can be said of the volume around the top of the piston, above the top ring, which gives similar problems, and which is why people try to place the top ring as high as feasible, trying to minimize that parasitic crevice volume.

The Bullet already has very challenging combustion problems from the initial design, and really needs all the help it can get. So, dealing with this parasitic crevice volume, and sealing the combustion chamber at the spigot properly, can help both of these issues, and also be done in a way that the head gasket seals the oil around the pushrod tunnels too.

I have had people who could not solve their oil leaks after many tries, send me their heads and barrels to be properly set, and their problems were solved in our first try, because we have done this so many times that we know the procedure. We can run any compression level we want, and have good combustion, and never have oil leaks at the head joint.

So, it's really just a matter of knowing what the ideal arrangement should be, and accomplishing it to solve the problems. It's more than just reading a manual. The manuals are the most sparse information available, and primarily centered on repair, and not necessarily focused on correcting the factory shortcomings, or understanding proper engine building techniques.

Regarding the process being too much for "3rd world", I have accomplished it with a hand file on more than one occasion. If you understand the goal, and are careful with your work, it can be done by hand.

[cyrusb]

There are times when things need to be changed, and other times which just require things to be put together the way it was intended.

This is one of those times when it just needs to be put together as it was intended.

The question was simple "Intended by who?". If you prefer your theory as to why that spigot is there, fine. But as I asked, Where is it written? If you are going to be speaking for RE 's "intentions" you need RE's data to back that up. Cheers, cyrus

[ace.cafe]

The question was simple "Intended by who?". If you prefer your theory as to why that spigot is there, fine. But as I asked, Where is it written? If you are going to be speaking for RE 's "intentions" you need RE's data to back that up. Cheers, cyrus

I don't speak for RE. But I do clean up a lot of their mistakes.
And their manual is by no means complete, nor without omission, about many things.

Here's a technical drawing of a VW aircooled engine which uses the same type system that might help to visualize the concept.


And one of a Lycoming aircooled aircraft engine, using the same type system.


Here's a 356 Porsche





They all show the same thing. The spigot goes all the way to the top inside the head recess.
It's just the way it's done. I provided the reasons in my other post.

So, to answer the question about "Who intended it?", the answer would be "the people who understand the design, and who know what they are doing, and who care about getting a good result, intend it."

[72westie]

Mmmmmmm....Volkswagens.... 

[baird4444]

" It's just the way it's done. I provided the reasons in my other post.
So, to answer the question about "Who intended it?", the answer would be "the people who understand the design, and who know what they are doing, and who care about getting a good result, intend it." "

    I think what ace is saying is "Because I say so..."
"the people who understand the design, and who know what they are doing"

   Now I feel like the lowly serf,
        being told what is right and how to think...
                     and that I'm not as good as....

 

[ace.cafe]

" It's just the way it's done. I provided the reasons in my other post.
So, to answer the question about "Who intended it?", the answer would be "the people who understand the design, and who know what they are doing, and who care about getting a good result, intend it." "

    I think what ace is saying is "Because I say so..."
"the people who understand the design, and who know what they are doing"

   Now I feel like the lowly serf,
        being told what is right and how to think...
                     and that I'm not as good as....

People are free to do it any way they want.
I'm not forcing anybody to learn anything, and I backed up my statements with real facts, not just "because I say so".
People can always go and do it like the manual doesn't instruct, if they can decide on a method that's not in there. Or they can take the advice of somebody that does this work regularly and knows how to do it, and has solved a lot of problems for Bullet owners in this oil leak issue and other things. And incidentally, I described a way to do it that they could do themselves, and wouldn't cost them a penny to do it.

[Blltrdr]

The first time the light lit was reading the article below. Problems with fitment have occurred on British designs according to this article ever since there machines started wearing out. So you take the same problem to India with machinery provided to the factory from England and run it non-stop for say 50 years and you are definitely going to end up with the same problems the Brits had years earlier. It is up to the end user to rectify this problem just as Tom has laid out. Now granted, this article is about doing away with head gasket but the article also makes very clear of the problems with the spigots mating correctly, not only on RE's, but on most other Brit brands. Who woulda thunk!

[baird4444]

and let's go one better....
     the composit head gasket IS the fix. I don't think there have been any
reports of it not sealing...

[Arizoni]

For what it's worth Ace, I appreciate you taking the time to explain how to assemble these engines.  Experience beats speculation every time.

I know it takes time to write these things up and I think I can speak for many of our viewers, your time is not wasted.

[ace.cafe]

For what it's worth Ace, I appreciate you taking the time to explain how to assemble these engines.  Experience beats speculation every time.

I know it takes time to write these things up and I think I can speak for many of our viewers, your time is not wasted.

Thanks, Jim!

[cafeman]

and let's go one better....
     the composit head gasket IS the fix. I don't think there have been any
reports of it not sealing...

That's what I've read, but when the time comes to install it I will be checking the gap with the head installed on the barrel just to make sure all is good.
But in the meantime, the rope around the perimeter will suffice ........................for as long as I'm lazy  

[Arizoni]

As long as your using the "rope" trick to fix your problem I think you will have to know the old British Motorcycle rule.

"When no oil leaks are detected your motorcycle is out of oil.  Top up as soon as possible."   

[mrunderhill1975a]

I have  been lurking on this thread for some time and have learned a great deal from this discussion.  I now have a question........If I were to lap the head to the barrel myself, how long would this process take?  One hour, 10 hours of lapping or more?

[ace.cafe]

If you want to lap the head, typically the spigot will be much too high to do this by just lapping alone.
A good method would be to use a lathe to bring down the height of the spigot to be just a hair longer than the depth of the recess in the head.
You can check it by putting the head on the barrel and pushing it down all the way to be sure it's fully seated home, without any head gasket in place. Measure with an automotive feeler gauge, the empty gap where the head gasket would normally be, and that is your gap which needs to be narrowed. Reducing the height of the spigot carefully bring the gasket mating surfaces very close together so that very little lapping will be necessary, is the goal. Frequent checking of the gap by putting the head on the barrel will help you to gauge your progress, so that you don't shorten the spigot height too far.

The goal is to have the top of the spigot mate perfectly home into the head recess, at the same time that the mating surfaces on the head and barrel(where the head gasket used to be) come fully home together.
This will be accomplished in the final stage by lapping with valve grinding compound, as Royce Creasey describes.

I have found that lapping often allows some oil seepage to still occur. It's very hard to eliminate it without some sealer. So, a very light smear of hi-temp silicone sealer around the pushrod tube area should take care of any slight imperfections, and seal the oil.

I generally do not do the lapping process, but on occasion we have done it for some people who are at high elevations that need to increase their compression to the maximum extent possible because of thin air conditions at their locations in the high mountains.

[neil]

Hello Fellow Bulleteers:
I had head/barrell oil leakage problems too. Ace suggested
using a mill file and carefully measuring the height of the spigot until you have a firm idea of how much of the spigot needs to be removed to get the proper seal between the recess in the head and the height of the spigot. I was able to do it and voila, the leaking has stopped. I used a copper gasket and gasgachinch on all mating surfaces around the top of the barrell and the surfaces of the gasket. It's not the type of material the gasket is made of, but the proper seal of the mating surfaces.

If I can do it --- everyone should be able to do it. Use a piece of glass to be sure the top of the spigot remains absolutely flat and parallel to the top of the barrell. The spigot seals the compression and a properly mating gasket seals the oil and - - - no more weeping of oil. 

Try it, you'll like it.

Neil and Buzzy the Bullet