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?