[Rockdodger]

The cylinder head on my '04 Bullet Sixty-5 iron barrel has always leaked a small amount of oil at the junction with the barrel on the pushrod side. During my last teardown,  I had major problems getting the head off due to a missing cylinder head washer from the previous teardown. Now it leaks worse and appears to be pressurizing the oil tank, possibly through the pushrod galley. Instead of the catchcan draining oil back to the oil tank it appears to have oil flowing backward through the return hose. This excess oil is making a mess. Neither the catchcan nor any of it's hoses is plugged. The internal duckbill is working fine. Since I have a K&N filter, I've got the hose that normally goes to the air cleaner routed to put any excess oil on the chain. I believe I verified my excessive oil tank pressure theory by revving the engine with the oil tank return hose off. Within seconds drops of oil started dripping out of the hose nipple which is located behind the cylinder at the top of the oil tank (just behind the gears that drive the distributor.) The dipstick vent is not plugged and the compression is 108 lbs. Does my diagnosis make sense? Because of the severity of the problem, I doubt if a simple lapping will fix it. Is there a specification for how much warpage is allowable? How much material can safely be re-moved in the re-surfacing process? Should/can the barrel be re-surfaced too? Thanks to all for reading this tale of woe.

[ace.cafe]

Unless there is some sort of pitting or uneven surface on the cylinder head surface, it should never be touched.

Any work of that nature should be done to the barrel surface.

Your compression seal is the spigot mating fully-home into the recess in the cylinder head. That's what holds your compression. The only purpose of the head gasket is to seal the oil around the pushrod tubes.

Seat your barrel spigot into the head, and see what gap remains between the head and barrel, using a feeler gauge. Use a head gasket that is thicker than the gap, making some determination of ability of the gasket material to squish(soft or hard).
If you have insufficient head gasket thickness to squish and seal the pushrod tubes, they will leak.
Your spigot MUST be mated fully home into your head recess.

[Ice]

There are two kinds of dipstick the push and twist variety and screw in variety.

On yours the first "click" of the dipstick top is the vented position for normal operation.

The second is the full closed position for storage and shipping purposes.

 I mention this as my oldest Son had a similar symptom happening.
Different cause but similar symptom.

 In his case the fix was run with the dip stick cap at normal position and the oil level half way between add and full marks on the stick.

About compression leaks.
 Yes you can surface and or lap for a good seal and make up the for the material removed if necessary with spacers that fit between the barrel and crank case but such things are not to be undertaken lightly.

Have you tried the composite or dead soft copper head gaskets yet ?

Just curious.

[Arizoni]

Ice:
Don't know if you've read Gordon G. May's book "OVERLAND TO INDIA" in which he rode his 1953 Bullet 8,400 miles from Manchester, UK to Chennai, India?
After checking his oil level one day his Bullet started loosing oil with much of it ending up all over the outside of the engine.

In his desire to keep from loosing the dip stick whenever he was checking and refilling his oil level he had tightened it good and tight.

His bike had the push and twist dipstick and after several days of loosing oil and refilling the tank he finally remembered what his mechanic had told him about the Vent and Sealed position so he turned the dip stick only to the first click. 

 Problem solved!

[Rockdodger]

Thanks Ace for the good advice on how to check the seal between the head and barrel. My mating surface looked pretty good on the last teardown and I used the new composite gasket. I will follow ice and arizoni's advice regarding the dipstick before I tear into it again. My owner's manual (which is for an older model) says nothing about two positions on the dipstick and I don't have a local dealer to ask questions of. To review-I twist the dipstick until it stops turning, but refrain from then pushing it down and twisting it again. That just sounds too darn simple Thanks guys.

[Arizoni]

I'm guessing but if you have the "screw in" type you may be doing things right.

If you have a push in and turn type you get into the first/second scenario.

In either case it is probably a good idea to check on it after riding a ways.

[ace.cafe]

All Bullet engines with the oil tank breather nipple have the screw-in dipstick.

The oil tank breather system was put on for some emission control purpose, and actually was a very poor design, which harmed the engine's breathing. The best thing to do is to restore the old breather design in that engine, by drilling out the original breather elbow on the left side of the crankcase, below the barrel. It can be done pretty easily if you are careful, and then you just plug the oil tank nipple and run a proper breather hose off the crankcase breather elbow, and you're all set.

If you do a search, I made a big thread here with instructions and photos on how to do it.

[Rockdodger]

Interesting. I just tried it with the dipstick cap turned only part way. (It's sort of like a radiator cap. You can turn it a ways until it hits a stop, then press it down and turn it some more-I eliminated the press and turn part.) Rode 8 miles with a straight duckbill breather hose, then 8 more with the OEM 04 Bullet catch can system hooked up. In both cases, the problem of excessive oil coming out of the catch can was virtually eliminated. Unfortunately, I'm still getting some seepage from the head gasket area.
I'll do a search for the breather mods and see how that works. Thanks to all.

[Ice]

 When it was time for the de carbon is when I got to fix my bikes leak at the head to cylinder joint. The technique I used was a  little overboard. When I had it apart I lightly scuffed the copper cladding of the gasket, the  head and cylinder in the area of the push rod holes only. The head,cylinder and gasket were thoroughly de greased.

 A light film of high temperature copper bearing silicone sealer was used as a gasket dressing. Looking downward through the push rod tunnels verified non had squeezed out into the tunnels.

 To get by the last six thousand miles until I could get to the de carbon and fix the leak proper, the following stop gap measure was used.

 The joint was cleaned and de greased and reaching between the fins with a thin artists paint brush, a couple coats of high temperature black engine exhaust paint were applied.

[Blltrdr]

All Bullet engines with the oil tank breather nipple have the screw-in dipstick.

The oil tank breather system was put on for some emission control purpose, and actually was a very poor design, which harmed the engine's breathing. The best thing to do is to restore the old breather design in that engine, by drilling out the original breather elbow on the left side of the crankcase, below the barrel. It can be done pretty easily if you are careful, and then you just plug the oil tank nipple and run a proper breather hose off the crankcase breather elbow, and you're all set.

If you do a search, I made a big thread here with instructions and photos on how to do it.

As you know Ace I did this mod to my bike and then did a write-up with photos that I posted on the forum (http://www.enfieldmotorcycles.com/forum/index.php/topic,5572.0.html). I'm just wondering about the info that Ice has posted about the dipstick cap having two positions (pos #1-vent & pos #2-shipping/storage) which I had not been aware of till reading his post. So I am now wondering if the old style dipstick should be installed in conjunction with the breather mod. It would make sense considering you are moving the breather from the top of the oil tank back to the original location. In doing so you would now loose any venting capability for the oil tank. So what would be your opinion on the tank venting?

[Blltrdr]

Not one to wait for answers I went out to the garage to see if I could at least answer part of my own question.

I took off the dipstick neck off my spare '03 motor and cleaned it up along with the dipstick removing the gasket and thoroughly washing out the cap of all grit and grime and afterward testing the vent then reinstalling the cleaned and lubed gasket. I then installed an o-ring on the neck (wonder why they don't at the factory) and applied some anti-seize to the threads. I removed the neck off my '05 motor which was kind of a bitch because the factory uses some kind of thread locker/sealer which is tough as nails. I unscrewed the neck out about half way then cleaned the sealer from around the top of the tank opening with a flat blade screwdriver (you don't want any of that crap falling in your oil tank) then removed it and replaced it with my old style neck, inserted the dipstick cap and turned it to the first notch (vent).

Well I truly believe this to be the missing link to the original breather mod. The bike does seem to run noticeably different now and seems also that it is breathing correctly. I will keep an eye on my oil use and any new characteristics that reveal themselves.

I will wait to update my breather mod post until I here a little feedback from Ace or anyone else that has an opinion on this subject. Now why in the hell did it take so long for me to find out about the two position dipstick cap? Did I not read this in the owners/repair manual? Well anyway I  want to thank Mike (Ice) for posting that info. The shared knowledge is why I love this forum so much.


Update: I have always noticed while cruising at higher revs in lower gears a kind of surging from the motor. I always believed it had something to do with the revised breather system RE came up with. When I completed the breather mod I notice most of the surging had gone away but not completely. Since changing over from the new style dipstick to the old style this morning it seems there is no more surging felt from the motor. I also noticed that when I put my hand behind the exhaust the pressure seems to be consistent when comparing before I changed the oil dipstick cap where the exhaust pressure seemed to come out from all different angles. Am I dreaming or is there an actual reason for what I'm noticing with the exhaust?

[Rockdodger]

We may be on to something here. Just twisting the dipstick to the first stop eliminated my problem of oil coming out of the catchcan top vent. With the catchcan still hooked up to the crankcase nipple (I'm fortunate that my '04 still has one in the traditional location), and the drain going to the oil tank, I'm still having problems with small leaks at the head gasket and tappet cover. I suspect the duckbill inside the catchcan is allowing the can to become slightly pressurized which keeps the oil tank from being properly vented. My next ride will be with the old-style duckbill from the crankcase vent to the front sprocket area and the oil tank simply vented to the atmosphere through the now non-functional catchcan. I will report back if it works.

[t120rbullet]

With the catchcan still hooked up to the crankcase nipple (I'm fortunate that my '04 still has one in the traditional location), and the drain going to the oil tank, I'm still having problems with small leaks at the head gasket and tappet cover. I suspect the duckbill inside the catchcan is allowing the can to become slightly pressurized which keeps the oil tank from being properly vented. My next ride will be with the old-style duckbill from the crankcase vent to the front sprocket area and the oil tank simply vented to the atmosphere through the now non-functional catchcan. I will report back if it works.

Is your return line going back to the oil tank or into the back of the timing cover ?
Either way you don't want to vent it to the atmosphere you want to cap it off. Any venting to the oil tank is done by the oil fill cap providing you don't have the screw in one.

[Rockdodger]

My return line goes to the back of the timing cover. I'm going to give it a good road test with it vented to the atmosphere. Then I will either vent it to the inside of my K&N air filter  (like the factory did with the stock air box which I assume creates a slight vacuum, much the same as a PCV system on a car). or just plug it off as you suggest. Might as well try everything to see what works best.

[Blltrdr]

My return line goes to the back of the timing cover. I'm going to give it a good road test with it vented to the atmosphere. Then I will either vent it to the inside of my K&N air filter  (like the factory did with the stock air box which I assume creates a slight vacuum, much the same as a PCV system on a car). or just plug it off as you suggest. Might as well try everything to see what works best.

Your hose to the timing cover is your drain. They are notorious for clogging which will result in some serious puking if you don't check your catch can on a regular interval. Having a duckbill or valve in your breather system is a must. That valve is the most important part of your breather system. There are some PVC type ball valves that others have used but you should do some research if you want to use something different than the duckbill. The large pipe at the top of your catch can has a hose that attaches to it and runs to the airbox. The hose can be disconnected from air box or completely taken off your catch can but not blocked. There is plenty of info on the site about the breather system. I would read as much as possible before you make any changes to your system.

[Ice]

Blltrdr you have hit the nail on the head I do believe.

I had theorized along those lines since day one but hesitated to mention the theory as I have not the parts to test it.

 One more thing about our screw in dipstick or late style breather engines.

Inside the timing chest there is a duckbill mounted on interior end of the return line hose nipple.

[Blltrdr]

Don't know anything about a duckbill in the timing chest. How does that let the oil drain properly?

[Rockdodger]

My catch can and the return hose are clean. There's a duckbill inside the can on the line coming from the crankcase vent.
Experiment # 1 was to run it with the dipstick turned to the first stop. (Big improvement!)
Experiment #2 will be to run it with an old style duckbill from the crankcase vent to the front sprocket and with the catchcan hooked up to the oil tank return fitting and vented to the atmosphere.
Experiment #3 will be same as #2, but with the catchcan vent hooked to a nipple on the K&N filter (like the original setup with the factory air filter.)
Experiment #4 will be the same as #3, but using the duckbill inside of the catchcan instead of the old-style duckbill (see experiment #2)
Experiment #5 will be the same as #2, but with the return fitting capped off.
If I can think of any more configurations I'll give them a try and report back on what worked for me.

[Ice]

Don't know anything about a duckbill in the timing chest. How does that let the oil drain properly?
[/quote

Not very well.

I will post pics and more info tomorrow perhaps.

[Ice]

Pics of the timing chest duck bill.

More info later.

[baird4444]

     Well I'll be damned!!!

             hey man....  you've  got a duckbill in yer Timing chest!!

[t120rbullet]

That's a pic of an AVL motor.
The iron motors would have a idler gear there driving the contact breaker housing that's missing on that motor.
Most of the iron motors that had the breather on top of the oil tank had a check valve in the line that returned back to the timing chest. Also didn't work very well.
Rockdodger's 04 65 was the last of the iron motors that had the breather on the left side of the crankcase right under the cylinder. The 04 Bullets had already gone to the breather on top of the oil tank.

Rockdodger,
You can save yourself a ton of playing around by doing a search on the subject. All this has been gone over hundreds of times and all 5 of your "Experiment's" have been done time and time again. Most don't work well and 1 of em does.
CJ

[ace.cafe]

My opinion of the "vented dipstick cap" is that it should be in the sealed position with no venting.
Any vent prior to the crankcase simply defeats the breathing circuit.

[Blltrdr]

My opinion of the "vented dipstick cap" is that it should be in the sealed position with no venting.
Any vent prior to the crankcase simply defeats the breathing circuit.

I do respect your opinion Ace. Why would the dipstick cap have a vent at all? I have never thought about the vent on the cap until Ice brought up the subject. I'm not sure where he read about the positions on the cap, hopefully he can clarify that. Wouldn't the cap vent act in the same way as a vent on a gas can? I mean the oil passage is at the bottom of the tank the oil is always above the passage so how would a vented cap effect the breather system? I know this subject gets a real work over from time to time but as you have stated Ace, it is very important to have it working properly. I feel the more we know on the subject the better. You can thank Ice for starting this whole string of questions.

[t120rbullet]

I mean the oil passage is at the bottom of the tank the oil is always above the passage so how would a vented cap effect the breather system?

There is a small hole (maybe 3/32) between the oil tank and the crankcase. The same hole that they expected the crankcase to breath through after they moved the breather to the top of the oil tank.
More than enough to relieve any pressure that expanding oil would create.
CJ
 

 

[Blltrdr]

There is a small hole (maybe 3/32) between the oil tank and the crankcase. The same hole that they expected the crankcase to breath through after they moved the breather to the top of the oil tank.
More than enough to relieve any pressure that expanding oil would create.
CJ

Your answering the follow up question to my prior question. And I am referring to the original breather system not the revised one. I don't know if the tappet cover gasket is air tight but if not it would also act like a vent through the drain hole in the timing chest. Hopefully someone could answer my original question of why have a vented dipstick cap in the first place. There has to be a reason and I would like to know.

[t120rbullet]

Your answering the follow up question to my prior question. And I am referring to the original breather system not the revised one. I don't know if the tappet cover gasket is air tight but if not it would also act like a vent through the drain hole in the timing chest. Hopefully someone could answer my original question of why have a vented dipstick cap in the first place. There has to be a reason and I would like to know.

I also was referring to the original breather system. Pre 2004 (except the 04 65 that retained the original breather).
Aside from the breather and the vent on the oil cap the rest of the engine is air tight and any pressures including valve guide blow-by could be handled by the crankcase vent.
The post 04 breather isn't even worth talking about.

Why they had the vented cap I really don't know. The Bullets used it for over 50 years and never had any breathing issues with the motors. And then they changed it to something that didn't work worth a poop. Why ? I can't answer that one either.
CJ

[Blltrdr]

I also was referring to the original breather system. Pre 2004 (except the 04 65 that retained the original breather).
Aside from the breather and the vent on the oil cap the rest of the engine is air tight and any pressures including valve guide blow-by could be handled by the crankcase vent.
The post 04 breather isn't even worth talking about.

Why they had the vented cap I really don't know. The Bullets used it for over 50 years and never had any breathing issues with the motors. And then they changed it to something that didn't work worth a poop. Why ? I can't answer that one either.
CJ

I stand corrected. I do see there is a small hole at the top of the tank. I would guess this would equalize the pressure between the tank and crankcase.

[Ice]

 Yes the pic is an AVL. a 2006 production engine with the old style ( but un drilled ) breather lump on the left hand side.

 My '06 Iron barrel has the same setup with the only difference being the duck bill is much shorter. Next time I have the timing chest cover off I will take a crappy cellular phone pic.

 In the early twist on style of breather system a small amount of fresh air is drawn in through the vent in the dipstick as the piston goes up and a partial vacuum is also created.
 
 Any combustion gasses leaking past the piston rings ( there is always some ) and unburned hydrocarbons are expelled out of "the lump" on the upper L/H side of the crank case ant through the duck bill and its associated plumbing. The duck bill of course providing a one way valve so as to keep fresh air coming in and the aforementioned waste gasses flowing out.

 This was good as the hydrocarbons, if allowed to build up, break down oils ability to lubricate and combined with moisture from condensation and exhaust gases turn the oil mildly acidic.

 The partial vacuum mentioned earlier, besides aiding the sealing of the pistons rings, effectively lowers the boiling or evaporation point of hydrocarbons in the oil and any moisture that may have condensed as well. ( easier to expel water as a vapor than droplets )

 I forget when but at some point in time a catch can shaped like a box was added to the system . The airflow in this system is in through the vent cap, through the oil reservoir, through a tiny opening between it and the crank case proper, out 'the lump" to the box shaped catch can ( breather box) where oil mist was separated from vapor and then into the air filter housing where any unburned hydrocarbons and airborne oil vapor were sucked into the carby for combustion in the cylinder.

 This system is o.k. I guess but burning the oil vapor does produce additional carbon to build on the piston crown, combustion chamber face, exhaust valve, etc. then too the breather box has to be emptied periodically.

More to follow later.

[Blltrdr]

Well the thing I notice the most since i changed over to the early model oil cap is......... I have no more mayo like goo spewing on the ground from my duckbill breather routed out the back of the rear fender. This is very interesting to me! Before the change from the screw on non-vented cap to the old style vented cap I had a blonde colored mayo blurped out onto the ground everywhere I stopped the bike for a period. Now I might have a little oil mist on the ground but no mayo. I think there is something to Ice's comments. Is it just his theory or is it RE engineering speak? I think it may be the latter. The bike runs great, maybe better than ever. I will keep running with the cap in the #1 position until I someone proves to me beyond a doubt that it is wrong. But that person would also have to explain to me the reason that having the puking mayo on the ground is a good thing. 

[Arizoni]

IMHO in a properly vented system the downward movement of the piston quickly expels most of the air in the crankcase. 
This partial vacuum greatly lowers the boiling point of any water (a product of combustion) that is in the crankcase or mixed into the oil.  Given enough vacuum, water will boil at room temperature and although this much vacuum is not created in the crankcase the boiling point of the water can easily be reached by the normal oil temperatures in the engine.
The resulting "steam" is blown out thru the vent along with any gasses that have gotten past the pistons rings.

Without water in the oil system the mayonnaise like mixture of water and oil will not exist.

This is good because the oil pump cannot suck the mayo like stuff  thru any filter gauze or even the oil pickup tube.

[t120rbullet]

But that person would also have to explain to me the reason that having the puking mayo on the ground is a good thing. 

Better on the ground than in the engine, I guess ? Maybe ?
All the older engines I have and had never had a mayo issue.  I have a 04 engine in the white bitch now with the breather off the top of the oil tank and the screw-in oil cap and there always is a layer of mayo on top of the oil. Gives some color to the dipstick when checking the oil.
CJ

[Rockdodger]

This has been a really interesting and informative discussion. I'm far enough along with my "experiments" to be convinced that the problem with my '04 Bullet Sixty-5 was too much pressure in the oil tank. Running the dipstick in the first stop position stopped it from puking oil out of the catchcan vent. Running a traditional duckbill from the crankcase and venting the timing case return thru the catchcan to the atmosphere appears to have eliminated the problem of leaking oil at the headgasket.. I now believe that my problems started when I installed the K&N pancake filter. The old airbox had a nipple that was attached to the catchcan vent. This created a slight negative pressure that kept air flowing through the oil tank. With no good place to attach the vent hose to the K&N, I left it off. The original duckbill which ventilated the crankcase into the catchcan apparently was then pressurizing the oil tank, timing case, tappet cover and valve covers, causing various small oil leaks, especially on the pushrod side of the head gasket. At some point the vent in my dipstick, must have gotten partially blocked making the problem of over-pressurization worse.   

[Blltrdr]

This has been a really interesting and informative discussion. I'm far enough along with my "experiments" to be convinced that the problem with my '04 Bullet Sixty-5 was too much pressure in the oil tank. Running the dipstick in the first stop position stopped it from puking oil out of the catchcan vent. Running a traditional duckbill from the crankcase and venting the timing case return thru the catchcan to the atmosphere appears to have eliminated the problem of leaking oil at the headgasket.. I now believe that my problems started when I installed the K&N pancake filter. The old airbox had a nipple that was attached to the catchcan vent. This created a slight negative pressure that kept air flowing through the oil tank. With no good place to attach the vent hose to the K&N, I left it off. The original duckbill which ventilated the crankcase into the catchcan apparently was then pressurizing the oil tank, timing case, tappet cover and valve covers, causing various small oil leaks, especially on the pushrod side of the head gasket. At some point the vent in my dipstick, must have gotten partially blocked making the problem of over-pressurization worse.   

The problem with the revised breather system is that it is trying to vent the pressure built up in the crankcase through a little hole between the crankcase and the oil reservoir up through the top of the oil reservoir through a hose that is bent in the wrong direction up to the catch can and out the duckbill tip located in the catch can. This screwed up design has caused many problems and can only be alleviated somewhat. The proper fix is to do the mod to return the breather to the original position it had been in for 50 yrs. RD I would suggest you do a forum search and read the miles of posts on this subject, especially the many posts written by ace.cafe.

[Rockdodger]

Blltrdr, you are at least 100% correct. My current configuration is the old-style duckbill in the traditional place. On my bike the factory did a pretty good job of applying an automotive-style positive crankcase ventilation (PCV) system which adequately ventilated both the crankcase and oil tank. I had no problems until I added the K&N filter without making provision for excess pressure to be relieved by a vent hose to the air cleaner, as with the stock '04 Bullet Sixty-5. I think the folks who have had problems with cream gravy clogging up their catchcan have a different vent system (i.e. it sounds like some bikes have a duckbill or checkvalve on the oil tank fitting instead of the crankcase fitting.)

[Blltrdr]

Well the thing I notice the most since i changed over to the early model oil cap is......... I have no more mayo like goo spewing on the ground from my duckbill breather routed out the back of the rear fender. This is very interesting to me! Before the change from the screw on non-vented cap to the old style vented cap I had a blonde colored mayo blurped out onto the ground everywhere I stopped the bike for a period. Now I might have a little oil mist on the ground but no mayo. I think there is something to Ice's comments. Is it just his theory or is it RE engineering speak? I think it may be the latter. The bike runs great, maybe better than ever. I will keep running with the cap in the #1 position until I someone proves to me beyond a doubt that it is wrong. But that person would also have to explain to me the reason that having the puking mayo on the ground is a good thing. 

Another update since changing over to the old style dipstick cap with my reverted breather system.

Since reading Ice's post on the dipstick cap setting and completing the mod I have to say that the performance has changed in very good ways. First off like I mentioned before, no more mayo out the back from the duckbill. Every time I would ride my bike and park it when I came back there would be a big mayo goober on the ground. Now it seems to be nothing dripping from the duckbill. I also notice a difference when I throttle on at high speed. Before it seemed to pick up OK but would seem like it had to work hard to get over 60 and now seems to pull hard past 60 and seems willing to go much farther. Not like I'm going to ride that fast but before it seemed like I had a governor on the bike and now it doesn't. 

[Arizoni]

This is good to know.  Thanks for the update.