Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board A65 problem with rings sealing

I rebuilt my A65 Lightning with new Emgo pistons and Hastings (IIRC) rings about 10 years ago, but never put any mileage on it. So I brought it our of retirement last week and took it out for some spirited runs. After some adjustments to side covers (that's another story) I got it oil tight, even when idling on the stand. However, after about a 100 new miles (total now of 300 miles since rebuild), it's now got so much blow by on the right cylinder that it coats the rear tire.

I disassembled it today to find that the rings sealed well on the left cylinder, but not on the right. Following are some photos which seems to indicate that the crosshatching on the left cylinder left by honing are still apparent, though it does not seem to have a blow-by problem. But on the right cylinder, the honing marks are almost non-existent, and the blow-by actually leaves oil on top of the piston.

Could the shop that bored it (+.060) have failed to hone that cylinder sufficiently?

Could the ring gaps being lined up have caused this situation (they seemed quite close to being lined up)?

If I re-hone that side, can I use the same rings over again? Getting new rings even from British Cycle right now is a problem.


cylinders showing honing marks

Close-up of right cylinder

Cylinder head showing oil fouling on right cylinder

Thanks for any advice.

Did you run it in carefully?

one piece or 3 piece oil ring ?
Sometimes a multi-piece Oil ring can get installed wrong .

Many years ago when I had my tiger cub rebored, I asked the the old school engineer how long to run it in for. His reply was "Twice up and down the bore"
Last year I asked about running in my brand new GM speedway engine, the engine builder replied "warm it up then thrash it"
So over the space of approximately 43 years the advice has not changed

Pics of rings please , are the RHS rings evenly matt allround? What are the ring gaps? Theres seems to b a lot of vertical scratches in the RHS , and a nasty patch near the top , if it was honed the marks should be clearly visible on the lower cylinder section beyond the ring travel.

Even in the left cylinder I don't see much of a cross-hatch honing pattern.
It may be the photo, but it looks messy and not what I would expect.
The right cylinder doesn't show any signs of honing at the same time and I agree with Gavin about the vertical scratches.
Also, are all those thousands of marks in the pic really there? Rust pits perhaps?

I don't know what tool was used to "hone" the left side, but I guess he chose not to repeat on the right side, so left it alone.

I'd suggest having it checked by a proper engineer for bore size/quality against the pistons you have.

No.

You can normally get away with it if you are brutal when you bed it in.

Looks like the head gasket was blowing that side so comp would be down, may explain some of it.

A few more photos. Tough to get good photos with the I Phone.



Here is the composite gasket I used upside down on the head. Yes there is a small dent in the head adjacent to the bore and a corresponding mark appears on the gasket.
I don't think the gasket was blown. The mottling pattern on the head is unusual to me so I'm blaming it on the composite gasket. It looks kind of like shellac or something that transferred from the gasket. I'll be using a solid copper one on the re-build.



Photo of the pistons with the rings. Not much scuffing at all that I can see.



I removed the top ring to measure the ring gap here. It's .013".


Andy, most of my builds go directly from my shop to the dyno, the road race track, or the Salt Flats, so wide open throttle. My road bikes go out on the road and get thrashed as well as I can on these back roads, up and back down the rpm scale. Is that what you would call run in carefully?

Nick, I could do that!

From Koan: "I'd suggest having it checked by a proper engineer for bore size/quality against the pistons you have."

I believe he best pros in the world on BSA's are right here on this forum. That's why I'm asking you guys for advice.

Tom

Measure the ring gap in the unworn part of the barrel near the bottom, if its 13 at the top expect it to be tighter at the bottom. If its not massively different then a fresh hone and new rings would do the trick.
Rings are supposed to rotate in operation, if they were all lined up that could just be a chance thing so long as they are free to turn, on a side note check the ring fit in the land, they should be free but not walloping around, if a 2 thou feeler goes in then the lands have taken a beating ( I dont think its that but its an easy check).

Does the bike breath through filters?, the vertical scores would suggest not, or the oil was dirty.

I believe I’ve caused similar issues as you by thrashing a set of standard rings. Following others advice to do this, but I guess one persons idea of giving the bike some hard pulls can vary to another. Does your oil tank stink of gasoline also?

Even with modern rings I prefer to use a running in oil and ride the bike normally.

The quickest way to get vertical scratches like that is to leave honing grit on the bore.

After honing, it has to be washed in soap and hot water until the bore surface leaves no mark on a white paper tissue. The bores cannot be cleaned properly with kerosene or solvent.

The usual advice is to make the engine pull, in bursts, as soon as possible after first starting it with new rings. I wouldn’t say “thrashing” is a good description of that.

Hi TT, I was making refrence to the previous comment.....


Everyone rides differently, I never keep my bikes reving low in a high gear (unless im on the motorway then it'll sit somewhere between 3500/4500 revs), I find this kind of riding is sufficient for running in. I have very good compression on both cylinders, the oil also takes forever to blacken. riding as previously mentioned the oil stank of fuel and the gas milage was pretty poor.

Worth having a read of the Hastings Cylinder bore refinishing guide Here.

It mentions that the cross hatch angles should be 45 degrees, the grit should be 220 to 280 and that they cylinders must be washed thoroughly afterwards as suggested. Difficult to tell but your cross hatch may be too shallow?

I guess the question is why only one cylinder is affected, some thoughts on this are:-
- maybe one piston was assembled with plenty of lube whilst the other was dry?
- cylinder honing different between cylinders, maybe wrong cross hatching?
- possible head gasket oil leak in one cylinder causing running in issues?

I would re hone the bores, use a dry assembly with the old rings and give it a hard run in.

I've remeasured more carefully today and found that 1" down from top the gap is .012" whilst at the bottom, .010". But the middle ring and oil ring had a whopping .024-.025" gaps. I also measured the bore 1" from the top and the piston front to back at about the mid point using telescoping gauge on the bore and then using my Mitutoyo 6" calipers. I get the piston at 3.006" and the bore at 3.010", so about .004" clearance. I don't have a bore gauge nor a 3-4" mic, so that's as close as I can get.

The bike has original BSA air filters and there's no smell of gas in the oil. Oil was new, less than 300 miles now. It's always possible the oil tank did not get cleaned as thoroughly as it should have, but the oil looks clean. However, the oil that gets deposited on the floor after a run looks dirty but could just be mixed with road grime and then runs off when I park it

I'm taking a ride up to Wolfville today to pick up some new rings, but no sure what brand. The ones I had were 1-piece oil ring, so not Hastings as I would prefer (3-piece oil rings).

Tom

P.S. I thought this forum was supposed to remember that I'm not a robot, but it doesn't seem to.

Re: Robot, might have something to do with your internet cookies....

Only other consideration is were the rings fitted the right way up? Its possible that it might be sealing well enough to stop blow by of fuel getting past the rings but might just be allowing oil to pass one way.

Another ring option is to give Ed V a call, he is a supplier of Total Seal Rings, I have these on a set of his JE pistons. Never had any oil/fuel cross over contamination issues with them....

Another alternative is there is nothing wrong with your piston rings, Infact you have a very good ring seal and its highlighted a problem in your inlet valve guide (I had this when I first fitted the TS Rings, I thought it was poor ring seal but found it was a bad valve guide pulling oil in and causing it to smoke, after having K-liners fitted it solved the problem)

It looks to me somebody forgot to hone your right cylinder at all, but pistons don't show this blow by. They really look pristine, like they have a good seal with cylinders. This is why I'd check your valves and guides per Allan's advice. I think your head gasket was leaking on this cylinder too.

Valve guides are a good call, always worth a check. Depending on the guides used these are sometimes very short lived, before I heard of Kibblewhite I was very wary of " Bronze" guides , they all seemed to be made of a soft rapid wear material, I much preferred iron guides, now running K guides and fairly pleased so far.

Every old A65 head/ valves I have had in my hands had valves that were worn fore and aft, no sign of valve rotation whatsoever, the guides wear the same to match.

Ive run both sorts of oil ring no preference.

Although large at 24/ 25 thou end gaps , motors will run fine like this without major issues, I dont think thats the smoking gun. i would be more concerned about the 10 thou gap top ring, if it has worn at all then that gap was too tight when fitted .

Current thoughts on piston ring end gaps are that its better to have a larger gap on the 2nd ring , 1-2 thou ,more than the top, learned it here from John Healy who had a very interesting link about how this was found.
It might be a good idea to give the head a wee skim to clear up the divot, you dont have to nix it completely if you win back 50 % of the divot with a 5 thou cut that would be a whole lot better., and if possible have the head bolt holes on the top side spot faced, the inner five are easy enough , the outer 4 are a bit more tricky. Solid Cu is a better bet than composite for A65 head gaskets.

4 thou piston clearance at the bottom seem about right , if the top ring only closes 3 thou from bottom to top then the wear is not huge ( 3 thou on the circumference is about 1 thou on the diameter), hopefully a good 45 degree refresh with the right stones will remove most of the wear marks, at 60 thou over you dont have many other options unless you sleeve the bores and start again.

There is a lot of carbon build up in both combustion chambers for a 300 mile engine

That's right but no burnt oil on the piston's sides at all. This is why I think guides are a culprit.

Looking closely at the pics again (and those are all we have to go on), for just 300 miles of use, both pistons have a lot of vertical scoring.
Some of those scores are really quite deep. This accords with the vertical scoring clearly evident in the smoother right bore (so easy to see) but I think similar vertical scoring is also present in the left bore (just masked by the rough honing).
As you know, this is indicative of honing grit remaining in the bores.

However, I find it hard to believe that both of those bores were honed in the same way. I'd doubt that the right bore was honed at all. If so, I'm thinking why has so much coarse grit entered the un-honed bore so soon after new build?
Of course some grit from the left bore would be dragged down, to be hurled about in the crankcase maelstrom, to find its way up between the right piston/bore.
Much of the grit would join the general oil circulation, to do its grinding mission on the rest of the engine, unless/until caught by a decent filter - not a pleasant thought. Was an oil filter in circuit?

Again depending on the pics, the top rings appear to be of a different material to the 2nd rings, and can you see how rough the surfaces of the 2 top rings on the left piston seem to be?

I return to your original pics of the bores/honing pattern. It may be just the pic, but the honing pattern in the left bore appears very crude and not what I would consider correct. Is it possible to show that more clearly?

At 300 miles only the left piston shows evidence of blowby, with minor staining of the land above the top ring (blowby to me is combustion gas passing to the crankcase).

However the head does show some indications of oil passing the rings to the right bore, the clean area suggests detonation (or maybe advanced timing) on that side.

In 3 hundred miles how many cold starts? could account for carbon, ticklers ( every time you tickle that carb till the gjuice runs out , thats washing oil off the bore) and worn needle jets who knows , , most folk run conservatively over jetted, if oil gets in as well . It couldnt have been too bad the exh v/vs are close in burn temp. To me its a dirty build with a leaky head gasket( seen worse ).
You should be able to eat your dinner with engine components on assembly, fog the air , put up dust sheets, warn the people around, add extra lighting, your preferred tunes, the full bhuna.

My personal opinion is the bore was not cleaned properly before assembly. While both bores show signs of striations left over from bits of the honing stone, I shouldn't have to explain that the right bore is by far the worst.

There is no tell tail signs that there wasn't enough piston clearance. Actually it looks like they had plenty of clearance. By the way, you measure the clearance on those pistons 1 to 2 mm up from the bottom of the skirt.

It wouldn't matter what the ring gap was. From what can be seen in the picture the contact face of the right hand set of rings are "toast".

Change the oil. Drain the sump. Clean up the pistons.

Get someone to hone the cylinder with a 180 grit stone (MAX 220). Get the cross hatch as close to 45° as possible. Then wash the cylinder in HOT SOAPY WATER. When you think it is clean do it for another ten minutes, no twenty. YOU CANNOT GET IT TOO CLEAN. AND NO, SOLVENTS WILL NOT DO THE JOB THAT HOT SOAPY WATER DOES!!!

You want a lightly oiled lint free white rag to come out as white as it was before you started!!!!!

The break in process REQUIRES that you build up the dynamic cylinder pressure - you want to do this by putting a moderate load on the rings during the first run through the gears. Do not let it idle!!!!!!! while you put on your helmet, gloves, etc. By putting a light load on the engine you increase the dynamic cylinder pressure which will push the rings out against the cylinder allowing them to seat ("break-in").

It is my opinion that Hastings has caused more grief in the Vintage British community with their universal 220-280 recommendation for honing. Yes, there are professionals have the expertise, equipment and who can hold the tolerance required, they are few and far between. That said, I believe the quality of the rings, or cylinder finish, had little, if anything, to do with this problem.

Another possibility is that one of the rings has a taper internally/externally and has been installed upside down, worth checking for any markings and also standing each ring on a flat surface and see if stands exactly 90 degrees from horizontal.

Here's what we know:
The bike was assembled with Hasting rings.
• Hasting's BSA A65 rings, part number 6939, are not taper faced. The top two tings are directional in that they have a chamfer on the back edge of the ring and this should go up. This is clearly shown on the pack the ring are supplied in. The chamfer is to allow cylinder pressure to get behind the ring and push it outward improving break-in and sealing. If installed Unlike the original AE Helpolite rings, which were taper faced, installing the top two rings upside down will not cause the rings to virtually pump oil upward into the combustion chamber. Albeit putting them in upside down will negate the positive effect of sealing offered by the chamfered ring.
• Given from what we can see, the cylinder bore, condition of the face of the rings and piston skirt, exhibit a classic symptom of assembly without proper cleaning. While you can get similar striations when ingesting something from the intake, the ones exhibited are typically related to chips of stone left behind during the honing process.
• As far as piston clearance is concerned engines that go through this syndrome will almost always suffer from detonation. This will impart a lot more heat than the rings can transfer to the cylinder. This heat migrates down the piston and it starts to grow. One of the first places the effects of the additional heat is the area at the top of the thrust face, just below the oil ring. This is one of two places where you will see the early signs that the piston is about to seize. The other in this situation is the area of the pistons skirt just for-and-aft of the wrist (gudgeon) pin (often called a 4 corner seizure - it must be noted that a 4 corner seizure in an engine that has a fixed wrist pin is a different problem than our free floating pins). There is no sign of potential seizure below the oil ring or indications of a potential 4 corner seizure in While I believe there must have been some additional heat from detonation there certainly appears to be enough (maybe extra) clearance.

Additionally things that are present, but probably had nothing to do with this problem:
• The RH cylinder bore shows signs of glazing.
• The angle of the cross hatch looks shallow, which would hold more oil, making it harder for the rings to seat.
• We don't which oil was used for break-in.
• We have no idea how it was assembled and broken-in.

But those striations on the cylinder bore, rings and piston skirt, however they happened, tell the story.
Just my opinion

Thanks for that tutorial, but as I said in my last post, I don't think these were Hastings rings, unless Hastings made the single piece oil control ring. The last few sets of Hastings I got, had the 3 piece oil ring. Also, these rings do not seem to have any taper at all. The new ones shown below have a tapered inside face with the taper intended to be installed up. The oil ring has not top or bottom indicated and appears symmetrical.

A few more photos here. I have a question for John Healy. You said the rings on the right side look like toast. First, the photo above of the two pistons still on the rods is taken from the front, so the left piston in the photo is really the right piston, the one whose rings did not seat. So the "right" one in this photo is the left piston whose rings appear to have seated. So have a look at these photos as I would very much like to know why the rings are "toast".



This one shows the marking on the top of the ring indicating that the ring was installed right side up in and answer to a previous comment.





And two more of the rings removed from piston.

A couple of you have mentioned valve guides. There are new bronze guides from British Cycle Supply and installed and fitted by Ross, who was the top machinist at a local engine shop that rebuilt everything from motorcycle motors to diesel trucks. He probably had well over 20 years experience. The shop was well equipped but sadly has closed, or turned into a body shop, for lack of engine work and Ross has moved away. He also bored and honed the cylinder.

In any case, please advise how leaking valve guides would lead to the extent of blow-by I'm getting?



And here are the new rings I got yesterday in a box labeled Cycle Pro. They appear to be cast iron to me so does that change the grade of the grit to hone the cylinder? The old ones appeared to be chrome to me.

One other question related to dry or wet installation. I heard both, but I always oil the rings lightly as I install the pistons.

Tom

Tom, you might want to remove your miss placed post from Ben’s A65 thread.

New valve guides puts another slant on things. As do the valves. I have had some valves which measure under size, also some valves which have over size stems and I’ve been able to ream an old guide to suit and it be fine.

Depending how the old guides were removed, damage to the head may have taken place on removal. Thus letting oil slip past.

You understand that the piston on its downward stroke with the inlet valve open draws a vacuum at the carb and pulls the mixture through.... well if theres a decent seal on the rings this will have a stronger effect, if there’s any oil leaks that will get pulled in too. As I say, mine smoked like a pig and I swore it was rings... but it wasn’t it was guides. It isn’t blow by and as Koan? Said unless your getting fuel in your oil it isn’t blow by.

Either bad guides or poor ring sealing.

Regardless of how good someone is supposed to be, ask Rod in the triumph section about supposed decent head shops.

I tried to edit that post - - deleted the content entirely but the forum kept telling me I hadn't filled in all the required info, so it didn't work. I'll try again.

And yes, I know that as the intake valve opens the piston creates a vacuum that can pull oil into the combustion chamber. But how does that lead to blow-by? The oil drawn in burns or fouls the plug or blows out the exhaust. But if the rings are seated, how does it lead to blow-by?

Tom

Hi All,
Looking back at the earlier photo's It looks like (maybe) oil is leaking from the centre head bolt to one or both cylinders??
The BSA head bolt seatings most always get damaged from the bolts being tightened and the thin washers originally fitted
spotface the seatings and fit thick washers, I machine my own from bar stock
A look down the inlet ports will show if there is oil passing down or outside the guide

John

If you magnify your pics of the old rings, the surfaces of the rings in the upper pic are as rough as guts. The surfaces of the rings in the lower pic are completely smooth.

Also, clear to my eyes, is that the top rings are of a different material to the middle rings, much shinier (perhaps chrome?)

Same rings, same location just turned them upside down and took a 2nd photo. It's only an I-phone photo.


John,
Your analysis makes a lot of sense. That would explain why the pistons show no signs of blow-by and the rings look fine to me, almost unworn. And the oil could be drawn in on intake and the blow back into the rocker box on compression and hence into the crankcases which would explain the massive loss of oil out the breather. That composite head gasket is one that came in a full rebuild gasket set so I used it. I should have annealed the old solid copper one.

And I agree that the washers under the head bolts are not adequate. The ones on the B50 are much thicker so I'll make some thicker ones to fit the A65. And get the head milled (I may do it myself although my largest milling cutter is only 3" in diameter.) I'll check those seats and spotface them as well. I just did that to all the holes in the primary cover and stopped that from leaking under the screw heads.

Tom

Hastings has both chrome top rings and one piece oil rings available. The Hasting BSA kits we distribute have all three rings in grey cast iron with a one piece oil ring. The Cycle Pro rings are made by Grant Ring in California. We also distribute them. The Grant rings in picture are grey cast iron. We recommend using 180 grit.

What I (and some others) are saying is that it isn’t blow-by.

You’ve established no fuel smell in your oil so it cannot be blow-by.

As per johns comment about oil in the port, I honestly cannot remember if mine did or not (I would have looked I’m sure) but it was 10+ years ago. I would suspect there would have been some burnt oil on the rear of the valve.

The tool to use is a stiff round dunny brush ( like a bottle brish on sterroids ) with the barrels in a dish of very soapy water

A useful piece of kit for determining combustion chamber issues is an old spark plug modified to take an air hose.
Put the piston to TDC and put about 20psi into the cylinder, listen for leaks. You will be able to hear if it is inlet valve, exhaust valve, head gasket or rings (air escaping from breather)

Allan,

I agree that if you have worn valve guides your motor will likely burn oil and may show signs of oil in the combustion chamber and on the spark plug. However, while I don't want to sound contentious (god knows there's enough of that going on now!), my initial issue was excessive oil being deposited on my rear tire and leaking onto the floor after a 25 mile jaunt, which would indicate either a faulty timed breather or blow-by or otherwise too much positive pressure in the crankcase. Of course, a bad job of motor assembly with leaking crankcase and or side covers, leaking main seals or oil being sucked into the motor from the primary or the gear box could also account for oil loss, but that should be evident as excessive oil loss while the bike is parked (would have to be a lot to cover the rear wheel). But as I said, I had no oil loss even while idling up on the work stand.

In any case, disassembly was indicated, and finding oil in the combustion chamber was a pretty good indicator that the problem originated there. I may try just resurfacing the head and using a solid copper head gasket and using the existing rings over again to see if I can learn something here.

Andy, I just saw your response. I usually use a leak down tester to perform that task, but I left my tester back in Colorado where my race bikes are as I usually spend Spring and Fall there. I just ordered a new tester but will have to wait up to a month to get it - - due to the slow-down in mail delivery these days. But I hadn't thought of just pressurizing the cylinder and listening.

Tom

lets call RHS Timing side or TS to save confusion
like wise LHS is Drive side or DS.

The TS cylinder head inlet valve is markedly different in appearance to the DS, oily , clearly not getting as hot as the TS, there may be more than one reason for this, lower cylinder pressure = less heat, or a leaking guide or both.
Unless you are certain that the new " Bronze " guides fitted were Kibblewhite brand I strongly suspect the inlet guide may be worn, or as Allan suggests passing around its OD.

Not seeing oil leaks at idle isnt much of a test, the timed breather works quite well at low speed, if the cases are being pressurised by a bad head joint then the timed breather will cope up to a certain speed , after that it will spew oil mist.

I may have picked this up wrong, koncrete Kid , did you say the RHS of the back wheel gets oily?
IME oil from the timed breather outlet goes to the drive side rear, if you see oil on the TS its more likely that the oil manifold block is leaking.

Interesting, John. So the rings I have may actually be Hastings. I had thought so because I used to get my Hastings rings from British Cycle Supply. But the rings I have show no sign of taper to the naked eye.

The top ring appears to be chrome plated. But ring number 2 looks to have a brownish tint, unlike either the top ring or one piece oil ring. So what would that be?

Tom

I like the comment about pressurizing the cylinder. I have been known to take the valve out of my compression gauge and then blow into it. sounds a bit strange but we must do what's necessary. If things are good it will hold pressure for a few seconds. If not, and this gets really weird, stick a hose in your ear and direct the other end to the intake, ex and the crankcase while blowing. Or, get a compressor and relieve yourself from this potentially humiliating scene! Also, how much oil is in the sump? If something out of order in the return she will pump it out from the breather. As you know I run the piss out of my junk and do not get anything from the breather. Good luck. Hope to see you in Sept.! PRT

This is a picture of a set of Hastings Triumph 650 rings. The kit comes with a chrome top ring. Not my favorite, but I was not on the committee who specified the chrome top ring to be included. It is a copy of the set of rings supplied with PowerMax Pistons sold by AE Hepolite as their performance series.

Picture of Hastings with chrome top ring

You are not going to solve your problem until you discover what is causing the vertical striations on the piston and the bore. As I said many times above the most probable cause, and most common, is bits of the honing stones used to size the bore. Sure, it could from other sources. Be dirt ingested through the intake, bits of metal from a failing internal part or the likes of bits of left over glass from blasting the parts. What ever it was, it needs to be identified, and removed.

The piston, or bore, should never show signs of vertical striations like seen on these pistons and bore.

As the rings rotate in use, they rarely show signs of the vertical striations. What they do look like is what yours look like. And for them to pass oil is one symptom of the problem you are having with the bore.

Upper pic magnified:

[img]https://imgur.com/VSP79PB[/img]


Lower pic magnified about the same:

[img]https://imgur.com/gbLqOpT[/img]


The roughness of the ring surfaces is clear in the well focussed upper pic.

In the lower pic the surfaces appear smooth in comparison, but on examination I think that is an artifact of the pic being out of focus (the camera seems to have focussed on your thumb), though some striations and damage is still detectable through the blur.

In the clear upper pic you can also see where the (likely chrome) upper ring has been confronting the abrasive particles at its top and bottom edges, though it has sustained less damage to its main surface, compared to the other 2 rings (presumably due to its hardness).

Did these rings come from the smooth bore? What were the rings like from the bore with very evident "honing" marks?


Are you able to view your pics on a decent size screen? If not, maybe that is why you're missing some of the detail.

To add to Gavin and PRT’s comments on the oil in the sump, this is a sign of blow by, if it’s pumping from the breather then you need to check the pumps ability to suck oil. You do this with the engine running, sump cover removed and a siphon pipe attached to the return pipe and the other side Placed in a measure of oil.

There is a service sheet detailing this.

Adding more to Gavins comment about the oil union, the pre 69 bikes had BSF bolts which were prone to stripping threads when tightened up. The fix is to put a 5/16” Helicoil in. The later UNC bolts appear to be fine. When the threads went on mine however it seemed fine whilst the engine was revving. But leaked oil when on tick over and leaked even more when parked. There’s a nice territory mark outside a post office in sleights near Whitby in Yorkshire with my name on 😂

Yes, it's the timing side that is the problem; oil entering the combustion chamber. It could get there because of a bad valve guide. I haven't disassembled the head yet, but the guides are new bronze guides and the motor has only 300 miles on it since the rebuild.

I don't believe I said RHS of the back wheel but if I did, I meant the left hand or drive side.



I don't doubt what you are saying and that I may not have cleaned the cylinder thoroughly enough or that bead blasting media could be the culprit. As I have new rings, I may as well re-hone the cylinders and use the new rings. Of course I'll change the oil, but other than that, I don't know if I'll be able to discover what actually caused the striations. I'll definitely use hot water and soap instead of just a solvent to clean the bores, as that is what I am currently doing with my rebuilds anyway (I built this motor in 2010 so I'm afraid I can't remember just what I did back then); don't know if I can source a "dunny" brush so I'll just have to use a scrub brush.

Do you have an opinion on using oil on the piston and rings upon reassembly?


Upon returning from my last run, I checked the oil, and it appears to be at the same level in the tank as before the run, and it doesn't seem to wet sump, but I'll check that again. It definitely shows good return to the tank when running.

The cylinder is marked 68- something which I believe is 26 TPI. I don't remember having any problem achieving the required torque on the bolts, so I'm not going to Helicoil the barrel unless I can't re-torque as specified.

Tom

I re-honed the cylinders, bought two new exhaust valves and had a nice 3-angle valve job done, annealed and copper coated an .049" head gasket, reinstalled everything and even added an oil filter.
Honed cyclinders:
Nice 3-angle valve job including 2 new exhaust valves (one is a rowe, one a GS, because that was all the BCS had in stock in N.S.):
Installed cylinders - here I have already removed one of the ring clamps which are homemade from hose clamps:
Cylinders installed with new copper-coated head gasket:
Oil filter mount - - this unit had failed by blowing out the return spigot, so I threaded it 1/8" NPT and used a close nipple and 90 degree fitting to re-connect (45 degree fitting shown here but did not use that) You can also see the modified Tee to hook up the rocker oil hose while blanking off the original one on the bottom of the crankcase:
Worm's eye view of the oil filter mounted with attached hoses. The outlet hose passes to the rear of the swing arm without touching it:
And finally, the socket I modified to be able to torque wrench handles when torquing the head nuts and barrel nuts:

I re-assembled everything and took it out for a ride in the manner prescribed by most members of this forum. I started it once for about 15 seconds and shut it off. Put on my riding gear and went for a 10 mile ride, but had to return home to put the muffler on which I forgot. Sounded glorious. It puddled oil on the floor again. I took it out for another 22 miles at speeds from 40 to 70 mph, returned home, parked it, and oil ran out on the floor exactly as before. All my refurbishment and no positive result.

I checked oil in the sump this morning (16 hours after my ride) - - 1/3rd cup was all there was. I checked compression and can get 150 psi in both cylinders with 10 good hard kicks. I drained the primary into which I had put 125cc, and I got 100cc out but it may still be draining a bit more.

Adding insult to injury was the new leak-down tester I bought on Amazon.ca which turned out to be a total piece of junk! Could not even get it stop leaking air before I hooked it up.

Other than a failed timed breather mechanism, anybody got any other ideas?????

Tom

Have you determined exactly where the oil is coming from? Use a mirror to check the breather hole. Also check the backside of the sprocket door to see if oil is coming through the seal. You have the chain oiler blocked off?

I thought that the original problem was oil fouling in the right hand cylinder, is it still doing this? If not then you may have fixed one problem and found another.

My A65 sometimes dumps a bit of oil on the floor especially after a hard run, difficult to see where its coming from but some possible areas are the alternator lead hole in the chain-case, the rear chain lube hole and the breather as mentioned.

Everything you did looks right and works how it should be working, you have to find a leak, that's all.
Could you make some pictures of an oily engine, after a ride?
To make you happier, I have an oil leak in my Trident, I can't pinpoint for the last 4 years.:)

Good idea, I'll try the mirror trick. The problem is, it doesn't leak when sitting on the stand idling. I may have to get someone to hold the throttle open to check that.



Looking at the plugs, I don't see any signs of oil. Also, the compression is higher, especially on the timing side. So yes, I may have fixed the leaky head gasket and/or bad ring seating on that side, but the amount of oil being blown out while on a spirited ride is getting on the rear wheel and tire, so not something I can live with. My alternator wire is gooped up well as is the primary chain adjuster and I have blocked the chain oiler.

I'm still thinking blown out the breather because my oil level did go down from the 5 to the 3-3/4 mark on the dipstick, and since the sump (empty when re-started) only holds 1/3rd of a cup and I filled the oil filter, that seems like too much oil loss to be explained any other way. I haven't noticed any smoke, but I'll have to look at that more closely when I restart it to see if I can see any obvious oil leaks.

Tom

Somehow bodge in a bottle, or tube and bottle,, using string or wire, so to catch what comes out of the breather tube. Then you will know.

Use ATF in the primary. It works well and since it is red in color you can easily tell if the leak is from the engine or primary.

I tried the flashlight and mirror trick but couldn't really see the breather outlet very well. I'll have to take the chain off and try again. In any case, I turned in the throttle stops by 1 full turn, so probably about 2500 rpm, but no oil was leaking out while I watched (about 5 minutes). But after I shut it off, maybe a thimble full of oil dripped off the bottom of the lower chain guard (part of the case). It seems as though it is really a higher rpm leak, with very little leaking at lower rpm, but seems to be accumulating somewhere.

So if the timed breather happens to be in the open position when the motor is shut off, is there some residual oil that accumulates in the camshaft trough that can leak out? This motor is a '65.
Good idea but hard to do. I'll look as another motor I have to see if there is any way to snake a copper or plastic tube up into the breather hole to confirm the source.

Just saw your post Htown, so I'll try that as well.

Tom

Hi Tom,
I am working on an A10 that is doing similar strange things
I found a few issues that while different to the A65 other checks I have to do will be the same

I need to remove the oil tank and devise a way to flush out the return stand pipe, Today I was told of a case where a random piece of gasket goo or other object would get pushed up the return pipe at high revs and partially block the outlet, stop engine and it would fall back down and hide till the next time

Another check to complete is to check the oil pump gasket then the mounting bolts plus the screws that hold the pump together for tightness to make sure there are no leaks

If there is a sump plate with magnetic plug fitted to your A65 either remove the magnet or place the plate with the magnet furthest away from the pickup pipe. I have first hand experience of the magnet causing the ball in the pickup to stick shut

John

Not possible to bodge a tube into the breather without taking the motor apart. It is just above the gearbox high gear bearing in the back of the main case. Without the chainguard you should be able to see it.
You have an early engine, so you have a seal between the primary and motor? Which way is the seal lip facing? It sounds as though you might be pressurizing the primary through the seal and it has no where to go but out the generator wire hole, sprocket door seal or the chain drip feed. Do you have an inspection cap with the tiny weep hole it it?

My Thunderbolt has always leaked oil from the primary. Like I posted earlier I use ATF since the engine and primary oil are separate on BSA's and the red color is a dead give away. One place it leaked was the primary adjuster bolt. Fixed that with some thread sealant. But it always dribbled out the back of the case. Mostly I ignored it and checked the fluid level regularly. This spring it got so bad that it was starting to get on the tire. I pulled the primary apart, replaced the seal in the sprocket door and installed a new gasket. I also plugged the chain oiler hole from the case side with silicon and sealed the alternator grommet with some. Dang think still dribbles slightly after a ride. I give up

the ill-conceived chain oiler hole is also a breather . weres the primary vent hole now ?
when you seal up one hole ... sometimes it just moves the leak .

Some people report that running a vented clutch adjuster plug
allows enough venting without leaking ,

Get yourself3 different coloured oils
Put ATF in the primary and different coloured oils in both the gearbox & the engine
Take the bike out for a short ride then prk it over a sheet of something white and adsorbent
Look at the colour of the oil\

Sounds silly I know but it is the fastest way to track down a phantom leak
Royal Purple used to make a nice bright purple gear oil which is great for this.

If the leak is mostly rd then the oil is coming from the primary.
If that is the case, drain the primary .
If the oil is polluted with the engine oil ( get a green one if you can ) then you know the primary seal behind the sprocket is leaking

If the oil is green then you have a bottom end problem.
Could be as simple as a leak from the oil manifold

And of course if it is purple then the oil seal on the sleeve gear is the prime suspect, followed by the splines followed by the gearchange lever

Remember that the oil will almost never drip from exactly where it is leaking from because that would make life way too easy.

A long length of hose on the oil tank breather is also a good idea just in cse you have excessive foaming and overflow from the oil tank.

I found primary covers earlier than 70 always prone to leaking because of common opening for oil level and oil dumping with screws holding a cover to the engine. In both cases ( both bottom screws ) oil gets by a gasket and on the threads of screws with only possible way to stop a leak by some seals or gaskets under those screws, which never works 100% in my experience. Have such a cover now, and still no idea how to deal with this problem.

Adam,
My cover is apparently later model, with separate level and drain screws. But, I noticed how chewed up the screw seats were, so I spot faced them all to 7/16". Not having a 7/16" end mill, I sacrificed an extra 7/16" bit and ground it to work as an end mill. I also glass sanded the inside of the cover but if you look closely, you'll see how little "meat" there is around the surfaces on the inside of the cover as well as the screw seats on the outside. It's no wonder it's not easy to get a perfect seal. I had already sealed the gasket to the cases with RTV Silicone, so just grease on the outside of the gasket. I also gooped up the screws before I screwed them in .
Spot facing of screw seats.

Inside surface of primary cover.

Tom

Oil can also leak out of the alternator wire tube.

A good move on the cover screws is to use the small copper washers used on the Triumph
unit 500 rocker box allen screws, they are 1/4 washers but have a very small o/d.

I find fibre washers are good at sealing leaks from the cover screws, the size I use is 1/4 id, 3/8 od and 1/16 thick. These fit nicely under the socket cap heads and dont foul the cover.

Hi Tom, you are lucky to have this cover. Gasket surface on mine is reduced to perhaps 2.5 mm near the oil dumping bolt, oil channel is bypassing gasket on oil level bolt altogether. I will have to use some alu, copper or fibre washers under those screws.

To determine more precisely where the oil is leaking from, I devised a "bodge" consisting of a shortened 1/4" barb fitting drilled out as much as possible, screwed into a 90 degree 1/8" NPT pipe fitting with a 3/8" shortened barb fitting with a 3/8" oil line which I epoxied into the breather outlet. I had to remove the rear wheel, chain, and chain guard to be able to snake this into the hole and hold it in place over night for the epoxy to harden.

I also discovered that the screw I used to block off the chain oiler was not tight so was able to tighten that as well as a few other things like adding a 7th plate to my clutch (machined off the lining of the first plate and added another plain and friction plate) and replaced a bad rotor. Before the rain came (yay!) I was able to get in another 22 miles of spirited riding and brought the bike back in and placed a container under the newly installed breather hose along with some paper towels. This is the result after about 5 minutes: The plastic container catches the oil from the breather, and the paper towels show the remainder of leaks.The next photo shows leakage which shows up on the fins of the cylinder head indicating other leakage, which looks to be from the rocker cover.

Another compression test indicated I was able to achieve about 160 psi after 10 good kicks. I then got out that leakdown tester I said was junk to see if I could make it work. I had to back up one O ring connection with a spark plug washer to stop it from leaking, then discovered that the quick connector just needed to be tightened, and replaced the right hand gauge which failed with one from an old compression tester. Unfortunately, because it reads to 300 psi it was hard to read actual leakage, but the right cylinder actually registered zero leakage. I could not hear any air leakage at 100 psi, anywhere. But the left cylinder did leak, apparently about 10% and that was at the breather as an audible leakage.

So I'm left wondering if the rings on the left cylinder haven't seated yet, or if there is head gasket leakage? Is 54 miles just too little to expect the rings to seat? Is there anyway to determine if it is the rings or the head gasket? The oil I'm using is 20/50W Castrol 4 stroke MC oil type SG/JASO M2, which is the only MC 20/50w oil I can find.

Tom

Check it again at 300 and 500 miles. It’s most likely rings haven’t fully seated yet, in 54 miles the bike hasn’t had much time to run in. Providing you anealled your head gasket I doubt it would blow after that mileage. You stand more chance of having leakage at/around the spark plug or from the valve seat.

Sorry if I’ve said this before, but John Healy’s dry assembly and Pete Russell’s (rest his soul) big second ring gap have seen bloody great ring sealing on my bike.

Compression test showing 170 psi, with a 7.25:1 compression ratio ain’t bad.

Apart from the breather hole leak, there seem to be leaks from several other areas including the chaincase screws and rocker cover. These leaks may be caused by overpressurization of the crankcases, possibly because of ring blowby and/or problems with the breather disc.

In the short term maybe you could add fibre washers to the chaincase screws and rocker cover studs to stop leaks. In the longer term, it might be worthwhile adding an extra one-way breather/reed valve to the rocker cover to help maintain negative crankcase pressure and stop leaks.

You did well to fit that breather catch pipe, thats a tricky access,
the front drip is most likely the primary chain adjuster, the rocker box leak may be oil passing down the stud, plumbers tape will fix that.
Have you retorqued the head after a couple of heat cycles, ?The centre bolt on my head usually nips up a tad more.

I annealed the head gasket and sprayed it with 2 coats of Permtex copper coat.

Allan, I haven't read Mr. Healy's dry assembly, but I lightly coated the cylinder walls and then wiped the oil off with a clean rag leaving just a whiff of oil. Then oiled the skirt only and installed the pistons with rings. My notes are out in the shop, but the ring gaps were all .014" or more.


Gunner, I had previously spot faced all the outside screw holes on the primary cover screw seats. I used annealed copper washers on the rocker dome nuts as well as a bit of RTV sealant, but maybe fiber washers would work better. The cover itself was glass sanded; the head surface was only planed with a 12 lathe file. I agree with the possible over pressurization causing some of the leakage; just need the rings to seal unless it's the head gasket. A one-way valve may help, but there shouldn't be that much leakage/pressurization if everything else is tight.


Gavin, I had already siliconed the primary chain adjuster on the inside, but maybe still a drip. I used ATF in the primary to see if it leaked red as was suggested. No sign of red oil, and although the primary oil will get dark, I wouldn't think it would in just 22 miles. As far as rocker box studs, I hadn't thought of sealing those and when I remove it to re-torque the head bolts, I'll try that. I've only gone thru 3 heat cycles and 54 miles, so I'll probably just put some more miles on it before I do that to see if the rings will seat better.

Thanks for the suggestions.

Tom

I can see you've done a good job prepping the chaincase so maybe the leaks aren't from the screw holes at all but could be drips from the cylinder head.

Interesting post from a few years ago where someone had a similar problem, see This link

It looks like the primary chain case is pretty well sealed. It also looks like in the second picture that there is a vertical streak of oil up the primary cover about three quarters of the way back. So that suggests oil is coming from higher up. The oil tank may be venting some oil. Check around where the breather line from the oil tank is venting. When are you checking oil level. Always do it after a ride when oil is hot as it expands. I generally run mine about half way between the marks. Seems like if you run it at the completely full mark some goes out the tank breather. The leak on the fins looks like it is coming from the rocker box cover. It's only on the top fins so unlikely head gasket.
Your compression of 160 psi sounds like the rings are seating to me. I'm still a bit puzzled why the oil comes out the breather.
If it's not using much oil and is running well, I believe I would try to put some miles on it. I've used the same Castrol oil to break in several engines successfully.

Went out today to put some miles on it. 5 miles out, it seized up. I disassembled it this afternoon expecting top end damage of some kind, but not. The left connecting rod is seized to the crank.

Interestingly, the head gasket looks close to blowing on the right side, but that was the side that showed no sign of leakage.

The problem is done here:

Waiting for a pickup, I snapped a nice photo of the girl.

I'm headed out for a few days, so the rest of the tear down will have to wait.

Tom

Amazing (and fortunate) that you could seize a rod to the crank without snapping the rod and/or putting it through the piston or the case!

Left big end seizure is typically due to oil starvation and nothing to do with the upper engine.

Inspect the crankcase very carefully. When I trashed a lower (due to oil starvation; I won't go into that here), I didn't notice the two little partial punch-outs at 4:00 and 8:00 until someone else (who knew what to look for) pointed them out. But my conrod was loose, not seized.

Sorry to hear you're "back to the drawing board".

Plus 1, that’ll be oil starvation. I had this, it cost me a rod (probably didn’t have to but I thought it best) set of shells, and being very lucky was able to polish the journal. There was no damage to the journal itself (the seizure happened at very low speed, I knew something wasn’t quite right so started to limp back to camp)

The shells surface melted and spread itself up both sides of the rod effectively wedging the rod against the cheeks of the crank. Fine wet and dry and metal polish cleaned it up fine. I then had the crank nitrided (I don’t think it was long before that hill billy biker did something similar to his race bike and the journal was sound after the bike had been nitrided)

Might be a good time to check that your oil pipes are connected the correct way around.

If the journal has the bearing lining stuck to it then hydrochloride acid will remove the Aluminium/tin and not touch the steel crank. Not sure if it work on bronze material. Tip I picked up from Briggs engines with a Aluminium rod which seizes on the crank.

Please tell us you don't intend to re use that rod