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The previous thread that I had added on to was getting kind of long, so thought I'd start a new one. If anyone wants the background they can go down a few threads to find the original.
Today I took the top end off my newly rebuilt engine which was burning oil and everything in the head looked fine, no cracks, loose guides, etc. The cylinders were quite glazed compared to the lower section of the bores, so that probably explains the burning oil: the "economy" piston set with its "economy" rings didn't seat. Also these rings were not tapered and the pistons/rings were very oily.
Rather than taking a chance and trying to fit other rings to these pistons, I am going to order a new piston set from AE/Hepolite, deglaze the bores AND INSTALL THE RINGS DRY as this may have been the reason for the rings not seating originally.
An expensive lesson learned, but that's life!
Thanks to all who offered their insight and experiences.
John

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John,

I had kinda the same problem you did. A bike came my way with NEW cycle-craft pistons/rings. Everything was fresh bored/inspected...

This bike on start up smoked so bad I thought someone was going to call the fire station...
Oil was dripping from both ex. ports....

I bought a set of AE/HEPO rings and all was well.


"Back in the garage with my [***] detector
Carbon monoxide making sure it's effective...
----THE CLASH-----

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John -
No matter how cheap the pistons are, they should accept new rings without bother. IMHO, I'd simply deglaze, add iron rings and assemble dry. Watch your ring end gaps.

Also change the engine oil over to 15W40 diesel oil. Your engine oil could be too slick.

:bigt:


Don't hide 'em, Ride 'em !!

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Agree with Richard, be carefull who does the hone and use good iron rings, then run in on varying backroads/hills and only a little gently.

The last "a little gently" is relative, do a search for opinions re preferred procedure, anyone who has not been jumped on as a goose has a valid opinion.

Do not allow a new engine to idle or run under no load for any longer than is absolutely necessary.


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Still cannot edit, do not start the engine on dry bores, neither soak the buggers in oil.


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Typical grey cast iron rings are not honed round during manufacture. Put a perfectly good grey cast iron ring into a cylinder and you will often see light coming from between the ring face and the cylinder wall. They are designed to be used in cylinders that are also not perfectly round due to their design and the ability of machinery of the day to produce a perfectly round. The process of break-in requires the cylinder bore surface to have between a 150 and 220 grit finish.

While ductile iron and steel rings, which are honed round during manufacture, can be used in these old Triumph cylinders, it requires a lot more attention to details. Also these type of rings have a lot less ring tension in the bore. While this does help with fuel economy, it makes it much more difficult to get them to seat in the cylinder. Typically the average owner is not going to take his engine apart to check to see if the crankcase cylinder mouth is square to the crankshaft. He is also not prepared to remove the step on the cylinder base surface between the crankcase halves which often is in excess of .010.” Neither is he prepared to have torque plates made to attach to the cylinder so that the bore will be perfectly round after installation. Certainly it can be done, and we routinely do it, but to guarantee good results with these modern ring materials one must spend time and money to get things right.

Typical grey cast iron compression rings are taper faced. The widest part of the taper MUST go toward the bottom of the piston. The taper helps control oil consumption until the oil rings are "honed" (broken-in) by the surface finish of the cylinder bore. Once the oil rings are honed to the cylinder bore they take over oil control. Installing these taper faced compression rings upside down will cause oil to be pumped into the combustion chamber.

You can tell if the taper faced rings are installed properly during disassembly and inspection, as a portion of the face of the ring will have been polished by the bore. The narrow polished part of the taper faced ring MUST be on the bottom.

While a lot of concern goes into the ring end gap and placement of the gap itself, it will have little, if any, effect upon break-in or the motor burning oil. The angle of the cross hatch pattern left by the hone is as much, or of more importance than the ring gap. If the slope of the groove left by the cylinder hone (called cross hatch) is too steep the rings will spin in the bore and all your concern about ring placement is for naught. So while I still follow my father’s advice on ring gap: stagger and gap placement (it can’t hurt) I am sure to check the work of the machinist for surface finish (grit) and cross hatch slope.

The real concern is too little ring end gap. Rings expand, closing up the ring end gap, as the motor warms up. There must be enough ring end gap clearance so that under the severest conditions, where the engine is at its maximum operating temperature, that the rings don't expand enough for the ends to touch. If the ends touch the rings will stick to the cylinder wall and remove a part, or all, of the top of the piston. Don't be surprised if you find your AE/Hepolite/Federal Mogul cast iron rings pre-fit with as much as .018" end gap out of the box. AE has done research on the effect of ring end gap upon oil consumption and has found that even with gaps of .050” increased oil consumption isn’t significantly increased over typical pre-fit ring gaps.

I find that it is not bad rings or pistons that cause the problems we see today (actually since the late seventies when they mandated oil as a part of improving gasoline mileage figures). What I see is mechanics/machinists that are using cylinder preparation techniques that are designed for ductile iron or steel rings. Both of these types of rings are designed to be run in stable bores that are true and round, and stay that way during installation and running (something our old air cooled cylinders are not) and the rings themselves are pre-honed during manufacture.

In fact ductile iron and steel rings require a protective finish be applied to the wear face and thus are not designed to be "honed" or finished by the surface finish of the cylinder. These rings require cylinder surface finishes of greater than 280 grit, often highly polished to a point where they seem dead smooth with no sign of honing at all.

When approaching a new machinists, ask if the cylinder surface he is prepared to offer you is appropriate for grey cast iron rings used in a bore that is not at right angles to the crankshaft (even though he is going to bore the cylinder from the base surface), the crankcase mouth surface is not flat (many Triumphs have a step between crankcase halves on the cylinder base surface), and that the cylinder is so fragile that it distorts during assembly from the head bolts and base nuts.

As far as assembly, current though with these grey cast iron rings is toward drier assembly. One must be sure to use engine lube on the wrist pin and rod bushing, though little oil is used on the piston, ring and cylinder.

During the honing process small bits of the honing stone break off and imbed themselves into the cylinder surface. These must be removed before the cylinder can be used. If they are not removed the pistons and rings will come out of the bore with hundreds of fine grooves scratched into their surface. These can lead to high oil consumption, ring and pistons failure. To remove these fine bits of stone the accepted practice is to wash the cylinder in HOT soapy water (NEVER wash a freshly honed cylinder in solvent as the stone bits will not be released from the cylinder) and then run a lightly oiled lint free paper towel on the cylinder surface until it comes out pure white… no grey haze from honing swarf. I then put a small amount of oil on the thrust faces of the piston leaving the faces of the rings dry. The oil left from the oily rag on the cylinder bore is enough oil to prevent the rings from galling on the cast iron.

As far as break-in is concerned the current thought is to use the natural pressure behind the ring caused by a vigorous combustion to push the ring out against the cylinder wall early in the break-in process. Grey cast iron rings are typically cut with a bevel on the back of the top edge to allow combustion gases to reach the back of the ring. This pressure expands the ring against the cylinder surface helping break-in and ring sealing.

Slow running or idling allows the oil, that has passed the rings, allow the heat of combustion to harden it on the cylinder wall. This surface is so smooth and hard as to prevent the wear required to finish honing the rings. This is what they call glazing. To prevent this a few reasonably hard pulls early in the break-in process insures that the rings make full contact with the surface of the cylinder causing the rings to be honed round.

As far as the quality of Carfel, or Emgo pistons which are both made by JCC in Taiwan, IMHO it isn’t the pistons, but the person doing the machine work and installation that should be examined. There is a racer on this board who has used standard JCC pistons in his 500 AHRMA racer to beat many 750’s in Sportsman 750. In my opinion, if the cylinder is prepared and installed by a competent mechanic, they are every bit as good as Hepolite. In fact in the late seventies we had more problems with people fitting Hepolite than we did with JCC pistons.

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WOW, John, It gets better every time. That was such a great explanation, I can't imagine any better.

Bravo.

Now I have to figure out what a thrust plate is.


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Thank you one and all for your input. Thank you John especially for taking the time to share your years of experience. I've been into British bikes for about 15 years now, and I'm still learning!
I am ordering a new set of rings, specifying cast iron Hepolites, if available.
My machinist has rehoned the cylinders, this time with a coarser pattern.
I'll report back when she's back together.

New Question: Is it possible to install valve seals over the guides and is there any advantage to doing this? (Don't misunderstand: I have new guides and they are tight in the head and fit with proper clearance to the valve). Was there a reason Triumph didn't do this?
Thanks again guys!
John

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Yes, it is possible, but unless you increase the oil flow to the head, as they did on the triple, they serve little, if any, purpose. Triumph 650 and 750 twin top ends run quite dry and excess oil coming down the valve guides is not one of their problems.

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Well, it took awhile to get my new Hepolite rings as they were on back order, but I received them yesterday and put everything back together following John Healey's advice in respect to dry installation, and making sure that each was installed correct side up (although they are well marked). I also used motorcycle specific 20W50 oil. My machinist did a bit coaser hone and also gave me some valve seals from a Chrysler 2.2 engine that fit perfectly. Neither one of us thought this was the problem, but figured it couldn't hurt.
I'm happy to report that my Bonnie no longer has a smoking problem!!!
Thanks again to all who offered their advice.

Lessons learned...use good quality Hepolite rings and install dry for good seating.Use motorcycle or diesel oil for break in. Don't let the engine sit and idle after start up...as soon as you have oil return to the tank, take it up the road.
John

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Originally Posted by John Healy
. . . typical grey cast iron compression rings are taper faced. The widest part of the taper MUST go toward the bottom of the piston. The taper helps control oil consumption until the oil rings are "honed" (broken-in) by the surface finish of the cylinder bore. Once the oil rings are honed to the cylinder bore they take over oil control. Installing these taper faced compression rings upside down will cause oil to be pumped into the combustion chamber.

You can tell if the taper faced rings are installed properly during disassembly and inspection, as a portion of the face of the ring will have been polished by the bore. The narrow polished part of the taper faced ring MUST be on the bottom . . .

I realize that this thread is 10 yrs old, but it is still one of the most valuable bits of information on the site. I quoted only a snippet from John Healy's long post, because I have a question about a middle ring that was installed upside down. It's on one of my (ahem) non-Triumph bikes, but I think this subject is pretty much universal.

Suppose someone (not me) installed the center ring upside down, as John described above. Here are a couple of illustrative pictures. First, look at the middle ring and note that the narrow, polished, part of the tapered face is on top, not on the bottom where it should be:

[Linked Image]

Also, the middle ring was installed with the pip facing downward, when it should have faced up (see the pip about 1/2 inch to the right of the ring gap):

[Linked Image]

Just as John said, this taper-faced compression ring pumped oil into the combustion chamber. The bike sometimes smoked like a chimney fire at startup, but would then seem to clear. It would sometimes seem as if the rings were "bedding in", going several days without much smoke at all. Then it would blow a cloud again. In reality, it was always burning oil. The level of smoke just varied from nearly invisible to intense.

So, I finally tore it down for a look, and found the middle ring upside down on both cylinders. My question is, do I really need to buy another set of rings, or would it likely work O.K. if I just flip the middle rings right side up and see what happens? The ring sets cost $49.00, which I'd rather not spend if I don't have to. However, the gasket set costs $94.00. If I try the old rings, and it doesn't work, I will need to buy new rings along with yet another gasket set. What is the best way to go?

I'm almost done cleaning out the scorched oil patty-cakes from the cylinder heads and I need to decide whether to order rings or to gamble with the old ones. The existing rings have been run just over 1,700 miles.

Ray



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So what grit hone did you use?

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Ray, you have a bit of soul searching to do. If it all looked real good, I'd be tempted to take the risk. Those rings have hardly done any work.

Talking about rings, pistons and barrels, when I assembled the dragbike engine, I rounded up all the spares I had. There was a number of +.060 pistons plus several barrels. I selected the most unworn barrels, then looked at the pile of pistons. Some were barely used so I matched the two best ones to the bores. Looking at the rings I noticed some had not been run long enough to even wear off the machining marks! I used them and they remained for the 4 seasons of racing. They are still there today.
Anyway we mostly fit new rings but the thought occurred. A man could carefully roughen up the ring surface of good-pre-used-rings for the same "finish" new rings have. I reasoned this would ensure rapid bed in. Not that I've tried this...!

BTW, I'd only buy the actual gaskets needed. A barrel gasket, 2 rocker gaskets and appropriate PRT seals. The existing head gasket would be annealed and returned to service.

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I think you can see the marks from honing in this photo, taken with borscope.

https://www.flickr.com/photos/[email protected]/36673529214/in/dateposted-public/

https://www.flickr.com/photos/[email protected]/36673895324/in/dateposted-public/

Last edited by btour; 09/29/17 3:00 am.

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Originally Posted by Excalibur
Ray, you have a bit of soul searching to do. If it all looked real good, I'd be tempted to take the risk. Those rings have hardly done any work.

Talking about rings, pistons and barrels, when I assembled the dragbike engine, I rounded up all the spares I had. There was a number of +.060 pistons plus several barrels. I selected the most unworn barrels, then looked at the pile of pistons. Some were barely used so I matched the two best ones to the bores. Looking at the rings I noticed some had not been run long enough to even wear off the machining marks! I used them and they remained for the 4 seasons of racing. They are still there today.
Anyway we mostly fit new rings but the thought occurred. A man could carefully roughen up the ring surface of good-pre-used-rings for the same "finish" new rings have. I reasoned this would ensure rapid bed in. Not that I've tried this...!

BTW, I'd only buy the actual gaskets needed. A barrel gasket, 2 rocker gaskets and appropriate PRT seals. The existing head gasket would be annealed and returned to service.

Thanks for the replies. CBS and btour, the hone and cross-hatch are almost irrelevant here. The upside-down intermediate rings are literally the "smoking gun" in this situation. As I mentioned earlier, this is not on my Triumph (hence the high cost of a gasket set), and I probably should not have even posted on BritBike. The reason I did is because I have read so many posts by John H about what would happen if the intermediate ring were to be installed upside down. What I did not read was anything about flipping the existing ring in such a situation and putting it back into service.

As Excaliber said, after a bit of soul searching, that is what I intend to do. I will post results when I know the outcome. The success of his dragbike with used rings is inspiring. We all know how that worked out.

Moral of the story is don't get lazy and farm out your assembly work to someone unless you know them very well. This guy had a very good local reputation. He should have known better than to make this mistake.


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Originally Posted by TR6Ray

Moral of the story is don't get lazy and farm out your assembly work to someone unless you know them very well. This guy had a very good local reputation. He should have known better than to make this mistake.


Amen -

I just recently took my rear wheel along with a new tire and wheel bearings to a local (britbike) shop. Got a phone call telling me the rimlocks were really rusty and needed to be replaced. Go ahead says I. Get my wheel back the next day and and as I'm re-installing the wheel, I notice some threads under one of the rimlock nuts are exposed.

1) Both rimlock nuts were barely finger tight.
2) The beveled washers, returned to me with the old rim locks were not installed on the new ones.
3) The speedo driving ring was only finger tight.

Now, this guy is a competent brit bike mechanic. I know him well. He has a young guy helping out in the shop, so I gotta assume the kid did the work. I'm going there in the next day or two to pick up a header bracket. I'll let him know about it then. If it was the 'kid' and I was the shop owner, I'd want to know.....and if it was the shop owner?? Well, then, maybe he had a lot on his mind that day! shocked

As Ronald "Ray-Gun" used to say, "trust, but verify!"

Apologies for the thread hijack!

Steve



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^^^Not a hijack, Steve, the principle is the same.

Anyway my buddy and I got my engine buttoned back up today. I did not buy new rings. I merely turned the intermediate rings right side up. I also did not re-hone the bores. I did clean them in my parts washer (with mineral spirits), then scrubbed them in hot soapy water. I then followed John's technique of oiling the bores and wiping with clean white paper towels until the towels came out clean and I had wiped out all the oil I could. At assembly, I smeared a little oil on the piston skirts. Thus, John's "nearly dry" assembly process that he has described on here numerous times.

The bike fired right up, ran great, and -- no more smoke! So, if nothing else, my pictures posted earlier in this thread should stick in everyone's mind as an illustration of the statement I quoted there from John.

If your freshly rebuilt engine smokes, there's probably something wrong. An upside down intermediate ring may be the issue. If so, running the smoking engine, in the hopes that the rings will eventually seat, is a futile exercise. The longer this goes on, the more crap there will be in the combustion chamber.

In this case, I had to do a lot of cleaning inside there. The valves were brand new just 1700 miles ago. Here are some pictures from when I disassembled the heads and was cleaning off the coke from the burnt oil:

[Linked Image]

The stripe here was from holding it against a rotary wire wheel:

[Linked Image]

Once the valves, springs, keepers, spring seats, and the heads themselves were cleaned up, we attached a plate and did a leak-down test. They were still good, so did not have to be recut.

All this for two rings placed upside down. What a nuisance, but at least it is back to normal.

Ray


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We've all learnt something here. Am really happy this worked out. Thanks for sharing.

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Well done, Ray!

Cheers,

Steve


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Is there any advantage to lightly oiling the rings in their grooves? I usually use a very thin coat of # 10 oil and wipe off the ring faces. also a very thin coat of #10 oil on the thrust faces of the pistons.
What I have run into a few times is oil on top of the pistons after very little running. I am very careful to put the piston rings in correctly. This has happened about three times and I have solved the problem with careful use of a Spyke crank vent breather twice, but I think something peculiar is happening in either machining or assembly and I have not solved it yet.

Are Hastings rings cast iron?

Who supplies ductile iron rings and do they look different from cast? I do not want to mix them up.


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