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John: "How can you compare airplanes to motorcycles." In the sense you seemed to take away from what I wrote, I'm not. Please read what I said.

Although they use similar technology, cast iron cylinders and grey cast iron rings which require the same break-in, I am comparing the steady, rational, measured application of known specified techniques, materials, and procedures in the old light aircraft enviroment to what has become the "wild west" in old British bike business. A situation exists, and Bruce reminds us of it, where anyone is an expert and the factory knew nothing!

Thus people who have little or no knowledge or historical perspective are getting advice from their second cousin's who works at a muffler store, but has read some magazine article where NASCAR engine use such and such and is trying to rebuild one of these motors.

If you ask the procedure for breaking in a Lycoming air cooled engine and you will get one response. If you ask 20 dealers which rings to use, cylinder finish to apply and how to break-in your old Triumph you are apt to get 20 different responses...

Just take the opinions on this site as to which oil to use or what heat range of plug to use. For most of these old air plane motors you have one choice - the spark plug and oil the factory specified!
John

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I see what you were getting at John (H), but then it isn't the same is it? The av gas hasn't changed to pi$$ like our fuel has which causes us to have to worry about detonation whereas the 'plane owner doesn't.

The' analysis paralysis' comment was funny, but not apt here perhaps?

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JH - maybe a "better" comparison would be the air cooled 911 motor, a little closer to a motorcycle engine's usage varying RPM and pump fuel rather than an aircraft engine that is run almost continuously at a single RPM with specially blended fuel. 911 engines use forced air and baffles to control the heat, have fine finning like an aircraft motor and squirt oil to the underside of the pistons for cooling. Unfortunately with Triumph's casting technique and years of non-improvement you have a motor that started out producing, what, 18 HP? now expected to put out 50 HP with no changes in the cooling scheme. However, it seems something had to be drastically wrong to burn a hole in the piston in that short a time. Maybe there was an air leak on the intake somewhere making that cylinder run lean? Certainly adding some engine sensors (exhaust temp., cylinder temp., Lambda, oil press., et cetera) would give ample warning of a problem but these are very crude engines and that probably is the attraction for most people.
JM, motorcycle engines are rarely expected to put out full power sitting at a stop on a hot day. The engine temperature is over 100 F higher than the air temperature so there should be plenty of cooling for the heat output.
A note on lubrication, when the piston is rising on compression the thrust is against the exhaust side and has the least oil film (since it was already scraped down on the downward stroke) and thrusting against the intake side on the power stroke where the oil film is greatest due to sling from the crank (although most probably ends up on the exhaust side due to shielding from the cylinder spickots).

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All the analysis is good for our knowledge base, but I DO believe it can cause paralysis. I'm almost scared to ride my TR6 I've had since 1986.

I'd try to shake off the scary technical stuff, build it back with the bore, pistons and ring end gaps measured and confirmed before assembly, check and recheck tappet clearance, set the static timing according to the Boyer install directions, get some 91 or 93 octane (it's a fact of life...low octane, detonation's gonna happen) and give it a whirl. I've done three brit engines and since I built them myself, I ASSUMED CATASTROPHIC FAILURE would occur as I broke them in...that way I was real pleased when they all ran fine. I use 20W50 for break in and normal use.

Is the lack of premium fuel in your area a temporary issue? I've only been in the southeast, but never been to an area where the convenience store didn't have 3 grades....


'Never argue with an idiot, they'll bring you down to their level, and beat you with experience'

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Fisherman, If I can point a finger at anything it would be my lack of knowledge on the fuel. The other thing is to re-torque & re-adjust the valves sooner and change the oil even sooner!


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I still stand by my analysis paralysis comment. We used the term in design school to describe a situation where you get so hung up in the process and so distracted by irrelevant or superfluous information that you never actually complete anything.

Hundreds of thousands of Triumph motors have been rebuilt, run on factory recommended oil and pump gas and have been problem-free within their limits. There is no reason why this one should be any different.



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Guys, how can I get you to understand that I am NOT comparing motorcycle motors and small air plane motors, even though they are more alike than you can emagine.

The physical process of breaking in grey iron piston rings making sure that the motor is operated in a manner that insures the rings are pushed up against the bore and the cylinder finish is prepared in a manner that is appropriate for the cylinder design and the rings being used is the same. In this case the Triumph factory used grey cast iron rings with a 150 grit. Not 200, not 220, not 280, but 150. They didn't planar honed, polished or apply the "soup of the day" cylinder treatment.

If you have a Triumph 650 or 750 twin and you are using grey cast iron rings and you want to follow factory specified cylinder preparation you will use honing stones that provide a 150 grit cylinder surface.

Can you vary from this, of course. Lots of people use ductile iron and steel rings and by their nature they require a different cylinder surface and cylinder preparation. They often require a more aggressive break-in procedure. There is plenty writen on this subject on teh web.

My point is you can only wish that you could get someone to do just what Bruce suggested:

" in the end all you can do is rebuild the motor to factory spec using good quality components then make sure the timing, spark plug and carb settings are correct."

This isn't about comparing one motor from another, but about comparing structure to chaos. I think Bruce is saying learn to do it by the book - Triumph's book and then experiment if you choose.
John

Will someone post Triumph's service bulliten showing the proper way to finish a Triumph cylinder... please.

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I thought everyone knew that the nn octane gasolene of today is not the same as the nn octane gasolene of the 1960s or 1970s. Besides the successive changes in the formulation of pump gas, the method of rating octane has changed.

Back in the 1970s (when I started riding), we were buying new machines or used machines that hadn't racked up enough miles yet to warrant an overhaul. Most of the riders I knew were not mechanically gifted, and many did not have a garage or even a good tool set. Much of the time these BSAs and Triumphs were ridden around in bad tune, BUT (and here comes the point):

NONE OF THEM EVER PINGED!


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If you told an FAA inspector you rebuilt your own airplane engine and couldn't show him certification papers he would laugh his a$$ off and ground your plane. We, on the other hand don't even think twice about wrenching on our poor old bikes whether we know what we're doing or not
LOL Alan T100R

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I have seen many triumphs with glazed cylinders, sunken seats,and valves edges you could shave with, new rings in tapered and oval bores (that didn't have a hope in hell of seating in) yet still survive catastrophe. Yours has melted two pistons, same side, in short order.
The cause may be any one or a combination of the suggestions mentioned.

I would like to know how the bike was being rode when it failed? (speed and load?) Same conditions both times?

Was the timing mark verified to be correct? (loose rotor?)

Is the 106 needle jet a true 106 thou.? (some are not, or shrink when threaded in.)

I can't help to think it must have been pinging/ knocking yet wasn,t heard by you, At higher speeds the noise might not be heard by the rider.

IF YOU CANNOT ESTABLISH THE CAUSE OF THE FAILURES WHILE REBUILDING IT THIS TIME. I SUGGEST RENTING AN HOURS TIME ON A DYNO TO TUNE AND TROUBLE SHOOT. FAULTS ARE EASIER TO PICK OUT WHILE RUNNING UNDER LOAD ON A DYNO, WHEN STANDING NEXT TO THE BIKE.....Rick




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Originally Posted by John Healy
I think Bruce is saying learn to do it by the book - Triumph's book and then experiment if you choose.
John

Will someone post Triumph's service bulliten showing the proper way to finish a Triumph cylinder... please.

What experimenting show me just where I experimented show me.!!!!
I didn't finish the cylinders Baxtres did!


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Yours has melted two pistons, same side, in short order Wrong the one photo is from when I got the damn e-bay thing!!!I did not do that! get off my back where in 500 miles of Keokuk, Iowa will I find a DYNO. And are you going to pay for its use! I didn't think so!


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John M. -

Just an objective observation:

You have some of the best and brightest when it comes to these old bikes trying to help you and you seem to be nothing but combative and taking it all personally. I sympathize with your plight, but maybe you should just take a deep breath; read a book; take a break; smell the flowers......

Then you can come back to the bike with a renewed sense of purpose and attitude.

Not that this suggestion was solicited, just works really well for me in situations like this.....

HTH,

Steve


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Your engine did hole two pistons in shot order. one by the previous owner and one by you, my mistake.

Those that don't learn from history are doomed to repeat it.

I wish you, your bike and your big hammer well.... Rick

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If there was prior mention of Baxters' involvement, I missed it. I've never done business with them, but many speak highly of them. I know engine rebuilders typically will not assume liability for these sorts of things, because they have no control over the assembly, break-in and tuning of the beast, but they may be willing to help you, at least with the forensics. Are you very near to Baxter's?


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279.2 miles or 5 hours


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Hi Everybody,

I have been reading this thread with great interest. This is one of those sagas, that by someone's misfortune, newbies like me get to learn a great deal, from the wisdom, gained from hard work and experience of others.

I would like to thank John Healy, in particular, for his participation, and for posting Kevin's incredibly insightful, treatise. Guys, John, seems to be getting a lot of guff, about what he is saying. Anything said can be taken out of context. I do not see any purpose served in doing that. Do you?

Sometimes reading a thread on this forum is a little like reading Plato. The analogy of the cave and the elephant come to mind, never mind aircraft engines and brit bike engines. Anyway, the ego, or false ego of having something to protect is the enemy of knowledge. An all to human failing, myself included, I am afraid.

John Michl,

I really do feel your pain. It is really horrible what happened. I know how you feel. My engine blew up too. I did not just hole a piston, but 'grenaded' the darn thing and broke a rod, and cracked the barrel skirt. Mine had not just been rebuilt, though so you must feel even worse. Mine was running great just before though. I had taken it to a shop to have the timing set and carbs adjusted though. Timing was set by strobe. Later we, John, found that the rotor was loose. Was "the" cause. Unknown. I had checked the timing myself later using the flywheel, and found it to be OK.

You said, Baxters did the finish on the cylinders. I have not re read the entire thread, but I am curious, and would like to learn. Did they know what type rings you were going to use?

Have you found any sharp edges of metal, in head, or anything else that might promote pre-ignition?

And I sure would like to hear what 'knocking' sounds like. I assume pinging is that sound you hear when making a mistake and trying to accelerate in too high a gear, which sounds like a bunch of small marbles in the thing. Maybe someday someone can post a link to a sound file, with the sound of a knock. I have heard a sound which I would describe as sounding sort of knocky, or I mean like more hollowy than a normal valve clacky, and found it to be a too loose valve. Gee, who can describe sounds without sounding goofy.

I have a thread with a long description of the perils of this E10 gas. I would think when breaking in a renewed engine it would be, prudent and worth the hassle and expense of ordering 'race gas', high octane leaded, just to be safer.

Just one more story about this so called gas. I was visiting someone with a huge amount of experience with our bikes, including racing them, and who makes a living doing that. And I had a chance to ride on of those rebuilt bikes, and it ran super. Real fast and smooth. Well, it had spit a paper base gasket, and needed it replaced. Next time I was visiting, he was breaking it in again, and we were going to go for a ride again to do that. -Hair raising, helmet blowing event I might add-. Well I was saved from the risk of death, because even though the bike had run wonderfully the day before, it would not then. Belching and bellowing, and backfiring even out one carb. Well timing and jets were checked, and what was the cause? 'The egg". That is what I call it. A glob of discolored 'gas' in the float bowl. 'Phase separation', maybe? That parfait of water and E10 make when mixed? When discarded the bike ran great again. Just a little funny aside. I was saved by the 'locking' gas cap I had added, because the generous guy was going to donate the drained gas to my tank, -Before the discovery of course!-, but cap was locked, whew. See John, it is not just the bars, or acts of malevolence, but even of kindness!

I know that even here in the regulated state of Mass., they do not check what is 'added' to the tanks of filling stations. They do not check the constituents of the gas. Each station is allowed to add whatever to its gas to control water etc. I make every effort to avoid filling from a pump that is even near a diesel pump, but I swear sometimes the gas I put in smells off, like it has diesel in it. Most likely my imagination. But I wonder. After my bike blew up, Jr. said he had heard it and it sounded like I was running diesel. One of the articles JH posted said gas with diesel in it was a cause of pre-ignition. I wonder just how that works. I would think in one sense the big D - I hate to type that word diesel- would raise the measured octane level, because it would not explode as easily. So I assume it cases pre-I because it leaves behind a smoldering residue. Just a wild guess.

I am glad for my locking gas cap. My over active paranoid imagination tells there are people out there, who want to get rid of an old Triumph, because it is not what the gang rides, but is admired, say by their old ladies, and would give a drink of the big D, if they could. Or there is just plain old jealousy out here, in this neck of the woods. I say this half in jest. A fellow just can't be too careful.

John M, It is not your fault. Many things can happen beyond your control, including just being 'unlucky' at the pump. Best wishes, and good luck! You have a lot of great advice from this thread. Please keep us informed so that no nothings like me can learn.



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Hmm ( testing )


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You said, Baxters did the finish on the cylinders. I have not re read the entire thread, but I am curious, and would like to learn. Did they know what type rings you were going to use?
Baxters supplied the rings.

Guys, John, seems to be getting a lot of guff, about what he is saying.
Thank you

ohn M, It is not your fault. Many things can happen beyond your control, including just being 'unlucky' at the pump. Best wishes, and good luck! You have a lot of great advice from this thread. Please keep us informed so that no nothings like me can learn.

Thanks


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I am posting from my cell phone during a break at work. That said, I am not a mechanic nor do I play one on TV. I think it was a valve thing. Too lean from the git-go.



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Hi John MichlHi John Michl,

I just re-read this entire thread. I am curious. I would like to know if you were ever able to look at the ring faces and see if they wore in all the way around. If they were making full contact with the cylinder surfaces?

Although there is some indication of how many miles and how much time you spent on the break in ride, I did not see a description of how you were riding, ie. what rpm's, hills, etc. Did I miss something? I am sorry to bother you if I did.

Also, Have you had the head examined by say Baxters to see what valve margins were, etc.?

At this point, it seems, that I would assume from my re-read, that the failure came about, because the rings did not seat properly, so there was excessive heat buildup, which was added to by the oil getting past rings, and too low octane fuel being used to compensate for that oil being added to the mix.

It would seem prudent for you to split the cases, and make sure there is no metal anywhere in the bottom end which would stop the oil pump. Then to prepare the top end again. It is unclear if you have to re-bore. I do not get the pictures on a dial-up, or even see the link. Many use photobucket to post pictures. Have the head checked. Maybe enquire from Baxters how you can run on the lower octane available in your area. ie. reduced compression pistons, etc. Although it would still seem cheap insurance to buy a can of 'real' or what they call race gas for the break in. IMHO 86 87 octane of modern gas is way too low to run a stock setup on never mind breaking it in. I do know I guy who runs a bitza on that stuff and swears it is OK, but he has re-built it three times, which he claims is easy, and is always experiencing "difficulties".

I did not see it specifically mentioned in the thread, perhaps I missed it, so I will say that it was news to me to learn from other threads that it is the combustion itself which forces the rings outwards against the cylinder walls, and if all is prepared properly they will wear in and "seat". So one must use a gas that will allow that, and one must ride it like they stole it. In other words, under load, and up and down through rpm range. Up to 4000, and down, and up and down. My natural tendency would probably have been to baby it bit, until I understood that.

My owners Manual does say to ride it like that, but they do not explain why.

I can relate to how you feel, that somehow it was your fault. I know I feel that way. And it is not a nice feeling. Most times I am even hesitant to do wrenching that is needed, because I may make a mistake, even though I have done it many times before, I mean the adjustment. The best advice I got from Jr. was "it is just a motorcycle".

Thank you, john M, and any follow up, would be greatly appreciated.


Bob, Lifetime bike: '71 T120R, bought in '71 at Ken Heanes, England.
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