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Re: Trouble starting new big bore [Re: Nick H] #713493
11/01/17 7:08 pm
11/01/17 7:08 pm
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Bishop, Calif.
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https://fagengine.com/tech/triumph-650-piston-installation-notes/

Nothing is a difficult as it looks nor as simple as it seems. This guy just did a bore & hone on my 68. The rings were seated within two blocks from the house.
Read it and make up your own mind.


1968 T120R
1972 T120RV
Any advice given is without a warranty expressed or implied.
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Re: Trouble starting new big bore [Re: Nick H] #713495
11/01/17 7:20 pm
11/01/17 7:20 pm
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Massachusetts, U.S.A.
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Nick,

Did you get my message yet?

If you are going to take the top end off, then confirm everything. Correct rings? Correct end gap on rings? Correct tolerances?

Check the step between the cases when you remove the barrels. You may have to compensate with the gasket. Just something tiny to remember, and save yourself from an oil leak there.


Bob, Lifetime bike: '71 T120R, bought in '71 at Ken Heanes, England.
Re: Trouble starting new big bore [Re: Nick H] #713501
11/01/17 8:24 pm
11/01/17 8:24 pm
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Posts: 291
Isle of Wight, UK
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koan58 Offline
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Nick, until you report back/show pics/measure pistons/bores clearance etc it is all wild speculation at this point.
In my younger years I knew even less than I know now of the advisable limits of wear in these beasts, eg on my 1st top end rebuild (~1977) as an ignorant 19 yr old with no real measuring equipment, money or knowledge, I (carefully) filed the wear ridge at the top of the bore, "deglazed" the bore with some emery I had around (what grade didn't matter!), gapped some new rings, did my 1st attempt at valve lapping, stuck it together, and got away with it. It ran quite well (I had no real comparisons, except it was marginally faster on the motorway than my mates RD400, he said he saw 102 on his speedo as I creeped by (depending on whether I had my fullface visor up or down!). Mind you it didn't smoke, and in all the top end builds I've done on my 650s, I've never known the smoking problems that I read of these days.
I wouldn't for a moment suggest this approach, it is only to illustrate how tough and tolerant these old things are. I'm sure many worse treatments have been employed, would be fun to hear of others desperate roadside/crude repairs.

I think clapped out bores and pistons can still work ok on these things for a long time, if you don't expect too much performance-wise.
Once the top ring of carbon is scraped off the bore, is there a ridge of metal at the top? If so, that is a good indicator that the bore needs proper measurement.
If you find that your bores and pistons measure up not to far from reasonable (say new is ~5 or so thou clearance) some would say 10 thou is clapped, but I would say you could get away with much more than that if the usage is to be moderate.
A lot depends on your budget, I think it is better to enjoy riding moderately than not at all.

I had no doubt when I saw your 1st pic that I saw gouges from grit, the pic was quite clear enough and not difficult to see that they were vertical. I was also concerned that the honing seemed to be in one direction only. This will only be ascertained when you open it. If that is the case, then the very least it needs is a proper hone job and new rings. I hope so, then follow John H's advice on scrubbing the bores. And you'll probably be well advised to give the piston sides a light rub with say fine wire wool (NOT emery in any shape or form) and a good flushing through of the engine, perhaps very frequent oil changes for the 1st 500 miles (and is there a filter in the system?)
If pistons and bores measure up reasonably, you will probably get away with the scratches, as long as the grit is no longer there to do its evil work on every wearing surface in the engine.

All the best Dave

Re: Trouble starting new big bore [Re: Nick H] #713505
11/01/17 9:22 pm
11/01/17 9:22 pm
Joined: Dec 2006
Posts: 3,878
Massachusetts, U.S.A.
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I mentioned the clearances only because someone did the build on the engine, and the piston to cylinder clearances for the "new" pistons are a different alloy, so the book specs will not work any more and he might not have known that. The original pistons did not expand as much as the new.

What is the word I am looking for? begins with an H ...aluminum?

The ring gaps need to be larger too.

This whole thing might be a blessing in disguise.


Bob, Lifetime bike: '71 T120R, bought in '71 at Ken Heanes, England.
Re: Trouble starting new big bore [Re: Nick H] #713506
11/01/17 9:48 pm
11/01/17 9:48 pm
Joined: Nov 2012
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Isle of Wight, UK
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I think you were looking for Lo-Ex maybe? I think eutectic and high silicon may be associated?

Re: Trouble starting new big bore [Re: Nick H] #713509
11/01/17 10:10 pm
11/01/17 10:10 pm
Joined: Aug 2001
Posts: 7,026
scotland
triton thrasher Online content
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Hiduminium.


Amateur Loctite enthusiast.
Re: Trouble starting new big bore [Re: triton thrasher] #713549
11/02/17 6:58 am
11/02/17 6:58 am
Joined: Sep 2013
Posts: 1,639
Pacific northwest
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quinten Online content
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Originally Posted by triton thrasher
Hiduminium.

[Linked Image]
... and I thought you were joking

Re: Trouble starting new big bore [Re: btour] #713566
11/02/17 11:16 am
11/02/17 11:16 am
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Naarfuk, UK
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Tigernuts Online content
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Originally Posted by btour
I mentioned the clearances only because someone did the build on the engine, and the piston to cylinder clearances for the "new" pistons are a different alloy, so the book specs will not work any more and he might not have known that. The original pistons did not expand as much as the new.


What make are these new pistons btour? Are they forged? If they are the normal JCC pistons, or the so-called 'Hepolite' Wassell/Emgo pistons, the material and clearance should be the same as it ever was (about .0045" skirt to bore). Forged pistons are different but they are uncommon, expensive, and ought to come with info sheets about clearances.

I doubt that pistons were ever made of Hidural 5 which despite the name contains no aluminium. As far as I know, Hiduminium hasn't been used for pistons either?


If anything other than a blank space is visible here, something's wrong.
Re: Trouble starting new big bore [Re: Nick H] #713606
11/02/17 4:35 pm
11/02/17 4:35 pm
Joined: Sep 2013
Posts: 1,639
Pacific northwest
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quinten Online content
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caution serious thread drift ahead ;
the interweb says it was used on one model/brand of aircraft Pistons
as early as 1933
[Linked Image]

Re: Trouble starting new big bore [Re: Nick H] #713613
11/02/17 4:58 pm
11/02/17 4:58 pm
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Massachusetts, U.S.A.
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I think the non brand name is something like heuristic? I just remember that it is different than current use. Current Expands more. It was special because it expanded less so tolerances could be closer. Can't go with manual clearances. I don't think anyone know what he has now. I was just pointing it out to him to avoid a problem later.

Last edited by btour; 11/02/17 5:00 pm.

Bob, Lifetime bike: '71 T120R, bought in '71 at Ken Heanes, England.
Re: Trouble starting new big bore [Re: Nick H] #713619
11/02/17 5:12 pm
11/02/17 5:12 pm
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Isle of Wight, UK
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As far as I know, these hi-strength aluminium alloys were developed for primarily aircraft use circa WW1 or so, the RR designation of many of them is testament to their origin.
They were used by some automotive manufacturers at stages, for pistons and other components, but in the context of our interest, the only application of Hiduminium was in the connecting rods. Of course the big demands here were cyclical stress/fatique, and nickel content/low silicon helps.

Pistons are different in their needs, being subject to higher temps and subject to abrading in their action. Far as I know, early Triumph pistons were made of an alloy which had a low expansion coefficient, I thought it was called Lo-Ex, and it was high silicon, but I often get muddled.

Anyone know for sure?

Re: Trouble starting new big bore [Re: Nick H] #713628
11/02/17 7:19 pm
11/02/17 7:19 pm
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Nick H Online content OP
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Warm day! So I widened my valve settings a tad and retarded my timing another tad and got the bike to start and idle! WooHoo! Wouldn't rev up though. Probably shouldn't be risking more damage to the cylinders and pistons but that's good news. Also, I have the primary cover off as i want to set the timing there with a strobe but I fear burning up my chain tensioner. I bought a later cover on eBay with the opening and I'll wait on that. I took some boroscope video inside the plug hole. I'll post if I can figure out how.


1966 BSA Lightning
1967 Triumph "Choppa"
Re: Trouble starting new big bore [Re: Nick H] #713629
11/02/17 7:25 pm
11/02/17 7:25 pm
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Nick H Online content OP
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1966 BSA Lightning
1967 Triumph "Choppa"
Re: Trouble starting new big bore [Re: Nick H] #713630
11/02/17 7:33 pm
11/02/17 7:33 pm
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koan58 Offline
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Brilliant Nick! So satisfying! Ride boy ride! It's a good feeling innit!

Re: Trouble starting new big bore [Re: Nick H] #713664
11/02/17 11:22 pm
11/02/17 11:22 pm
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Boston, Massachusetts
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John Healy Online content

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Quote
What make are these new pistons btour? Are they forged? If they are the normal JCC pistons, or the so-called 'Hepolite' Wassell/Emgo pistons, the material and clearance should be the same as it ever was (about .0045" skirt to bore).


Triumph has had two different suggested clearances for the 650 pistons. First when they made them (marked Lo-Ex) and different when they started using Hepolite in the mid-sixties. This has confused even experienced dealers/experts. When Triumph made their own pistons, the minimum clearance at the bottom of the skirt was .0035". When Hepolites were introduced it became .0045". You can fit the early pistons to .0045", but it would not be wise to fit the Hepolites (JCC copies) to .0035".

Quote
If pistons and bores measure up reasonably, you will probably get away with the scratches, as long as the grit is no longer there to do its evil work on every wearing surface in the engine.


We buy the Aerco long rod big bore kits we supply to dealers from Aerco simi-finished. We do the final honing in house. We selectively sort the pistons by size so there is no confusion which piston goes in which bore Then using Sunnen AN220 stones hone (with honing oil which gives you about a 180 grit finish) the cylinder to .0045" clearance. We cover the shipping box with at least 10 labels that say, 'WASH ME" and "Wash cylinder in hot soapy water. Wipe with a lightly oiled white cloth until rag stops picking up traces of honing residue. When you think it is clean, do it for another 10 minutes!" Point being you cannot be too careful when you are cleaning the cylinder.

Quote
In my younger years I knew even less than I know now


I agree whole heartily, in fact I have HAD TO forget a lot of the things we got away with 50 years ago. Because we had fuel with much more than adequate octane levels and the oil had no "energy conserving" additives we had a huge safety factor keeping us from a lot of the disasters we see today. Because of this we had a much wider margin of error. We were weaned on grey cast iron rings because they were to be used in cylinders that were anything but straight, round and true. By today's standards they would not be suitable to be used in a lawn mower. Because of their design, any attempt to get them perfect will be defeated the first time you warmed them up.

Back then there was a safety factor built into the gasoline, and oil. Also the rings were very forgiving considering you used the correct cylinder finish. A lot of that safety factor can easily be erased when we stray away from the tried-and-true engine building techniques of our thousandths world (.001") into the new tenths of thousandths (.0001") world. We are led to believe, by people preparing cylinders for engines that live in the .0002" world, that there advice is backward compatible to our .001" world we live in.

The last time I checked our cylinders they do not have the giant - ported (in the sense you would port a head for flow) water jackets, are not honed using heated honing oil and held to .0002" in all directions. With these old bikes the learning curve today is just what of the pallet of modern technology is truly backward compatible.

At least with the effort of the Big Four Japanese companies, who went to war with the API and the SAE, we have learned that the "Energy Conserving" oil is not backward compatible. Because of their effort that took nearly 10 years (there efforts started in the mid-1990s and was resolved around 2005) we have a wide selection of API SG oil for our motorcycles, SG is the last iteration of API ratings that didn't carry the "Energy Conserving" logo.

Quote
When fettled, my Matchless 500 will make chuffing noises if kicked over with the valve lifter operated


Simply stated the vapor pressure of fuel is a blend of varying compounds with different vapor pressures. The compounds that make up the part of the gasoline blend that allow you to start an engine are referenced as the "front" end, or aromatics, and are made up of very light compounds. They are referenced as light because they vaporize easily (they have a low boiling point). Because you don't want them so light (low Read Vapor Pressure) that they boil at ambient air temperatures they are blended so . If this happened, you would never be able to start your engine. So they are blended to vaporize, and the gasoline must vaporize to mix with air so it becomes combustible. Gasoline will only burn when it has vaporized and mixed with air. To this end, aromatics are blended by season and expected ambient air temperatures. They are lighter in the winter and heavier in the summer. The average temperature where the aromatics vaporize in is the 120°ish range. Thus for it to vaporize, and thus deliver a combustible air/fuel mixture you have to get heat from some other source other than ambient air temperature. Thus we have the requirement that it be compressed. If you have stale gas where a lot of the aromatics have vapored off, leaving ONLY mid-range compounds that vaporize in the 160-180° range, the engine becomes hard to start. This can happen in storage, or the aromatics can vapor off at the end of a ride leaving only heavier compounds available when you try to start the bike sometime later. Tickling usually solves the problem.

The chuffing when you kick the bike over is some of the very light compounds of the front end gas burning, but not enough of it will vaporize to create enough energy to turn over the engine. This is something a lot of you can relate to: Aromatics are similar to the hit of alcohol vapors you get off a glass of neat Cognac. Wrap your hands around a glass of Cognac to warm it up and notice how the alcohol vapors develop as the liquid warms. You can light it with a match. Try it with a glass of cold Cognac, it will not light.


www.slideshare.net/mcfalltj/halderman-ch066-lecture
www.epa.gov/gasoline-standards/gasoline-reid-vapor-pressure

I have to go home. We were busy today and I wrote this in 5 and 10 minute chunks between building seats and taking phone orders.
Hope this makes some sense as it is not often discussed in relation to problems.

Last edited by John Healy; 11/02/17 11:41 pm.

Re: Trouble starting new big bore [Re: Nick H] #713670
11/03/17 12:04 am
11/03/17 12:04 am
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Ta John or clarifying the Lo-Ex business, and also the importance of ridding the bores of the grit.
The understanding of volatiles is homeground for me, so well with you there.
I couldn't care less whether one calls them non-hi silicon or hiconfusion, any modern pistons will require the larger (say 5 thou) clearance
. Johm I gave my crude judgement to Nick, that he may get away with those scratches maybe, what do you think? What does anyone else think?
I understand where you are Nick, as a newbie, we've all been there, use this resource to the max!
Dave

Re: Trouble starting new big bore [Re: Nick H] #713708
11/03/17 1:16 pm
11/03/17 1:16 pm
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Nick H Online content OP
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I am definitely getting an education here! Next question: Could it have been overly tight valve clearances that were causing my starting and running issues? It certainly seems that way. I originally had tried to set them at .002 intake and .004 exhaust. This time I went to closer to .004 intake and .006 exhaust. (intake a little less than 1/8 of a turn, exhaust a bit more) The bike was idling but wouldn't rev up. Maybe it's time to go back to the Mikunis.
My big bore kit came from J.R.C. engineering (I think these are Aerco)- so my clearance should be .0045? Do I just fit a feeler gauge between piston and cylinder?

Last edited by Nick H; 11/03/17 1:22 pm.

1966 BSA Lightning
1967 Triumph "Choppa"
Re: Trouble starting new big bore [Re: Nick H] #713773
11/03/17 11:32 pm
11/03/17 11:32 pm
Joined: Oct 2001
Posts: 237
Monclova
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Monclova
good boy, now you have the valves set right, check the timing, make sure its right. Get your basics set as close as you can first. fine tuning is just that, but start with a baseline and work from that point. With all the information your getting I bet you found it hard not to tear the motor apart in a million pieces to look at it. Its tempting but try to set it up first and ride it. Kinda sounds to me from your explanation that its to far retarded. You wouldn't believe the people that bring there bike to me because it will not take throttle but say its timed right. Upon inspection timing is way off. I had one this summer that the guy fought and fought. Hed call looking for answers blah blah blah. When he finally brought it over I simply could not believe that it would even start. simply amazing. The timing was so far back it would run but backfire, no pull etc. Check your timing, check to make sure your magnet rotor didn't slip. If its a Boyer check the length of the bolt they supply, I always cut some off because they are to long. Keep checking, your getting there.

Re: Trouble starting new big bore [Re: Nick H] #713774
11/03/17 11:44 pm
11/03/17 11:44 pm
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Nick H Online content OP
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Thanks. Just waiting on a primary cover with a hole for timing - should be tomorrow. Then I can time with a strobe. Noticed today that my floats were too low despite all the care I thought I took (same situation as my valves!) Used this technique to find the actual fuel level:
[Linked Image]
Supposed to be .21" from top of bowl. Ended up making the floats just about level with top of bowl. Go too high and it just leaks forever. I can see it now - I'll get it running right and snow will start to fall - Ha!

Last edited by Nick H; 11/03/17 11:44 pm.

1966 BSA Lightning
1967 Triumph "Choppa"
Re: Trouble starting new big bore [Re: John Healy] #713792
11/04/17 9:31 am
11/04/17 9:31 am
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Originally Posted by John Healy
Quote

When fettled, my Matchless 500 will make chuffing noises if kicked over with the valve lifter operated


Simply stated the vapor pressure of fuel is a blend of varying compounds with different vapor pressures. The compounds that make up the part of the gasoline blend that allow you to start an engine are referenced as the "front" end, or aromatics, and are made up of very light compounds. They are referenced as light because they vaporize easily (they have a low boiling point). Because you don't want them so light (low Read Vapor Pressure) that they boil at ambient air temperatures they are blended so . If this happened, you would never be able to start your engine. So they are blended to vaporize, and the gasoline must vaporize to mix with air so it becomes combustible. Gasoline will only burn when it has vaporized and mixed with air. To this end, aromatics are blended by season and expected ambient air temperatures. They are lighter in the winter and heavier in the summer. The average temperature where the aromatics vaporize in is the 120°ish range. Thus for it to vaporize, and thus deliver a combustible air/fuel mixture you have to get heat from some other source other than ambient air temperature. Thus we have the requirement that it be compressed. If you have stale gas where a lot of the aromatics have vapored off, leaving ONLY mid-range compounds that vaporize in the 160-180° range, the engine becomes hard to start. This can happen in storage, or the aromatics can vapor off at the end of a ride leaving only heavier compounds available when you try to start the bike sometime later. Tickling usually solves the problem.

The chuffing when you kick the bike over is some of the very light compounds of the front end gas burning, but not enough of it will vaporize to create enough energy to turn over the engine. This is something a lot of you can relate to: Aromatics are similar to the hit of alcohol vapors you get off a glass of neat Cognac. Wrap your hands around a glass of Cognac to warm it up and notice how the alcohol vapors develop as the liquid warms. You can light it with a match. Try it with a glass of cold Cognac, it will not light.


www.slideshare.net/mcfalltj/halderman-ch066-lecture
www.epa.gov/gasoline-standards/gasoline-reid-vapor-pressure

I have to go home. We were busy today and I wrote this in 5 and 10 minute chunks between building seats and taking phone orders.
Hope this makes some sense as it is not often discussed in relation to problems.


Thanks John. The chuffing Matchless point was that if everything else is in good order, particularly a big fat blue spark, then a single cylinder bike with minimal compression will show signs of life. Would be interesting to see what compression a Panther 600 runs at with the half-compression lever engaged, 4:1 perhaps?

Re: Trouble starting new big bore [Re: Dibnah] #713801
11/04/17 11:59 am
11/04/17 11:59 am
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Posts: 473
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16H Norton is 5.9:1 and they start very easily with a decent mag.


If anything other than a blank space is visible here, something's wrong.
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