Britbike forum Forums British Motorcycle specific Brands Triumph bulletin board TR5T forensics

Not all rings have tapered or napier faces. The Japanese Rikon rings I used a few years ago did not. The two top rings were identical .The 750 done a few months ago had rings for position in the package but no napier faced second ring....

The first item to bed in is the rings, even with a very low mileage there should be some sign of wear. Something was keeping those rings from rubbing against the honing. The honing is the sandpaper finish that wears the rings so they fit the bore properly, contact has to happen early on for this to work. Later once the bedding in is complete the wear rate rapidly drops.



This ring shows 2 area's where the ring did not wear, also a tapered ring with some wear would show the silver wear either on the bottom or top of the outside edge depending on which way the taper was installed.

Indeed ,

a model aero trick , is to put the ring in the bore & square with the piston .

Hold the sleeve / barrel - up to light . You can see if the things ' fully seated ' .
though theyre talking of say 3/4 inch bore ! Fancy pants LAP the Ring to the Bore .

Likey this wasnt uncommon back in 1914 or so . People - the better tuners - were very particular regarding ' fits ' .

ANYWAY , if you want to see if youve got a oval bore , or ring . install one ring at various places DOWN , square .

hold up to a lamp , see if the light gets through twixt rig & sleeve . then you know if its time to panic , pull out more hair ,
have a tantrum , or find a better machinist or parts supplier .

THEY LOOK LIKE HARD CHROME RINGS . Theyde take a bit of thrashing to seal . In a Commando , Stock , it was 2.000 MILES .
Before theyd stop passing oil . As in consuming oil / out the back .
So rings aint rings . Theres all differant types .
Cast Iron being soft 7 fragile but kind on the bores . unless they crack up . Anyone mention piston skirt to bore clearance ?

Looks like everythings RIGHt , actually .
Its just been pussy footed & neglected ( sitting around )

If the gasket faces check out flat , give Gary Nixon a call
and get him to ' bed it in ' . ( keep it below 80 for the first 50 miles )

use intermitant 5.000 rpm . Dont Hold twist grip ' on the stop ' .
She should be fine . one can get to caught up in imaginings .

No forifgn Matter - debri is important . lapped gasket faces is True Blue .

Triumphs are as tough as they come , if theve not been messed up .

Double check visually the piston pin circlips are seated true .
rounded face in , Sq face OUT , if stapped ones . WIRE
you usually check the tension / all match size - free . Check Grooves are spotless .

Those 500s go like stink with twin 30 Amals on them .

https://magazine.cycleworld.com/article/1967/2/1/triumph-500-road-racer

two double pages , click away . youll gettem .

Feb 67 . Quite a bit on them there , around then / earlier .
Good fork oil . often rear springs to stiff ( 145 lb dual , 110 solo )
K 70 tyres were the dirt track race set up . o.k on tarmac too .

Snot a toy one , give it grief , but excellence in maintanance .

I haven't tried the "ring in the bore and look for light" trick, but I measured the bores and they are round, and piston clearance is good, so it doesn't look like boring will be required. I'm not sure if I care if the rings are round, since I'll be replacing them.

Back to the head gasket issue, I noticed after a bit of sanding, the center of the head is higher (lower?) than the sides (i.e., sandpaper not making contact in the center). I'm thinking the head may have been "hung up" on the pushrod tubes. I'm sure I used the correct squish washers, but it may have been hung up on some previous rebuild, and I didn't resurface the head until now.

So the plan now is, resurface the head and the barrel, have the barrel re-honed, change the piston rings, head gasket, and pushrod tube squish washers (making damn sure I have the right ones), and reassemble. (That's a summary; I AM paying attention to the recommended details.)

BTW, I'm having a head gasket made by an outfit in Phoenix, AZ called Copper Gaskets Unlimited. Their gaskets are cut, not stamped, and they can vary the bore diameter and thickness of the gasket as specified. I had them make a gasket for my A65 and I was very pleased with it.

I'm still undecided about what rings to buy. I see recommendations for Harris, Hepolite, and Rikon. FWIW, I used Rikon rings on my last A65 rebuild, and they broke in very well, nary a puff of smoke, ever.

Hi mark, I had problems with head gasket not sealing due to push rod tube problems. That's why the marks on the head struck me right away earlier in the thread.

It's not about buying the correct seals, it's about measuring and then seeing if you can find the right seals for your actual situation. If the head has ever been skimmed, then you are in unknown territory and you need to go back to first principles. The trick is to build the head without one of the push rod tube gaskets, and then measure the free play. The casket must then have a certain amount of squish. I've got it written down somewhere but someone will chime in with the recommended amount.

Note that you can bend the head back straight. John Healy talked about it, and I reached out to him for more details but he never got back to me. Very few people online seem to have done it, but I got some pointers, gave it a try and my head has been fine for a long time now.

The problem with Machining out a bent head is that the bend remains on top with a rocker boxes sit and can compromise things on that side.

I also use one of the loctites like 510 as recommended by Don which has worked fantastically, but note that you have a time limit as copper acts as a catalyst at speeds up it's sitting time. Try to try the copper coat spray once and it was not great, but maybe there was something else going on , who knows.

Obviously there are different approaches if there is a burnt Channel in the head versus an equal and smooth Bend from side to side, just bening it down will remove most of the bend from the latter.

My head bolts also seemed a bit dodgy on close inspection and I replaced them at the same time. Look closely at everything.

Good luck.

"It's not about buying the correct seals, it's about measuring and then seeing if you can find the right seals for your actual situation."

Yes I see; I will check and measure as prescribed.

"Note that you can bend the head back straight."

I probably won't go that route, as I think the bend is very slight. That is, I think I can take care of the problem with sanding.

"Try to try the copper coat spray once and it was not great, but maybe there was something else going on , who knows."

Coppercoat seems to have worked well on my A65. Two coats helps, and giving it time to set up, even overnight.

By the way, I thought y'all might like to see what I'm working with. Note the alloy rims and Shinko tires. The rear fender is a B50 MX, stainless steel; as such there were no holes in it, so I had to drill all the holes for the (aftermarket) tail light/license plate bracket assembly and the breather hose. This will be a fun bike if we can get the engine running right!

Should be a real fun ride. I like my B44's and B50's, but I also like my Triumph T100 because it's so smooth. The combination should be great.
Tom

I think I'm on to something here. Putting the head to the cylinder barrel with the existing squish washers, O-rings, and head gasket in place, there's a gap of just under a tenth of an inch between the head and the barrel. The head is not torqued down, but it is pushed down firmly by hand. I think this gap is too large, more than what would be required to squish the washers. Plus, the washers are already compressed. It would seem these squish washers are too thick.

Seeing this, I'm surprised the motor ran at all!

Hope this helps;

http://vintagebikemagazine.com/technical-articles/push-rod-tubes/

Yes! It's all there! When I got to the bottom, I saw that the author is John Healy... of course!

Lesson learned: Fifty years of riding, maintaining, and rebuilding BSAs does not automatically qualify one to put a Triumph engine together.

But actually, maybe it does.

On BSA twins you have to sweat the crankshaft end float shimming, which can be a decidedly fussy process.

On Triumph twins, the crank is less of a bother but it seems they make up for it with push rod tube fitting problems.

Looks like you found the problem.

"On Triumph twins, the crank is less of a bother but it seems they make up for it with push rod tube fitting problems."

...and bolt-on rocker boxes.

It's been said (and you've probably heard this) that if someone could figure out how to put a BSA upper on a Triumph lower, you'd have one hell of an engine. (I know, it's a joke; one camshaft vs. two puts the kabash on that idea.)