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Hi,
handlebars
end of the bar is not the same as the end of the grip. Due to the positioning of the air "choke" lever, the throttle end is not pushed entirely on the bar. IIRC, it's about an inch out to allow the choke to not rest on the handlebar curve.
Regrettably, your most recent (only?) photo. of the bike isn't enlargeable; without searching through this very long thread for only the possibility of a better photo., it's difficult to discern what the problem is more likely to be.

As standard, the choke lever mounting is part of the front brake mounting - '69 500 parts book, .pdf page 72 or paper page 70, parts #15, 16, 22-25. So:-

. either you're talking about a replacement later front brake lever mounting with a separate choke lever mounting on the 'bars;

. or the bike has non-standard 'bars, with a shorter length between each end and the nearest curve, the throttle side being too short for both twistgrip and front brake lever;

. or the bike has grips that look like the original Gran Turismos but are actually made by Beston, which are longer than the original GT's?

If a separate choke lever mounting on the 'bars, have you considered moving simply moving it to the left 'bar? Fwiw, my T150 has the choke lever mounted on the front brake lever; absent a six-inch long right thumb, I have to let go of the twistgrip to fiddle with the choke lever, which is then a pita if the choke's in use. 😖 If you use the choke, lever operated by the left hand independently of the twistgrip would be much easier?

oil leak
seems to be mostly the top ring of the exhaust push rod tube.
just an inevitability of 50 year old rubber
order parts first or take it apart first?
'69-on PRT O-ring seals are a vexatious subject, for various reasons but more so on the 500/350 thanks to the really stupid Meriden Misprints in the '69 parts book, which border on bungling incompetence ... 🤬 It's easier to start with what's correct:-

. (y) The "E9512" PRT part number listed on the T90 pages and all three PRT illustrations; the part number is correct for any '69-on C-range.

. (n) The PRT and seals part numbers listed on the T100S/T100C and T100R/T100T pages weren't updated from '68.

. (n)The "E7310" O-ring listed on the T90 pages was superseded early in '70; 71-1283 is the O-ring part number you should always use both top and bottom of the PRT.

. (n) Certainly original E7310 turned out to be the wrong material (Buna-N) particularly for the exhaust PRT upper seal in the head, where it gets hottest between the exhaust valves ... 😖 The superseding 71-1283 O-ring is at least Viton, it's the same size as E7310 so it makes sense(?) to preclude any confusion by using it/them for all four top and bottom PRT seals.

In addition, look particularly on your bike at what's at the bottom of the PRT:-

. If you see a steel ring separate from each PRT, if they can be pushed up the PRT, you should see they hide an off-white or translucent seal between the bottom of the PRT and the tappet guide block. To replace these seals, order 2 each of 70-3547 and 70-4752 (you won't need both, they're just different thicknesses).

. The off-white or translucent seals and separate steel rings (71-1707) weren't fitted originally to '69 twins, they're another early-'70 retrofit to 'fix' :rolleyes: the PRT oil leaks that the new-for-'69 E9512 PRT and E7310 O-ring were supposed to fix ...

replace head gasket,
If your bike's is copper, it can simply be heated to cherry-red to anneal it then it can be reused. (y) Who knew Triumph was fitting its bikes with recyclable parts over half-a-century ago? ;)

replace
base gasket, and rocker box gaskets.
Be aware these are available in a couple of more-modern varieties than original Triumph:-

. Copper or aluminium, reusable same as the aforementioned head gasket. If these have a 'downside', it's they're less tolerant of imperfections in the component gasket mating surfaces.

. "Covseal" - I think invented by US parts wholesaler Coventry Spares, the material is rubber sandwiched between two layers of either aluminium or stainless. Specifically intended to be highly-tolerant of component surface imperfections, (y) their only downside is they aren't reusable. :(

top end kit from the likes of the Bonneville shop or CBS adequate?
Not bought from either specifically, because they're in the US.

I've never had good experience with general "kits". :( Triumph changed small parts like seals several times over the life of all the twins; the kits I've encountered seem to try to include every variation, fail but include some random seals to make up the numbers. The buyer then needs experience of the different variations to know which parts fit the bike in front of them ... :rolleyes: If I namecheck @The Bonneville Shop Dave, he'll get a link to this thread next time he checks in; he can offer more specific advice on what he sells.

Anything else?
Consider buying four new pushrods - otherwise pita if you take it apart, find any bent ones and have to wait for new.

tappet guide block tool.
chrome ones are substantially less $, but I'm not sure it matters. Does it matter?
You'll be hitting it with a hammer. Imho, always buy the best tools you can't really afford - down the road in time, pita when a 'less expensive' tool fails and you really can't afford to replace it ...

Ideally, I'd like to do this once
:ROFLMAO: Wouldn't we all ... non sequitur when you're talking about Triumph PRT ...

Because I've dealt with retailers by post for decades, I keep a small stock of spares like rocker-box gaskets, PRT seals, etc., because they leak at the most inconvenient times. :( Spares on hand, I can change them whenever, order replacements the next working day and not be fretting how long the post's taking 'cos I've got a bike in bits on a sunny day. (y)

Hth.

Regards,
 

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Discussion Starter · #222 ·
Thank you. Very helpful (as usual (y)).

I'm sure I'll get back to the handlebars at a later date, when that's my most pressing concern. I appreciate the input and we'll sort it out eventually. :)

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It's easier to see with the eye, but the second pic is the leaking top ring and the oil is evident down the outside of the tube and travels to the left side of the bike via the bottom fin. I don't see the "wedding band", just the cushion. They all look to be black. The first pic has the stamping at the bottom. Not sure how relevant that is.

I think I'm going to disassemble and see what I've got. Patience may be required on the back end. 😠
 

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Hi,

Errrm ... all unit Triumph twins, the top PRT seals are in the underside of the head ... :whistle: Only the triples allow PRT seal replacement just by removing the rocker-box.

Hth.

Regards,
Apologies!
My 650 is pre-unit! I’ve not had a unit motor in bits , yet
 

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Discussion Starter · #225 ·
It's in pieces. Stay tuned. In the meantime, I see slight evidence of exhaust escaping the head gasket on one of the cylinders. Thoughts? Vehicle Automotive tire Motor vehicle Rim Gas
 

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Hi Daryl, I've jumped into this thread a little late, but on Stuart's suggestion, I can add some suggestions for sealing up the top end of your 1969 T100. We carry a full line of parts for the unit-construction Triumph 500 models, and are continuing to expand the inventory, as we see the demand increase.
These are just a few items that are germane to the most recent discussions. I have to admit I didn't go all of the way back to the beginning of the thread, but if anything else comes up in the group discussion, I'll keep an eye out for any opportunities to suggest solutions for your parts needs. Looks like a great project you have underway!
-Dave
 

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Hi,

Regrettably, your most recent (only?) photo. of the bike isn't enlargeable; without searching through this very long thread for only the possibility of a better photo., it's difficult to discern what the problem is more likely to be.

As standard, the choke lever mounting is part of the front brake mounting - '69 500 parts book, .pdf page 72 or paper page 70, parts #15, 16, 22-25. So:-

. either you're talking about a replacement later front brake lever mounting with a separate choke lever mounting on the 'bars;

. or the bike has non-standard 'bars, with a shorter length between each end and the nearest curve, the throttle side being too short for both twistgrip and front brake lever;

. or the bike has grips that look like the original Gran Turismos but are actually made by Beston, which are longer than the original GT's?

If a separate choke lever mounting on the 'bars, have you considered moving simply moving it to the left 'bar? Fwiw, my T150 has the choke lever mounted on the front brake lever; absent a six-inch long right thumb, I have to let go of the twistgrip to fiddle with the choke lever, which is then a pita if the choke's in use. 😖 If you use the choke, lever operated by the left hand independently of the twistgrip would be much easier?


'69-on PRT O-ring seals are a vexatious subject, for various reasons but more so on the 500/350 thanks to the really stupid Meriden Misprints in the '69 parts book, which border on bungling incompetence ... 🤬 It's easier to start with what's correct:-

. (y) The "E9512" PRT part number listed on the T90 pages and all three PRT illustrations; the part number is correct for any '69-on C-range.

. (n) The PRT and seals part numbers listed on the T100S/T100C and T100R/T100T pages weren't updated from '68.

. (n)The "E7310" O-ring listed on the T90 pages was superseded early in '70; 71-1283 is the O-ring part number you should always use both top and bottom of the PRT.

. (n) Certainly original E7310 turned out to be the wrong material (Buna-N) particularly for the exhaust PRT upper seal in the head, where it gets hottest between the exhaust valves ... 😖 The superseding 71-1283 O-ring is at least Viton, it's the same size as E7310 so it makes sense(?) to preclude any confusion by using it/them for all four top and bottom PRT seals.

In addition, look particularly on your bike at what's at the bottom of the PRT:-

. If you see a steel ring separate from each PRT, if they can be pushed up the PRT, you should see they hide an off-white or translucent seal between the bottom of the PRT and the tappet guide block. To replace these seals, order 2 each of 70-3547 and 70-4752 (you won't need both, they're just different thicknesses).

. The off-white or translucent seals and separate steel rings (71-1707) weren't fitted originally to '69 twins, they're another early-'70 retrofit to 'fix' :rolleyes: the PRT oil leaks that the new-for-'69 E9512 PRT and E7310 O-ring were supposed to fix ...


If your bike's is copper, it can simply be heated to cherry-red to anneal it then it can be reused. (y) Who knew Triumph was fitting its bikes with recyclable parts over half-a-century ago? ;)


Be aware these are available in a couple of more-modern varieties than original Triumph:-

. Copper or aluminium, reusable same as the aforementioned head gasket. If these have a 'downside', it's they're less tolerant of imperfections in the component gasket mating surfaces.

. "Covseal" - I think invented by US parts wholesaler Coventry Spares, the material is rubber sandwiched between two layers of either aluminium or stainless. Specifically intended to be highly-tolerant of component surface imperfections, (y) their only downside is they aren't reusable. :(


Not bought from either specifically, because they're in the US.

I've never had good experience with general "kits". :( Triumph changed small parts like seals several times over the life of all the twins; the kits I've encountered seem to try to include every variation, fail but include some random seals to make up the numbers. The buyer then needs experience of the different variations to know which parts fit the bike in front of them ... :rolleyes: If I namecheck @The Bonneville Shop Dave, he'll get a link to this thread next time he checks in; he can offer more specific advice on what he sells.


Consider buying four new pushrods - otherwise pita if you take it apart, find any bent ones and have to wait for new.


You'll be hitting it with a hammer. Imho, always buy the best tools you can't really afford - down the road in time, pita when a 'less expensive' tool fails and you really can't afford to replace it ...


:ROFLMAO: Wouldn't we all ... non sequitur when you're talking about Triumph PRT ...

Because I've dealt with retailers by post for decades, I keep a small stock of spares like rocker-box gaskets, PRT seals, etc., because they leak at the most inconvenient times. :( Spares on hand, I can change them whenever, order replacements the next working day and not be fretting how long the post's taking 'cos I've got a bike in bits on a sunny day. (y)

Hth.

Regards,
Thanks for the nod Stuart...I'll keep an eye on this thread. Cheers!
-Dave
 

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Discussion Starter · #228 ·
Thanks Dave. I beat you. I just ordered the top end set and the block tool. That should get me down the road a piece to where I see what else i need.
 

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It's in pieces. Stay tuned. In the meantime, I see slight evidence of exhaust escaping the head gasket on one of the cylinders. Thoughts? View attachment 773454
It looks to me from the small photo, left cylinder by the exhaust port and between the two cylinders.
measure the head for flatness, a true straight edge and feeler guages to slip under any gaps will help.
The head might need to be pressed flat again, and maybe need machining (machine only as a last resort)
Anneal the new gasket before fitting, check that the gasket is clearance around every stud hole.
use copper coat surface spray on the new gasket before fitting

good luck
peg.
 

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Discussion Starter · #231 ·
Thank you for your input. (y)

What does pressing the head flat entail? Is that something I can do? (I mean that in the sense of what's required, special tool wise. With the right tool, I'm confident I can do most anything.) I have yet to put a straight edge on the head. number one on the list for today. Could this also be caused by insufficient torque at one of the head bolts? I found the nuts holding the barrels to be much tighter than the head bolts. For those who joined this thread late, this bike seems to have very few miles on it. I'm not really sure it was completely broken in before I inherited it. Is a retorque a standard maintenance procedure for these bikes? While we're here, what is the consensus on torque value for the head bolts? I'm sure it's in my books, etc, but I no longer trust the correctness of many of the documents. ;)

I've been puzzling on the head gasket situation. There are a lot of opinions. Reuse the old one. Use a new one. Install bare. Install with a coating plus different opinions on what to use. By copper coat, I believe that is literally a copper spray, correct? The flip side of the gasket looks to be sealed perfectly btw.
 

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I’m going to take a wild guess ;-)
Maybe the PO never took the bike back for its first service when the head bolts would have been re-torqued.
 

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Hi
pressing the head flat is not difficult, I have done a few now.
you will need a hydraulic press with pressure gauge a dial gauge, a straight edge +feeler gauges and an oven (optional)
I use a nylon block to transfer the load without damaging the surfaces.
After ascertaining the amount of bow using the straight edge and feeler gauges.
I like to heat the head to 150 degs C (300f) in the oven and hold it there for a couple of hours.
Then press the head to flat using the dial gauge, and note the pressure. Then continue to press to plus 25% of the bow figure and note the pressure.
release the pressure and measure, the head for flatness after it has sprung back.
if it has sprung back too far, reheat and repeat the press with extra pressure/movement to 50% over,
release and measure.
keep repeating and measuring until the head springs back flat.
the two steel plates are the pivots to press against, the plastic plate prevents head surface damage during pressing.

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The upthrust of the pushrod tubes is a cause of the head bending, ckeck that there is not too much pressure imposed when you refit the head.
Machining the head flat on a mill is usually considered a last resort option.

regards
peg.
 

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Discussion Starter · #234 ·
Thank you so much for the pictures. That was not how I was picturing it. I thought the valves would have to come out. Looks way more bending than flattening than I was expecting. Much appreciate that visual.

I checked the flatness today. (All I really got done in the garage today.) The smallest feeler gauge I have is .002". I'll say neither the head surface nor the cylinder surface is perfectly flat. However, it's less than .002" everywhere and the low spots on both are between the cylinders. Outside of that middle, the rest is very flat. Where it was blowing out was not different from the rest of the periphery. I think that degree of flatness is adequate. Correct me if i'm wrong.

I was surprised when i looked up the head torque numbers. I guess there is a misprint in something that said 25 ft-lbs, but the correct number is only 18 ft-lbs. When I get to the point of torquing it, I think I will have a good idea whether it was at something like 18 ft-lbs when I removed them.
I agree with newsh that it's a definite possibility the PO did not get regular service, if any, done. He was a quirky guy. He spoke about the bike like a long lost love and yet he basically left it sitting to decay. Not sure what that means for getting it's initial service done. It still bums me out that he's not around to both experience it and also to answer my questions. C'est la vie.
 

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Hi
With that particular cylinder head, I think that I would be tempted to try to get rid of the 0.002" discrepancy.
Your photo shows a darkened area between the cylinders, indicating that combustion gasses have been creeping over the head gasket.
This area has been a particular problem for Triumph due to the upthrust of the pushrod tube. Triumph added an extra central bolt on the 650cc, and two extra central bolts on the 750cc, eventually fitting a composite gasket to resolve cylinder leakage past the head gasket.
your head does not have the central bolt to assist pulling down the middle of the head.
The reduction clamping pressure on the gasket is not directly related to the amount of bend, if the head isn‘t pressing on the gasket by a 2 thou bend, or by a 10 thou bend, it is still not pressing on it.
The head is resilient, in the photo I was removing a 3 thou bend from a T140D head, it took several progressive attempts, using several tonnes load, I expect a lot more than can be generated by the head bolts.

good luck
peg.
 

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Discussion Starter · #236 ·
I see. That explains a lot.

I had a thought (at 3AM, naturally) that I should put the bare head on the bare cylinder and see what that gap was. On the intake side, in the middle, it is between .003 and .004". On the exhaust side, it is .0055".
Additionally, I hadn't taken a good look at the PRTs yet. I was surprised when I did. There is no bottom cushion that I was expecting. What I have is exactly like the image in the repair manual at BB13. There is a bottom oring inside the PRT (that looks in good nick) and a top oring (between the head and the PRT top (that looks like it's completely had it. The exhaust one that I looked at is caked in oil and black bits). I feel like everything I've read implied a cushion at the bottom. I'm a bit lost as to how to improve this situation. It seems that there is only the top ring spacing the head from the PRT and then it's the PRT that's clearly holding the middle high. The head gasket bears witness to the fact that there was pressure in the vicinity of the bolts (shiny), but less through the middle and also where the exhaust was escaping.

Related, I don't think I have a pressure gauge. Pretty sure I have the rest. What is the pressure gauge taking a reading of? Is it strictly necessary? :D

Thank you again for all the help.
 

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I see. That explains a lot.

I had a thought (at 3AM, naturally) that I should put the bare head on the bare cylinder and see what that gap was. On the intake side, in the middle, it is between .003 and .004". On the exhaust side, it is .0055".
Additionally, I hadn't taken a good look at the PRTs yet. I was surprised when I did. There is no bottom cushion that I was expecting. What I have is exactly like the image in the repair manual at BB13. There is a bottom oring inside the PRT (that looks in good nick) and a top oring (between the head and the PRT top (that looks like it's completely had it. The exhaust one that I looked at is caked in oil and black bits). I feel like everything I've read implied a cushion at the bottom. I'm a bit lost as to how to improve this situation. It seems that there is only the top ring spacing the head from the PRT and then it's the PRT that's clearly holding the middle high. The head gasket bears witness to the fact that there was pressure in the vicinity of the bolts (shiny), but less through the middle and also where the exhaust was escaping.

Related, I don't think I have a pressure gauge. Pretty sure I have the rest. What is the pressure gauge taking a reading of? Is it strictly necessary? :D

Thank you again for all the help.
Sorry for being imprecise with the description, the pressure gauge is on the hydraulic ram, so that you can compare the forces placed on the cylinder head, so that successive applications can be applied progressively. i.e. If the first application of force straightens the head by 1mm, you can then apply a slightly greater force for the second application, the pressure gauge on the press hydraulics makes this easy to judge.
 

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Hi @Peg
What stops the gasket face of the head getting marked by the supports underneath? Have you got bits of plastic there too?
 

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If you look closely you can see a nylon buffer underneath.
It is actually a kitchen nylon cutting board for bread or Vegtables.
Hand Food Tableware Dishware Ingredient
 
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