Recommissioning a ‘new’ TSS

Onder said:
What he said about the cable connected master cylinder! Insanity. Brakes were never a high point on my early R90s.
Click to expand...
Didn't BMW say it was for safety in the event of an accident the rider was less likely to get brake fluid on him
Or something like that
 
<probably more the worry of getting brake fluid on that stunning smoke and silver paint job!>
 
I think it had more to do with their integrated throttle/brake lever/switch perch assembly. With the under-tank MC they could use the same one across their entire lineup.
 
In post #11 I said “I might stick a bore scope down the bores”.

Scope creep already…

Recommissioning a ‘new’ TSSRecommissioning a ‘new’ TSSRecommissioning a ‘new’ TSSRecommissioning a ‘new’ TSS
 
No, you are doing it correctly. Look now and know rather than know after you have a problem and the work is the same anyway.
What is sad, is this head should have been on the twins day one. Nothing technically would have prevented it. Imagine it on
the Trident. Hey, don't trudge it Rudge it! :-)
 
Onder said:
No, you are doing it correctly. Look now and know rather than know after you have a problem and the work is the same anyway.
What is sad, is this head should have been on the twins day one. Nothing technically would have prevented it. Imagine it on
the Trident. Hey, don't trudge it Rudge it! :-)
Click to expand...
Well I must say, it’s lovely to work on. After all it is actually brand new !

I decided to strip the top end for a few reasons.

Main one is the powder coating is so hideously thick on these things. It’s like wrapping an insulating jacket around the head and barrel! I’m planning on stripping it and getting it re-done in something like Cerakoat.

And I know a racer bloke who makes nickasil barrels, excellent things, so am thinking of putting a set on.

These subtle mods combined will make a huge difference to cooling. And not having the liners removes few potential TSS known failure modes.
 
Fast Eddie said:
Well I must say, it’s lovely to work on. After all it is actually brand new !

I decided to strip the top end for a few reasons.

Main one is the powder coating is so hideously thick on these things. It’s like wrapping an insulating jacket around the head and barrel! I’m planning on stripping it and getting it re-done in something like Cerakoat.

And I know a racer bloke who makes nickasil barrels, excellent things, so am thinking of putting a set on.

These subtle mods combined will make a huge difference to cooling. And not having the liners removes few potential TSS known failure modes.
Click to expand...
Flow porting it? ;)
 
kommando said:
There was an experiment on this forum that showed powder coated barrels performed as well as painted.
Click to expand...
IF applied correctly!

I would agree that a like for like thickness would likely give like for like results.

But it would be IMPOSSIBLE to apply paint as thickly as it is on this head and barrel !

Look at the attached pic, and this is just the front of the head. How thick is it gonna be where it’s welled up in between the fins etc? In between the fins on the top of the head is where I saw it the thickest when I stripped the powder off of my old TSS head.

Some TSS’s have been known to drop valve seats. My hypothesis is that insulating the head in plastic may well have caused unduly high head temps which contributed to this.

Recommissioning a ‘new’ TSS
 
Onder said:
Even on frames poweder coat always seems too thick. But on jugs it is really a bad move. Wonder what would anodizing
would do?
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I don’t think anodizing is the answer, but there are a number of specialist ‘heat dissipating’ coatings available these days which I will be exploring for head and barrel.

I stripped my old TSS engine of all powder and left it like that, it looked great, but I want to keep this one looking more close to factory spec.
 
gortnipper said:
Flow porting it? ;)
Click to expand...
I will not be doing anything heavy, but it would be rude to put it back together without tidying things up in there a little bit.

I have decided not to use the Bings, so am now trying to decide between 30 and 34mm Amals. They had 34 as stock, but the inlet stubs narrow down to 30 to match the head, after which they open up to split into two ports, and I’m thinking that keeping 30 all the way through would aid charge velocity ?

But, on the other hand, Triumph had use of an engine brake dyno, so it’s just possible that they put the 34s on for a reason !?
 
Fast Eddie said:
IF applied correctly!

I would agree that a like for like thickness would likely give like for like results.

But it would be IMPOSSIBLE to apply paint as thickly as it is on this head and barrel !

Look at the attached pic, and this is just the front of the head. How thick is it gonna be where it’s welled up in between the fins etc? In between the fins on the top of the head is where I saw it the thickest when I stripped the powder off of my old TSS head.

Some TSS’s have been known to drop valve seats. My hypothesis is that insulating the head in plastic may well have caused unduly high head temps which contributed to this.

View attachment 131040
Click to expand...
I presume this is the head on your first TSS, not the current new one?
 
Fast Eddie said:
I will not be doing anything heavy, but it would be rude to put it back together without tidying things up in there a little bit.

I have decided not to use the Bings, so am now trying to decide between 30 and 34mm Amals. They had 34 as stock, but the inlet stubs narrow down to 30 to match the head, after which they open up to split into two ports, and I’m thinking that keeping 30 all the way through would aid charge velocity ?

But, on the other hand, Triumph had use of an engine brake dyno, so it’s just possible that they put the 34s on for a reason !?
Click to expand...
Gemini says: You should definitely go with the 34mm Amals.

Your instinct regarding charge velocity is mechanically sound for a traditional 2-valve head, but the 8-valve Weslake-designed head on the TSS operates under a completely different breathing philosophy.

Triumph's dyno engineers went large for several reasons:

The Taper is a Venturi: The neck-down from 34mm at the carb to 30mm at the head inlet stub is intentional. It acts as a progressive venturi nozzle. This configuration accelerates the air-fuel charge right, maximizing cylinder-filling efficiency.

The 8-valve configuration uses smaller, lighter valves set at a narrower angle (30°). This design was explicitly engineered to let the parallel-twin breathe deeply and rev cleanly past 6,500 RPM. It produced roughly 58–60 bhp compared to the standard 2-valve Bonneville's 49 bhp. Dropping down to a 30mm carburetor body would choke off that top-end volume, defeating the entire engineering purpose of the TSS engine.

If you're replacing the Bings, a pair of 34mm Amal MkIIs will give you exactly what Meriden intended.
 
gortnipper said:
Gemini says: You should definitely go with the 34mm Amals.

Your instinct regarding charge velocity is mechanically sound for a traditional 2-valve head, but the 8-valve Weslake-designed head on the TSS operates under a completely different breathing philosophy.

Triumph's dyno engineers went large for several reasons:

The Taper is a Venturi: The neck-down from 34mm at the carb to 30mm at the head inlet stub is intentional. It acts as a progressive venturi nozzle. This configuration accelerates the air-fuel charge right, maximizing cylinder-filling efficiency.

The 8-valve configuration uses smaller, lighter valves set at a narrower angle (30°). This design was explicitly engineered to let the parallel-twin breathe deeply and rev cleanly past 6,500 RPM. It produced roughly 58–60 bhp compared to the standard 2-valve Bonneville's 49 bhp. Dropping down to a 30mm carburetor body would choke off that top-end volume, defeating the entire engineering purpose of the TSS engine.

If you're replacing the Bings, a pair of 34mm Amal MkIIs will give you exactly what Meriden intended.
Click to expand...
Awesome!
Decision made.
Thanks for that 👍
 
This is the stock 34-30mm inlet stub in the stock head.

I think y’all would agree that without changing the port shape / design / size there is still scope for some ‘tidying’ …

IMG_2589.jpeg
 

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