Triton T120R pre-unit engine

This is in addition to the question I asked in the wrong forum, my apologies (it’s an age thing )

I have just purchased this Triton from the widow of the owner, Brian, she’s family to my wife so I intend to do the right thing with it and not sell it on, and want to bring it fully back to life. It’s going to need a lot more than a coat of polish.

The frame is 1960 - how do I identify slimline or wideline as they are just terms to me so far? It seems quite narrow to me astride it. The alloy fuel tank has seen a lot of dings over the years, I’m hoping there are specialists I can use to sort it out.

The engine is T120R and has been dated to 1961

I am the second owner, Brian built it himself in 1963 when he was 16 years old. Later on he installed 750 barrels. Would the 9 stud head have been original too?

For now it is sat in the garage sandwiched between the T160 and 850 Commando until I can consider starting work on it - I need to appraise exactly what is needed, and it is a lot!

Here’s a couple of pics for now.

That’s a slimline, you can tell by the way it ‘pinches in’ at the front of the seat and by the design of the subframe / shock mounts.

I’d be interested to know if it really is a 750, if I saw that I’d assume it to be a 650.

Fast Eddie said:

That’s a slimline, you can tell by the way it ‘pinches in’ at the front of the seat and by the design of the subframe / shock mounts.

I’d be interested to know if it really is a 750, if I saw that I’d assume it to be a 650.

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The owner’s wife and son both told me he fitted a 750 top end to it - and I have the spare barrels and pistons within the pile of old spare parts. Along with a spare gearbox, crankshaft and a set of TR6 engine cases from 1960, a very early low number.

Without stripping it is there a way to identify 750 barrels from 650?

Flatspot said:

The owner’s wife and son both told me he fitted a 750 top end to it - and I have the spare barrels and pistons within the pile of old spare parts. Along with a spare gearbox, crankshaft and a set of TR6 engine cases from 1960, a very early low number.

Without stripping it is there a way to identify 750 barrels from 650?

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By far the most common 650-750 kit was the Morgo, but on those the barrel fins are the same shape as the head.

There was a ‘Routes’ kit back in the day that looked stock.

In more recent times, stock looking 650-750 kits have become more common.

Yours could be a Routes or similar kit from back in the day, or it could be a 650.

AFAIK there’s no reliable way of telling without measuring the bore size.

I guess in theory you could measure how much it takes to fill a cylinder with oil at BDC.

Then measure the combustion chamber volume by filling that with oil at TDC.

Subtracting the combustion chamber from the total cylinder volume should give you the swept volume.

In theory …

What are your plans? Isn’t an engine strip on the cards anyway ?

Can't remember all the differences
But is it a 10 stud top end?
From the photo it doesn't look like it has the oil port extension in the front offside barrel flange

It is definitely a 9 stud head and there isn’t anything on the rh barrel flange apart from a circular impression of something that isn’t there. The barrels appear to be the same as the other stock 650 set.

I did want to throw a bit of fuel at it and see if it starts - it was last run last year apparently. After that who knows?

I expect I will follow my usual practice of tear it all to bits and refurbish everything. First of all I need to see what exactly needs doing. For example it has no sidestand and the centrestand has no piece to stand on to help put it up. The 2 lugs for the oil tank and lh box are missing, so I need to see what needs welding back on before I paint anything. As it is I don’t know what I don’t know, so expect lots of questions.

e.g. what is this Allen screw doing? The vertical one. And what is that sat on my switch?

I had a spare few minutes and popped out into the garage, and while I was there I did a bit of spannering to get an idea of what I’m dealing with. I wasn’t going to touch it for a while longer as we are off on holiday soon for a couple of months. But I just couldn’t stop myself.

It’s not a pleasant sight under the seat and tank. There’s no evidence of having had a battery fitted, although there’s a zener and rectifier under the tank.

I really dislike the strange angle the seat and rear mudguard are at, it looks extremely poor - any suggestions what to do will be welcomed.

Also the headlamp is missing something, a switch unit probably, any thoughts what it is. Otherwise I’ll just use a generic 7” chrome headlamp assembly.

Flatspot said:

I had a spare few minutes and popped out into the garage, and while I was there I did a bit of spannering to get an idea of what I’m dealing with. I wasn’t going to touch it for a while longer as we are off on holiday soon for a couple of months. But I just couldn’t stop myself.

It’s not a pleasant sight under the seat and tank. There’s no evidence of having had a battery fitted, although there’s a zener and rectifier under the tank.

I really dislike the strange angle the seat and rear mudguard are at, it looks extremely poor - any suggestions what to do will be welcomed.

Also the headlamp is missing something, a switch unit probably, any thoughts what it is. Otherwise I’ll just use a generic 7” chrome headlamp assembly. View attachment 113355View attachment 113356View attachment 113357View attachment 113358

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I was going to say the worst thing about that bike is that rear mudguard/seat
I'd junk that mudguard
Fit the seat where it needs to go
Then fit a section of mudguard where needed
Junk that loom and make a new one

Thanks Baz, all contributions are welcomed.

Yep, the seat/mudguard combo are crap. The mudguard is cracked anyway and must go. I have a single seat I can use as it will become a single seater anyway. I’ve seen this on eBay as an example of what to fit.

I’m quite happy to make up my own loom from modern equipment and the old one is already off and junked.

Flatspot said:

Thanks Baz, all contributions are welcomed.

Yep, the seat/mudguard combo are crap. The mudguard is cracked anyway and must go. I have a single seat I can use as it will become a single seater anyway. I’ve seen this on eBay as an example of what to fit.

I’m quite happy to make up my own loom from modern equipment and the old one is already off and junked. View attachment 113359View attachment 113360View attachment 113361

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This seat unit combo looks a lot better
But if starting from scratch I prefer the seat loop to be under the seat if possible
And the taillight unit must be level and not sloping down

I’ve pulled a few more bits off today as I got a bit bored watching the incessant torrential rain.

I know I need to get a tank strap as the old one is broken at the seat end. How does it fix at this end? There’s nowt for it to be attached to, the sole crossmember in front of the oil tank is 4” forwards of the rear of the tank. How is it held? The only pictures I can find so far online are for wideline frames and they are rather different. Have a look at my frame, and advise please.

Also, does anyone have a contact who can beat out an alloy tank as this one is rather dinged all over.

Sweet bike!

Don't know what that upright bolt in the timing cover is for. Nothing under there that I remember, and it's not a stock thing.

Otherwise, looks like a great start to a super clean bike.

The 9 bolt head is not original, but generally preferred for better sealing. There's some inlet/valve/combustion chamber differences in different 9 bolt heads, but nothing to get too wrapped up in, and nothing sneaky that's going to ruin the bike, but take some notes and pics while it's apart.

Podtronics makes a nice 12v reg/rec/capacitor to get rid of that zener. Works fine without a battery, as long as you're not expecting running lights while at idle.

There's quite a bit of difference in top tube width between the wideline and slimline, and anything that's in the tank/seat/subframe area will be specific to one or the other. There's different center stands too, some with long levers to aid standing (but which may detract from your street cred! HA!). I think they'll all bolt up to the same frame tabs though.

If it's your first Triumph, you're going to love sealing the push rod tubes! Tell yourself it's a labor of love, and take note of what comes out when you unbuild the motor. It can really be a nightmare

The gearbox is the "slickshift", that has a cam mechanism on the shift lever shaft that bumps the clutch pushrod for faster gear changes, particularly when flat track racing and the flag drops with your clutch hand in the air. Some love them, some hate them, and some remove the cam. You can also fit a 5 speed gearset into the box with a few easy mods, but the shifting isn't as crisp as the AMC 'box (in my opinion).

There's usually a brace tube that's welded in with a Manx toggle attached to hold down the tank. Tanks also seem to want to slide forward, so a forward stop can be nice. Rayson's Exhaust will have the tank strap, toggle, and subframe loop. NRP also has a lot of the same parts, and may advise for tank ding repair.

These bikes are always pretty fun to get into/look over, as they're not straight forward with everyone applying their own solutions to the problems, with some being quite clever. Your bike has a lot of the "right" parts though. I'm sure Brian is already pleased at the attention it's getting, if he's out there somewhere.

Many years ago, over 45, I had a couple of Triumphs, a couple of all alloy T100 including one with reversed heads and forwards facing carbs. Yes, I do recall trying to seal the tubes, I believe seal types have improved since then. One was a form of the Grand Prix motor without splayed ports, used as a generator engine on a Lancaster bomber I seem to recall.

Yes a podtronics will be in the list, the same as I fitted to both my 850 Commando and T160. Probably a tiny Lithium battery somewhere.

I’ve been looking through NRP’s website for inspiration and Kev is being helpful too.

The centrestand will stay, but needs a foot lever adding to it to help getting it up, I’ve got an old T160 stand I can rob one off. I know I could bolt on a sidestand but it’s light enough to not need one

t ingermanson said:

The gearbox is the "slickshift", that has a cam mechanism on the shift lever shaft that bumps the clutch pushrod for faster gear changes,

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Very few have that unpopular mechanism.

Triton Thrasher said:

Very few have that unpopular mechanism.

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Hmm. Maybe it's that I'm in a former flat track hotbed that most of the ones I've come across have the slick shift still operable? It made the shifts feel additionally vague to me, but I've only ridden bikes with it "working" a few times.

Flatspot said:

I’ve been looking through NRP’s website for inspiration and Kev is being helpful too.

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Kevin has always gone above and beyond for me as well. Ben from Rayson's is also a very solid guy.

That Daytona square barrel racer sounds exciting!

t ingermanson said:

Hmm. Maybe it's that I'm in a former flat track hotbed that most of the ones I've come across have the slick shift still operable? It made the shifts feel additionally vague to me, but I've only ridden bikes with it "working" a few times.



Kevin has always gone above and beyond for me as well. Ben from Rayson's is also a very solid guy.

That Daytona square barrel racer sounds exciting!

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Plenty of pictures on the we , here’s an example. Of course when I was a teenager it meant nowt to me, only years later I realised I should have kept it - the same could be said of several of the bikes I’ve had over the years.

the centrestand has no piece to stand on to help put it up.
Thats so it cant scrape . Buy some Winklepickers instead .

what is this Allen screw doing?
Its blocking a hole .

The Headlamps like a 51 A 10 Beeza , Rotary Lighting Switch POanel , fitted .

Route Did 800 barrels . Pull the SUMP PLATE , with a white icecream container to INSPECT things .
THEN fire it up . Wont matter if its not entirely oil tight .

The Latter 8 stud heads dont crack . Ports bored to 1 1/8 th & 750 valves ( Which are likely the sam,e size )
and it'll blow off a Nine stud ! as the ports arnt impeded by the inner rear studs . ( You Gotta watch THAT on a 9 stud . )

Used to run 3/8 B T D C Ign. Crankey . Some Manuels say 11 / 32 , Which might be a bit less grauchey . Ran 9,75 : 1 ( Measured )
with 9.5 Hepolites

The 67 crank , pear shaped counterweight throws and square cut flywheel , is the TT / Thruxton LIGHTER one . Which helps the crankeyness & get up n GO .

1 3/4 pipes cut to Boyer Spec , and It'll below . about 1 1/2 off the top , so they slide back further so they tuck in better , On the Tri Frame helps .
So dont buy little ones . Theyll impeed it .

Unit Primaries go in , but single rows less loss . Cork Plates are Wunderbar . Should pull a 25 T engine sprocket , then . 1 5/32 or 1 3/16 Carbs .
Monoblocks even .

The HEAD STEADY is a crucial THING . In more ways than one . So dopnt skimp there . Or with the fasteners , Cycle Thread being superior .

SHEDET .
That Head Steady ,

Pre Unit HEAD BOLTS ( Rocker / head bolts ) have threaded over the nuts , for FASTENING the Head Steady .
But ITs a NORTON .

The transverse torsional loads BREAKING BRAKEING & breaking the frame at the cross tubes , if you know how to brake . break .
SO a rectangular 1/8 in. Mild Steel PLATE , with a delta welded cenerline , going up & forward , A zig zag , so centers align . Maybe a second / doubler top . ( 1 in by three , catching Frame Bolt & two 5/16 H T , will hold it al;l FIRMLY .

A Pre Unit without a steady working the case bolts not taraned down , will whip the top end fore & aft . Almost figure eight , flat . side on .
with the bottom end in opposition . With the alternator connected direct . No Battery . Itll cut thru the fog like a locomotive lamp , doing it .
at The Ton .

You wanna cary a bit of oil , as they can boil it / Use the reinforced clear marine hose there . Anmd Fuel Lines . With Quality s.s. screw clamp fasteners / So it wont self imolate . When a bit of fuel gets out & it kicks back .
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BSA Folding Footrests , The ONES with the folded footrests on te machined inner . U can dress or weld if neccesary , to sit flat or just inclned skyward . Some are tapered outward , end folded up 1/8 . For Ends . The Square parrallel , welded washer ends meet race requirements .
Non Perforation of opposition .

That FOOTBRAKE really wants scraping , I overdrilled a cast dunstall . and it fitted thuys . WITH a STOP . So it fits FLAT . Immediately to hand . Or Toe .
And dosnt drag you off .

Not a lot else to complain about .https://www.accessnorton.com/attachments/triumph3-jpg.46019/

Headers Cut as per ' R ' or ' R R " , getumMufflers ( like wot you got ) tucked up n in . out of the way .

of course , on a real Triumph , those End Caps are Removeable .

As the PRIMARY at the Clutch Drum is where it hammers the pipe into the deck , if its left on the left .
( Most of theSwept Backs DONT remedy this , There UP f they do . Up & outside .
The Olde " 45 Degree Isle of M " scrutineering clearance . Mandatory . Seated .

Some ' R 's the left pipes jointed , so cobbled up isnt deropgatry there .That opnes even got brakes .
Needlke roller layshaft bearings on the Cams . Hot ones & followers . Dual Carbs . 1 1/16 tooned . onna five unred .
With 1 5/8 JoMo intake & 1 7/16 zorst valves . W&S springs . for Eight Grand . Authorised . Ex Factry .
https://www.accessnorton.com/NortonCommando/triumph-t-100-r-t-100-rr-1955-57.12638/


The 55 1/2 inch wheelbase and 24 degree stgeering head angle , of the superior 61 / 62 , Velintino Rossi later copied .
See All Fasteners are Secure .

No Paint in the JOINTS . Anywhere ( or you feet will fall off ) Bring em down , and as you run it ,. Progessively . Then it wont shake about .,

By the Way . That Fancy Cranks the 72 % Balance factor . As far as that goes .

The Steady counts there . Evaluation on test . ( called sympathetic vibration ) Or if dismantled . measure & note - weights / calc. . % .
Bar End Weights .
If Neccesary .

Pre War bumpers wernt mild steel .
End Weightrs were to copunter axle patter , wheel tramp . So the Two Stroke ring ding dingles foundem helpfull THERE . At the Bar Ends .

Not THAT bar !
Stoopid .

Pull the springs OFF , Set the rear guard 1 1/4 in. clear .

Seat P:an Edges should be down over the rails . Big Hump in seatnbase to clear guard .
Id used Tri. Seat pan , a werdge ( Thicker aft ) of Hi Density fleck foam ) so humpeder,
with the Tri. seat foam & cover . So Racing Dual Seat .

And put your Chin ON the tank pad BEFORE you hit the bump . NOT over it . Clang Jangle .
and dont poke out your tongue , whatever you do .

I have decided to do a total strip and ground up nut & bolt etc. resto in order to do it justice as a somewhat rare motorcycle - and because I can, and just because…..

Not too unexpectedly I’m uncovering items that should not remain covered, and I’ll be able to sort them out. Cracked engine as an example, and a mullered clutch basket and plenty of wrong nuts and bolts, and plenty more.

So, now it is finally in a lot of scattered components all around the garage, and also time to start to do the resto. except I can’t as I’m about to go away on holiday for a couple of months.

Here’s a few of the tear down pics. Including a set of carbs fresh out of the ultrasonic cleaner awaiting rebuild.