Obscure preunit Triumph Identification..

[montessa172]

So I picked up a pre unit Triumph twin at a ridiculous price. Upon initial inspection at the sellers house I thought that I'd found a early T - Bird 650.


side by Montessa172, on Flickr

Got that assumption from the serial number and some blindness caused by my excitement.. :


serial by Montessa172, on Flickr

But as far as I can tell and have had confirmed the serial number for a T - Bird should have the suffix NA not an asterix - thanks alexmac. Problem number 2, T - Birds should have a iron head I think , this one doesn't, and it has close pitch fins, total of 16 as opposed to the 12 that a T Bird should have..


fins by Montessa172, on Flickr

So I started looking at the individual part numbers, the barrel and case come back as 1952 T100 and 1954 T100 respectively..

Barrel

barrel by Montessa172, on Flickr

Case


case by Montessa172, on Flickr

And the cyl head number I can find no record whatsoever


cyl head by Montessa172, on Flickr

So I have two known T100 components and a serial number from a T - Bird and a head that I can't reference.. If anyone has any ideas or corrections to what I think I've figured out then let me know.. The input is greatly appreciated.. ;D ;D

 

[Speedfiend]

I am, by no means, a pre unit expert. Hell, I'm no expert at anything. But I have had a few pre units. That being said, Ive never seen #'s like that. And they don't come up in any of the normal Triumph number registries. That engine is likely a 5T or a T100(500cc).
I suspect the numbers have been tampered with. It looks like that portion of the case has been machined. It should have the cast texture that is on the rest of the cases, behind the stamped numbers. BUT, I'm headed to British in the Blueridge Rally this weekend. Someone there will surely be able to ID it for you. I'll report back on Monday.

I'd also suggest joining the BritBike.com forum. Lot of smart guys over there.

 

[teazer]

Top end is T100 alloy motor. Crankcases appear to be 6T (T'Bird), but that number was re-stamped and cannot be trusted. I seem to recall that 500 top end and 650 top end are not interchangeable, but can't be 100% sure of that. Suspect the bottom end was a 5T (Speed Twin) which are the same cases. That one has a distributor and that was only used on the 5T and not the T100 IIRC.

The box is a pre-slickshift so that dates it as early fifties as well.

Alloy T100 is a great motor with 3134 cams, 3059R followers, 650 crank (82mm stroke vs 80mm) and twin 1" carbs on a GP type manifold. Use a late model crank and fit alternator (short) primary cases with alternator and use a K2F magneto and it should run out of steam at 8000 revs and 120'ish MPH. That's what i ran as a daily driver cafe racer back in the day.

The only issue is that parts fall off all the time. I lost footpegs and even a complete exhaust in city traffic which I had to grab and tie on.

 

[WeberKid]

from my experience, as often as not, Triumph case numbers are fake. My cases had a K series which would have been impossible. You really can't go with numbers - you need other identifying features. PLUS people often mix and match things. for instance I'm using a pre '65 tranny cover on my 71 cases just for the sheer fact that I'm running GSXR wheels and don't have any other means for a speedo, so I'm running a tranny driven speedo. Triumph engines are the legos of the motorcycle world

 

[beachcomber]

Looks like a 500 that's been "rung". The 6T number has been stamped over the original which has been filed down - look at the finish. The star symbol is all bollox as well - it's been done with a chisel - NOT the factory star symbol.

Looks like someone had original papers for a 6T and fitted a moody motor.

All that said - who cares, that's one lovely motor !!!!!!!!!! AND far better than if it had been a 6T [ Iron ].

All you need now is a set of GP barrels and head !

 

[swan]

Sorry for the delay with your PM, (out of town) but agree with most of the above comments. The original number has been filed, ground or machined away and a new number stamped in to it. The star symbol is not even close to the original stamp and looks to be done free hand. It is an earlier type motor with the earlier tranny (gearbox).

Break it down, clean it up, replace what is needed (bearings, cams etc) and yo have a bike for life. Beautiful.

 

[montessa172]

Thank you all for your help. Tremendous assistance! Picked up a complete functional although some what ratty '53 gearbox today for 50 bucks! Stay tuned for a build thread in the near future.

Regards, Graham