Triumph unit small twins

[iansoady]

I'm embarking on a new project - a Grumph / Tri-Greeves. I have a Hawkstone frame and a job lot of Triumph engine parts - both 500 and 350. I'm not at all familiar with Triumphs so would very much welcome any hints and tips from the collected wisdom here. I will have a load of surplus bits so these will become available once I understand what I need and what not.

Thanks in advance

[chaterlea25]

Hi Ian
Tim Britton has written at length on the trials and tribulations of building a unit Triumph
in "Classic Motorcycle magazine" over the last couple of years
Apparently there were lots of minor changes through the years, making building from bits a challenge

John

[iansoady]

Many thanks, I think I remember seeing a couple of these articles although at the time wasn't interested! I can get electronic versions of 2 years' worth of back copies of the mag through my local library so will start looking!

[Rex]

It was quite an interesting series of articles but majored more on the typical "how I modified a BSA top yoke to fit" rather than info on the Triumph power unit.
Mr Britton certainly can waffle for England.
There was an article many years back in the mag "Classic Mechanics" by Hughie Hancox (IIRC) and that was excellent as a rebuild guide to these units. That said, they're a simple robust engine unit and there's lots of info and spares available for them.
Nothing difficult about them and only a couple of special tools needed.

[iansoady]

Yes, I don't anticipate any real difficulty once I've sorted out which bits are serviceable and which not. I've started collecting the Britton articles but as you say a lot of waffle - although reasonably well written - and much of no interest to me. But all grist to a somewhat overwhelmed mill.

I think I have a decent 500 barrel which is either standard or on first rebore and a set of +.040" low compression pistons to suit. One crankshaft seems to be in good condition with good threads and no play on the big ends (although will strip to check) and no marks on the timing side journal. The relevant head is very corroded but will have it vapour blasted to see what's underneath - hopefully will be OK with maybe a light skim of the head face.

I'll print out the parts list and go through methodically to see what is useable, what is scrap, and what I need to source. In parallel sorting out registration for the Greeves which I need to do while it still retains its (non-original but correct period) 9E engine.

[Rex]

There is a UK-based F-B group purely for buying and selling Meriden spares which may be worth a look for you.
In the early days of Ebay there were some great bargains to be had from the US, but it would appear that they've now caught on to the value of used parts.

[iansoady]

Yes, joined that group but it's not very active. I have found some good resources however so am happy that I'll get there in the end. I've just been having a look at camshafts etc and fortunately one of the exhaust shafts I have (or maybe even 2) have the taper in the end for the side mounted points so no distributor - which is a good job as I don't have one. I do however have 2 side point type timing covers.

I like the way Triumph actually stamp the part number on bits so I can check I have the right ones.

[Rex]

Unless you have a good ATD assembly I'd go for a Boyer (or similar) ignition set-up using the side points parts.
I tried to post some parts for sale on that F-B group and the moderator rejected my post as I hadn't provided the relevant part numbers. I didn't bother again..

[Mark M]

Good luck Ian, quite a challenge! I've built bikes in a similar way (although always to the relevant Royal Enfield parts books) and I relish the challenge, especially finding or recreating the more obscure bits. Most recent was a 1958 only "small frame" Meteor Minor and after several years getting it all together from the heavily edited (and retrospectively issued) Parts BookI can see why it only lasted for 6 months!
Looking forward to hearing about 'the journey', as they say these days....
REgards, Mark

[rgsjohn]

Don't know if it's still available, but Hughie Hanncox did a DVD on rebuilding Triumph unit twins. it might even be available through the local library to order



















 

[iansoady]

Thanks John, I might try that. I've tracked down all the Britton articles and compiled them into a word document. He does make heavy weather of some things, and much of it is frame stuff which has no interest for me but useful all the same.

Something else I've found really useful is a set of youtube videos by a bloke called Michael Waller. He built a Triumph Otter so rebuilt the (500cc unit) engine which again is very useful to me. He's here: https://youtu.be/Q4tNS8rHKmY

I've weeded out the Triumph parts. I've found almost enough to build a 350 engine and have sold a fair bit of surplus on ebay and elsewhere. I'm taking the residue to HJ Pugh who will include the bits in their April auction.

In other news I've been visited by a Greeves Riders' Association machine examiner who's happy my bike (with its Villiers engine) is pukka and the club is in the process of issuing a dating certificate so I can register it. I need to keep it more or less standard until I've gone through that process.

[Rex]

In this month's RealClassic mag there's a write-up on a Grumph, and it looks a nice bike.
Only downside is the article is written by the arch narcissist Miles....

[iansoady]

I'll look out for that. I share your opinion of said "gentleman" AKA the self-obsessed optometrist.

[iansoady]

RC arrived at my local library yesterday. Remarkably uninformative (and uninformed) as usual from Mr Miles - eg the comments about banana forks (those fitted aren't) and that only certain frames are suitable for Triumph engines (all the pre-65 or so frames are OK). I was hoping for some useful hints & tips.....

Slowly cracking on with dry engine build while I wait for date confirmation documents so I can register it. Yesterday I ground in the valves and was rewarded by no leakage when all assembled. I did have to remove some pitting from the exhausts by putting them in the lathe and using a hand-held dremel with a small grinding stone.

[cardan]

I did have to remove some pitting from the exhausts by putting them in the lathe and using a hand-held dremel with a small grinding stone.

I tie the Dremel to the tool post with cable ties!

Good luck with the build - sounds like fun. Any photos welcome.

Leon