Carburettor Thunderbird 900

Q1 when you say leaking do you mean overflowing? If so did you check/replace float needles? Kit available from sprintmfg.co.uk.
Q2 Sorry don't know but would expect them to fit with changes to jets, needle position etc. Are they the same diameter?
I see this is your first post, why not introduce yourself in newbie section and show us a pic of the bike.

 

Good morning Jan.

First, welcome to the wonderful - but often very difficult - world of Triumph T300 ownership!

(In case you're unaware of the background, the term 'T300' is used to define the early '90's range of triple cylinder motorcycles made by Triumph, Hinckley and coversmodels such as Trident, Trophy, Tiger, etc.)

Second, you need to be aware that this range of motorcycles has, largely, been out of production for more than 20 years so I'm afraid it's inevitable that spares will often be difficult and scarce to find. That in itself has the effect of keeping spares (new and used) prices high, often shockingly so, and you will need to be prepared to do a lot of searching of both wallet and soul if you want to stay in this non-exclusive 'T300 club'! I would add that the rewards of membership can be equally high when you actually get to experience the visceral emotions of owning and riding a machine that has so much of that over-used term 'character'!

OK, to your current situation.

First, this link should take you to Sprint Manufacturing

https://www.triumphparts.co.uk/product-category/triumph-parts/triumph-all-parts-stocked/

Sprint have a good stock of new and used parts and are (in my opinion) by far the best "independent" supplier of parts for the early Hinckley models.

Second, this link will take you to the page for carburettor parts for your model of 900 Thunderbird.

https://www.fowlersparts.co.uk/part...-carburettors-t1240930-t1240194-t124064030656

Fowlers are a main dealer and distributor of genuine factory Triumph parts and their mail order service is usually excellent - other main dealers and distributors are available but I have always had good experience with Fowlers and can recommend them.

You'll notice that the float assembly (item number 19 on the drawing) for the carburettors on your machine cost almost £38 EACH and, with postage, you'll be looking at over £120 excluding any import duty that might be applicable in Switzerland! As I said earlier, these bikes are NOT cheap to own and run!

Which leads me on to the slightly more technical side of your post - i.e. the carburettors and overflowing fuel. Fuel overflowing from the carbs is most likely to be one of 3 things :-

1) float chamber gasket(s) leaking
2) float ruptured
3) fuel inlet valve not fully seating

Pretty much regardless of the specific cause in your case, I would suggest that the carbs will need to be removed and re-cleaned. You don't mention if you changed the float chamber seals but, with the other work you mention having been done, I would think this might be a good starting point in looking at this particular problem.

On the question of whether carbs from a TBS will fit, from memory, I think the TBS carbs are a different make and type so jetting will probably be completely different. The Sport engine delivers almost 20% more power than the 'standard' T'bird models and I imagine some of that gain comes from carburation changes. While the TBS carbs might physically fit the mounts and may even work, I suspect that it will need a mountain of tuning work - and replacement parts - to get them to run properly.

If the TBS carbs you have access to are good and reasonably priced I might be interested and maybe we could work out a mutually beneficial trade with Sprint parts?

I do hope that you get the T'bird up and running and can enjoy some of the real pleasure and delight of owning and riding one of Hinckley Triumph's finest!

Good luck and do, please, keep us updated.

Adie

 

Sorry about the sprintmfg, forgot it was triumphparts as I have saved it as a fave and don't look. They list or used to, float needles and gasket sets and their prices are always better than OE parts.
As stated fowlersparts.co.uk are very good and cheaper than World of Triumph too.
For carb bits there are also
allensperformance.co.uk
nrp-carbs.co.uk

 

How do you mean "leaking" ?

If it's when on the sidestand, engine switched off, the left hand float bowl gets flooded by the other 2 and fuel leaks into the airbox.
You need to switch the fuel off at the petcock and let the levels in the float bowls drop a bit before switching the engine off.

 

Hi Jan.

It's probably worth your while buying one of these :-

https://www.ebay.co.uk/itm/313536454950?hash=item49003aa126:g:A-8AAOSwPZpgpp5a

or one of these :-

https://haynes.com/en-gb/triumph/thunderbird/1995-2004-0

Clearances should be measured cold and are quoted with a range :-

Intake clearance is 0.10 - 0.15mm or .004-.006in.

Exhaust is .15-.20mm or .006-.008in.

I think the aim is to be somewhere mid to high range since (I understand) the clearaces reduce overtime.


A real expert will be along shortly to correct any inadvertant errors!

 

Great to hear that you got the cards sorted. And a valve check is never wrong. I'd have an eye open for coil problems too though. If one cylinder is acting up I would move the coils around to see if the problem follows the coil or is consistent to one cylinder. If new coils are needed, a stick coil conversion is recommended. And easy.

 

If it was running before, though with the occasional miss, I would guess you have either shimmed the valves wrong or done something else. Go back and check everything again. Check coils too by substitution, faulty cps? You say fuel is ok so writing that out for now but needs check maybe?

 

I wouldn't think the air filter would make that much difference tbh. Can you take the airbox out and check the butterfly valves in the carbs are opening fully?
Dont know about the diaphragm, sorry.
Fuel starvation? Blocked filter or tap.
Throttle cable problem?
Going back you had it running but missing sometimes, did it rev up fully then? If so you need to go over everything you have done and re check. Are you sure you have done the valves correctly, never done them myself but know some people have got it totally wrong, did you follow a manual?

 

The diaphragm rubbers maybe shot !
If they are leaking , they won't lift the throttle body pistons ?
Just a thought , you've had something apart that hasn't been touched in year's and probably wasn't designed to last anywhere near that long ...!

 

Hi Guys, is there a forum on here dedicated to our venerable Thunderbirds? i cant seem to find one.

ta

Tony