TT9 carburettor

[roadrocket]

Hello, trying this one:

Does anyone have any experience with the Amal TT9 carburettor, which was originally fitted to the Road rocket? I have seen that it can be obtained sparkling new direct from Burlen Fuel Systems, albeit at a soemwhat hefty price. Is it as temperamental as the GP is claimed to be?

Otto in Denmark

[dpaddock]

The TT9 is essentially similar to all central-needle Amals but with with larger fuel passages and with the air slide operating in a separate chamber a la RN and GP types. It is easier to tune than the GP and offers somewhat better performance than other central-needle types. Incidentally, the GP is not nearly as temperamental as claimed by some.

[Rocket Racer]

Can anyone clarify the slide cutaway specified for the 10TT9, I'm planning to fit one to my A10, but it was originally fitted to a velo so has a 6 cutaway which seems big although they only appear to range from 4 to 7 with no half sizes in between. At forty two quid + postage it will pay to get it right.

[beezalex]

Well, the Road Rocket in standard trim came with a #6 cutaway.  If I were you, I would try that slide and if it doesn't work, get a #4 cutaway, which will likely be rich and then tune by increasing the cutaway until you get the right mixture.  You can get 1/2 cutaways this way, too, though the GP and TT cutaways are already incremented by smaller amounts than the standard carb series.

[alanp]

Ha Ha this reminds me of a BSA Gold Star I had nearly 50 years ago! Never did get it to run right all the time with the 10TT9 carb and tick over was non-existant to the extent that once with it on its centre stand I had my girlfriend hold onto the throttle to avoid it stopping while I nipped into a shop, cue horrendous noise and vibration from outside which was the goldie rampaging across the concrete with a girl attached trying to hang on and turning the throttle the wrong way!!!!! Happy days. The wife and I still laugh about that today.
PS I agree with 'dpaddock', with care and patience the GP can be made to work really well, but only use one if you really really must have one, same applies to the TT.

[Rocket Racer]

Well, the Road Rocket in standard trim came with a #6 cutaway.  If I were you, I would try that slide and if it doesn't work, get a #4 cutaway, which will likely be rich and then tune by increasing the cutaway until you get the right mixture.  You can get 1/2 cutaways this way, too, though the GP and TT cutaways are already incremented by smaller amounts than the standard carb series.

Thanks for that, good advice! my existing #6 slide is fairly worn so I may investigate if I can make economic repair to it, having said that still good to test mixture.