Misc: Carburettors Amal TT Carburettors

[Cyborg]

Engineering archeology?
Try doing a search for “ Notes on Amal Motorcycle Carburetor Developments 1924-1976. There is a brief mention of it on page 24. Let me know if you are unsuccessful finding it.

 

[Cyborg]

 

[oexing]

You might as well look up Dellorto SSI carbs. They got exactly same air correction valve. I see its only use in test runs for finding out if mixture is too weak or rich. In races I cannot see riders having the nerves for adjustments on the correction valve. So after trying settings by correction valve you better have suitable jets in the carb and leave the valve alone in race.

Vic
Dellorto SSI

 

[TRexler]

Thank you very much! I've found the journal and that's some good, referenceable basics on how they worked/were used.
And yes, necessary archaeology to help with the machining of a raw casting (a 10TT or 15TT, I'm not sure)

As for the frequency of the air valves use, it shouldn't matter for the purposes of this if it was never used or used every race. I need to have a good understanding of the geometry and function of the air valve so I can know not to balls up the machining of it.
Thanks for the Dellorto lead as well, I'll see if I can find any patents under that name.

 

[Cyborg]

I have a few TT carburetors, so if you need any details, photos etc, just ask here. You may be aware already, but…the TT carburetors have mating stamps on them. Presumably because they were bored as an assembly. I… or someone else can provide location/ photos of the markings if you need. What material are you going to use? Amal carburetors were usually Mazak, but the TT carburetors were originally brass ( at least everyone called it brass) and later ones were aluminum.
In that article, I think it mentions the spigot carburetors were eventually replaced by the flange type due to problems with leakage, but the spigot type were still used fairly late in the game.

 

[vibrac]

GP carbs circa 1955 onwards also have the air enrichment slide it is only a mixture correction device either for tuning main jet or for the TT course when allowing for the effects of ascending the mountain

 

[TRexler]

I will probably be asking for some specific photos at some point, thank you for the offer. I am using a casting from a few decades ago, a brass, flanged one.

I have an aluminium AMAL TT carb as a reference and to reverse-engineer but I see no mating stamp or model stamps. Only the size, stamped into the blanking plate in the side of the air valve.

 

[davidd]

I used the enrichener on my first racer. It does what it is billed to do. Make sure the handlebar lever will not turn due to vibration or your tuning will go off.

A standard 10TT9 32 mm Grey Flash carb. A nonstandard Matchbox float.

David

 

[oexing]

Is it an enrichener ? I did not find a fuel jet in the system of "enrichener" on the Dellorto SSI of same design. Seems you just add air by this for weakening the mixture on test rides. Similar looking chokes on Mikunis and modern Dellortos open a fuel jet when pulled for rich starting only.

Vic

 

[kettlrj]

I run TT carbs on my Rapide and have always closed the air slides for starting from cold. When the slide is open it obviously adds to the overall air flow so therefore it must reduce the flow when closed and enrich the mixture. As it is a racing carb it can be used to adjust the air/fuel ratio throughout the range of throttle opening without impeding the air flow in the way that a ‘normal’ wound do