10TT9 carbs 32mm for twin

[Black Flash]

Hello there,
the twin I bought last year came with 10TT9 carbs, the slides of which are worn beyond repair so new ones are needed. the slides are stamped #7 and are available from AMAL company at a price.I cannot tell the mainjet size as I mislaid my glasses.
going through various literature the size should be around 400 which seems really big to me.
My question is anybody using TT carbs on his twin and does it make sense at all. can you also tell me about the # of slide and mainjet size? I have also been told to drill a small diameter hole through the bottom of the slide to compensate for the missing throttle stop/ idling adjustment. does anybody roughly know the size of that hole?
all hints and tips welcome.

keep polishing summer is coming.

Bernd

 

[A-BCD]

I have 10TT9s on both of my twins, No 5 slides and 340 main jet. 1 1/8" on one bike and 1 3/16" on the other. Fuel consumption is not excessive, and I don't hang about !! I have cut a little slot in the rear of the slides to give a tickover, but I'm sure a small hole would work. Advantage of the slot is you can gradually cut it deeper until it's just right !!

 

[davidd]

Bernd,

Good advice from A-BCD. I run a 32mm on the racer and I am running a no. 6 slide this year (no. 7 last year). I think no. 6 is probably the highest you want on petrol and the Flashes and Lightnings were almost always mixed with benzol and sometimes it is not clear in the literatures. I also have a no. 4 slide that I can increase. It is 1/16" for each slide number. I have bought slides from Surrey and Burlen depending on what they have in stock.

I am at sea level and running a 340 jet. I also use the air slide and find it useful for changing jets. I once was in the mountains and I overjetted. On the track the bike would barely run, then I hit the air lever and it came to life. It was nice not to have to waste a practice session.

David

 

[Black Flash]

thank you for your informations, but what are your experiences with those carbs, can you ride the bike as any other bike or are they a pain in the neck concerning starting, tickover, pick up etc.

cheers
Bernd

 

[vibrac]

Ron Kemp had a tt9 on his 500 and raced it. once at the MCC he kickstarted it on the grid so fast they complained he jumped the flag-he also rode the same machine in the MCC Lands end trial on knoblies .As I recall he had a 1/4"X1/4" cut out at the back of the slide-oh and he always held the fixed portion of the twistgrip when he kicked: happy days...

 

[A-BCD]

Took a while to get the jetting and needle position right, but now I have no real problem with starting or tickover, and the bike goes really well without hesitation !! I have '105' cams, 9:1 squish-band Omega pistons, 35 degrees full advance, but I wouldn't say that the bike is in any way temperamental.

 

[A-BCD]

As a matter of interest, I took the B for it's MOT test yesterday. Hadn't been started for at least 3 months, standard unleaded in the tank since October. Just turned on the petrol, tickled the carbs and it started second kick. Ran sweet as a nut !!

 

[Tom Gaynor]

I have a TT on a Rudge Ulster. It makes the bike a delight. The TT (and GP) are far better than the road carbs, because fewer compromises were made with the design optimum to accommodate mass production. (When Amal were deciding to make the Monobloc, they apparently polled the motorcycle manufacturers to find what features they wanted on this new carb for the post-war era. They all had one need: 10% cheaper than the 276...)
As someone has suggested, tick-over is a problem with the TT and GP, because they rely on precise cable adjustment to keep the throttle open a crack. When it is right, it'll tick-over like a steam engine. It rarely stays right for long. I'd heard of the Ron Kemp mod., a square slot cut in the back of the slide. Sid Biberman had a slightly more elegant solution, using a Dremel tool to grind a cutaway on the rear edge of the slide. The slide sits down on its (fixed) stop, cable slack, but the cutaway at the back keeps the throttle slightly open so it ticks over. So long as you don't need a "snap shut throttle" - and racers do - then it works, although getting the right "cutaway" has to be an iterative process. Ron's solution was just as effective.
One of the features of classic racing was to sit in the parc ferme before going out, blipping the throttle on an 1 1/2" Gardner, and observing the guys with the motors prepared by Faberge craftsmen, at Faberge prices, sitting with their arms crossed on Manx Nortons that were ticking over at 1000 rpm. On NGK 10 plugs. Mind-blowing!