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Amal 10TT9 install on Comet

craig

Well Known and Active Forum Website User
VOC Member
I have a nice 10TT9 (2 bolt) and fitted manifold for Comet that came with the Vincent. A Mk2 cam is fitted. Low hours on engine and a clean new 020 piston indicate this Comet simply putted around on its last rebuild in 1966.

I am wanting to know if the 10TT9 (1 3/16)can be made to start and idle as a normal street ridden bike?
There appears to be no throttle slide stop, 320 main jet, #3 float bowl, top banjo double feed for bowl (not particularly handy), #7 slide (7/16 cutaway?), needle all the way down, short stack, etc. Ths choke cable control is missing, but available thru Amal.
thanks
Craig
 

Bill Thomas

Well Known and Active Forum Website User
VOC Member
Hello Craig, You can get them to run nice, But not as good as road carbs, last year I took mine off my twin because I now live in a slow area. There is a trick some people try, You file a groove in the bottom of the slide, About a quarter of an inch deep and adjust the cable so that it lets some air in. But if you don't like it, It will cost you a new slide !!. Good Luck Bill.
 

craig

Well Known and Active Forum Website User
VOC Member
thanks Bill, anyone familiar with what would be good set up for Comet? right now it is -
10TT9 1 3/16
320 main jet
7 throttle valve
01 needle
.109 needle jet
seems to be marked with 24TI on top of jet block and on venturi lock ring
 

Bill Thomas

Well Known and Active Forum Website User
VOC Member
Hello Craig, Why not try it as it is,You don't say what spec' the engine is, It would need an open exhaust and a Mk2 cam I would think to run on that setting,Cheers Bill.
 

craig

Well Known and Active Forum Website User
VOC Member
My current engine spec is a street ridden Comet with a Mk2 cam not assembled yet, but close
I find Black Lightning use of a 10TT9 as follows -
mix chamber body no - 175/047
internal bore - 1 3/16
center line to flange - 1¾
bolt pattern - 2"
bolt holes - 11/32
flange end dia - 1 3/16
jet block - 175/101D
jet size - 360
throttle valve - 7
needle pos - 4
needle jet - .109
float chamb type - 14/533
float chamb body - 14/225R
parts list - 449
I will not be racing, simply spirited to everyday street riding.
 

craig

Well Known and Active Forum Website User
VOC Member
10TT9 disassembly

I would like to remove the spray tube from the 10TT9, but the jet block and body seem delicate and a special blade tool looks as if it is required.

any help with this?
does the spray tube need to be removed prior to jet block coming out?
Craig
Explodedview10TT9.jpg
 
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A-BCD

Well Known and Active Forum Website User
VOC Member
Hi Craig,

to remove the jet block just take out the grub screw 34/105. I've not removed the spray tube so can't help there.
I have 10TT9s on my B rapide, which has 105 cams ( Mk II with modified overlap ) 9:1 Omega pistons. my Rapide has 10TT9s, with 9:1 Omega pistons and Hamilton '105' cams ( Mk II with modified overlap )

The carbs were originally 1 1/16", but the bore on these is 1 1/8" except for the last section before the flange - so I bored this section out so they are 1 1/8" all the way through.

These are my settings:

Jet Block 6ZR

Slide No 5
Needle jet .109

Main Jet 340

Needles I have I think are not TT ones, they are stamped RN so may well be from a Remote Needle carb, I think they are longer than the correct TT ones and have 7 notches for the clip. I am using second from top. To get a tickover I have cut 2 slots in the back of the slide with a junior hacksaw, you have to be patient to get this right, but it supplies a small air bleed. Alternatively you can drop a long screw down through the slide from the top and adjust it from there, but I think there could be risk of jamming. My bike ticks over nicely, I really like these carbs. Ignition timing 35 degrees full advance, BT-H magneto.

The float chambers are TYPE 302, I have put a small fibre washer on top of the float, under the aluminium valve, to lower the float level by about 1/16".

To balance the heavy spring ( I have two to contend with !! ) I have used a contra-spring ( A twin kickstart spring is just right ) inside the handlebar to give a light but positive throttle action.
The bike has a Toga silencer on it, it seems pretty quick to me.

Hope this helps !!
Cheers, Brian
 

craig

Well Known and Active Forum Website User
VOC Member
Thank you Brian, I have removed the grub screw, but the jet block is not moving. Not having enough experience with a 10TT, i am being very cautious. Can the jet block be tapped out using the bottom banjo bolt screwed in place? Or is there a better method? The rest of the carb is disassembled. I was concerned the spray tube may be adding to the difficulty removing the jet block as it may be adding to the tightness of fit.
Where is your jet block stamped 6ZR? Mine has a 24TI stamped on the top, same as air tube lock nut.
Thank you for your help on this,
Craig
 

A-BCD

Well Known and Active Forum Website User
VOC Member
Hi Craig, the jet block is stamped on the top, I think these numbers are not part numbers, but maybe batch identitfication should replacement parts have been required. The block should tap out, but no harm in soaking with WD-40 or solvent to ease things - is there a specific reason why you need to remove the jet block ? I took the blocks out of a pair of TTs so I could mount them on a mandrel when I converted them from flange fitting to clip-fitting. Good luck.
Brian
 

craig

Well Known and Active Forum Website User
VOC Member
Jet block removed, reinstalled and removed

Hi Brian, I removed the jet block by -
1) heating up the carb body with propane torch, not particularly hot, such as to kill loctite, but heated beyond handling.
2) installed 15/625 fitting as a tapping bolt
3) placed an alloy shim on 15/625 to avoid any minor damage when tapping
4) tapped out the jet block with moderate tapping. Actually the jet block is held in place by a 1/4" band at its bottom, so the tapping was for only 1/4".

reason for removal - inspect the internals for accumulated dirt and grit - found plenty that was causing the slide to wear fast.

It became obvious that reinstalling jet block would only be done by pulling it back in place - NOT tapping the top.

I cleaned all to my satisfaction. The jet block smoothly pushes into place except for this 1/4" band at the bottom. Everything now room temp. I used three or four 1/8" alloy spacer rings and 15/625 to pull it back in place.

I think it might be better to heat the body, chill the block and they will probably drop together. My next trial.

It was well worth taking this 40 years out of service jet block out to clean, deburr and polish the internals.

My 24TI stamps are to match all the pieces to this specific 10TT9, I am sure.
thanks
Craigjetblocktapout.jpg
 
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