AMAL TT CARB PROBLEM

[Goldie]

I have just fitted a Amal TT 10 carb with fixed remote float bowl.

For some reason when I turn on the fuel, petrol drips out of the very small hole situated directly below the air mixture screw.

The hole can only be seen by looking up underneath the carb.

I am led to believe that because the float bowl is attatched to the main carb body, that the float height is pre-set and should be correct, and not like the GP carb remote float bowl which you have to manually set to the correct height.

I have read on other forums that the dripping of fuel from this hole is common and will stop when you start the engine.

I do not like the idea of dripping fuel. I don't fancy my bike going up in flames.

I have ordered a viton tipped float needle thinking that the old type original one is worn, and allowing the float level to be too high.

Has anyone any thoughts on this, and is the small hole there as an overflow, as there is no mention of it in any of my books?

Thanks.

[Revband]

Hi Goldie

I have just been through similar problems on my DBD34 with a GP carb, both the GP and TT where designed for racing use, I finally gave in and bought the MK2 concentric conversion from Surrey Cycles the difference is worth every penny, the bike now starts easily hot or cold and even ticks over.

[Goldie]

I think I have worked out what the tiny hole below the air screw is for.

Having looked at it again, it looks like a drain hole which runs right through to the main choke to stop any fuel running into the combustion chamber if the float level is too high.

I have just taken a concentric off my DB32 to replace it with the TT.

I will persavere to get it set up correctly.

New viton float needle arrived today.

I run a 34 mm Mikuni on the 500 Goldie, which is absolutly superb.

[Goldie]

Fitted viton tipped needle and petrol continues to drip out of hole at bottom and also from the hole on the main body to the left of the air screw, which is saying to me that the float level is too high.

Can anyone advise me what the correct level should be and how I achieve this?

[Revband]

Hi Goldie

It looks like this question may be answered here  http://www.scotttechnicalities.com.au/technicalities/Son%20of%20Technicalities/Amal%20TT%20Carburettor.pdf

[geoffus]

 :)there are probably three main problems the first ones float level to high but you seem to have had a good look at this another problem float needle seating correctly and not allowing any weeping.but I think your main problem is down draft angle this means that when the bike is stationary pilot jet weeping is inevitable unless petrol is really pouring out its quite normal when the bike is on the stand front wheel on the ground back in the air you have increased this angle and therefore weeps a little more you could try putting ruler across the carby making sure the ruler is level you'll probably see that the float level is higher than the pilot jet until the float level drops it will drip i believe BSA made a tray to go over the magneto what I've found is to let the bike tick over for about 20 seconds and these drops afloat level just enough to stop the weepage  they brought a the GP2 to overcome this problem  or do as others and fit a concentric.
regards geoff

[Goldie]

Thanks for your replys Revband and Geoffus,

Tomorrow I will lift the front wheel of the deck to level off the bike on the center stand and see if it makes any difference to the dripping of fuel.

If no success, then I will try putting a very thin tiny washer between the float and the floar needle to see if that will slow up the amount of dripping fuel.

I have just taken off the concentric carb, because it just did not look right on the big fin engine, even though it made easy starting and no leaking fuel.

I will persist with the TT10 carb for the time being in getting it right.

I can always go back to the concentric, or even better still fit a Mikuni VM carb.

[Hangflyer]

Hi Goldie,

I know this is a very old thread, but I have the same problem with the Amal TT on my Norton and wondered if you ever did get to the cause of the fuel leak.
I know one other person that had this problem, gave up, and used a Concentric carb and yet other people tell tell that the TT should not leak from the pilot air hole.

Thanks,