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Triumph TR6 - Leaking Carburetor

I recently rebuilt both carbs. The one carb still overfills and leaks as if the needle valve is not sealing. I have read the archives and it seems the culprit is likely the needle valve. However, it was new during rebuild. Can the old valve be cleaned to use as a test? If so with what? Is there any rubber or plastic inside that would be affected by solvents. Or, are there any other ideas as to what may cause the leaking.
JOHN BRUNATTI

Hi John

I am no expert, but I did rebuild my carbs last year. It sounds to me like either the valve as you suggest, or the float. Did you make sure the float level was right on both carbs? Does the float actually float? I checked mine for buoyancy in a bowl of water and when I had the valve and float back on the body of the carb I checked by blowing through the fuel inlet to make sure the valve closed when the float was up. I know, I know - I probably shouldn't put 30+ year old carb parts in my mouth! You might be able to do this without removing the carb by removing the plug at the bottom of the float chamber and using something soft to push on the float, and attach a hose to the fuel inlet (probably best not to use the one with fuel in it!). At least that would let you know if it was the valve at fault.

Just my thoughts - I am sure someone will come up with a better idea soon!

Cheers
Alistair
A Hewitt

Two main problems with fuel overflow from the float chamber:
1) Needle valve: They tend to get stuck open when
your vehicle is stored away for awhile. Check
if yours is stuck or has some debris clogging it.
I prefer using Grose jets
2) Float out of adjustment: you need to bend the metal
tabs on the floats. If they are out of adjustment,
the needle valve will not close completely.
Hope this resolves your problem.
benji

Thanks guys but both are still leaking. I have removed and inspected to find everything clean twice. After assembly, I blow air thru fuel inlet and valve seems sealed when valve is closed by float.I set the level at 16-17 mm from the casing to top of float when the carb is upside down and resting on valve as instructions state. Is this measurement correct?

John
JOHN BRUNATTI

John

Did you set the level using mm or inches? As memory serves the inch conversion was incorrect in at least one manual. I am pretty sure 16-17mm is correct, though.

Where is the leak coming from? If the valve is closing and the float levels are right then I don't really know where it could be coming gettign out - is it the O-ring on the plug at the bottom that hasn't seated right? Unlikely if it is both carbs. With both leaking I would suspect that the float measurement is off, otherwise I guess try a new valve? I can put one of my old valves in the post for you to try if you like - they weren't leaking when I took them apart!

Cheers
Alistair
A Hewitt

The carb is leaking from the throat and the cold start assembly. I believe the carb is overfilled requiring the fuel to exit somewhere. I will disassemble again and adjust float to better seal. The valves are new.

John
JOHN BRUNATTI

I disassembled the carb and checked the float level. It is correct. However, I did find a particle of lacquer at the bottom of the jet when it was removed. This area was previously cleaned thoroughly. Is it possible that sediment is coming from the tank or gas line?

John
JOHN BRUNATTI

Particles from the gas tank may clog your valves. More so if you use Grose jets. Verify if there is a lot of sediment in your fuel filter.
Good luck

benji

I believe I may have found the problem. Soneone removed the filter and I had not noticed.
JOHN BRUNATTI

Yep!! Fuel filters are kind of important. I would recommend that you purchase a clear filter so that you can see if it ever gets clogged.
benji

This thread was discussed between 04/01/2008 and 16/01/2008

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