CD150 fuel leak (GT6)

[rulloyd]

Hi all.  Having just changed the two needle valves in my carbs, on the rear carb, the chamber vent on the air filter side is chucking out fuel, which is quite annoying!   Pretty sure i put it together right and apart from the ‘dreaded slivers’ possibly being a cause, I read that new valves sometimes need a bit of use before they work properly.  The recommendation was to tap the body of the carb to release it.  Does this sound like a reasonable solution? (Bit worried that it will stick again and I won’t know).

Also, I’m assuming that if I cut off the tab from the 2nd fuel chamber gasket provided in the Paddocks kit (as below pic), It’s ok to use even though they are different colours?!

I also changed the fuel pump at the same time btw.  Paddocks standard pump for GT6 mk2.

Thanks for any advice

Rich

 

[johny]

yes the carbs changed over the years so youll have to check the grey gasket fits ok however the colour difference isnt important.

If the needle valve doesnt settle down you might have to reduce the fuel pressure as its not unheard of for new pumps to produce more and cause overflow. This is done by trial and error, putting more gaskets/packers between the pump and engine casing...

[Pete Lewis]

the gasket profile changed a few times as the carbs evolved  you really have to check the gasket 

does  it actually cover every bit of the float chamber mating face    whilst they can look the same its easy to fit the wrong one and you get a leaker 

pete

 

[dougbgt6]

I had annoying flooding. The pin, bottom right goes through the floats, at the top and is held by a clampy thing which is just bent metal. One end had opened up and as float rose the whole thing slide forward and the float never got to press on the valve and cut it off. Took ages to find it!

Doug

[rulloyd]

Thanks all.  Good shout re pump pressure.  I think it’s very likely to be the new pump as I have literally just changed it at the same time as replacing a leaking float in one of the carbs and both needle valves.  I  have the old one which I can refit to see if the problem goes away.  I removed it primarily as a precaution but now I read that that is probably a bad idea!

The grey gasket seems a little bit narrower but fits ok.  I cut the extra tab off it. If I can avoid opening the chamber, I’ll leave it and see how it goes.

I’ll report back.  Thank you!

Rich

[Pete Lewis]

and from dougs snap you can see  the pivot is offset  so  you can fit the float upside down  quite    easily 

Pete 

good place for decent working clues  is Buckeye Triumphs Carburetors — Buckeye Triumphs

good for clear clues  not just TR  they can be used for the whole range if you read between the clues and pick what suits 

Pete

[rulloyd]

Hi all.  Happy to report that changing the pump back to the original cured the fuel leak through the chamber vent.  Looks like new pump has too much pressure as suggested. 🤬 With the new pump it’s a pain in the ass to trial and error different gaskets width as the nuts won’t take a socket because of the design of the device and are hard work to do up / undo with an open spanner.  Anyway, sounds like the better pump is the original so all good.  Thanks for the advice, easy fix.

Out of interest, has anyone ever managed to service the bottom half of the pump or does that last for ever??

Rich

 

[Pete Lewis]

glass top and others do have repair kits which include the valves and new diaphragm included 

if you strip the new pump cut a bit off the spring to reduce its output pressure.

all in new can be a bit of a pain 

the old glass tops seem the best and were fitted to so many makes  , and the cam arms are easy to swap 

so a ranom pump can soon have your orig. arms fitted 

Pete

[Gully]

You can mix and match the top and bottom halves of the pumps. I fitted a new top with new diaphragm and valves to the old block-mounted spring / cam etc - that worked fine and avoided the over-pressure issues the complete new pumps seem to have.

Gully