9 replies to this topic

[tino]

Not been on here in a while, as I finished the project over lockdown and forgot to update here!

I have a new problem, which is puzzling me slightly. There is fuel leaking from the top of the carb float. This is either after idling for 5 minutes or after cutting the engine off.


I checked the float clearance and valve and it all seems to be working ok, although the bowl itself was filled with debris. So I stripped the carb down and cleaned it up.


It however is still leaking. I am not sure if the pump itself is pushing too much fuel through, the below link is a video of it on tickover. It seems fairly steady and smooth.
https://imgur.com/Ub74fCf

Needle is a AAU which I think is a Stage 1 kit needle. I can't see anything wrong with the chamber itself and the operations feels fairly smooth.


Am I missing something obvious?

Is it now doing it as I have thrown the fuel/air mixture out completely when I stripped it down or likely to still be debris somewhere in the assembly?

Thanks as always for any help and guidance.

Edited by tino, 08 October 2023 - 05:07 PM.

[cal844]

Check the needle valve under the float for wear (any rings around the tip and it needs changed) then I'd be tightening or trying to reposition the clip on the fuel inlet.

Edited by cal844, 08 October 2023 - 06:23 PM.

[nicklouse]

Float chamber leaks are valve being worn/crudded up or not set correctly. Or float leaking/has a hole in it.

[mab01uk]

FLOAT NEEDLE VALVE HS2/4/6 (VITON TIPPED)

"If living where Ethanol is dominant in your petrol(10%)and causing problems there is an alternative WZX1100A with a viton tip."

http://www.minispare...c/WZX1100A.aspx

 

FLOAT NEEDLE VALVE MINISPARES OWN SUPERFLOW TYPE

"If fuel is overflowing the float bowl the needle valve is leaking. This may be caused by the float WZX13040(GSU200) being misadjusted, stuck or leaking OR the needle may be fouled with a bit of grit or worn and not sealing. This is an alternative updated version with brass/bronze rod which flows and wears better."
Fits HS2,HS4 and HS6 carbs but not HIF range. CA90 is ethanol tolerant

http://www.minispare...assic/CA90.aspx

Edited by mab01uk, 08 October 2023 - 07:44 PM.

[tino]

Thanks both, I’ve got this kit on order.

http://www.minispare...c/WZX1100A.aspx

I’ll update if it fixes the issue or continues after.

[Lplus]

There's four reasons you can get fuel on the top of the float chamber;

 

A leaking float leading to a high fuel level (though this would lead to a high fuel level at all times)

 

A leaking needle leading to the fuel level rising quickly or slowly above normal level in the float bowl (depending on the leakage rate)

 

The rubber delivery pipe either being perished or not seating on the brass inlet pipe,

 

The brass inlet pipe not being fully sealed where it is pressed into the alloy float chamber. (unlikely, but I have seen it on one of mine leading to some fuel on the lid)

 

Once the fuel eppears, loosen the three screws holding the lid on - if fuel runs out of the joint, it's probably one of the first two, if it doesn't then the second two become relevent.

[tino]

There's four reasons you can get fuel on the top of the float chamber;
 
A leaking float leading to a high fuel level (though this would lead to a high fuel level at all times)

I have put the float in water overnight and its not let any in.
 

A leaking needle leading to the fuel level rising quickly or slowly above normal level in the float bowl (depending on the leakage rate)

I think you mean the float needle, rather than the carb needle. This is hopefully the cause of the issue.
 

The rubber delivery pipe either being perished or not seating on the brass inlet pipe,

I replaced that with a new one to be sure and it's still occuring.
 

The brass inlet pipe not being fully sealed where it is pressed into the alloy float chamber. (unlikely, but I have seen it on one of mine leading to some fuel on the lid)
 
Once the fuel eppears, loosen the three screws holding the lid on - if fuel runs out of the joint, it's probably one of the first two, if it doesn't then the second two become relevent.

I don't think it's this one, but it's one to think about.

 

 

Thank you all for your responses.

[Rorf]

With the amount of crud in the fuel bowl then it would not be surprising if the float needle is sticking in the seat. Install a plastic in line fuel filter just before the carb.

 

I had endless problems with that Super flow needle and seat from Mini Spares, flooding all the time!

[tino]

Well the new float needle appears to have fixed the issue.

Here are two photos of the old one.






Finally one of the new one fitted, I have a different float to the one you can bend to set it correctly, but from what I read elsewhere you can just put a washer in the part you screw in to set the height so I did it that way.



Thanks for everyone's replies.

I'll be back if the issue comes back after I've been on a decent run this weekend.

[kiwimike01]

Hey there I had the exact same issue a while back. I asked on the forum and tried all the suggestions of different floats, needles, gaskets etc and it still kept leaking. Found a guy here in NZ who had a spare lid and ordered that. Once i put it on, it never leaked again so somehow the lid was faulty. The old lid looked fine so was very puzzling trying to find the leak and trying a new one was the last resort and it actually worked.
Worth a try if you have any more issues.
Cheers