LM2 carb drip...

[Dukedesmo]

The float bowls on my carbs (PHF36) drip fuel, it's a slow leak that doesn't really cause a problem whilst riding but makes a mess if I leave the fuel taps on when stopped.


They leak through the interface of the fibre washer and the nut that screws through the float bowl to the jet housing. I have replaced (many times) said washer/gasket with new, genuine Dellorto parts but they always leak, I have tightened them as much as I dare (nuts are ally) but still they leak.


I can't see anything wrong with the surfaces where the washer sits, presumably others have the same problem?


Any tips, better gasket/'O' ring/sealant etc.? 

[Stevex]

My LM2 carbs don't leak.
If you had one leaking I'd say check for hairline crack in the float bowl, but both is a bit weird.
You're positive it's not a float bowl seal or breather issue?

[80CX100]

If it only leaks when you're stopped and the fuel taps are left on I, I'd say your float needle tip and seat aren't seating properly and creating a seal, cutting off the fuel flow,fwiw.

If it's sealing properly and the gaskets and o rings are in good shape, and it still leaks out the plug due to a poor fit, maybe run a bead of "seal all" on the base of the plug on the washer the next time you install it?

Good luck with it

Kelly

[Dukedesmo]

The leak is very slight, generally if you touch the bottom of the carb there is just a film of fuel and it looks to be leaking from the nut/washer as everything is clean & dry above there. I recently replaced all the gaskets/'O' rings etc using a genuine Dellorto kit and the washers are also Dellorto parts, nothing looks to be damaged and the carbs are in top condition.


Probably try some sealant on the washers.   

[moto-uno]

  Before installing any more gaskets , verify that the float bowl nut will tighten up against the float bowl without a gasket on it . Peter

[MotoG5]

  Before installing any more gaskets , verify that the float bowl nut will tighten up against the float bowl without a gasket on it . Peter

Great suggestion! I was wondering if he might not be getting enough compression on the gaskets before the nut bottoms out to completely seal for some reason.

[wirespokes]

I've never torqued mine, but am curious how many ft/lbs are spec'd. One of mine leaked recently, but cinching it up a bit more fixed it.

[jwinwi]

Try using an Aluminum washer? I forget what washers plastic banjos use vs. metal banjos...

[Dukedesmo]

To update on this; I used 'Wellseal' on the fibre washers, left it for a while until yesterday when I switched on the fuel and left it for a few hours - dry as bone now so appears to have solved the problem.


I've not ridden it yet or even run it but previously there would have been fuel stainage on the block from drips if I had left the fuel on, so all good now - thanks.

[moto-uno]

  ^ A bit more follow-up , did you apply this sealant to both sides of the gasket ?
  I have no experience with this sealant , does it damage gaskets on removal ?
Peter

[Dukedesmo]

Applied to both sides, I don't think it will damage them on removal as it doesn't fully harden (at least not under normal use, I'm not sure what fuel might do to it?) but the fibre washers are cheap enough to replace every time they're removed.


I've got a few in stock for next time...