as title suggests,
i started up my trackbike the yesturday just to keep things going between race meets.
started fine, revved smooth and everything seemed O.K. i shut the bike off and go inside, i go out to the shed about 1 hr later and the smell of fresh unburnt fuel hits me,,,,, WTF. i look in the belly pan and theres fuel in there, i take the drain plug out and a fair bit of fuel comes out, about 100ml.
i turn the tap off and go inside, planning on working on it today.
i get to the bike today and started it, started fine and everything seemed normal, turned tap on and still everything sweet. so i shut her off and went inside, again going out in and hour and same thing, about 100mls of fuel in the belly.

so i took off all the body work and fuel tank to have a look at whats going on, it seems that the front left (whilst sitting on the bike) carb is leaking fuel into the intake. Being pot luck the inlet valve must be shut so not alot of fuel, if any, is going in the engine instead going on floor. not all bad i guess

am i right in thinking i need to give the float seat a clean and inspect its seal??? as this is a pain in the ass as i usually leave the tap in the ON position and its never been a problem.

or should i leave it alone and just turn the tap off between runs and hope it clears itself as i have just had it dynod and i dont want to mess up the settings

cheers guys

The flooding may be grit under the float valve needle or a worn seat.
Don't leave it, if you get a hydraulic lock and the engine starts or even fires, damage may occur.
The fuel sitting in the inlet track with the valves closed will go straight into the head when the engine is turned.

Dave

This is the reason I say it's not worth doing the 'HRC' fuel tap mod.

If it does this and the valve happens to be open you could fill the crankcases with fuel, this can wash the oil from bearings, rapidly followed by big end failure...

You need to sort out why it's overfilling and make sure you always turn the tap off, I'd suggest shutoff connectors for the fuel too.

Druid

As been said already get the carbs off and get it sorted asap.

It's more than likely going to be a worn needle valve that isn't shutting off the fuel when the carb is full, causing it to overflow out of the bike / into the engine etc etc.

bit of an update,
went to the bike this arvo, and sucked out as much of the fuel from the inlet track very carefully with a seringe (spelling)
started it up and let the carbs run dry, then filled it back up with fuel and so far its sealed the fuel

hopefully it stays good, i will just have to remember to turn the tap off in future. although if it happens again it will still leak whatevers in the float chamber into the inlet and possibly cause hyd lock ay?

which sucks but hopefully the bit of shit or whatever it was has now gone

cheers guys

randallbass wrote: which sucks but hopefully the bit of shit or whatever it was has now gone

If you fit a fuel line coupling it will ease your mind in future!

hopefully it stays good, i will just have to remember to turn the tap off in future. although if it happens again it will still leak whatevers in the float chamber into the inlet and possibly cause hyd lock ay?

which sucks but hopefully the bit of shit or whatever it was has now gone


I normally turn it to the off position just as I'm coming in off the last lap. So it leaves as little fuel in there as possible.

It's all very well and good turning the tap off but can you be sure it actually turns it off?

I did the 'HRC' mod to our trackbike once, swiftly reversed it when I realised that the fuel tap still dribbled when 'off', yours may not now but can you be sure it won't do it in the future?

You may argue that it'll be fine that the floats (without the grit in there!) will prevent it but when on a trailer or in a van the bouncing can cause the floats to bounce *and* fuel to splosh down the inlet tracts, if the tap doesn't seal you may find yourself with a hydrolocked bike.

Druid

my tap doesnt currently leak when in the off position

i guess i will have to look into the dry break coupling as it seems like a good idea, but if its going to happen it still got a bit of fuel to drain and which may still cause Hyd lock, running it fairly dry seems like a good idea..

cheers guys