Why is petrol leaking out of my carb?

[Jonathan]

Hey everyone!

Just finished reassembling my bike after 8 months repairing cosmetic damage and repainting (while full time at uni and doing a part-time job). All seemed to be well, went for a ride out to Plimmerton, but on the way back the bike began misfiring at high revs like the plug was fouled.

So got home and cleaned up the plug with a piece of sandpaper though it did not look that fouled. Anyway, I rode the bike up to the top of the street and back and when I stopped fuel was pouring out of the hose that leads from the bottom of the caburator. It continues to do so when the fuel is turned on. Can anyone tell me why? I have only been riding two years... still a newbie...

[Posh Tourer :P]

1. I assume you meant fuel turned off, so that means that your fuel tap isnt working... (Or there is a *lot* of fuel in the carb) This isnt a huge problem, although it would be better fixed. Are you sure you went to off??

2. But.... Your carb isnt shutting off either. Pull it apart and check (if your fuel tap doesnt work you will need something to plug the hole, or just drain your tank and refill it when you put it back together). Pop the bottom of fthe carb - you may need to rotate it. Loosen the clasps either side of the carb and turn it. Check that the floats are ok, and still full of air not broken. Check that they are able to shut off the fuel feed too (push them up and they should push a switch). If they dont you will need to replace them or the entire carb...

[Steam]

fuel was pouring out of the hose that leads from the bottom of the caburator.

That's the carb overflow hose, it sounds like your needles are buggered in some way, or maybe just dirty, or maybe it's the float. Ayway, they are letting way to much fuel in. I ain't never been in there, so I can't be any more help. Good luck though.

[Edit: Oh, Posh replied before I finished typing, so him smart, me not so much]

[Jonathan]

1. I assume you meant fuel turned off, so that means that your fuel tap isnt working... (Or there is a *lot* of fuel in the carb) This isnt a huge problem, although it would be better fixed. Are you sure you went to off??

2. But.... Your carb isnt shutting off either. Pull it apart and check (if your fuel tap doesnt work you will need something to plug the hole, or just drain your tank and refill it when you put it back together). Pop the bottom of fthe carb - you may need to rotate it. Loosen the clasps either side of the carb and turn it. Check that the floats are ok, and still full of air not broken. Check that they are able to shut off the fuel feed too (push them up and they should push a switch). If they dont you will need to replace them or the entire carb...

Cheers! There's nothing wrong with the tap, the leaking stops when I turn it to off (sorry I wasn't very clear). I'll open up the carb tomorrow and check it out.

Thanks to you too Steam!

[slimjim]

yup as with all things that is designed to hold liquid, if its been sitting dry for so long, the gaskets can become cracked and are fucked, as to with your float needles which get a dry sluch mark on them and will not sit in place correctly, generally pull carb off and with a soft steelo wipe needle clean, check gaskets too, and refit, if still leaking float may be cracked dry as well,and is allowing fuel to enter float and sink,

[Jonathan]

I pulled out the carb and opened it up. Fortunately the floats seemed fine. There was, however, quite a bit of red powder clumped up in the bowl which I presume is rust that traveled down from the tank when I first ran the bike again. I think it was probably this that was sticking the floats. I cleaned this all out with some petrol and an old toothbrush. Hadn't read slimjim's post yet so didn't do a good check of the gaskets but just cleaning it out seemed to do the trick.

The carb is no longer overflowing but the engine is still missing when I have been going at over 90kph for a short while. I think I must need a new spark plug? I will get one soon and see if the problem is solved.

[Paul in NZ]

Check the fuel cap vent is open and if you have the carb off that the main jet is clear.

If you can get up to Kapiti I can help you take a look see.

Cheers

[Jonathan]

Check the fuel cap vent is open and if you have the carb off that the main jet is clear.

If you can get up to Kapiti I can help you take a look see.

Cheers

Cheers for the offer Paul in NZ!

But I don't think it would make it in its current state and I shouldn't be riding without a WOF anyhow (I get one, hopefully, on Friday).

I will take the carb out again on Monday and do a proper rebuild. Haven't done one before but it seems straightforward enough.

[Paul in NZ]

Have you got other wheels?

Just bring the carb up one evening ?

Cheers

[F5 Dave]

First rule of the 2 stroke: Suspect the plug. Cleaning it up rarely works, though propane torch is more likely to work. Change it anyway.

Take the carb apart & one see if it has attracted more rust dust from the tank, if so you might need to flush the tank & consider a filter (but have to be careful how routed or will kink hose), or sealing the tank.

Either way cleaning the carb out properly is pretty easy, just take it fully apart & blow through the holes, not being tempted to poke wire through anything. Check airfilter as well.

[Jonathan]

Cheers Dave, today I cleaned out the entire carb. It's sparkling clean inside and out. All jets and various other tubes are clear. Checked the bowl gasket - no cracks etc. There didn't appear to be anymore rust build-up since the last time I cleaned the bowl.

I took the bike out on the motorway and after it warmed up and at high revs the bike started missing again. I pulled over and replaced the plug with a new one I just bought today. It was fine for about two minutes, but halfway up Ngauranga Gorge it started missing and backfiring again. Filled up the tank and the missing stopped.
Still have no idea why my bike is doing this.

Hi Paul in NZ - I only have the two wheels but I think I can make it out to Kapiti if I keep the tank full. I would be grateful to have a person who knows what they are doing to take a look at it. When are you free and how do I find you?

Cheers, Jonathan.

[Ixion]

Cup of meths in the fuel tank.And have you stripped the fuel tap ?

[F5 Dave]

So the petrol was 8 months old? If so there is your problem.

If not then a feed to the carb is the issue. Either as said the fuel tap has a filter in it that may be blocked or the fuel cap or tank vent if fitted (less likely) may not be breathing, or a fuel line is kinked or collapsed.

[Jonathan]

Problem Solved!

Opened up the fuel tap to find the bowl beneath the filter full to the brim with rust sludge. It was so thick it was like putty, quite spectacular really. Scooped it all out and gave the tap a thorough cleaning.

I rode out to Plimmerton again, battling gale force winds. There was not a cough out of the bike. It is now running smoother than ever!

Thanks for all the help everyone!

[Posh Tourer :P]

Oh yeah... forgot about that filter!!
Doh!