Leaky Carb?

Spaz_Static · Mar 26, 2012

I've noticed my carb tends to get this gunk (old dirty fuel mix) collecting under the float bowl, yet I'm not entirely sure where it is coming from. It's not bad enough to collect on the engine between the clutch actuator arm and the gear reduction cover, but enough to annoy me and make a mess if I ever fidget with anything down there.

I've also noticed a few other things, one being air bubbles running up my fuel line (only noticed this once, it was after a short 2 mile jaunt to the grocery store, before I headed back home) and the more noticeable fact that my fuel line seems to empty after a couple of days without running my bike. If I didn't close my petcock, I think my tank might empty this way.

As a side note, what size fuel line do I need? The cheap crappy rubber tubing that came with my engine has grown hard and I fear that it might break one day.

I'll see if I can find a picture of my carb, as I don't know what kind it is to tell you guys... Apparently I have a picture loaded here: http://motorbicycling.com/showthread.php?p=364748#post364748

rustycase · Mar 26, 2012

That's an NT carb, SS.
They are a good product.

Any size fuel line that will slip over the fittings is sufficient.
Be sure to run a fuel filter!

You may need a small adjustment to the tangs for the needle valve, or there may be a bit of crud stuck in there.

Brand new, the tanks generally come with garbage in them that can easily plug them up.

All that not-with-standing, you should check to see that your petcock actually shuts off!
.... and, you should shut it off every time you shut down...

Could not tell from your sideways pic what angle your carb may be situated at, from the motor mounting in the frame... angle can affect the float performance.

They will always spit back from the carb, in normal operation, and eventually the filter will become pretty wet, and drip some fuel/oil down onto the top of the case.
Periodic cleaning will help.

Best
rc

gokart25 · Mar 26, 2012

Over the winter, I was moving my bike all around (from horiz.. to vertical), and without a fuel filter, and mine started leaking.
I took the carb apart, cleaned it out real good, Put it all back to gether with a fuel filter, and it hasn't leaked since.
That is what I did to fix mine, maybe that will help.

(The little plunger on the side of NT carb that you push to fill the bowl, can get stuck sometimes on the cotter pin on the inside.)

biknut · Mar 26, 2012

The correct size fuel line is 1/4"

As long as your bike runs well, don't worry about bubbles in the fuel line. Mine does it too. However it's always good practice to close the petcock after every ride.

Gas leaking out of the carb can be limited by lowering the float level a little bit.

Spaz_Static · Mar 26, 2012

Carb seems to sit pretty level, tilted slightly towards the front of the bike (see pics). There is an inline filter as well as the coarse filter on the petcock in the tank. I think I did a decent job cleaning my tank out when I got it, though after a month, some clear plastic (or something, no idea what it was or where it came from) had been caught on the petcock mesh, which I removed as it was limiting fuel flow. I do know that my petcock shuts off the fuel flow as I used to have a problem with my tank rotating around my cross bar, and it would pull the line off the petcock.

rustycase · Mar 26, 2012

That looks real close to perfect as one can get with a chinagirl, SS !

Probably what Biknut said... fiddle with the float level a bit and it will come around to the program.

Best
rc

Spaz_Static · Mar 26, 2012

Bent the tangs down a little, things still run well, so with luck, that will have resolved my problem. If not, well, I didn't hurt anything... at least according to the twenty minutes of cruising around my neighborhood.

2door · Mar 26, 2012

Did you try tightening the two screws that hold the float bowl to the carburetor body? If the float is pushing up against the needle valve and there's no crud in the needle and seat my money is on a leaking bowl gasket.

Dry everything off real good, turn the petcock on and keep a watch. If the float is too high the fuel level will be high enough to allow leakage at the gasket. If the float level is good then the fuel will be agitated in the bowl when the engine is running and that will cause the gasket to leak too. If the leak is the gasket.
Take a close look at the barbed nipple where the fuel line attaches. I've had them loosen. Also if the fuel line has a loose fit, it will also leak. If the line is slightly oversized you can use a small tie wrap or twist a wire around the line over the nipple. They do make clamps small enough but they're hard to find.
Tom

Spaz_Static · Mar 26, 2012

Yeah, I thought about that as I was reassembling it. As soon as I can relocate my %$#@ gasket material, I'll be making a new one. The cork one that came in there didn't seem like it was that great.

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