Leaking gas from airbox boots???

[Guest]

As the title implies. Any suggestions would help. Only one carb after clean and readjust, by the way.

Thanks in advance.

[81g11]

the only way i can think of that gas could get into the air box is if one of your floats is sticking. otherwise theres no entrance to the air box is through the carb the float could have got bent up a little bit without noticeing it and that would cause it to overfill the bowl

[kichigai]

Yup, I agree! I had the same problem before!

Try this trick first before attemting to remove the carbs or bowls!

There should be a screw at the bottom of your float bowl to drain the gas. Take off the screw from the bowl and drain the gas in a container or cup. Now, remove the gas line from the petcock and get some compressed air to blow into the gas line. This is to blow out the debris out from the float valve and line. Do the same for all 4 of the carbs but one at a time. Try adding some fresh gas and try it again if it didnt clear the first time. It worked for me!

[renobruce]

a bad petcock can cause gas to go down the vacuum tube also.

[Nessism]

Before you go too far, take a large screwdriver and rap on the floatbowl with the handle. Sometimes the float hangs up after a rebuild and just needs to be jostled to get it moving. Worth a try.

[chef1366]

Petcock, sticking float or bad float needles and seats.
Or AOTA.

[don]

O.K. Latest update.

I let this thing run for like 40 minuits while I was puttering around with other things. Every so often I would go over and bring the revs up to about 3-4000 for a good 10 seconds or so. Never leaked. Next, I took it up the road about 200 yards and back. No Leak. Then, I took it about 2 miles down the road to the gas station. Leaked when I stopped to look. Took it back home, let it cool enough to need the choke to start it. No leak.

So, I take the bowl off of the carb in question and check the float, needle, etc. The pin was tight in the carb body so i figured, woo hoo, found it!!! Fiddled and cleaned all that stuff, put it back together, did the whole deal as above (idle for awhile, short triip up the road, couple miles up the road) and got the same results as before.

Renobruce mensioned the gas in the vacuum tube for the valve. I do have that issue but the carb that's leaking is the carb that does not have that vacuum port on it.

I'm so @#**@@# confused.

[renobruce]

Fix the petcock and you will probably fix your problem. To prove it, disconnect the vacuum hose from the petcock and carb, and plug the ports. Turn your petcock on prime, run the bike and see if it leaks.

[don]

Excellent thought! I'll blame senility for me not thinking of that. (Dumb A$$) And I knew the fuel valve wasn't in the best working order.

[argonsagas]

No matter how you look at it, and no matter how much it annoys you to admit it, you have a float and/or needle/seat problem.

Yes, the petcock can contribute to the problem in some circumstances, but if the needle/seat are working properly, and the float triggers them as it should, the fuel that gets through the petcock does absolutely nothing if the passageway is closed, as it should be.

There IS one possible problem that stays with the petcock, and that is when the engine is stopped (no vacuum0 the fuel MAY leak through the vacuum line and into the carbs.

That means repairing or replacing the petcock, but the check for this is easy....just pull off the vacuum tube (the small tube). then wait a minute and see if anything happens.


If you see a leak you identified a problem in the petcock

If you see no leak you identified a problem with the carbs.

[don]

Renobruce,

I see you have a couple of yamaha's. There is one of those 350cc 2-stroke YPVT bikes for sale near me. I think it's going for $3,500.00. motoconsult.net and go to bikes.

[renobruce]

One of the key statements he made was that it leaked when he stopped. So He's probably getting gas through the vacuum port on the carb.

[renobruce]

Renobruce,

I see you have a couple of yamaha's. There is one of those 350cc 2-stroke YPVT bikes for sale near me. I think it's going for $3,500.00. motoconsult.net and go to bikes.

Those are nice bikes. Sounds high on the price unless it's fairly new. Everyone should have a dirt bike. Lots of fun, and it makes you a better street rider.

Oh, and I'll update my signature. I just acquired another bike for my son. It's a KTM SXR50.

[don]

Argonsagas,

Exactly what you are saying about the needle is my only logical conclusion also. I just don't understand why it will only start to leak after I ACTUALLY ride it for a few miles...EVERY time. In my experience, if a float is stuck, it's stuck, and it will continue to leak until you unstuck it. I have shut it off with gas dripping all over, (from above the level of the bowl), let it set for a couple of hours, fired it up and it won't leak again until it's ridden a few miles. There must be some kind of mystical, alien, magic at work here. lol I don't know....... maybe I'll have to go through the float and needle again......?

The crappy thing about all of this is it runs like a champ besides leaking all over my engine.

[don]

I just got through reading the " a lesson learned" thread. I DO believe I fall into that category. I am still going to do the vacuum tube removal test though, just because I'm old and suborn (aaagggghhhh, damn kids). lol