float valves?

Couple days I fired up the bike. It'd been sitting for a few months while I was away on a job. I'd filled the tank and carbs with stabilized fuel. I opened the petcock (I've got a on/off/reserve petcock, not the factory vacuum one), and the carbs flooded, sent fuel back up into the airbox, dripped all over the place.

I assumed this was the float valves getting stuck, so I took off the carbs and checked them on the bench. They behaved fine, no leakage, and when I put them back on the bike, took a ride around town they were fine, no leaks.

But today, I tried to fire up the bike again, and the carbs immediately flooded back up the air box, and all over the ground. Two questions:

1) Do I need to change my oil every time this happens? I'd heard that the gas might be mixing with the oil in the crankcase, which has a vent tube up into the airbox, so I've been changing it.

2) Is the flooding just moody float valves?

 

The vent tube comes in fairly high and there is a drain in the air box. Unless it is clogged I doubt you got any gas into the crank from the vent tube. You should certainly check for strong gas smell in your oil to be safe. But I doubt you will have any since it happened while you were there.

I put mine on prime yesterday to fill a new gas filter and to my surprise same thing happened to me. My guess is moody valve for mine. I would like to get to the bottom of the issue too.

 

I put the carbs back on the bench, and figured out which ones are flooding. But I can't figure out why. The float valve hinges are fine, I pulled em out and cleaned em. The only other thing I can think is that the rubber tips have gone bad, but I just bought these things a few months ago. Can you think of any other reason why a carb might flood?

 

Check for a good seal on the needle seat. Look for missing washer under the seat.

Do they stop flooding if you tap them?

 

Well, I isolated the leaking to just one carb, and switched needles with another carb. The leaking followed the needle, so I assume that's the problem. I'll get a new one in my next order from chac. Any luck with yours?

 

Haven't had time to pull the carbs - reluctant to do it since I don't have any issues unless I put it on prime and it's fairly nice ridding weather. I replaced my needles and seats just a couple of months ago. Maybe this weekend...

 

Hmm. New needle ddn't solve the problem. I'm scratching my head now. When I tap the float valves up on the offending carb, the leaking stops, so I'd guess it's not the float valve itself, although I suppose the pressure I apply with my fingers might be greater than what the gas in the bowl does naturally on the floats. I cleaned out the action on the float hinges pretty thoroughly, too.

Can float levels cause this sort of thing? Seems like even if they were way off, the bowls would eventually fill enough to push the needle up.

 

oak,

I know i am a noob here but just went through the same thing. when i did the carb tear down and rebuild i used the clymer repair guide. One of the sections suggested to take all of the floats out, and individually put them in a "noncaustic" solution and submerge them. The floats should not have any air bubble coming to the suface when they are under the fluid. If you do notice this, the floats become "water-logged" (for lack of a better term) and can sink causing the needle valve to be open. This was the problem in one of my carbs.

In the other one that was leaking fuel, at some point during my cleaning i had bent the float. Not sure how it happened, but when i put the carbs back in i had to take them out again because i still had gas coming out the air box. After a few choice words, i took the carbs out again tore them down and noticed that the float was ever so slightly bent. Replaced that, and all has been good, going on about a week now.

Just my 0.02 hope it helps.

--eriedoc514

 

I answered my own question. The float on the leaking carb was set a hair too high. I wasn't aware that float levels could cause flooding, I just thought they caused too rich a mixture, or something.

Good look on those newly cleaned carbs, erie.

 

The floats close the needles which sets the bowl fuel level. So if it isn't closing it will flood for sure. Took mine apart this weekend and everything was fine - could not make them overflow at all.

I had done some work without the tank running off the bowls. I thought I refilled them but may not have, then the bike sat a few days. Dry needles will stick so I think that is what happened to me.