Three times over the past month or so after riding for a while and parking my bike I returned after 20 minutes or so and found my bike was flooded out and wouldn't crank unless I held it wide open. Everytime this happens there is gas leaked on the ground underneath the engine. Is this my "float" hanging up in my carb, and if so what is the fix?

Thanks,
Vince

Not really a fix but I have seen it recommended to turn off your fuel before you shut the bike off to burn any fuel left in the lines up that way theres nothing to flood. keeps it from happening but doesnt really correct the issue. I'm sure one of the carb guys will chime in here in a sec.

revit wrote:
Three times over the past month or so after riding for a while and parking my bike I returned after 20 minutes or so and found my bike was flooded out and wouldn't crank unless I held it wide open. Everytime this happens there is gas leaked on the ground underneath the engine. Is this my "float" hanging up in my carb, and if so what is the fix?

Thanks,
Vince

Probably. The float level is either off or it is sticking. There is an article in the tech section on setting your float. http://roadstarclinic.com/content/view/59/96/

You can also search carb puking, there is alot of reading on it here in the forums.

I cleaned my bike up today and rode over with a buddy to Pops about 15 miles away. It was through the country and didnt really get out of 4th gear. I went out to ride up to the store about 15 minutes after I got home and it wouldnt start right off. There was also gas leaking out onto the ground. The fuel pump kept working and I opened the throttle and it finally started. What do I need to do to correct it?

Take off the float bowl. Make sure that the float moves freely. Make sure that the float valve shuts off the fuel flow properly. And make sure that the float level is set properly. Put it back together.

Clifford

sounds like percolation ... or carb puking.. first thing, make sure your float valve is closing and float level is set correctly... if it only does it when the engine is hot... then you've probably got carb puking.. BUT MAKE SURE FLOAT LEVEL IS CORRECT AND CLOSING COMPLETELY...

CARB PUKING: the gas boils in the float bowl, our carb sits between the cylinders and get hot.. gas boils at about 150F degrees lower temps at higher altitudes and lower temps with higher ethanol levels (as is used in winter to prevent fuel line freeze up in cars)... doesn't take us much to get the float bowl hot enough to boil gas...

as the gas boils, it pours liquid gas out of the overflow (a high port on the outside left of the carb that attaches to the back of the stock air box)... as the gas boils out of the carb it pushes the fuel level down and the floats drop opening the float valve, this allows in fresh fuel which is why your pump continues to pump... on a gravity system this wouldn't cause to much of a problem... because the pressure of the boiling gas would slow down (but not stop) the fuel from pouring in... causing a vapor lock ... but we've got a pump behind it which pushes the fuel into the bowl, and out the overflow... right onto the engine and hot pipes

the reason the bike will only start wide open is because the gas is pouring out of the jet and by opening the slide you're allowing the mix to add more air keeping it from flooding the engine...

1. potential fixes... extend the over flow from behind the air box to below the engine...doesn't fix but prevents fuel from being vaporized on the pipes and vaporized fuel is VERY flammable and can be ignited by a backfiring engine (a flooding engine can backfire) and with gas all over the back of your carb and engine... this can be a bad situation... don't ask how I know...

2. open air flow around carb between cylinders ie... removing pump on back side of engine.. changing to a smaller air box from stock (I don't know empirically if this will work but makes sense to me)

3. allow bike to cool down before shutting down by allowing it to idle for 5 min (old biker trick... a revving engine gets very hot... an engine at idle will actually cool down from it's running temp)

4. turn off gas before turning off engine and don't turn on gas until you're moving... (a bit cumbersome especially turning on the gas while moving) theory is gas is cool and will cool down the bowl of the carb but the gas has to be moving if it sits ... it gets hot... and turning on the gas after moving allows air to start moving around the engine and cools the carb.

5. allow the engine to cool completely before restarting.. >20 min

6. don't shut off bike if only stopping for a few minutes.

LASTLY: how to know when your percolating?
1 turn on the key and fuel pump continues to click...
2 smell of vaporized gas ... seeing gas pour from behind carb
3 engine may stall and you will hear pump continue to click

WHAT TO DO:
turn off key (don't try to restart right away)
turn off gas
allow hot gas to dry
turn on key and attempt to start
if runs get moving and turn on gas

if won't start you may need to allow fuel to fill bowl
turn on key, turn on gas, turn off gas after second or two. make sure no gas is collected on engine. attempt to start you may have to open throttle wide open just like when starting an old engine and you flooded it...

if that doesn't work.. go get some lunch... try again in 20 - 30 minutes

~Guido

My 04 Roadstar did this a couple of times... always when hot.... is this a Yamaha problem or is it subject to all Motorcycles with a Carborator?
tt

Many brands that are air cooled and have the carbs close to the cylinders can suffer from this. It is not Yamaha specific. BB

Just my .02, but, I beleive that it is the fuel heating up in the fuel line running between the jugs from the pump to the carb that pressurizes and causes the carb to percolate fuel out of the overflow. There is a lot of heat with no air circulation between the jugs after it's shut off and that's where Yami ran the fuel line. It has some insulation tape wrapped around it and that's fine while you're riding, but, once you stop, the heat gets through that.

I came to this conclusion after I moved my fuel pump for appearance reasons under the right side cover and haven't had a problem with puking since.

I personally found that if I would turn off my fuel petcock about 20 - 25 seconds before I shut her down, that the puking wouldn't occur. This too supports my theory, because the fuel line was 'de-pressurized' when I shut her down.

Hope it helps.

Ratl.

Certainly a good theory .... but why do not all bikes that have the line running between the cylinders have this problem.

Case in point. Mine has no insulation at all and I've never had that problem.

Doc