Fuel starvation. Float bowl running dry.

[shang]

So I just spent a day at the Little Sahara sand dunes and suffered some fuel delivery problems. The sand was soft so there was some extra load. I was running a paddle as well. My current jetting is what was recommended by Richard Wilson at House of Horsepower. Running his pipe and silencer. Number 8 slide, 172 main, JD red 2 plus 2 needle. My head has been cut for squish and compression.

At wide open throttle for the really long climbs it would start to get lean and hot to the point that it would have melted down. Pulling the choke didn't do a thing. That made sense once I realized I was sucking the float bowl dry.

Has anyone else had this problem? My float height is set as per the recommendations on this site.

Any suggestions?

[husley]

Things that come to mind:

Fuel Cap Vent not venting/allowing air into the fuel tank as it should

Needle (spring loaded needle) is sticking in the closed/seated position and not allowing fuel into the bowl

Stuck Float not allowing fuel into the bowl

...and I'm sure others will have many other possible causes

[shang]

Originally Posted by husley

Things that come to mind:

Fuel Cap Vent not venting/allowing air into the fuel tank as it should

Needle (spring loaded needle) is sticking in the closed/seated position and not allowing fuel into the bowl

Stuck Float not allowing fuel into the bowl

...and I'm sure others will have many other possible causes

Thanks for the reply! I runs fine everywhere else. It's just wide open throttle for a really long period with lots of load. The bike is a total rocket ship until it runs out of fuel. A friend of mine with me on his '11 300 had the same issue. Except instead of leaning out, his would just die. The difference is that his has an inline filter adding just a little more resistance to flow.

Keep in mind this would only happen on the really big dunes. Maybe 2/3 up sand mountain, which is really steep, soft, and about 700ft tall.

Maybe we will just have to run the float bowl at 16mm vs 18mm for the sand?

[hamilton]

I've had the same problem. I found better results setting the float level with the bowl off using fuel flow, so you can see what's going on. I just adjust the float seam parallel to the carb body. Keep safety in mind. When done put bike on stand and lean 45 degrees it shouldn't leak from overflow vent.
As mentioned be sure carb vents and tank vents are clear, and petcock allows good flow.

[shang]

Originally Posted by hamilton

I've had the same problem. I found better results setting the float level with the bowl off using fuel flow, so you can see what's going on. I just adjust the float seam parallel to the carb body. Keep safety in mind. When done put bike on stand and lean 45 degrees it shouldn't leak from overflow vent.
As mentioned be sure carb vents and tank vents are clear, and petcock allows good flow.

Thanks guys. I'll check that stuff first.

[Zman]

I had a similar issue with a 250 that revs very high and ran out of fuel.

1. Check to make sure both floats are even relative to each other so one does not hang lower than the other.

2. Make sure the carb is level relative to the frame. Take the seat and tank off so you have access to the carb. Level the bike on a stand. Take off the top of the carb and make sure the carb is level to the bike. The GG bikes are on a complex double angle so it is hard to line up by eye until you do it with a level. I was surprised how far the top of the carb needs to be tipped inward, for it to be level.

[shang]

Originally Posted by Zman

I had a similar issue with a 250 that revs very high and ran out of fuel.

1. Check to make sure both floats are even relative to each other so one does not hang lower than the other.

2. Make sure the carb is level relative to the frame. Take the seat and tank off so you have access to the carb. Level the bike on a stand. Take off the top of the carb and make sure the carb is level to the bike. The GG bikes are on a complex double angle so it is hard to line up by eye until you do it with a level. I was surprised how far the top of the carb needs to be tipped inward, for it to be level.

I should have mentioned that I have done this exactly as you said. I too was really surprised at how far I had to tip in the top of the carb. I marked the boot and carb to make sure I put it back the same every time.

[Zman]

Do you run a separate fuel filter? Some filters can restrict flow. Check to see if the petcock filter is clean. Make sure there is nothing stuck in the carb upstream from the needle and seat. If all else fails you can raise the float level until it dribbles fuel when tipped 30 to 45 degrees. Boyesen sells a Super Bowl with extra capacity. http://www.ebay.com/itm/Boyesen-Supe...pWW4RC&vxp=mtr