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So I have been working on my girlfriends 08 1100 for the past few weeks. She bought it with somewhere around 500-600miles on it less then a year ago. The bike sat with the previous owner, Since getting the bike up and running the bike now has about 1400miles on it. I pulled the carbs off of it as down low and idling the forward cylinder wasn't firing.

When I pulled the float bowls we learned that the bike had hex bolts already installed in the carbs so its been opened before which is where the problems started. I disassembled the carbs cleaning the seats and jets, after that the bike ran beautifully and still does. But I have no idea why they were messing with the carbs before us and she bought the bike at a ridicules low price. I did not touch float height while inside the carbs.

Now for the issue, After riding if the fuel is in the "on" position it will flood the bike out. Its only a problem on the Aft cylinder and will develop a pool in the airbox elbow in front of the carb. Also it will fill the aft cylinder up entirely with fuel, We learned this coming out in the garage to find a strong fuel smell accompanied by a few drips of fuel running out of the exhaust. I pulled the spark plug to find it soaked, rolled over the starter and it was like a geyser with the amount of fuel in the cylinder. After cleaning up the mess, checking the oil which has some fuel in it, and getting it running we ran it out of fuel and this is where I am at.

Its been so long since I have torn into a mikuni carb, I am going to pull the carbs again and check float height as its something that stands out to me that could be the cause. What confuses me is the fact it has a electric fuel pump so I don't see how it could be gravity feeding unless that pump is only to assist. Am I on the right track here or should I check something else?

Thanks in advance.
 

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I had the same problem as you last year. gas was leaking from the main jet needle into the rear cylinder and flooding it out while riding. when the bike is shut off the leak stopped because the fuel pump is off. I found this out by removing the rubber elbow in front of the carb and turning on the ignition. as soon as the pump kicked in it started leaking. I put a new needle valve and seat assembly for the float in and the problem was solved. https://sites.google.com/site/vstar1100kb/ this site has all of the info you will ever need to maintain and repair the 1100 vstar. if the link wont work then look for it else where on this forum.
 

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But its leaking with the engine and pump off is why I am confused. It runs and drives fine, just when you leave the fuel on with the engine off it fills the rear cylinder up with fuel. Thanks for the link though, I am reminded every time I work on her bike why I enjoy EFI lol.
 

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It may just be the residual fuel in the bowl and what ever amount continues to flow until the pressure is relieved off the line. No matter where it is coming from, the only way fuel can leak through a carb. is if the needle/seat are leaking or not closing completely. Personally I wouldn't worry so much about how it gets there. Replace the needle and seat and it should stop leaking.
 

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But its leaking with the engine and pump off is why I am confused. It runs and drives fine, just when you leave the fuel on with the engine off it fills the rear cylinder up with fuel. Thanks for the link though, I am reminded every time I work on her bike why I enjoy EFI lol.
Yeah...EFI is OK...but I'll always prefer carbs. When you abuse an EFI bike like that 1100 was..... by leaving fuel in the tank..... it's going to be VERY expensive to get it running again, and perhaps not even worth the price to fix it. Carbs are simple and cheap, but you do have to know what's going on.

My guess is that the needle/seat is letting fuel by. That's the only check vavle for fuel in the system on a carbed bike.

If you want to know why it's doing it with the key off, it's really pretty simple. The fuel system is pressurized to 3-5 lbs. Jut because you turn off the key, everything from the pump to the carbs still has 3-5 pounds of pressure.....it doesn't all magically disappear just because the key is off. If the needle/seat isn't working right, it'll keep pushing fuel until everything fills up...or it runs out of pressure.

I'm not there to look at it to know anything for sure....but my guess is that a couple 5EL-14107-12-00 needle valve sets from Mama Yama for about $15 a pop will get you going....
 
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