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Discussion Starter #1
The bike is a 99 M750 with a 99 900 motor in it. Related mods include hi comp pistons, Sil Moto pipes, and a half opened airbox.


I am having one hell of a time trying to get my new FCRs to work properly. I went for a short ride across town and the bike seemed to work fine. Towards the end of the ride it wouldn't run unless I held the throttle at least 1/4 the way open. That night I parked it and decided not to screw with it until the next day. The next evening when I went out.. I had at least a gallon of gas on garage floor. I went to investigating and found that the vertical cylinder was full of gas... as was my crankcase. (Sounds like a stuck float, right? It would make sense that it was a stuck float seeing as my bike ran fine during the early part of my ride and then turned to shite toward the end.) I changed the oil and drained the bowls thinking there might have been a little piece of dirt fowling things up. I took the bike for a quick spin and everything seemed to work fine. As I pulled into my driveway the bike died suddenly. As I was pushing the bike the rest of the way into the garage I realized there was quite a bit of gas coming from the vent tube. WTF! I'm at a loss. I finally got around to taking the carbs off and dropping the bowls. They're spotless... as they should. They've got less than 150 miles on them. I pulled the floats and placed them in a bowl of water to insure that they did in fact float. I checked the valve operated by the floats and they looked flawless as well. (I added a new fuel filter when I installed the new carbs) What to do now?

When I had the carbs out on the bench I noticed something else. On the 'engine' side of the slide of the carb for the vert cylinder, I noticed that some type of grey coating (teflon, maybe??) is flaking off. What to do about this?
 

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Discussion Starter #2
I took a few pics of the coating flaking off of the slide....




The one of the right is flaking.... :-/
 

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Check your fuel pump, as dj found out, if the diaphragm is torn then it will allow fuel to flow freely into the intake manifold eventually filling up the carb. It acts like a stuck float too. with the carbs off, see if fuel is flowing into the manifold.
 

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Regardles of the fuel pump, the carbs should keep the fuel from free flowing. You've done everything that I can think of, check with Chris K., or the guys at Carb Parts Warehouse.
 

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Did you test the operation of the float valve? Meaning that you turn off fuel, remove float bowl, gently lift float by hand, turn on fuel supply, and no fuel came from float valve? Then you gently let float down to allow fuel flow ... gently move float up to stop flow ... etc? When my FCRs did their fuel flowing "trick", they "failed" this test. In my case, there was small piece of something like plastic baggie on top of float needle.

About the flaking... I would consider this "normal" but not normal for new carbs. If you'd like me to ask Sudco about this, send me an e-mail...

Chris
 

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Regardles of the fuel pump, the carbs should keep the fuel from free flowing. You've done everything that I can think of, check with Chris K., or the guys at Carb Parts Warehouse.
Hi Norm,

If the diaphragm in the pump tears, there is possibility of alternate fuel path which bypasses the carbs. In this case, the carbs have nothing to do with it. Fuel flows from tank to fuel pump to vacuum line that "drives" fuel pump to intake manifold to port to valve to cylinder and form there into crankcase and/or exhaust pipe.

Chris
 

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Ahhh, I forgot about the vacuum line!!
 

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Discussion Starter #9
I think I may have fixed my problem....

With the carbs out of the bike and with the bowls off, I hooked up a fuel line and checked each float for proper flow and shut off. For a few moments I just let fuel poor out of them into a clean metal bowl I had positioned underneath them. Low and behold a few tiny pieces of black rubber were lying in the bottom of the metal bowl after I shut off the fuel. I wonder if my fuel line is dry rotting somewhere. I've got plenty of new clear fuel line that I think I'll re-plumb the system with. I put everything back together and started the bike up. Everything seems ok at the moment. It was getting too late to take the bike out for a spin so tomorrow I'll take it out and see what happens. I really hope this works... I haven't been able to put very many miles on my bike (~150) since I put my new motor in. If all goes to plan, I'll be riding to the local showing of "Faster" tomorrow night!!! ;D

Thanks everyone for all the help!
 

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Right on MonsterJ. I would replace those lines just to be on the safe side, as pulling the carbs is not the 'funnest' of jobs.

Good luck! Oh, and I hate you for getting to see Faster ;)
 

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Right on MonsterJ.

Good luck! Oh, and I hate you for getting to see Faster ;)
Best movie of all time. I saw it twice when it was here in LA. If you live near where it is showing you HAVE to go and see it.
 
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