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Mrmonk7663

Carb spilling fuel please help

15 posts in this topic

I installed my carb today. Turned the fuel on and fuel started spilling out the vent tube from bottom of carb bowl at a steady rate. This was with bike not running. I took the carb off and with float hanging I blew into fuel line and air went through. I pushed float up and blew and no air went through...so the float and needle are working. I also noticed that the vent tube on the bowl is attached to some long rod that goes way high into the carb. So what could be causing this. Thanks everyone.

Mike

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most likely your float is sticking open. if it moves freely it may have a pin hole and be filling with fuel so that it wont "float" and shut the fuel off:ride:

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Also keep in mind that you checked that it seals, but did you check the height? If it's set wrong it will still overflow.

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No the float height has not been checked. I don't know how to do that. Can u explain? Thanks.

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This is a fairly common problem in older FCR carbs and is often due to a deteriorating O-ring around the float needle valve. They are easy to replace. These are very specialized Sudco O-rings, and sometimes difficult to find separately without buying a whole fairly expensive new float needle/valve assembly. Yamaha shops have these O-rings available separately now. We had one go out at Spangler Hills last week and the Honda shop in Ridgecrest,CA had them in stock in Yamaha labelled bags at $5 each.

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Only problem is that the needle valve is brand spanking new along with the main jet pilot valve needle float bowl accelerator pump and diaphragm by accel pump :-(

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ok. I just took the float off and the needle valve. What Oring are you referring to? There is none visible. The needle valve has the viton tip but I see no oring . I can see a bronze needle vavle seat but this is NON removable. Parts diagrahm shows an oring under the seat but again the seat is non removable in the 2004 Carb. Thanks.

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The O-ring is on the needle seat. I am sure that the needle seat is replaceable on all FCR carbs. The needle seat is held in by a retainer. Unscrew the retainer, pull out the needle seat and replace the O-ring.

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My needle seat on my 04 doesn't come off. I even took it to yamaha and called Tokyo mods too. They said some years has "pressed in" non removable seats. There is nothing to grab on to unscrew this seat. I tried before when I was rebuilding this carb :-(

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The needle seats are no l9nger removable since '04 I believe, so the O-ring leak isn't the issue. I think if you go here http://www.yamahaownershandbook.com.au/?r=0 and download the service manual for your bike you should be good to go for the float height setting, which seems to be your issue. If you have it set too high it will not seal and you will overfill the float bowl. WR Dave

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My needle seat on my 04 doesn't come off. I even took it to yamaha and called Tokyo mods too. They said some years has "pressed in" non removable seats. There is nothing to grab on to unscrew this seat. I tried before when I was rebuilding this carb :-(

I didn't realize there was this difference in carbs. The FCR carbs I am familiar with are on KTM's, although the repair needle seat O-ring used had a Yamaha part # on the container.

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There is nothing to grab on to unscrew this seat. I tried before when I was rebuilding this carb :-(

Pull.:thumbsup:

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I'm having an issue similar to yours. Lets us know how it works out for you.

I will start a new thread with my question to keep from hijacking yours. Good luck.

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I didn't realize there was this difference in carbs. The FCR carbs I am familiar with are on KTM's, although the repair needle seat O-ring used had a Yamaha part # on the container.

The Yamaha Part# for the O-ring is: 8 F2-14147-00

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