Keihin FCR: overflow tube necessary?

I have a Keihin FCR carb with a broken fuel overflow tube (which goes from inside the float bowl through the bottom with a hose connected to it).

I can repair it, but I also have a backup float bowl - which doesn't have such a overflow tube.

Can I just switch the float bowls? Therefore, do I really need the overflow tube?

Thanks! :p

I feel less stupid now, since there are no replies yet :p

No one? :thumbsup:

The float bowl requires venting in order to operate properly.

The float bowl does not have a vent tube. The little tube that comes out of the bottom of the float bowl is for draining the float bowl. If the next time you want to drain the bowl you just stick a tuna can (which is what I do) under the carb and loosen the drain screw, you can just ride it as is.

You do have two vent tubes, one on each side of the body of the carburetor. If you are referring to one of those, it's a different story.

Thanks for the reply, guys.

But no, the tube I'm talking about is not about venting, and it's not the drain tube (only 'FCR MX' carbs have a drain tube) (this is about a 'FCR' carb).

Here's a pic of the bowl and overflow tube I'm talking about:

DSC03269-2.jpg

Some FCR carbs have such a overflow - other's don't. So my idea is to use one without, but I'm not sure if this carb needs one (since it originally has one).

Edited by FrankV

Jeez... now I feel stupid because I see that the picture shows the same overflow tube that my bike has and it drains out the same place that the bowl drain does. I don't think you'd want to run without one but, I couldn't say for sure. I can't imagine an FCR carb without an overflow drain. Maybe your alternate float bowl has a different type of drain port?? You probably looked for that already.

If you don't have an overflow drain, then I would imagine that your bike would have to "eat" any excess gas in the bowl until it returns to the proper level.

Maybe I should've posted this pic a little earlier for clarity :p

I believe the FCR float bowl without overflow is used on these 'sets' of 2 or 4 racing carbs. Then, since they appear not to need an overflow, why would this one need one. Questions, questions... :thumbsup:

Eddie?

I would think that a dirt bike that hits all of those bumps and jumps is gonna need an overflow tube more than a streetbike that rides on smooth roads.

with out the over flow if the carb floods it will go into the motor. thats the only risk.

I would add, Or if the bike is tipped over" The object of the overflow is to dump the flooding fuel onto the ground rather than into the engine!

Also we have 1 or 2 things there

1: To the best of my knowledge they all have the overflow, that is the brass tube that sticks up to above the fuel level

2: Some have a drain screw on the side to drain the bowl, when the screw is loosened gas in the bowl flows out the same hose.

they dont all have the over flow. the float bowls on aftermarket slant body fcr do not have it.

Thanks for the reply's! :thumbsup:

Just FYI: here are 2 pics from a float bowl without overflow tube:

DSC03591.jpg

DSC03592.jpg

Thanks for the reply's! ;)

Just FYI: here are 2 pics from a float bowl without overflow tube:

DSC03591.jpg

DSC03592.jpg

did you install this one? and do you have the full part number? I am in exactly the same situation

Dude, 6 year old post....

did you install this one? and do you have the full part number? I am in exactly the same situation

I didn't install it, I found one with an overflow tube, in the end.

Hi guys!

I had the imprudence to break the float bowl of FCR39  carb.

can anyone have?

4bc511g0044.jpg

On ‎22‎/‎11‎/‎2010 at 4:05 PM, NemadjiMan said:

These must be pretty rare I'm after one as well with the overflow tube as mine was split,manage to cut a new bit of brass tube and JB weld it in as the fit is a touch loose, but I don't think it will hold up long term so if any one wants to sell one with overflow please pm me

 

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