fcr 41 flooding problem

popup · Dec 7, 2009

tell me o knowledgeable ones...
i have a fcr41 mk1 on my old 01 fe650.
i have always had trouble starting the thing when it has been flooded,for instance if i layed the bike over on the side of a hill.
starts not a problem,1st kick hot or cold,but flooded not a hope of getting the thing going, in any less than 40-50 kicks.
on my old xr600,all i use to do when it was flooded, was kick it through 1/2 a dozen times with the manual decomp in while holding the throttle wide open , then next kick it would start.this old girl just wouldn't clear itself.
take a look at these pics of my fcr,i'm thinking there should be an overflow outlet on each side of the carb at where i am pointing with the zip tie,cause there ain't none on it.
what cha recon?
..weed..

Taffy · Dec 7, 2009

no. your problem is the float valve. pull the float valve out and then remove the philips head that holds the female housing in the carb body. pull it and you'll see a rubber 'O' ring that fails to seal when they get older.

regards

Taffy

ned37 · Dec 7, 2009

ya, what taffy said. my mkI only has the bowl vent tube.

husabutt · Dec 7, 2009

When prepping my 450 for this desert season the carb kept overflowing out of one of the tubes when I filled the tank. A couple of taps with a screwdriver on the float bowl helped but did not stop the stream completely. After riding it for awhile it stopped. I had left the taps open during the summer with a little fuel in the tank so as not to gum up the jets. Could this be a symptom of the o-ring starting to fail?

popup · Dec 7, 2009

thats strang?
yep,i replaced the needle & seat & o-ring that seals the seat to body of the carb less than a year ago.thats all good.float level is set to what the kehin manual says, that is shut off at 11mm below ,from where the bowl bolts on to the main carb body.thats always worked fine for me,as long as i don't lay the thing over.
so i'm taking it all kehin fcr41 mk1's has no carb overflow.
if the needle & seat sticks it just pours straight down the intake flooding the engine?
it has nowhere else to go... so it has to.
like husabutt just said with his 05 model being a mk2 fcr41,thats what the overflow is for,at least its pouring out on the ground until the carby is tapped (to unstick the needle).
think i better have a good look at a mk2 fcr.
i can't believe knowone else has this problem with the mk1.
then again i've always been a bit different.
maybe you blokes never come off??
..weed..

bushmechanic · Dec 7, 2009

I have a yz400 with that carby

the overflow comes out the bottom of the bowl through one of dem brass tubes that runs up past the flaots that sits above the normal fuel level

maybe you could put one in ?

it also has an external hot start that I have to use to start it after I come off, usually takes a few good yanks but it happens

its just a tube that lets air into the intake boot by bypassing the carb, runs from the airbox to the intake boot.

maybe one of those would do it ?

do you run carb breather tubes off the lil upper vents?

ned37 · Dec 7, 2009

so i'm taking it all kehin fcr41 mk1's has no carb overflow.

my fcr mkI has a bowl vent tube that comes out of the bottom of the bowl just aft of the drain. according to your pics, yours doesn't. i would pull off the bowl and start blowing on passages inside the upper part to see where the vent might be. its got to have one or the bike wouldn't run.

bushmechanic · Dec 7, 2009

ok dirtyest carb pic comp

bottom black tube is the overflow

upper brown ones are the vents, the vents on yours must be working somewhere like ned said

Chas · Dec 7, 2009

I prefer to fun the float level in my FCR carbs 2mm lower than stock.

Taffy · Dec 8, 2009

there has always been a discrepancy over the actual float height and where you measure too. anyway - 9mm is what they ASK for but husaberg measured different to keihin and others.

regards

Taffy

popup · Dec 8, 2009

thanks for responses lads.
although i do hear you on the different float levels,i have tried different heights in the past & still do believe that isn't the problem.
i think these fcr41 carbys are made to bolt on to dirt bikes as well as roadies.
i think ,as far as i can see,probably the only difference between a road bike fcr & a dirt bike fcr would be the fuel bowl.
the carby that i have would not be a problem on a road bike,cause they don't get layed over,as dirt bikes occasionly do.
knowing the price of kehin parts i think i might drill & tap fittings into where i was originally thinking.if it don't work i will just have to put a plug in & buy a different fuel bowl.
yeah, the vent tubes was the 1st check i done,they were all good,there is 2 of them,little brass fittings,one either side of the carb,up near the "k"for kehin.
..weed..

fcr 41 flooding problem

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