need suggestion: jetting FCR41 on XR600@644cc

anyone have suggestions about a good jetting of an keihin FCR41 flatslide carburetor installed on a '94 XR600R with 644cc, worked head, and open exhaust ?

my local dealer say:

needle: OCEM R

slow jet: 50, 52

main jet: 168, 170, 172 or 175

too much items to buy...

something more exact ?

I have my FCR41 set up this way on a '98 XR650L with snorkel removed, smog removed, UNI filter, WB E-series can with 12 discs and WB header, and I live basically at sea level:

Main jet..............#170


Needle clip...........5th position from top

Float level...........9mm

Slow air screw........1.0 turns out

Main fuel jet.........#200

Pilot jet.............#48

Idle mixture screw....2.5 turns out

It might be a tad lean on the main, I am going to try a #172 main.

wow... :)

thanks very much... I will try with this parametres

sorry I can't find the "main fuel jet" in the exploded wiew :).. can you help me another time ? :D



Oops! Main Air Jet, not Main Fuel Jet. Sorry about that.

Also, that diagram is for the FCR downdraft. Mine is a sidedraft, as shown at:

you are right...

this is the correct carb.. like the mine

this "main air jet" tou are talking about, what item number have ?

because on my FCR I don't find this nozzle.. :)

If you intend the item n°26, I can tell to you that on the mine nothing are writed on it :D


No, it's number 103 in the diagram I referenced on Sudco's site. It's inside the intake side of the carb, you have to take the intake bell (held on by two black allen screws) to get at it.

ok, this evening i'll check it

thanks another time.

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