Are all 41mm FCR created equal?

[barnapkin]

I have a set of 39mm (side-by-side) FCR carbs on my 900 track bike. Bike runs well, but would like to run the split carbs. The the shorter intakes will give me some additional top end. With 15/38 gearing my GPS sez it pulls a consistent 129-130 with my fat ass. I've already purchased the malosi intakes.

I see a lot of 41mm FCR carbs from dirt bikes out there on ebay. Is it possible to get two and rejet them vs. paying $1K for NIB factory set?

Are the dirtbike FCRs the same as the FCRs you see for sale for ducks?

[Iconic944ss]

I wondered the same thing but, all the dirt bike FCR's I saw all had Throttle Position Sensor (TPS) equipment on them so I decided against trying them.

I was going to say its possible to cut down a set of long OEM inlet tubes but you have the Malossi's already so, good for you!

Yamaha TRX850 also have an upgrade route of FCR's - I got a pair cheap via Ebay UK but the spacing is different, I've not know anyone use split singles on them sadly.

I've also vaguely remember a company converting dual FCR's to split single's and it was VERY expensive, like $300+

Good luck - Frank

[henk155]

the probleme is if you buy two FCR carbs from a dirt bike you will have two carbs that are designed for vertical cilinders.
if you buy the kit you will have a carb for a vertical cilinder and one for the horizontal cilinder.
it possible to set one of the carbs up for the horizontal cilinder but you gonna have to look good how you place it so that the bowl is not overflowing.

henk!!!

[wdietz186]

A cheaper alternative could be using Mikuni TM41 Pro flatsides. The low end and midrange response isn't quite as silky as the FCR's but they do work well.
The only real downside is the float level on the horiz. cyl. has to be low to cope with the mounting angle [to keep from overflowing] and if you are producing lots of power you run the risk of going lean if the fuel flow can't keep up. I ran them on my 900 for about 6 season with good results though.