For those with 440's, Which Carb?

[rob-u/21]

I have a complete Duncan 440 national kit on my ex. I currently have an edelbrock carb which was bored to an eichner series but I am sick of this carb. I have never been able to make it work good. I am ready to switch. Which carb would work best? I have seen some people go with a 450r carb which I can get a killer deal on. But I have always read great things on the FCR's. What would work better.

[440_Turtle]

I think that you will be fine with a 450r carb but you could always step up to an FCR carb also if you want a littel better response. I believe it has some special pump that puts raw fuel in teh runner for better throttle response. Im sure someone will correct me if im wrong. I have an FCR and love it, havent had any problems.

[GPracer2500]

Yea, FCRs have an Accelerator Pump. So does the stock 400EX carb and the stock 450R carb.

My first choice for a 400EX carb would be a Keihin FCR for sure.

[rob-u/21]

is there a big noticeable performance difference between the FCR and the 450r carb.

[jordan_m6]

the 450r carb just slips right in correct. without minimal work like the choke being removed. and is that the only thing that needs to be done.

[chapmanmd]

we have the duncan setup on my wifes quad. we tried an fcr but just like other quads, i was not smart enough or patient enough to get it setup right. Go with the 450R carb all the way. you wont regret it. If youre running high compression, big cam, etc like us, try the CR450F carb.

[dist5mxer]

what ever you do, stay away from the edel brock carb if you're not a patient person.

[honda460ex]

Unless you are running 3,000rpm's or above all the time and riding like your pants are on fire, go with the 450r. The FCRs have a natural hesitation on the low end because there is no restrictive air flow, it's a pure straight shot of air right thru. FCRs are meant for race use only, they even have it stamped on them. I have owned an edelbrock, 41mm fcr, and a 450r carb now. I love the 450r carb all the way.

[rob-u/21]

I think I will be going with a 450r carb. Is there any special mods that have to be made to make it fit? How are you guys jetting them? What do you guys do about the wires in this carb?

[F-16Guy]

There are a couple of companies that make billet aluminum adapters for the 450R carb. It makes the carb sit back a little farther so you don't have to modify the airbox mounts. I'm pretty sure it attaches to the front lip of the carb and is held in place with epoxy.

[honda460ex]

Mine, to make it work, I had to shave out a little rubber on the intake boot and the air boot both. No big deal. Get a drimmle and just go around it. It's still a tight fit honestly and can be a pain until you get used to puting the carb in, but it is possible and works great once your done. Now, the choke lever will need to be removed. I have known of people making a custom choke lever. I tried keeping the choke lever on mine, but it rubbed a hole in my gas line twice so I had to remove it. But honestly, I've never needed my choke on it. Even when the temperature was in the teens. Pump the throttle three times in the cold, crank on it and it will fire up and then die, repeat this again and hold a pinch of throttle to it. I usually turn my idle up until it warms up a bit and then turn it back down gradually. Works great! As far as jetting, I can't help ya... I'm running a 220 main jet with a stock pilot and needle position. Mine runs great! But I'm also running 13 to 1 compression, stroked, and msd ignition which sparks twice as strong as a stock ignition system. So don't go with my jet. Someone else help him out there....

[honda460ex]

Oh yeah, and the wires, don't worry with them. I zip tied mine up just so they weren't hanging down burning on the motor.