Carburetor upgrade

[red200040ex]

Hello,
I'm looking for a carb upgrade for my 2000 400ex with 440 11:1 piston, stage 3 hot cam, CDI box, and the rest stock. I've been thinking either a 2004-2005 trx450r carb or an FCR from sparks racing. Thanks in advance!

[CJM]

04-05 450r carb gets my vote. I found it easy to tune and woke the quad up well. Its also WAY cheaper than the sparks FCR.

[Stickman400]

x2

[ish416]

I found the FCR extremely difficult and very finicky on its jetting. The 04-05 carb is where I would go if I had to do it again.

[JOHNDOE83]

04-05 450r carb deffinetly better for overall performance.

[red200040ex]

Very good, it's nice to hear from people who have tried both.

[WoodTRD]

My 05 42mm carb wasn't that hard to get on with the adapter and was a piece of cake to tune, my first plug chop was dang near perfect. I'd say it added just as much oomph as the 11:1 piston did, they worked perfectly together for me. Do you have an exhaust and filter/opened up airbox? More air and fuel in needs to be able to get out the other end to get the most from your motor...it all works together, and the little things add up, trust me!

[jhtrx250r]

I bought the sudco 39 fcr for my wifes , woke it up came jetted perfectly , it is a waaaay better choice than a OE 450r carb , it is made to fit right in the 400ex, no mods at all no hot start to mess with , dosent Evan have a choke , and seriously way more responsive than stock or the ones I rode with either the 04-05 450r carb or a retrofitted fcr, save your self time and money tuning and wasting time on your trips.
The sudco 400ex fcr is $800 but worth every penny. I'm not sure if it the same as the sparks but I think it is?

[jhtrx250r]

Just checked sparks site, same carb way better price , hands down buy that one , don't wast time on 450r carb retrofits .
Unless you get one for free have a dyno with a o2 monitors system and can find the proper parts to get it to fit at least half right , the spraks will drop right in and work like a champ , when the quads hot or cold , back I'm the day that's what the big boys used for a reason, just my 2 cents

[red200040ex]

To respond to WoodTRD; yes I do have a full exhaust, open air box, and a k&n filter. To jhtrx250r; thanks for the input, did yours come prejetted, and do you know if the sparks one will?

[AtvKid4Eva]

paying $500+ for a sparks FCR is crazy when you can find a good deal on a stock 04-05 carb for 1/4 the price and still see great gains.

[jhtrx250r]

yes the sparks should come pre jetted,the sudco and CPW carbs do come prejetted,and if you have any issues you can call them and they will tell you how to tune it

[red200040ex]

Okay thanks, I do like the fact I could just buy the sparks carb and put it on versus buying adapters and having to plug several things.

[CJM]

FWIW the sparks setup is very nice, but a 450r carb will cost you 1/2 if not less than the fcr sparks.

Sorry, but its a 400ex. Will you see good gains-yep, but you aint smacking a 450r nor are you gonna make high horsepower unless you got a stroker setup. And then why not just get the 450?

[odog]

sparks all the way it was worth every penny.to be honest with you i was mad that i rode two years with a stock carb that was rejetted because some companys and even my mechanic told me it wouldnt make that much of a difference.Needless to say i repeat i actually was mad at myself for going so long without it.

[red200040ex]

Odog, did yours come jetted accordingly to your quad?

[ds268]

Originally posted by AtvKid4Eva
paying $500+ for a sparks FCR is crazy when you can find a good deal on a stock 04-05 carb for 1/4 the price and still see great gains.

In part, ignorance is how they make money! 500 bucks for a 125-150 dollar carb is insane; especially if it's still 39mm! Jets and needles are cheap. Nothing that a dyno tune couldn't solve if tuning is needed for $125 ($275 total). Heck have a nice bore done for another 125 and you'll have a tits FCR still for way less.

Someone better sweet talk me off my feet to invest 5 bills into a stock bore fcr!

[jhtrx250r]

This will be the last time I comment on this thread, red20040ex just do some checking around with with performance shops you will get the real info on carburetors.
The sudco, sparks,cpw 39 fcr made for the 400 ex is the best carb you can get for it , the 2nd best is the edlebrock made for the 400 ex,
why? well its not a retrofitted carb from a 450r , why not a retro fit? well OE carbs have to pass emmisons and have many pointless devices to make them pass such as leak jets, causing the need for a hot stat or a pain in the *** when its hot button.
the after market fcr is a "racing only carb" so no bs , no hot start not even a choke it will show in in a box fit right in with no mods and work like a champ right out of the box .
the retrofitted fcrs require adaptors still dont fit right and are a pain in the *** to tune and get started when hot.
my 2 cents, as I have ridden all the diffrent options at the track.

[ds268]

Originally posted by jhtrx250r
This will be the last time I comment on this thread, red20040ex just do some checking around with with performance shops you will get the real info on carburetors.
The sudco, sparks,cpw 39 fcr made for the 400 ex is the best carb you can get for it , the 2nd best is the edlebrock made for the 400 ex,
why? well its not a retrofitted carb from a 450r , why not a retro fit? well OE carbs have to pass emmisons and have many pointless devices to make them pass such as leak jets, causing the need for a hot stat or a pain in the *** when its hot button.
the after market fcr is a "racing only carb" so no bs , no hot start not even a choke it will show in in a box fit right in with no mods and work like a champ right out of the box .
the retrofitted fcrs require adaptors still dont fit right and are a pain in the *** to tune and get started when hot.
my 2 cents, as I have ridden all the diffrent options at the track.

Glad that's your last post because I'm gonna say it's a bunch of crap. Sorry but "retrofit" with a cheaply fabricated adapter ring is a pain for you?? Give me a break. Spending 800 dollars for a simple fcr is worth every penny to you?? HAHAHA oh boy. If you feel that spending that much for a carb is worthwhile, they'll love you! Nothing against those companies that sell them either.

The leak jet was not designed for emissions but to allow adjustability in the amount of fuel in the accelerator pump shot. All it does is "leak" a portion of the fuel away from the pump. In some cases it's better to just plug it off.

Sorry if you're having such a pain doing what many others do without issues.

[CJM]

^ Agreed.

Given some effort i could easily make a yfz carb fit an EX. The trx450r carbs are a bit too high to make it work easily.

Like I said, 500 bucks for a carb? REALLY!!! Gimme a friggin break. If your gonna invest that much into a 400ex you will be sadly shocked when a stock 450r eats you alive. I mean unless (like I said earlier) your gonna do a stroker-and at that point why even bother when a 450r is still faster in the long run?

I understand your point-you like it and feel its worth it. But I were in your shoes Id buy a 450r in a heartbeat and not even bother with an EX. Funny, thats pretty much what everyone has done anyways.

I used to think the 400 was worth it, and dont get me wrong its a great quad. But its old dated technology and cant really hold a candle to a full out racequad like a yfz or 450r. It wasnt designed to even come close to them either.

[red200040ex]

Well I really appreciate the feedback from everybody.

[Cool Guy07400EX]

Hey man if you're interested I have a 450r carb all setup for a 400ex. It's even modified to use the 400ex throttle. Comes with some jetting mostly for a 440. Also a complete rebuild for the carb. I'd take 200 bucks! Let me know if you're interested.

[red200040ex]

Thanks for the offer but I since got a Keihin FCR carb and couldn't be happier.

[Cool Guy07400EX]

Right on man! Glad your happy with it. If you don't mind me asking, how much did you end up paying for it?

[red200040ex]

It was 510 to my door, and not bad considering it was all good to go and I was riding 30 minutes later.