400 EX with a 450r carb

[skipjack]

can anyone tell me what the size difference of a 450r carb verses a 400 ex carb. if i install one, will it make a big difference or not.

[curious george]

the 400ex is a flat slide 38mm but the 450R is a 42mm big diffrence with a biger bore now you will have better reaction but the gas tanks fillings will dissaper real quick lol

[curious george]

but if you go with a 426 or a 440 with a cam and exhaust you will screw 450's in the trails and dunes straights they will still have you because 450's transmissions are diffrent gearing. this is all in and if you want to have a awsome 426 or 440 that will make 450's cry then the carburater all plays a part in this roll:D hope i could help with my rambling

[underpowered]

Originally posted by curious george
the 400ex is a flat slide 38mm ..........

correct on the size, but neither carb is a flatslide, both carbs are round-slide carbs. 400ex is a 38mm and the 450r is a 42mm.
it makes a huge difference, throttle response is great adn power is increased across the board.

[curious george]

oops i ment to write round slid sorry:confused:

[skipjack]

will a 450 carb bolt right on or is there a big difference between the two carbs.

[underpowered]

if you do a search, you will find step by step on how to install it. you have to ream out the intake boot (carb to head) some to get it to fit as well as heat the airboot (airbox to carb) to stretch it over the carb as well. it is a fairly easy install with great results.

[phildogg]

does it help even with mild mods?
phil

[Rico]

Stock 400ex carbs are 35.5. The 06 400ex's I believe come with a bigger carb, reverse and different gearing but all other year 400ex's are 35.5, mines been bored out by sparks racing to a 38.

Yes it's a huge difference in power stock or worked motor.

[underpowered]

Originally posted by Rico
Stock 400ex carbs are 35.5. The 06 400ex's I believe come with a bigger carb, reverse and different gearing but all other year 400ex's are 35.5, mines been bored out by sparks racing to a 38.

Yes it's a huge difference in power stock or worked motor.

:confused: huh? my stock one off my 2000 400ex is a 38mm, says it on the parts fiche and measures out to be a 38 (well 37 and some change)as well

[Rico]

Originally posted by underpowered
:confused: huh? my stock one off my 2000 400ex is a 38mm, says it on the parts fiche and measures out to be a 38 (well 37 and some change)as well

YOu measuring the inside diamater???

[premiumtommy]

here a bunch of links to people whom already done the mod

http://www.exriders.com/vbb/showthr...rb&pagenumber=2

http://www.trx450r.org/forum/index....opic=4150&st=30

http://www.exriders.com/vbb/showthread.php?s=&threadid=160988

and here is a link to a great price on a dynojet kit for the 450r carb

http://cgi.ebay.com/ebaymotors/HOND...67537476

[skipjack]

will a dynojet kit for a 400 work on a 450r carb or are they different

[Rico]

Originally posted by skipjack
will a dynojet kit for a 400 work on a 450r carb or are they different

Good question.

I thought I read that you could use the 400jet kit but I'd like to know for sure also.

[Mobile Dyno]

You don't need a jet kit for the carb swap. I just needed to bump the main up on min. The needle and the pilot were on with the A/F. Just put a K160 in if you run the airbox lid off. What do you plan to do?

[Buffalo400]

mine suck with a stock pilot jet and I try all fuel screw setting(400cc motor) and Puff black smoke with a 50 pilot jet...... So I will try with a 45 pilot jet and I wish the motor run fine...... I'm sure he's rich because he run fine when the motor is warm and when he's hot, he runs like sh%?.

[Mobile Dyno]

Yea, I forgot to mention to put in a 45 pilot if its a stock bore. I have a 440 and the 48 pilot is perfect.

[skipjack]

so pretty much jets are jets are jets. If I have a 170 jet on my 400 carb it will work in a 450r carb -- right. and if a stock 400 except for a few mods ( pipe, air filter, etc.) i should run a 45 main in it -- right.

[Rico]

Originally posted by Mobile Dyno
You don't need a jet kit for the carb swap. I just needed to bump the main up on min. The needle and the pilot were on with the A/F. Just put a K160 in if you run the airbox lid off. What do you plan to do?

I've got a velocity stack intake tube from GT Thunder in mine, 2 inch hole basically. I guess I'll get the carb in first and see what the jets are in it. Should be all stock. Then order a new pilot and probably 2 mains.



OH yeah, Dynojets between the 400ex and 450R are NOT the same. I checked this weekend.

[skipjack]

so i can not use the same jets, but by reading through these post i can put a 45 pilot and a 170 main in and be pretty close. i wouldn't have to buy a new jet kit. is this correct.

recap: i'm considering putting a 450r carb on my slightly modded 400ex. i will have to buy a 45 pilot jet and a 170 main jet. i will then put in on using the instructions provided on this thread. i will have to modify my choke a little and it will run better. is this accurate?

[Rico]

Originally posted by skipjack
so i can not use the same jets, but by reading through these post i can put a 45 pilot and a 170 main in and be pretty close. i wouldn't have to buy a new jet kit. is this correct.

recap: i'm considering putting a 450r carb on my slightly modded 400ex. i will have to buy a 45 pilot jet and a 170 main jet. i will then put in on using the instructions provided on this thread. i will have to modify my choke a little and it will run better. is this accurate?

Your motor will need what ever Pilot and main that it needs to run right. Just because someones has a 170 does not mean yours will. Jetting sucks and has to be tweaked to work properly.

[skipjack]

thanks to everyone for all the info. i am going to give it a try. i will let you know how it works out

[mach5racing4]

So will a 400ex jet kit fit a 450r carb? anyone know

[skipjack]

In previous post in this thread, someone check on it and said no.