450r carb jetting

[Quad Dude]

ok i need help with the jetting on my 450r carb on my 400ex
all i got is pipe 11:1 piston and web cam if any one with close to the same mods has a 450 carb could you tell me what your running

[Honda5]

I would like to know also, I'm putting one together now (13:1 ,stage3 hotcam , and porting)

[Mobile Dyno]

I have a 440ex with 12:5:1comp, White Bros. XC Cam(same as the web), and airbox lid off. I tuned my 450r carb on the dyno. I'm running the carbs stock pilot, stock needle setting, stock mixture, and a dynojet 170 main. If you have a standard bore you might want drop one size on the pilot, needle in the 2nd clip from top, and if you put a keihn(sp) jet in I would do a 160 and if you put a dynojet jet in I would do a 165 mains. Where do you live because elevation will play a big role in your jetting?

[Quad Dude]

i live in south west wisconsin along the mississippi. i dont have very many jets i got 165 175 178 keihn but i can get more. how many turns out on the fuel/air screw are you. i had it running on the carb but idle high then low and would back fire. so i tried a few thing and it got worse so i gave up and decided i would ask on here.

[1fast400ex]

i tried a 450 carb on my 400 never could get it rich enough dont know if somethings wrong with the carb or what. yes i searched over and over for a air leak. any suggestions would be greatly appreciated

[Mobile Dyno]

Try 2.5 turns out on the mixture screw, needle in the 2nd position from top, and a 165 main. Also, did you plug the Hot Start opening?

1fast400: did you jet the carb from the stock 118 main? if so what did you use?

[dirteater74]

Once you get this thing jetted correctly can you post some results like if you noticed an improvement over stock? I have a 400 for my second bike and been wanting to do some improvements to it. Would this upgrade help with a stock 400 or just compliment engine work? Sorry for the hijack but since we are talking about the same thing I thought this would be a good place to ask.:)

[Quad Dude]

ill try what you said as soon as i can. what should i plug with the hot start hole with? it is the hole on top near the front. correct

[Mobile Dyno]

Yes, it is the fitting that the hot start cable attaches to in front, on top of the carb(black fitting with a rubber end or dirt seal). . I plugged mine is silicone. Something to keep the dirt out. Just to let you know I do not have any problems with this setup. No problems on starting or riding.

[Quad Dude]

would a 60 pilot jet be way too big i just took it a part to see and i thought it was a little big im going to try the pilot out of my stock ex carb

[Mobile Dyno]

Originally posted by Quad Dude
would a 60 pilot jet be way too big i just took it a part to see and i thought it was a little big im going to try the pilot out of my stock ex carb

YES:eek2: Don't go that big. What size did you say you had in now?

[1fast400ex]

yes i rejetted all the way to a 225 then started drilling jets up to 1/8 drill bit

[Quad Dude]

i put in a 40 pilot jet and it runs decent but back fires alot when you let of the gas. what should i do?? the plug is a golden brown color

[honda92]

i'm gonna be screwing around with mine this weekend, what pilot jet is everyone running? mine seems to run alright with the stock 450r pilot. i put in a 52 pilot and that seemed a tad rich, sure started nice when it was 15 degrees though lol. still waiting on the hmf exhaust, i havn't really spent too much time on it so far.

[Mobile Dyno]

Quad Dude, Try coming out another turn on the A/F screw to richen it up. How many are you at now? Did you ever try a 42 pilot? How does the rest of the carb feel like 1/2 throttle and full throttle. Does the bike run good, no hesitation at these postions?

[honda92]

alright i screwed around with mine for a couple hours today. its 14 degrees and i found a 50 pilot jet gave a nice tan color. i left the needle at the stock location and ran it half throttle and killed it, didn't really leave any color. so i went 1 notch down (richer) and ran it around at half throttle for a bit and then checked it and there still wasn't really any color. i also put a 168 main jet in it and i cant get a tan color. it pulls really good down low, midrange, and full throttle. just a little confused because everyone is leaving the needle in the stock position, do i have something screwed up? any ideas welcomed. thanks