any use installing 450 carb on ex or should i wait?

[shazzam007]

have a 400ex bored to 86 mm with 11:1 piston and hot cam stage 2. also mild port and polish on head , lexx slip on exhaust , header welds ground. the situation is that i need it ready to ride this weekend after having new crank installed but did not have time to go to the 88mm overbore im about to do. already have the 450 carb waiting for after the overbore. my question is whether or not it would be worth the time and trouble to install the 450 carb with my present bore or would i be just as well off to run with my stock carb already dialed in for the present setup? will i get any significant gain from the 450 carb with the 86mm bore ? anyone ever run a similar setup? sorry such a long question and thanks in advance for any feedback.

[CJM]

I would wait since you probably will have to readjust the carb once you get all the work done.

The 450R carb is worth it too. Its my next mod.

[slightlybent47]

I would go ahead and put it on, other then a $6.00 jet to adjust for the deference everything else should be the same. Your going to tinker with it anyway and the main jet is the one you’ll probably be adjusting and there cheap and east to install. I can replace one in about 3 minuets so it’s easy to do.
The biggest deference will be in throttle response, it’s a good mod and you will like it.

[supertrooper90]

i have the same setup as yours. the only difference is i have a sparks x1 cam instead of the hot cam and i have an fmf powerbomb header. when I put mine together i finished it the night before we were leaving for a long weekend. i decided to throw the stock carb on since i was familiar with it. I was impressed with the power over stock, but not really what i was hoping for. A few weeks later i went back to that track with the 450r carb on and all i could say is how happy i am with the build i did!!! Even my buddy with his yfz450 couldn't beleive how much better it felt. if you have the time to do it right i would do it you'll be happy!

[shazzam007]

supertrooper- how do you have the r carb jetted?a starting point would really be helpful. also what method did you use to fit it to the intake boot? and by the way guys this is the best forum out there........ ive really used it a lot on my journey with the ex!

[supertrooper90]

i have a 50 pilot 2 turns out and a 178 main i havent checked the plug yet but it ran very well I was running the 178 in the ex carb so i just switched everything over and seems pretty good