Is this a good idea?

[slosh13]

I recently rebuilt my 400ex motor into a 416. Im happy with it so far but im still running the stock carb and cam. Should i upgrade to a high-performance cam and carb? How much of a gain will a notice? I have been looking into the hotcam stg2 cam and an FCR39mm carb. Now i have also read numerous posts on here where the new 04 400ex's come with a 38mm carb instead of a 35mm. Has anybody tried this switch? I have also heard ppl tell me that i can use a yz426 dirt bike carb on there as well? I race mostly MX and the ppl i have talked to have said with the mods i listed make the 416 rip. Tell me what you think i should do. thank you. Im open to any suggestions.

[H_W]

I love my hotcam stage 2 and my 39 mm FCR carb. I wish I had went ahead and gotten the 416 kit instead of keeping the stock bore. I have plenty of top end and mid range power, I just wish I had a little more bottom end. I think the 416 with the hotcam stage 2 and the FCR carb would be awesome.

[cals400ex]

i am running a 11:1 compression 406 with the stage 2 hotcam and my bike is definately quicker than stock. i also have a x-6 exhaust, modded airbox lid, cdi box, etc. i don't have different rockers or anything else internally. if you don't want to spend the money on hard faced rocker, you will need a drop in cam. from what i hear, stage 2 is one of the most aggressive drop ins. you can't run hardened rockers with this cam, and many others as it will ruin the cam over time. i am running the stock carb so i can't comment on that. the only thing i can say is, make sure it is jetted right. i hear good comments about the power gains with the fcr carb. however, some complain about an instant hesitation with that carb. the difference i noticed with the setup:

i had a gutted stock pipe, air box mods, filter, and jets and a stock kfx with a sprocket 3 teeth smaller than stock beat my by about 10 atv lengths by the end of fifth gear in a race. now after the pipe, cam, and piston i beat him by that much.

you will notice a nice difference, but you will get use to the power the day the thing is broke in. i just get on mine now and think it is no different and i only have 3 tanks of fuel through it. :D

[stupid driver]

the fcr will help you in many ways.
For one, it will make the powerband a lot broader, it wont all be in the low end or top, but will pull hard in both.

2nd, it will seem like the thing will rev through the roof. A built motor and a carb will pull forever.

your throttle response will be killer also. Not to mention, this carb is fairly easy to jet. (easy needle and main jet access. you will want to buy a fuel screw from C&D racing though. Best 20 buks you can spend. )