What carb to get or should I modify?

[JhallettEX]

I am thinkin about gettin a new carb after i do my motor work. I am goin with the 416 10.8.1 or 11.1 and a xr400 cam ( is there anything else i should consider to do while I have this apart) I also want to get a new carb, What will be better for me to do. FCR 39mm, Quicksilver or should I just modify my stock carb with sparks racing or is there someone else better out there? Also where is the cheapest place to by a FCR or Quicksilver. THanks alot guys.

The newest issue has a carb shootout that listed the 41mm FCR as the best overall. It's what I plan to go with FWIW. The tests were run on a hopped up 440EX, so it may or may not be the best choice for a 416, but I can't imagine it being too far off... not to mention that you'll already have the best choice when you resleeve and bore to 440 one day.

Soldier

[JhallettEX]

What issue is that in because i do not remember seeing it and I have looked through that mag about 100 times now. Anyone else with an opinion?

[NJ300ex]

It wasn't in dirtwheels. I believe it was in ATV sport.

[86atc250r]

41 seems too large for anything but a drag racing application with a big cam...

Look to the OEM high performance bikes:

YZ426F -- 39mm FCR
YZ250F -- 37mm FCR
KTM520 -- 39mm FCR
DRZ400 -- 39mm FCR
CRF450R -- 40mm FCR

All these bikes (with maybe the exception of the YZ250F) are going to be putting out more HP & turning more RPMs than most modded 400EX's.

The 41mm may put out better peak numbers, but I bet power is down below the peak...

Both the Edelbrock and FCR should put out good power - look at previous discussions about these two carbs advantages and disadvantages to make your choice.

If you want to make real power, forget the stock carb. Also, don't put much stock into magazine articles, too many factors influencing them....

...perhaps not. The other factors are, of course, the other mods done to the motor. The tests were done on a dyno measuring RWHP and to 41mm FCR was chosen because it was the easiest (tied the 39 FCR) to install AND it provided the best power increase across the ENTIRE powerband. I know how most (if not all) motorags will manipulate test results to favor the companies with the deepest pockets....but Keihin? Not to mention the so-so results that the 39mm received by comparison. Maybe not the results every engine setup can expect, but impressive nonetheless.

Sorry. I could've sworn it was Dirt Wheels, I can't find my copy to verify.

Soldier

[Dave400ex]

The Carb Shootout was in 4 Wheel ATV Action. I would get the 39mm FCR.

the 41mm fcr would flow way to much for the 416. You'd lose bottom end power. i'd go with the fcr but if your not good with jetting the quicksilver would probly be better for you.