[WINGNUT450R]

I have a 2002 39mm fcr carb from a KTM520exc.It has the tps hookup.Will I be able to use this carb on my trx450r and if so what about performance??I know the crf450r has a 40mm so I wonder if 39mm would be sufficient?Thanks

 

[nacsmx450r]

YES you will!!! I am using that same carb on my bike and it RIPS you have 2 options when it comes to the airbox. contact mark baldwin at www.baldwinmotorsports.com and tell him what you are doing, he has an adaptor to go to the stock airbox to the carb. Of you can you a 400ex airbox that fits perfectly. and just drill some holes on the side where the stock mounts go and you'll be ripping in no time.

 

[86atc250r]

When I switched to a 40mm FCR, I found that throttle response and low-mid power increased across the board.

However, I also found that I lost around a tenth on my 300' drag times.

Unsure if that loss represents loss of traction or loss of top end because of the smaller carb bore. My guess is a small loss of top end because my MPH also went down a touch.

All in all the quad "feels" faster across the board, from bottom to top -- but the drag strip timing system doesn't lie.

So, in the end - for general rideability - FCR = Good. For drag racing, do not expect it to help you much if at all.

 

[WINGNUT450R]

Thanks for the help,I also have a 41mm fcr off my 426ex without the tps hook up ,will I be able to rig it to be used on my 450r?

 

[86atc250r]

Not worth the trouble - you will lose the 3D timing curve.

With that you'll lose a lot of throttle response and introduce some stumbling problems at part throttle.