ok I am wondering how much better it would be to change from a stock 04/05 kehien carb to a bored fcr like 41-43mm is there really going to be a big enough change that would be noticed for the price?? would like to see some numbers between different bored carbs???


this is for a 04/05 ported stock bore/stroke and all the usual other stuff.

I did it on mine and it really helps on the throttle response and i also gained 3 hp and it was one of the best parts i put on my bike

Do it. You will love the improvement.

thanks for the feedback

Now which is the better choice to buy if you're going to get it bored? The TRX 06 and up or the YFZ carb?

Some of these other guys will have more info on the best fit.
I do believe the 06 and up will have gas tank clearence issues.
I used a 03 CRF MX style. After installing a NOS adapter for the
intake to hook up. Everything else connected up. Including the
Hot Start. I love it.

Personally, I just could not install a Yamaha part on my RRRRRR.

By chance do you know which ones bore out larger?

the 39 yfz carbs can be bored to 44mm

do you guys know what all years of the CRF 450 carb will work on the 05 trx450???

I do believe all CRF carbs will work. Contact this Dude. Chad @ DRG, Phone #301-910-9850
The guy is a wealth of information. He will direct you in the right direction.