question for the Motards

hey people,

i am planning on doing the conversion soon on my '14 wr250r

i have a question for those who have motarded their Wr250r or ride a wr250x

1. what size sprocket do you use on the back ? (i will be goin to a 17" rim, i know the overall wheel diameter will be smaller)
1a. did you do this because of the wheel diameter or for other reasons ?
2. did you upgrade the the front rotor ?

I have not made a WR250R into a WR250X, but I have owned both bikes.

1) On my WR250X, I used a 49-tooth rear sprocket.
I felt that gearing ratio was ideal for the power output and characteristics of the engine and transmission.
Gear spacing from gear-to-gear felt very good, and I easily cruised at 50-60 mph and had a top speed of 80 mph.
I felt that was pretty impressive for a 250cc single-cylindered bike.

1a) I went with a 49-tooth sprocket for the obvious reason:
The stock rear sprocket has a WR250X ridiculously over geared (too tall), and I believe this was in order to pass some sort of drive-by sound test conducted during the pre-production phase of the bike by the Yamaha factory, not because the stock sprocket was the best choice for performance.

2) If converting a WR250R to a WR250X, I would MOST DEFINITELY change to a motard-spec front rotor AND caliper.
I felt the stock brake setup of the WR250X was very good.
I also felt the stock brake setup of the WR250R while on the street was on the average-to-weak side.
I believe the easiest way to do this is to buy or trade your WR250R parts for WR250X parts - front wheel, wheel spacers, front wheel axle, brake rotor, caliper, brake line, master cylinder, fork guards.
Install some new HH-rated pads, and ride.

I've done it. Just yesterday in fact. I went with 13/46 gearing on the 17" rims. I also opted for the whole WRX front hub/caliper/disc setup.

It's an excellent little conversion. I dont think you can go too far wrong between 46 and 49 teeth rear on the 17" rim, bike feels veeery different from the WRR setup. In a good way of course :)