Re-Gearing a Yamaha 02 WR250F

I have an 02 WR250F that I have dual sported for riding to and from different trail systems in northern Michigan.  For the off road  (tight and snowmobile trails) ) I prefer the gearing and drive train of my stock YZ250F.  I could convert my YZF into a dual sport but the bike would only do about 65mph wound to the limiter. Ultimately I would like a YZF with an overdrive for riding the road to and from trail systems.

 

 I would like to change the first three or four gears of my WR to YZF gearing.  Along with changing the gearing I would also change the drive train to stock 12/48 with a 19 in. rear rim.  I want a dual sport bike that would  be trail friendly but also do a top speed of 75- 80 so I won't be winding it out on the highway at 60-65 mp

  •  Has anyone ever changed/swapped gears in the tranny?
  • Can I swap out 4 of the 5 WR gears with YZF gears?
  • With the changing of my WR drivetrain (12/54) to the higher drive train ratio of  YZF12/48 (best I can recall for drivetrain ratios), should I use a WR 4th gear as my final drive or a WR 5th gear.  For the final drive, the  WR 4th gear might not achieve the needed road speed (75-80mph) and the WR 5th gear might be too high (60 mph is achieved with just a crack of the throttle with the 12/54 - 18 drive train. 
  • What should I do.
  • Are there any other gearing recommendations to achieve YZF type gearing with an overdrive?

I do have the mechanical skills to disassemble and reassemble the entire engine and tranny.  If this at all possible, i need some engineering help or advice from someone who has done this to get it right the first time.

I can't answer any questions about swapping tranny gears but if you do put WR gears in I can tell you you'd be taching about 7k in 5th gear doing about 50mph with 14-51 sprockets. My bike had 13-51 when I bought it, but was just too buzzy on the street. I still don't like going over 50 mph for any length of time.

How would installing gears from a YZ-250F make the WR now overdrive-equipped?

I think the YZ has a closer-ratio transmission, with a taller 1st gear and a lower 5th gear, and it's a taller 5th gear you want for road cruising.

Why not just put a 13-tooth front sprocket back on as the 2002 WR-250F came with and mate that to a smaller rear sprocket?

A 2002 WR-250F came stock with 13/52 sprockets.

 

The bike I ride every Sunday is also a 2002 WR-250F and the trail loop I ride uses stretches of paved road to connect the trails together.

Being only a 5-speed and with a pizza-sized 52-tooth rear sprocket, it is geared low for any kind of normal street use, so I merely putt along at 35-40mph.

In my estimation, if I wanted to run with typical traffic comfortably, I'd need a 47-tooth rear sprocket, anyway.

Of course, the off-road gearing would suffer.

I've never heard of anyone running 12/54 gearing before.  I have 13/52 on my 01 WR250F and first gear seems almost too low.  Try the stock gearing and 60 to 65 mph won't be a problem. 

add a 290 kit a 1 larger countershaft sprocket and your problems will disappear. Easier than swapping gears too.

 

Seriously, 3rd gear in both of your bikes is the same.  1-2 and 4-5 are the differences . 

Edited by vents

I have swapped gears and currently running a 2011 yz 250 f with a wr 3rd 4th and 5th.  I am running a 13/49 gearing.  80mph in the dirt is probably a stretch, my bike cruses down the road at a purr at 40mph.  The Wr ran two sets of gear ratios.  01 and 02 had the tallest 4th and 5th gears, I believe after 03 4th and 5th are not as tall, I run the gears from a 07.  If you take the gears from a WR 01,02 you can get away changing 4th and 5th,  If you take the gears from 03 or later you must change 3rd, 4th, 5th, because they have more engagement dogs.  If you want more info on this send me a private message and you can call me I do not like to type.

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