WR vs YZ transmission in a 290

[dmozer74]

I’ve done some searching, but can’t find quite the right answer, I’d love some opinions. I bought a project 2006 YZ250F and picked up a 290 cylinder and piston. Included with that purchase was a low hours WR transmission. I’ll be mostly riding trails with a little track time. Probably 75/25. I have to split the cases as part of the repair. Which transmission would you put in?

[nuity5]

     It really will depend on your specific area and type of riding. I have a 03 YZ250F with a 290 kit and have ridden it with both transmissions. I ride technical, tight enduro to hs style trails with very little MX.  

     Each of course have their advantages. The YZ transmission is to me better for a little more open trail / woods situation. The closer ratio setup makes easier to pick the “right” gear to be in. I swapped to the WR transmission to make it better to ride between trails around my house. I have 3 areas I ride that are separated by a couple of miles of power lines / highway between each. If I dropped a few teeth on the YZ setup then first was a little aggravating for the tight / technical stuff I do.

     When I first swapped to the WR transmission fifth was basically an overdrive to cruise down the road. However it was tough to ride because of the bigger jump from gear to gear. After a few months I got a sprocket setup that works great for me and now I love the WR transmission. To me it makes for a very flexible bike. 

     My advice would be WR transmission, get sprockets worked out, 290 kit of course, spend some time to get jetting perfect and as much flywheel weight as you can get. I actually run a WR flywheel from a 01 / 02 for lights and it helped quite a bit with stalling and luggability. This makes the tight stuff fun again. 

     Sorry for the long ramble. If you have any specific questions I’ll be happy to answer. Clay

[dmozer74]

That’s a great response. It’ll be mostly tight single track in Colorado. I’ve been looking at the absolute heaviest weight from Steahly, which is 13 oz I believe. And I’ll be putting in a JD Jetting kit. What gearing did you end up running? Any recommendations on cams? I was planning to run stock for a season and then replace with Hot Cams next winter when checking valves again.

[HORSEPOWER35]

I have ridden both trannies as well. To make a long opinion short, run the close ratio!

[HORSEPOWER35]

Oh, I completely disagree with flywheel weight on a 250f in co. You will want every bit of throttle response and h.p. You can get out of that motor. This is also why I like the close ratio, especially on a 250f.

[nuity5]

I wound up with 12 / 50. I run stock cams, ported head and a 03 450F CDI. The 290 setup won’t make power as high in the rpm range as the 250 so I focused everything on bottom end / midrange torque. Colorado is definately different riding than SC though! As HORSEPOWER35’s post shows your question will  have riders on each side and there were definately things I liked about the YZ transmission also. Look at it this way, if you can do the work yourself it’s not the end of the world and costs very little money to swap transmissions later if you want. Clay