Transmission Gear Swap - Yamaha YZ250 3-4-5 WR4xx


First off, the part numbers for the new gears are as follows:

Gear, 3rd Wheel 5BF-17231-00

Gear,3rd Pinion 5BF-17131-00

Gear. 4th Wheel 5BF-17241-00

Gear, 4th Pinion 5BF-17141-00

Gear, 5th Wheel 5BF-17251-00

Gear, 5th Pinion 5BF-17151-00

There's a pattern, as you see, "5BF-17XY1-00". X= shaft# (main axle/drive axle[countershaft]), Y= gear# (3, 4, or 5).

If you want/need to replace the bearings, you can get the part #'s from Yamaha's web site and order from them or the TT-OEM store. TT-OEM is cheaper if you order all your gears (and bearings, if need be) from them.

I'll start this off presuming you dove in there and split your cases on your own. It's pretty simple, just undo every bolt you see. It's helpful to have a proper crankcase splitter to press the crankshaft out of the main bearings, but a steering wheel puller will work in a pinch. Even better if you're replacing the bottom end while you've got the cases apart (I'll cover that in another how-to). Then you can smack the crank out w/a hammer.:busted:

I'll also presume you have a manual handy. I won't cover all the intricacies that Yamaha does, though most of it is straightforward no-brainer stuff.

Without further ado:

Step 1: Look at your manual!

Get an idea of what you'll be doing. Check out the diagram and see the order in which the gears/collars/snap rings go. Compare the diagram in the manual to the actual gears on the shafts. The shift forks are individually labeled and pretty foolproof, they can be set aside for now.



Step 2: Lay out your new gears.

I recommend leaving them in the bags until they're installed to avoid confusion. I put my old ones back into the bags as well, just in case.

And yes, I know my 3rd wheel and pinion gears were on the wrong side.


Step 3: The front shaft (main axle). This is the one the clutch mounts to.

Using snap ring pliers, set to external, remove the first snap ring, then the gear. Repeat. I laid mine out in rows. Snap ring, gear, (next row) gear, washer (next row) snap ring, gear, etc...


Step 4: Once you've got the old gears removed, simply reverse the process with the new gears, minding the proper order of gears, washers, and snap rings.

The gear machined onto the shaft is 1st pinion. Next to it goes 5th gear pinion. The new gear is on the right, substantially more teeth.


After the 5th pinion gear comes 3rd gear pinion. The dogs on 3rd gear interlock with the grooves on 5th. This is part of the 'constant mesh' design. All gears are always spinning, however, the load is only transferred through the selected gear combination.


Next is 4th pinion gear. It has an internal collar that it rotates on, rather than the splines of the axle shaft. The way it interlocks with 2nd gear pinion provides the drive for the drive axle (countershaft).


It should look something like this when you're done.


Step 5: The drive axle (countershaft).


This one is a bit easier, as there's only one snap ring to deal with.

Pulled apart it looks like this, because we don't need to remove 2nd gear:


The order is the same as the other one, but backwards; 2,4,3,5,1, which makes sense because the gears need to mesh with their counterparts.

So, first we install 4th wheel gear against 2nd wheel gear. Once again, the new gear is on the right, 'face' up.


Next comes 3rd wheel gear.


Followed by 5th wheel gear.


Top it off with the stock 1st gear. Then lay the shafts alongside one another to check that the mesh is correct.


If that works out, set into the left side crank case with the shift forks and shift drum in place to confirm proper installation (and for a little practice). It may take a little wigglin' and finesse. Also, remember to dribble some oil (assembly lube) on the gears and especially the shift drum when putting it back together for real.


User Feedback

Great write up with clean clear pics, love it! I wanted to ask. what year range of YZs and WRs is this for. I am thinking of doing the 4th and 5th gear mod to my 2005 YZ250.

Share this comment

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

  • Similar Content

    • By SoCalMX70
      BRAND NEW in the box, still shrink wrapped, white Clarke tank that I bought for my YZ last year. I was going to go with the all white look with retro red graphics, but later decided against it. My loss is your gain! These tanks retail for $240.00 brand new.
      No pictures... It is literally sitting in the box it was shipped in, still wrapped! It's a stock white tank. Here is a link to the info on it if you need it:
    • By SoCalMX70
      BRAND NEW in the box, still shrink wrapped, white Clarke tank that I bought for my YZ last year. I was going to go with the all white look with retro red graphics, but later decided against it. My loss is your gain! These tanks retail for $240.00 brand new.
      No pictures... It is literally sitting in the box it was shipped in, still wrapped! It's a stock white tank. Here is a link to the info on it if you need it:
    • By Bryan Bosch

      Rockstar Energy Husqvarna Factory Racing Rally Star Earns Third Overalll at the 2018 Edition of the Event in Morocco
      April 20, 2018 – (Motor Sports Newswire) – Determined to wrap up his week-long adventure in Morocco on a high, Rockstar Energy Husqvarna Factory Racing’s Pablo Quintanilla has topped the fifth and final stage of the Merzouga Rally to secure a solid third overall in the event’s final overall standings. Continuing to make progress Andrew Short has claimed a spot inside the top 10 in the overall.
      Featuring a mass, motocross-styled start in the dunes of the Merzouga Desert, the fifth and final stage of the event saw Pablo Quintanilla put in a dominant performance. Posting the fastest time for the day, the Chilean rally star solidified his strong third position in the overall standings.
      Putting in his best individual stage performance Rockstar Energy Husqvarna Factory Racing’s Andrew Short crossed the line in eighth position. Wrapping up the Merzouga Rally 10th in the overall, the American is content with the progress he made during the week in Morocco.
      The Rockstar Energy Husqvarna Factory Racing Team will return to action at the third round of the 2018 FIM Cross-Country Rallies World Championship, the Atacama Rally in Chile on August 11/19.
      Pablo Quintanilla: “Today was a really fun stage. We had the motocross start and it was good to battle with the guys from start to finish. I got off to a good start but five or six kilometres into the stage I had a small crash that dropped me back a few positions. Then I had to push until the end and 10km before the finish I got the lead back and was the first to cross the finish line. It felt really nice to win a stage that way. Overall, I’m satisfied with my third position in the overall. This was a tough race with tricky navigation and to be on the podium is always good. We continue to gather experience and look ahead in the races to come.”

      Andrew Short: “I really enjoyed this week in Morocco. Especially this last day was really fun, bringing back memories from my days racing motocross. Before the flag dropped the nerves were there and I was maybe a bit late off the start. It was a good experience racing alongside the fastest guys in the dunes and being able to see their pace. The adrenaline kicked in and I had some really good fun. Overall, the week has been great for me. I enjoy the atmosphere in rally racing and I feel I am improving, getting closer to the top guys. I might still have a long way to go but I understand it needs to be done step-by-step. This week was a positive step in the right direction.”
      2018 Merzouga Rally – Stage 5 Provisional Classification
      1. Pablo Quintanilla (Husqvarna) 38:12 
      2. Kevin Benavides (Honda) 38:15
      3. Toby Price (KTM) 38:18
      4. Lorenzo Santolino (Sherco) 38:36
      5. Joan Barreda (Honda) 38:38
      6. Ignacio Cornejo (Honda) 38:54

      8. Andrew Short (Husqvarna) 38:56
      2018 Merzouga Rally – Final Overall Classification [Provisional]
      1. Joan Barreda (Honda) 13:28:19
      2. Kevin Benavides (Honda) 13:34:29
      3. Pablo Quintanilla (Husqvarna) 13:39:44 
      4. Franco Caimi (Yamaha) 13:47:08
      5. Ricky Brabec (Honda) 13:48:23
      6. Toby Price (KTM) 13:49:23

      10. Andrew Short (Husqvarna) 14:29:44
      Husqvarna Motorcycles. Tradition on two wheels since 1903.
      Husqvarna Motorcycles are widely known and respected in the off-road world for a heritage of competition and numerous motocross and enduro world championships. Originally founded in Sweden in 1903, Husqvarna Motorcycles have been designed and manufactured in Mattighofen, Austria since 2013.
      Rockstar Energy Drink
      Rockstar Energy Drink is designed for those who lead active lifestyles – from Athletes to Rockstars. Available in over 20 flavors at convenience and grocery outlets in over 30 countries, Rockstar supports the Rockstar lifestyle across the globe through Action Sports, Motor Sports, and Live Music. For more information visit:
      Source: Husqvarna Motorcycles GmbH

    • By chizznasty
      Do these bikes have a speedometer and/or hour meter form the factory?