1994-2001 Yamaha YZ125 Swingarm Rebuild

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1994-2001 Yamaha YZ125 - Full Swingarm Service Rebuild With Torque Specifications - Featured
1994-2001 Yamaha YZ125 - Full Swingarm Service Rebuild With Torque Specifications - Featured

How To Service The Swingarm On Your 1994 Through 2001 Yamaha YZ125.

Service Notes:

  • Since you are removing the back part of your dirt bike, make sure it’s strapped down tightly.
  • Remove the rear wheel and brake caliper, but you do NOT need to disconnect the brake line. Just slide the caliper off the swingarm and hang it on the frame.
  • This is a good time to service your shock linkage, so loosen the pivot bolt and connecting rod bolt now, while you still have leverage.
  • I have the walkthrough for the Yamaha YZ125 rear shock linkage rebuild HERE.

The Tools You Will Need:

The only specialty tool you need is bearing driver, which you can make out of grade 8 hardware and sockets. When you see what I’m using, you can easily make your own.

Depending on your level of corrosion, you may also need a torch and hammer, like I did.

The Parts You Will Need To Service Your Swingarm:

Swingarm Removal

  • Loosen and remove the swingarm pivot bolt nut. Mine needed to be hosed down with PB Blaster, but you might get lucky.
  • Push the bolt into the frame, then pull the bolt out while jostling your swingarm.
    • If your bolt is stuck, you will need to beat on it with a sledgehammer and punch, then buy a new bolt because yours is now mushroomed. But I wouldn’t know anything about that!
  • Drop your swingarm back, and remove the shock linkage pivot bolt.
1 Loosen and remove the swingarm pivot bolt nut. Mine needed to be hosed down with PB Blaster, but you might get lucky.
1 Loosen and remove the swingarm pivot bolt nut. Mine needed to be hosed down with PB Blaster, but you might get lucky.
2 Push the bolt into the frame, then pull the bolt out while jostling your swingarm.
2 Push the bolt into the frame, then pull the bolt out while jostling your swingarm.
3 Drop your swingarm back, and remove the shock linkage pivot bolt.
3 Drop your swingarm back, and remove the shock linkage pivot bolt.

Pre-Service Cleaning

  • If you ride your dirt bike in the dirt, now is a good time to clean up your swingarm.
  • A simple degreaser and stiff brush will work, but a pressure washer is where it’s at.
4 If you ride your dirt bike in the dirt, now is a good time to clean up your swingarm.
4 If you ride your dirt bike in the dirt, now is a good time to clean up your swingarm.

Yamaha YZ125 Swingarm Disassembly

  • With your swingarm nice and clean, start disassembly by removing the chain guide.
  • Before you proceed, mark your swingarm so you know which side is which
  • To keep things organized, grab two shop towels and label them left and right, as the bearing pack is different on each side
    • I am working on my swingarm upside down, so I have my towels arranged Australian style.
  • Start removing the collars, washers, seals, and thrust bearings, and keep track of how they are arranged.
  • If your bearings are corroded like mine, you might need to use heat and picks to get the old needles out. Whatever you end up using, just be careful not to damage the bearing bore.
  • Your swingarm bearings consist of two needle bearings with a gap in the middle.
  • Assemble your bearing driver, and drive the bearing race out of the swingarm in the same direction.
    • Mine weren’t, uhh, cooperating, so I had to get violent.
  • Wrap up the old parts and set them aside; you will need them later.
5 With your swingarm nice and clean, start disassembly by removing the chain guide.
5 With your swingarm nice and clean, start disassembly by removing the chain guide.
6 Before you proceed, mark your swingarm so you know which side is which
6 Before you proceed, mark your swingarm so you know which side is which
7 To keep things organized, grab two shop towels and label them left and right, as the bearing pack is different on each side
7 To keep things organized, grab two shop towels and label them left and right, as the bearing pack is different on each side
8 Start removing the collars, washers, seals, and thrust bearings, and keep track of how they are arranged.
8 Start removing the collars, washers, seals, and thrust bearings, and keep track of how they are arranged.
9 If your bearings are corroded like mine, you might need to use heat and picks to get the old needles out. Whatever you end up using, just be careful not to damage the bearing bore.
9 If your bearings are corroded like mine, you might need to use heat and picks to get the old needles out. Whatever you end up using, just be careful not to damage the bearing bore.
10 Your swingarm bearings consist of two needle bearings with a gap in the middle.
10 Your swingarm bearings consist of two needle bearings with a gap in the middle.
11 Mine weren’t, uhh, cooperating, so I had to get violent.
11 Mine weren’t, uhh, cooperating, so I had to get violent.

Cleaning And Inspection

  • Clean the swingarm bores and check for burs, cracks, or deformation.
  • You can clean and inspect the pivot bolt at the same time.
    • Wrap your pivot bolt in sandpaper, and hold it while you spin it with a drill.
    • Start with as coarse as you need, working your way up to 600 grit and steel wool.
  • The pivot bolt does not have a specified runout tolerance. So, as you spin the bolt in your hand, if you feel vibration from the rotating bolt, it is bent and needs to be replaced.
  • Smooth the swingarm bores using the same drill method, using sandpaper taped to a screwdriver handle.
  • Then finish up with a Dremel, if you have one.
12 You can clean and inspect the pivot bolt at the same time.
12 You can clean and inspect the pivot bolt at the same time.
13 Smooth the swingarm bores using the same drill method, using sandpaper taped to a screwdriver handle.
13 Smooth the swingarm bores using the same drill method, using sandpaper taped to a screwdriver handle.

New Yamaha YZ125 Swingarm Bearings

  • Install your bearings one side at a time.
  • Match your new parts with your old parts.
    • The left and right bores have different stacks, with the left side having an adjustment shim and washer.
  • Assemble your bearing driver and install your new bearings flush to the bore from each side.
14 Assemble your bearing driver and install your new bearings flush to the bore from each side.
14 Assemble your bearing driver and install your new bearings flush to the bore from each side.

Apply Bearing Grease

  • Your bearing set might come with a tube of grease, but I don’t think it’s enough. I suggest getting a tube of EP moly grease.
  • Start by greasing your needle bearings.
    • Pack the bore with as much grease as possible; that’s why the gap is there.
    • BE CAREFUL when applying grease to the needles. The grease is sticky, so if you lift off the needles, they will come with you. So ALWAYS drag your finger out of the bore.
  • Grease and install each part as you go.
  • If your seals have a lip, pack the lip with grease and install the seal lip side in.
  • With your bearing pack installed, wrap the ends in a towel.
15 Your bearing set might come with a tube of grease, but I don’t think it’s enough. I suggest getting a tube of EP moly grease.
15 Your bearing set might come with a tube of grease, but I don’t think it’s enough. I suggest getting a tube of EP moly grease.
16 Start by greasing your needle bearings.
16 Start by greasing your needle bearings.
17 With your bearing pack installed, wrap the ends in a towel.
17 With your bearing pack installed, wrap the ends in a towel.

Bonus Inspection

  • While your swingarm is off your bike, inspect the axle adjustment bolts and replace as necessary.

Yamaha YZ125 Swingarm Installation

  • Remove the towel wrap and install the chain guide.
  • Grease your pivot bolt, and set it inside the frame just enough that it won’t fall out.
  • Align your swingarm and install the pivot bolt.
  • Grease and install the Pivot Bolt Washer and nut
  • Torque the pivot bolt nut to 63 ft-lbs.
18 Remove the towel wrap, and install the chain guide.
18 Remove the towel wrap, and install the chain guide.
19 Grease your pivot bolt, and set it inside the frame just enough that it won’t fall out.
19 Grease your pivot bolt, and set it inside the frame just enough that it won’t fall out.
20 Align your swingarm and install the pivot bolt.
20 Align your swingarm and install the pivot bolt.
21 Use a dead blow hammer if you have one.
21 Use a dead blow hammer if you have one.
22 Grease and install the Pivot Bolt Washer and nut
22 Grease and install the Pivot Bolt Washer and nut
23 Torque the pivot bolt nut to 63 ft-lbs.
23 Torque the pivot bolt nut to 63 ft-lbs.

If you have any questions, please let us know!

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