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Replacing a rear wheel bearing on a Yamaha TTR250

It's a pretty simple operation. Just follow this step by step pictorial guide.

In this guide I am only going to replace the bearing on the brake disc side as the bearings on the sprocket side are perfectly OK. There are two bearings on that side but the removal and fitting process is basically the same although don't forget there is a circlip to remove first. This might apply if this guide is used to help change wheel bearings on other makes and models so take a good look before trying to drift out those bearings!

Tools needed:- wheel-nut spanner (24mm), plain screwdriver, 32mm socket or similar diameter item, drift with good edge, wire brush, piece of wood and a hammer.

Parts/supplies: 60/22 2RS bearing, oil seal size 28x47x7, grease.
 

Clear a space and get the bike up on a stand with the back wheel able to spin freely. 

First job is to get the rear axle out. If you use the spanner in the TTR's toolkit to undo (and replace) the axle nut then you know that you will be able to get the wheel out if you get a puncture on the trail. If you use a longer spanner from your workshop then you may use more leverage than you can undo  with the shorter toolkit spanner!
 

If the axle hasn't been out for a while you may need to drift it out with a hammer and block of wood. Put the wood over the threaded end of the axle to prevent damaging the threads. Once it has started to move it should be possible to pull it out from the other side.
 

Put the adjusters back on the axle and put it safely to one side.
 

Lift the chain to one side to allow the wheel to be removed.

The spacer can sometimes be difficult to get out. I used a proper bearing drift but an ordinary drift will do the job.

Prise out the old oil seal.

Next you have to displace the centre spacer enough to show an edge on the bearing to allow you to get a good hit on it with the drift.
 

The bike hadn't been used in a while and the following pic shows the damage from moisture.

Clean all the rust off the spacer and grease it well before replacing it.

It is now time to press in the new bearing. I used a 32mm socket. Be very careful to make sure the bearing goes in square.
 

After the bearing is fully home, it should be possible to push the oil seal in with your thumbs but fill it up with grease first. That doesn't leave any room for water.
 

Clean up the spacer and check that it isn't too ridged where the old seal rubs on it. This one was absolutely fine.
 

Grease it well and it should be possible to push it in place by hand.

Clean up the axle, grease it well and put it all back together.

Job done!

Brian Sussex