Have you ever seen someting like this

Marylucky wrote:

But the slider seems to be ok, I don't think it's damaged.

As Sarah said, yes it is. In fact, it's toast and beyond even a temporary fix like I did with mine.

You can see it in your last pic:



Your red circle, where the damage is, is where your slider should extend up to. You can see the remainder of the right hand side of your slider in the right hand edge of the circle.

The damage to your slider is exactly like mine, except not quite as extensive. Half the slider is worn away, allowing the chain to contact the swingarm. In the pic below you can see my destroyed slider next to the new slider (which I then destroyed in about 20 miles). In the pic, the bottom of the slider is oriented towards the top of the picture. Notice that half of the leading edge of the slider is still there, just like yours, but most of it is worn away:



You have very little damage to your swingarm right now. But until you replace your slider, your chain will continue damaging your swingarm as the slider is no longer providing protection. You can probably continue to ride it with minimal additional damage (the wear isn't all the way back on the slider) now that you have new chain & sprockies and proper chain slack set. But why do that unless you need the bike for transportation.

A new slider is $33 from Yamaha Sports Plaza; but they had to get them from Yamaha first. I found that none of the dealerships stock them; they also have to get them from Yamaha first and then wanted $55. Maybe you'll get lucky being in Montreal and it won't take long to get your hands on one. But I'd get on that today, right now.

Changing it is simple. Take the bolt out, take the rear tire off to get max chain slack to work around, then work the old slider off to the rear and put the new one on the same way - I now have more experience doing this than probably anybody else. Sadly...

Of course, if you haven't greased up your swingarm and suspension linkages yet, now would be a good time to take her pants off and do that at the same time. If so, be VERY, VERY gentle handling those needle bearings in that MTH matrix and DON'T clean them with solvent - unless you want to tear the MTH right out of there to have bare needle bearings. You're on your own if you choose to do that... Just get as much of the old grease out as you can with gentle little wipes (here it will be useful to have girly fingers), then spend some time packing in grease, gently turning the bearing, pack in a little more grease, gently turn the bearing, etc. The idea is to get the needles to carry some of the grease into the space between them and the MTH. And carefully replace the collars as well - it is very easy for them to pick up and tear the MTH. DAMHIK.

Easy job. Just don't be hamfisted about it.