Originally Posted by 8gv
Thanks for the insight on this. Has some entrepreneur developed an alternative swing arm protector? I saw a pretty ugly picture of what can happen when the chain rubs there.
May have been my photo
And, now that I've gone through the experience, I think I've learned a bit. It happens most often to pure offroad based bikes and because the WRR's suspension and frame geometry is closer to an offroad bike, yet allows you to rack up lots of miles relatively maintenance free, it is susceptible to this. The rear suspension has 10.6 inches of travel...
The chain runs close to the bottom of the swingarm pivot. When the rear wheel hits an obstacle and moves upward, the chain gets even closer to the pivot, and on occasion will even rub against the protector. No problem, that's how it's supposed to work.
My belief is that swingarm damage can
1. Too tight of a chain.
2. A small (12 tooth) front sprocket.
3. A loose and poorly lubricated chain that has links that are kinked.
4. Too much weight on the bike (max. load rating is 408 lbs.).
None of these things alone are sufficient to cause swingarm damage, as there are lots of owners out there running 12 tooth sprockets, tight chains, loose kinked chains, etc. without suffering damage. I think the biggest contributing factor is a combination of one or more of these along with riding long distances with lots of obstacles.
Do I think this is a "design flaw?" Nope, it's a maintenance issue. If you keep the chain well-maintained, keep the slack adjustment correct, don't overload the bike, and stay with the stock 13 tooth sprocket you're not going to have this problem. I would buy a spare seal guard (Yamaha-ese for the swingarm protector) and take it with me on any long trips--it's a wear item.