As I mentioned yesterday, I had a problem with the modified swingarm that made it pretty much unusable. I could have done a lot of work to realign the swingarm pivots that are now misaligned due to the distortion caused by welding in the reinforcement plates. It would have taken a LOT of effort and the results would have little chance of being good. This is because I have no easy way of insuring the straightness of the swingarm as a whole. It's probably better that I found the swingarm pivots were misaligned because that tells me the other end of the swingarm is misaligned as well. And that could cause handling problems that would be hard to diagnose. Those thoughts and the rapidly approaching track season made me want to move on with the show, so here's what I did:
I still needed to position the engine so that the rear mount would be aligned with the axis of the swingarm pivot. I thought about moving the engine forward 30mm and just living with the extra chain length and its effect on the swingarm. But if I did that I would have had to make pretty much all new engine mounts.
What about just removing the rear mount?
I found that (on the XR650R) the rear mount area is separate from the parts of the engine that are lubricated by oil by looking at pictures of case halves online. My next thought was to take the entire engine to work and machining off the rear mount on the mill. Because I wanted to leave as much material as possible, I wanted to make a cut concentric with the rear mount hole. I realized that a hole saw with a bore guide would do the trick. I went to Home Depot and bought a 1.5" hole saw and a 5 inch long bolt. Back at home I drilled a 1/4" hole through a 3" long piece of 1" diameter dowel. The dowel was just slightly larger the the rear mount hole, so I chucked it up in the drill press and sanded a bit off the diameter. This would serve as the bore guide for the hole saw:
Cutting through the rear mount:
Done:
Cleaned up and motor installed for a test fit with nice clearance for an unmodified swingarm:
The welder did a very nice job on the upper shock mount:
Starting to look like we're getting somewhere:
