So despite everything I have tired for the starter clutch I was not successful in getting it working properly. It continued to slip. I bought new springs, new pins, and one new starter roller and I measured it and compared it to the other rollers.
I stumbled onto this thread (
http://www.xs400.com/threads/starter-clutch-modification.13334/) about a starter clutch mod. I tried to get with the person that built the modified mode over on the other forum about purchasing a modified clutch. The person never responded but based on one of the comments in that other forum it appears that the xv250 starter clutch was a very close match to the xs400. I verified this with some measurements I got off an aliexpress listing for a xv250 starter clutch from China.
So I bought this
xv250 starter clutch off of ebay and started the modifications.
I drilled out the threaded mounting holes on the new starter clutch bearing assembly with a 5/16 inch bit. Then I manually centered a 1/2 inch bit over each hole and slowly drilled down to drill out part inner circle part by the bearing. I then match drill, with the 5/16 inch bit, a starter divet with the assembly in place on top of the rotor just to mark a position for a new hole to tap. I then drilled that hole with a 17/64 drill bit and tapped it with m8-1.25 thread tap. I had to drill down the 1/2 inch bit lower into the new starter bearing assembly as you can see here:
I have only tapped one new mounting hole into the rotor as I just wanted to test this to see if it fixed my problem. If I had to do it again I would probably find 3 new mounting holes and just tap them in between the existing holes on the new bearing assembly. Reusing the existing holes puts the screw right on the outer edge of the rotor making it a bit hard to get a real good tap on it threads for that hole. I will post pictures of what that looks like underneath once I get back from taking my kids to the park.
Here is a video before the mod:
Here is a video after the mod: