I have been testing a 415 GP chain conversion for the 250 on my race bike. After 2 track days and 2 complete race weekends, the set-up appears pretty bullet proof. The chain has stretched less than 1 full index mark on the chain adjusters. That is about how much stretch I had with a stock chain on one race weekend, so....
It isn't o-ring chain, so I suppose if you wanted to run it on the street you would need to take good care of it and clean/lube it very regularly.
Anyway, one of my sponsors has the sprockets and chains. I don't know if I will get in trouble for posting it here, but this is the link to get them.
http://www.aftermarketcycles.com/fea...ocket-set.html
I have no affiliation. Just trying to show you guys where to get some cool unobtanium stuff for your racers!
TimO