Standard gearing works well on a pretty much standard (delimited) bike. It gives good acceleration and a reasonable enough top-end for sane road-riders. 15/40 is also good, the motor pulls it quite happily, and it will also increase your fuel mileage slightly, without too much compromise on performance. I am lead to believe that an X-ring chain is better than an O-ring, but keeping it clean and well-lubricated is the key.

For track and power potential, a cheap'n'cheerful non O-ring chain has seen a very slight power increase at the wheel on the dyno over a similar O-ring chain.

I personally use D.I.D. chains, but I think anything with a well-known brand name is much of a muchness... a bit like fully-synthetic 2T! They're all good, and down to personal preference.

Just buy any 520 chain with 110+ links, and shorten it to the required length. No problem using a split link on a 250. (15/40 and 15/42 both run with 108 links)
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Andy.
NSR-WORLD.COM

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