Everybody will tell you to go 30/1, but I have run an MC21 on track for many years, as well as RS125 and RS250 at 40/1 with no problems at all, Silkolene comp 2 on the nsr and Castrol 747 on the RS's, but realy any good quality oil in the nsr should be fine.
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Proud Father of , 05 ktm 400exc supermoto 2018 honda crf rx supermoto