The 200 models have come with either a N427-BFQ or -BFP in recent years, but I don't know if that is a good choice for your SR model. What other differences were there between it and US models? :think:
I've also tried a -CCN, but both of my first 2 rides with that needle have been in a few inches of snow, so can't really make any comparison with the stock BFQ. It did seem kinda sudden above 1/4 throttle, which may work well for your MX interests.
Hopefully acutemp will drop in as he seems to have an assortment of suggested combinations.