i have a 65 metrakit puch with a 15mm bing, tecno bullet pipe and a stock airbox. i'm using regular oil for my break-in period, then i'll switch to motul. i use an ngk b7hs plug. but what octane of gas should i be using? i know this is a somewhat tricky issue, not just a more-expensive-is-better thing . . . so what octane?