Motorcycle Repair: Fuel / oil mixture, oil mixture, race bikes

Question
Rich,
I just purchased an older 250 elsinore not sure of year but early 70's 2 stroke. what is the proper fuel / oil mixture. The person i purchased from wasn't sure either. Can you help me out, starts right up and idles ok but boggy when you first start off. Want to make sure the mixture is right before I go any further.
Thanks / Barry

Answer
My second race bike was a CR250 Elsinore.  I loved that bike..light and very quick for that period. Compared to today's technology, it might as well have pedals but in their day, few race bikes could stay with it.  The oil to fuel mixture depends on the type of oil you are using.  If it Dino based use 20:1 but if it synthetic I'd start with 32:1.  You can probably go leaner but I'd follow the oil manufacturer's recommendations.

The bogging may be a  partially clogged low speed jet or a poorly adjusted float level.

Regards
Rich