I am rebuilding an all-original running 1977 YZ80D for my daughter for a Christmas present. Wondering, when I check the Service Data Sheet on the Yamaha site, for fuel type used is says only "Premium." It's an old 77--- is it supposed to take LEADED gas, or is UNLEADED fine? And, I'm gathering I have to mix 2-cycle oil at a ratio of 20:1. I'd like to verify this and know whether I can use UNLEADED...thx in advance. r.

Leaded/unleaded is meaningless in this instance its a stroker so there are no valve seats to damage, i would say that as its a race bike it means run on the full fat 98ron super unleaded. As for the oil, if thats whats on the data sheet then that would do for me.....