Hi I am new to this, Last time I rode a trails bike was 1972, I found a nice old Aprilia 311 in good shape. Just a few questions to start, What fuel mix should I run in the bike? Is there anyplace in the Us that has any parts? I started it on a 50 to 1 mix seemed to run ritch, but everything seemed fine. There is also a engine compression adjustment device on the front of the engine, I have never seen one? Thanks for the help, Mark