Dave,

You could use 104 but I'm skeptical as to how the solvents might affect the lines and tank. There are a lot of chemicals, including Acetone and Toluene, that can provide octane (we used it in Drag Racing) but can also damage fuel system components. I used 104 a long time ago in bikes and didn't seem to have any problems at the time as I remember but it possibly may also have caused crazing cracks in my old TY350 tank. I get race gas at the local motorcycle shop (unleaded) and mix about 30% to premium pump (93 octane here). You might ask around at the auto shops, a lot of car racers use race gas and some petroleum distributors also have race gas at their plants. You want about 95 octane so you don't need much race gas. If you retard the ignition, that lessens the need for octane and may work for you, and you might like the smoothness it provides too. I use 650cc's in my bike. I'd use 5W-30 instead of 10W-30, it will cause a lot less clutch drag.

Jon