Formula 150 equipment rules

Bike and motor produced as 150cc or less four stroke air cooled two valve mini-cycle, no motorcycles. Maximum wheel size front 19", rear 16". Engine must use cylinder, cylinder head and main cases originally produced as 150cc or less fourstroke mini-cycle which may be modified in any manner not to exceed 150cc maximum displacement. No supercharging, turbo charging or nitros oxide.
No four valve heads, air cooled only.