I am building a f2 engine for my f2 frame. I had a good f3 bottom end so I put my good f2 head on the f3 bottom end. I put the engine in the bike and wired it up but it would not start...not turn over or spark. The only wiring discrepancy I found was the speed sensor in the bottom end of the f3 that the f2 doesn't have. I know the electrical system for the bike is good because the motor I dropped out of it ran but had a bad valve tap and oil leak. I took the valve cover off today and checked my timing again which was fine...I'm at a loss. Anyone have any hints or suggestions???? I am new to cbr's so any help would be great!