I had a similar problem, mine would turn over all day but not start. It would start if I pushed it however. What it turned out to be was a crappy ground from the body to the engine. The starter was pulling so much amperage from the battery that the little that was required to fire the ignition system was degraded because of a bad ground. I replaced the ground cable to the battery but also installed an additional cable from the body ground point where the battery lead connects to one of the starter mount bolts. I also ran a new ground cable from the ignition coil/ic igniter to the body just for GP.