I rebuilt a quad 17057504 for my hobby stocknew shaft bushings and all the set up as described in Cliffs book, and upon completion in my shop reved fine, on my road very slight hesitation at part throttle thought we would correct it at the track. next day out of the pits ok but on the track for hot laps it lost all get up and go. Idled off the track into pits. Thought it was ignition but is not. out of gear, not under load revs fine but, anything else no balls. The first test run was very satisfactory, any suggestions where to start. I put another one on that I built and is fine