Motorcycle Repair: broken ring gear, domed pistons, fxstc

Question
Hi, Help,
1994 fxstc, domed pistons,srm egle heads running about 10:1 compression. starter was not working. new fully charged battery. removed old stock starter, tested. solenoid tested bad.About 45000 miles on bike. ordered a new aftermarket starter. 1.4kw installed correctly. examined coupler,jack shaft gear, splines all parts seemed to be in good shape. Stared the bike fine on first try. second start, bad sounds. removed primary found jackshaft gear broken and many of the teeth on ring gear destroyed. Cleaned up the mess. replaced ring gear, jackshaft gear. Had others check my re-assembly in accordance with service manual. Every thing put back according to specs. Same thing happened again. First start good, second start destroyed same parts again. The new starter that I bought came complete. It bolted up flush and seemed to sound and act very strong when I started the bike. Would appreciate any thoughts.
                                       Thanks KBm

Answer
If your timing is to far advanced it will do what you are describing. Also, make sure the jackshaft is sliding back in when you let off the button. Last, check to make sure the end of the jackshaft slides in the bushing on the primary without binding.
Good luck and happy riding
Mike