bought a 1979 ironhead sportster on Ebay, nice bike motor runs great but whenever I take off in first gear and give it some throttle it pops into nuetral by its self. Any ideas on what causes this to happen?

 

Might be worn gears, have you tried changing your tranny fluid?

 

Tranny fluid isn't going to fix this problem. Either you have a bent shift fork (maybe), improper spacing or the shiftdogs are wore down on first or it's mating gear(most likely). Bottom line: GET IT FIXED BEFORE YOU BLOW THE CASES. Don't take offense to the yelling, I just want to get my point across. Take it to someone who really knows sporty transmissons and get it fixed. Transmissions on ironheads are their weak link. If it's not acting or shifting right it's trying to give you a hint. Good luck with it.