Good day all. I’m having an issue with my big bear 1989 it’s been running great but now I can’t get it to start without the battery booster pack hooked up runs great till I shut it off. New starter, carburator solenoid and battery. Not sure what to do love the beast but getting me down as I replaced so much and still needs the booster pack to start

 

Check all connections, be sure they are squeeky clean and tight. Then check your battery, even if a new one, sounds like you might have an internal short in your battery.

 

ive checked both batteries on my daughters and works great. I was thinking maybe the stator/generator

 

Even if the genny was bad, a good battery shoukd still crank it over. When a cell shorts out, the battery may show an almost full charge but when a load such as a starter is put on, the battery drops voltage instantly. Take your battery to an auto/battery shop for a load test, normally free.
The next thing ro look at, is the starter under a heavy load, mabey tying up or failing that would cause a heavy drain on the battery?