What could have happened

Just picked up an 84 LT185 ATV, I understand there was an accessory add  on that gave it electric start, anyone have any info about that kit? 

2008 400 big bear was running now will not start
have power to relay, in neutral, press start have power to starter but nothing happens starter does not turn
i have good ground at battery to frame and added ground from wire harness to frame beside batter/ frame ground
blue white wire to cdi has power with key on
I believe the neutral lock out is working since is was before i shut it down
if i put  it in gear and hit the start button with key on the relay does not click or send power the starter
The 3 wires at the relay have power with key on
What should i test next?
thanks ahead

Hi guys, I have a 2004 big bear 400. Last winter while plowing the driveway, I heard a loud pop from the left side of the engine. It continued to run as I looked for leaky fluid, but then died shortly after backing it up and won’t start now. The oil light comes on when I try to start it, no noise or anything else. 
No blown fuses that I can find.

What's a good size to start a 10 year old on?

The one I need to replace has a 2 wire plug coming out of it. Searching eBay I see tons of them with only 1 wire . WTH???