Shouldn't be too complicated to make a wiring schematic just for a start system.
You'll need a battery (obviously), starter solenoid (from a car), & a starter button or switch.
Mount battery in sled & connect 1 cable from Batt Neg (black) to eng ground.
Batt Pos (red) cable to 1 large post on solenoid.
Another red cable from other large post of solenoid to the starter.
Using about 12 ga wire (red), connect to Batt Pos to one side of a (momentary - normally open) starter button/switch. Other side of switch gets connected, using same type wire, to the small post on the solenoid. This circuit is used to energize the solenoid, which in turn will complete the circuit of the Pos cable from the battery to the starter.
A couple of qualifiers to this method:
1)The solenoid MUST be grounded to either the battery or the engine.
2)This method will not provide a charge to the battery, so it must be charged from other source (trickle charger) while not being used. To set it up to charge the battery from the engine, you will need a voltage rectifier/regulator and many other wiring mods.
3)You will still need to use the on/off key & any other safety tethers, just as if you were pull starting.
This is a very, very basic method to get the starter moving. I think there are others on this site who can/will add some details I may have left out.
Hope you get it to work!
