Leopard Starter Motors

[Bryan W. Joplin]

Starter motors experience three types of failures, brush wires, armature bushing and armature windings.
All three result in the starter either not working at all, or not having the ability to turn the engine in complete cycles.

Brush Wire Failure

The braided brush wires fail at the carbon brush due to vibration. Some karters reduce the failure rate by gluing the wires with silicone, to the brush holder and starter housing. I eliminated the braided wire and seldom have brush wire related failures. If you prefer OEM equipment, talk to your local kart shop. I understand IAME may have improved the wires and install procedure to reduce the failure rate.

To eliminate the braided wire, wait for your first wire failure. Or if you are into prevention, take a good brush and cut the wire at the brush. Using 22 gauge sheet metal (plus or minus, thickness is not important) fabricate a connector that will fit between the brush spring and brush. This connector will look like a small shovel, with the spade end rectangular and the dimensions of the end of a brush, and the handle a metal extension from the spade. The spade should easily fit between the brush and spring and travel unrestricted in the brush holder. The handle of the shovel should fit through the slot designed for the original brush wire. Make the handle long enough, so it can be rolled over to form a crimp point for a new wire. Even though the new wire will be crimped at this point, this joint should be soldered. Using stranded wire (approx. 14 gauge) fabricate a new wire of proper length between the brush holder and internal electrical connection. This one hour repair will significantly reduce brush wire failure.

Armature Bushings

The starter uses a two piece brass bushing at the opposite end from the commutator. Over time the bushing wears and falls out. Check this bushing anytime the starter is disassembled. Check the sides of the armature for drag on the magnets. A worn bushing will allow contact between the magnets and armature, reducing motor power. After market replacement bushings are available.

Armature Winding

Armatures do go bad, even if their physical appearance is good. If you are having trouble with a starter, and you have checked the battery, wires and bushings, the armature is suspect. Wire the starter to a battery and compare its sound and speed to a known good starter. The bad starter will spin slower and draw fewer amps. If this is the case, replace the starter.
According to the manufacturer of aftermarket starters, the main cause of armature failure is bad, or poorly charged batteries. A poorly charged battery will increase the cycle time to start the engine, draw more amps and increase heat in the starter armature. Heat ruins starters. Try to keep engine cranking time to a minimum. Re-charge your battery every time you come off the track. (sounds crazy right) The starters are very voltage sensitive. I have a starter that will crank the engine well, if direct wired to the battery with heavier gauge wire than the wiring harness. The lower gauge wiring harness, starter solenoide and various connections create enough voltage drop to make the starter erratic. I re-charge my battery between races, and it is still going strong after 3 plus years. I know racers who have had several batteries in this time period and starter issues.

Low amp trickle chargers will not properly charge the battery. The battery needs that last small voltage increase to make the starter spin fast. This can only be achieved with a full size 12v auto type charger.

Bryan