Join Date: Aug 2005
Location: Orangeville, Ontario, Canada
1 Check battery condition, use a volt meter and Hydrometer to verify each cell. Charged and OK VDC 12.5-13.xx after sitting a couple of hours, S.G. at 1.2+. Voltage reading at 12.xx and higher does not = good battery, the cell condition must be checked because you can have voltage but no amps
2 Check the condition of the big wires and connections, any failing connection and that includes wires = too much resistance = too little push of current
3 Check the condition of the main and auxillary contacts on the starter relay. The contact must be good and complete, the whole contact is used to carry the large amperage at starting. Anything less than good contact = no start, poor conductivity, the starter draws 100A to torque over motor in cold condition. Minimum voltage during start up is 10.xx volts
4 Check grounds and main cables along with stud connection at starter, any failure = start problems
Before rippng apart verify the above, tools needed: Good volt ohm meter and the ability to understand the readings. A $10 hydrometer and knowledge how it works. Your senses to feel smell and see and knowledge to differentiate the input.
If the things listed in above are OK, then diagnostics to verify that each component works and in the proper order ie. kill switch, starter switch, in neutral, neutral switch.
Still problems and you are positive everything above checks out now look at the starter motor.
Take motor out, but remove battery + and - connections, check to FAQ for how to. The motor is a DC series wound so running it under no load does no good. In general is it clean if not clean it out, check brushes for length and if they are stuck, check commutator for segment spacing undercuts, check the ground connection, could be burnt from years of use.
Motor field coils should be cleaned and all copper checked for scrapes nicks, cuts, the com may have to be machined round. Bearings checked and spacers verified.
Check overall condition annd check for voltage leaks with a megger or a good DVM. To test run the shaft must be hooked to a load, a motor shop, any good rewind shop can test for you. It is a simple motor but strong by design.
If everything checks out electrically you may have a mechanical problem!