In Reply to: 641 wont start (2020) posted by Mike in Michigan on July 11, 2020 at 08:21:21:
You are going to get a lot of advice to stop guessing and start troubleshooting. You are wasting money.
From the sound of it you should start with the ignition. Do you have an ohmmeter? You can pick up a cheap digital for around $15.00. Not the best but probably good enough to find your problem.
Meter in hand, measure the voltage to the coil from the switch. Should read full battery voltage. If not check the input from the battery to the switch. Check the wiring and battery cables. Are the battery connectors clean and tight? Does the cable to ground (tractor frame) clean and tight?
Next check the voltage on the wire from the coil to the distributor. If the points are open is should read full battery voltage. If the points are closed it should read about half battery voltage. Check both ways. If the points are open and you only read half voltage, check for shorts to ground within the distributor.
Post back after you have gotten this far.
Jack - Iowa