Having trouble getting spark on my '78 350 Honda single. New set of points still shows slight resistance when open. No apparent leak to ground. Does this matter or is the trouble elsewhere?
E
This motorcycle very likely has a flywheel magneto to supply the spark. With the points open, you are probably reading the resistance of the magneto coil.
Magneto, I wish! I include an era when everything of this kind (small engines)had a mag. As long as the points werent shot and were set right you were in business. Still, theres probably something of the sort you suggest. This thing needs a battery to run. I’ll parallel in another battery to make sure I’ve enough juice.
Thanks
Yea, you’re right, this model, XL350 I assume, does have a battery powered points and coil system, the points are on the end of the camshaft in the cylinder head.
You might very well read a resistance to ground when the points are open. The ohm meter current instead of going through the points flows through the ignition coil primary and then through the headlight/taillight bulbs to ground when the battery power is disconnected by the ignition switch.
Unplug the ignition coil’s 12 volt lead and then the points should read open to ground when they are open.
There are three possibilities here. You have a low battery, you’re kick starting this bike, right?
The coil could be bad, this includes the spark plug lead. Check the plug cap before buying a new coil.
The condenser could be bad. An open condenser makes for no or an extremely weak spark.
Oh yea, and make sure your spark plug isn’t simply fouled.
Put a car coil on that puppy and get some SERIOUS spark. “Universal” coils are available in 6 or 12 volt configuration…
12 volt car coils were meant to have a ballast resistor in series with the coil. If you go with that modification, be sure you wire in the proper ballast resistor or your points will not be long in this world.
Also, you will be amazed at how hard it is to find a good place to mount that larger car coil on a motorcycle. I have done it myself on a couple of different motorcycles for a stronger spark.
I got a 6v coil and condenser from a tractor supply (this is a 6v system), does the balast go in the high tension or primary circuit? I’m not familiar with using a balast resistor. I suppose its got to be 6v. In which case its back to the tractor supply, auto stores dont know from 6 volts anymore. We used to put car coils on Maico and Yamaha 250’s for better spark. Not much room problem with those, but on the Honda I was thinking I might mount it on the handlebars. Kick start, yes.
Erl