My bike commando MK11 roadster 828cc has been garaged for some years. My young some wants to attend an event with his Dad on Norton. Only had one problem ballast resistor. Now after sorting that it was running well but after it starting first time for a few days it has stopped. Thinking it was the resitor again I replaced it -no joy. I then had varying output from the coils so I borrowed two coils from a friend after checking the resistance on the secondary windings they were both 2.6 Ohms same as the two that came off the bike- no joy. I Put both plugs on casing and cannot get spark. I currently have 12.5 volts to both sides of both coils which reads minus 12.5v. I have cleaned the points now I am stumped. Can anyone help? I can't imagine both leads to plug could be faulty. The wiring to the coils is currently 1 yellow & black and one white and black to each positive side. White and violet to both negatives of coils. Help
Help no spark
- Thread starter Lochnagar
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Lochnagar said:
If there's voltage reaching the coils and points then you should be seeing some sparks at the plugs?
Can you be certain the replacement coils you fitted were the correct type to use with the ballast resistor (two Lucas 6V 17M6 or similar coils with approximately 1.6-1.9 Ohms primary resistance)?
Did you disconnect the wires from the points? If so, are you sure you haven't refitted the points wire ring terminals directly under the nuts (which would earth them) instead of fitting them under the insulator so they rest against the points spring.
The points havn't been tampered with other than light cleaning with emery. I was puzzled with the coils because the manual stated the coils would measure out below 2ohm for 6v coils and 3ohm for 12v coils. The coils I obtained I measured at 2.6 ohm and the ones that came off the bike were the same. I wanted to change them because one coil had 12v either side and the other 12v at one side and only 1.7v at the other so my assumption was one of the was faulty. Also after leaving the ignition switch on for 5 mins or so I found the coil with low voltage at one side to be quite warm as was the ballast resister however the other coil was cold. Its a puzzler now I have blown the 35amp fuse so finding another won't be easy. The bike was running fine and starting first time but I came out in the morning and no spark.
DogT
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Not a good idea to leave the ignition on, current is going through the coils and balast full time, will drain your battery quick and also pit the contacts in the ignition and kill switches. Don't forget at that low ohmage to remove the leads Ω which can add up to .5 Ω or more, even 1 or more depending on the leads. The good leads on my Fluke 189 are about .15Ω.
Dave
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Dave
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Lochnagar said:
In your first post, you said 2.6 ohms was the secondary resistance (measured between the + or - and the HT output) which wouldn't be correct.
Lochnagar said:
But the reading depends on whether the points are open or closed.
Lochnagar said:
Yes if the points were in the closed position then the coil and ballast resistor will start to get hot if the ignition is left switched on.
Lochnagar said:
You don't keep any spare fuses?
The old 1-1/2" "35A" blow (17.5A Continuous) glass fuses are available from most British bike shops or online from auto electrical suppliers such as Vehicle Wiring Products and others, and you can always replace the old glass fuse holder with a modern blade type, however modern fuses are marked with their continuous ratings so the nearest equivalent fuse is 15A or 20A (note that the 25mm glass fuses are also continuous rated).
http://www.vehicle-wiring-products.eu/V ... /fuses.php
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