Question about Harley Davidson Harley-Davidson Motorcycle Desktop Telephone

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I have a 1984 Harley Davidson FXRS. I have a single fire crane hi 4 ignition system. It ran flawlessly for a few years and now the bike missed a few time then quit entirely. Now have no spark and would like to know how to trouble shoot it, resistance checks for the coil,voltage checks that sort of thing. Kenny

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There's no real way to check the coil, it either works or it doesn't. I've found that with my Harley's when I lose spark it's generally a bad wire or loose connection. If the wires/connections are good, then it's either the coil or the ignition module. I'd say with the newer Crane on it, that the problem is going to be with the coil. Check the voltage from the ignition module going into the coil. I'm not exact on the voltage, but as long as you have a good strong current getting to the coil, and low to nothing on the plug wire side, then the coil is bad.

Posted on Aug 06, 2008

Coils can be tested dynamically with an oscilloscope which you probably do not have so your next best approach is a ohm meter. not knowing your coil will make it hard to suggest a reading but you can get the spec's from the manufacturer or web site. the primary side could be from one ohm to 3 to 5 typically, could be more depending on coil. you can also check the ohms on the secondary by probing the primary terminal and a secondary (plug wire hole) terminal. here you should have a few thousand ohms depending on coil. if you get no readings, then the coil is bad. by the way, if you are checking voltage as pyrhyc says, you will have 12 volts on both sides of the coil. why? most ignitions will open the ground side of the coil to make it fire because as the current is pulled down, the magnetic field will colapse inducing electrical current in the secondary thus firing the plug. one redneck check is to take a 12 volt battery and hook one wire to one primary terminal and drag the other wire across the other terminal (bike wires removed for test) and watch plugs, if you get fire, check module.

Posted on Aug 27, 2008

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