Topic: 71 CB500 ignition coil help

[lrburke]

 Hi everybody. I am new to this forum so I don't really know about tags and all that so I will just ask the question. My 71 CB500 suddenly lost the center 2 cylinders. I know the left hand coil sends the spark to these two. I am getting 12 volts to the primarys and the signal is being received from the module(aftermarket ignition module).I took a test light and put red lead on the yellow terminal and the other to ground and was getting a steady flashing on the light when cranking the engine. I also checked the resistance on the primarys and got just under 5 ohms and with the spark plug caps removed I had about 14k ohms on the secondaries. I am certain it is not carb related since there is wet gas on the 2 and 3 plugs which are brand new and definitely no spark. Is there any other tests I can perform before concluding the left hand coil is somehow defective.  Thanks for any help 

[bradweingartner]

You can always put the 1-4 coil on 2-3 and swap the leads from the points. The 2-3 leads are probably too short to reach 1-4 though.

In any case, if it fires on the second two cylinders you've found your problem. And you don't need any tools for this test.

Should verify if it's a coil issue or ignition module/points issue.

[number13]

Also, make sure the spark plug caps are
nice and tight. It might be a good idea to
pull the caps off, they just unscrew, nip off
about 1/4 inch and screw them back on.

[lrburke]

Hey thanks guys, I in fact just got through switching the outer two plug wires to the inner two cylinders and switched the blue and yellow primary wires as well and the inner two cylinders lit up. Earlier today I trimmed the ends of the plug wires and even switched the outer and inner caps around. You guys are good!! Unless you have any more good advice, I am going to get me a new coil. Should I get an oem or something else?   Thanks again