Hi everyone,
I've owned my 79 XS650 for about 10 yrs now. It has always been good to me and never left me stranded. After many miles of riding, it finally died on me. It was running fine and I shut it off at a parking lot for maybe 15 minutes. During this time, the key was removed (ignition off). Not sure on kill switch position, but I usually switch it off. When I returned, the bike would crank and turn over fine but would not start. After cranking, if I switched the kill switch off, I would sometimes hear a POP as if the fuel ignited, but no start. I checked for spark and found I had none at either plug.
I have a PAMCO unit (still mechanical advance) with a dual output coil. I think the coil is a 17-6803 coil from MikesXS. Upon disassembly I found that one of the clamps holding the coil to the frame was missing. I don't think this matters since, if I'm not mistaken, dual output coils don't require a ground. I did the usual tests, and found the following:
Battery voltage (ign. off) - 12.2v
Battery voltage (ign. on) - 11.7v
Coil power (+) from kill swith - 8.9v
Pamco green wire (- on coil) - 1.1v
Secondary to secondary - 14,500 ohms
Primary to primary - 2.5 ohms
Primary to secondary - Infinite
Left plug wire - 0.5 ohms
Right plug wire - 0.8 ohms
I did the PAMCO test by removing the locating pin and spinning the rotor with the ingition/kill switch on. No spark. I then disassembled my kill switch and checked for voltage drop. I had 9.6v on one side of the switch and 9.4v on the other. As a final test, I attempted to bench test the coil by removing it and directly connecting it to the battery. I connected the negative primary terminal to battery negative. I then connected the spark plugs and grounded them against the engine block. I connected a wire to the positive primary terminal and quickly swiped it across the batttery positive terminal. I had no spark at the plugs, but a spark would occur at the battery terminal every time I swiped the wire, so there was some current flowing. In an attempt to rule out a bad engine ground, I held the plugs against an exposed piece of the negative wire to the battery. Still no spark when I swiped the positive.
The only thing I haven't done yet is tried different spark plugs. I have BPR7EIX Iridium plugs. They appear in good condition. I checked with my multimeter and had continuity between the electrode and center of the plug, so all appears well.
I would say the coil is bad, but the resistance tests appear normal. Any thoughts before I spend the money on a new coil?
Thanks.
I've owned my 79 XS650 for about 10 yrs now. It has always been good to me and never left me stranded. After many miles of riding, it finally died on me. It was running fine and I shut it off at a parking lot for maybe 15 minutes. During this time, the key was removed (ignition off). Not sure on kill switch position, but I usually switch it off. When I returned, the bike would crank and turn over fine but would not start. After cranking, if I switched the kill switch off, I would sometimes hear a POP as if the fuel ignited, but no start. I checked for spark and found I had none at either plug.
I have a PAMCO unit (still mechanical advance) with a dual output coil. I think the coil is a 17-6803 coil from MikesXS. Upon disassembly I found that one of the clamps holding the coil to the frame was missing. I don't think this matters since, if I'm not mistaken, dual output coils don't require a ground. I did the usual tests, and found the following:
Battery voltage (ign. off) - 12.2v
Battery voltage (ign. on) - 11.7v
Coil power (+) from kill swith - 8.9v
Pamco green wire (- on coil) - 1.1v
Secondary to secondary - 14,500 ohms
Primary to primary - 2.5 ohms
Primary to secondary - Infinite
Left plug wire - 0.5 ohms
Right plug wire - 0.8 ohms
I did the PAMCO test by removing the locating pin and spinning the rotor with the ingition/kill switch on. No spark. I then disassembled my kill switch and checked for voltage drop. I had 9.6v on one side of the switch and 9.4v on the other. As a final test, I attempted to bench test the coil by removing it and directly connecting it to the battery. I connected the negative primary terminal to battery negative. I then connected the spark plugs and grounded them against the engine block. I connected a wire to the positive primary terminal and quickly swiped it across the batttery positive terminal. I had no spark at the plugs, but a spark would occur at the battery terminal every time I swiped the wire, so there was some current flowing. In an attempt to rule out a bad engine ground, I held the plugs against an exposed piece of the negative wire to the battery. Still no spark when I swiped the positive.
The only thing I haven't done yet is tried different spark plugs. I have BPR7EIX Iridium plugs. They appear in good condition. I checked with my multimeter and had continuity between the electrode and center of the plug, so all appears well.
I would say the coil is bad, but the resistance tests appear normal. Any thoughts before I spend the money on a new coil?
Thanks.