Post by grizld1 on Sept 1, 2011 8:51:48 GMT -5
Chased a gremlin through the electrics for 8 weeks: ignition breakup with Acewell electronic tach going crazy at 6200 rpm.
Metered everything. At rest, no system showed a flaw. Consulted with Mark Whitebook at Probe Engineering. Mark suggested stray EMI from the load-dump reg-rec. on the Sparx PM system. Moved the reg/rec to a bracket in the passenger peg frame loop (better place for it anyway, more cooling) and grounded its casing. No joy.
Installed Magnecore suppression plug wires. No joy. Added resistor plugs to the Magnecores, though the manufacturer said resistor plugs/caps are unnecessary. No joy.
Figured the kill switch or ignition relay might be fluttering when vibration hit a certain point. Replaced both and serviced every connector on the bike. No joy. Tried hooking coil and box to switched power instead of relayed power, one at a time and together. No joy.
Mark asked me to send the ignition to him for troubleshooting. It checked out perfect on the oscilloscope and on Marks's own XS650. For yucks, tried reinstalling the Boyer-Bransden ignition. No joy.
Figured coil might be to blame, though the Dyna unit metered out fine. Pulled an Accel coil out of the stash and fabbed a bracket for it. No joy.
Finally did what should have been Step One, and hardwired the ignition to the battery. No more breakup at 6200, but after a clean run to redline through 4 gears, the aftermarket tach/speedo unit went wonky, and at my local shop, where I made a stop for some odds and ends, the battery showed too weak to turn the starter. We threw a charge to it, and after I'd ridden home (around 10 miles), the battery showed 9 volts.
The gremlin had finally come out of hiding, and thumbed his nose at me. This time the tester showed a short in the tail light bulb holder. Interesting that the condition only got bad enough to detect after I finally got around to the total bypass that should have been done to start with.
The noise from the short had been getting to the ignition, even though the iggy and coil were on a completely separate power line from everything else, powered straight off the battery via a relay. Evidently when the critical rpm was reached, the intermittent short was enough to make the relay flutter. The 13th commandment (right after "Thou shalt not get caught" and Thou shalt not volunteer"): Thou shalt not assume.
Metered everything. At rest, no system showed a flaw. Consulted with Mark Whitebook at Probe Engineering. Mark suggested stray EMI from the load-dump reg-rec. on the Sparx PM system. Moved the reg/rec to a bracket in the passenger peg frame loop (better place for it anyway, more cooling) and grounded its casing. No joy.
Installed Magnecore suppression plug wires. No joy. Added resistor plugs to the Magnecores, though the manufacturer said resistor plugs/caps are unnecessary. No joy.
Figured the kill switch or ignition relay might be fluttering when vibration hit a certain point. Replaced both and serviced every connector on the bike. No joy. Tried hooking coil and box to switched power instead of relayed power, one at a time and together. No joy.
Mark asked me to send the ignition to him for troubleshooting. It checked out perfect on the oscilloscope and on Marks's own XS650. For yucks, tried reinstalling the Boyer-Bransden ignition. No joy.
Figured coil might be to blame, though the Dyna unit metered out fine. Pulled an Accel coil out of the stash and fabbed a bracket for it. No joy.
Finally did what should have been Step One, and hardwired the ignition to the battery. No more breakup at 6200, but after a clean run to redline through 4 gears, the aftermarket tach/speedo unit went wonky, and at my local shop, where I made a stop for some odds and ends, the battery showed too weak to turn the starter. We threw a charge to it, and after I'd ridden home (around 10 miles), the battery showed 9 volts.
The gremlin had finally come out of hiding, and thumbed his nose at me. This time the tester showed a short in the tail light bulb holder. Interesting that the condition only got bad enough to detect after I finally got around to the total bypass that should have been done to start with.
The noise from the short had been getting to the ignition, even though the iggy and coil were on a completely separate power line from everything else, powered straight off the battery via a relay. Evidently when the critical rpm was reached, the intermittent short was enough to make the relay flutter. The 13th commandment (right after "Thou shalt not get caught" and Thou shalt not volunteer"): Thou shalt not assume.
