Main Motorcycle: 04 Thunderbird
Join Date: Apr 2009
Location: Suffolk UK
Hi, I am having the same problem, replaced pick up coil and igniter bypassed all the lockouts (side stand, clutch, alarm, etc) tested coils and still no go.
I noticed when it was stumbling the tacho was dropping and the alarm light was dimly flickering. Spoke to a motor mechanic friend and he suggested one of the coils was arcing internally and spiking the igniter through the live feed, causing all coils to cut out for a split second, after 4000 rpm or so the stumbling would disappear as the resistance in spark plug would drop allowing the spark in the coil to follow its normal rout. We found the faulty coil by running the motor, disconnecting and reconnecting each coil till we had a steady miss on one cylinder and the throttle could be whacked wide open without any hesitation or stumble.
I notice some people say their coils fail at low mileage ( mine 4700) and some folk say they have done thousands with no problems.
Could this be because the low mileage bikes don't like sitting around or do the high mileage bikes not have alarms fitted. Two reasons I wonder about the alarm, mine died and was replaced 2 weeks before the failure of the coil and the alarm light flickering in time with the cutting out of the coils.
Sorry about the rambling first post, great site.