Hi Folks,

My 1987 R80 (which I bought new in 1987) was sitting in a barn for 10 years, and I've been getting it back in shape. That meant rebuilding the Bing carburetors and also clearing out the mice damage to the airbox. There were also some frayed/nibbled wires, which I replaced.

The bike starts and idles just fine, but when I increase RPMs to around the 3000-5000 rpm range, it runs roughly, surging and skipping.

I tested the battery's output (which is 12.5 volts, normal), and the voltage delivered to the ignition coil's #15 terminal (11.8 volts), which seems fine. I then tested the voltage between pins 2 and 4 of the ignition amplifier (the black module mounted on a heat sink with 6 inputs) with the ignition ON, and found the voltage to only be 3 volts with the ignition amplifier connected to the wiring harness and also when I tested between the connectors on the disconnected wiring harness. That voltage is very low.

Any idea where I should look to find the issue? The wiring diagram in my Haynes manual is not very helpful.