I'd like to safely check the injector spray patterns on my '87 K75 and NOT have a fire (like I did last year when a couple injectors popped out of the rail, gas got sucked into the injector ports and ignited the left side of the bike!) and also not damage any ignition electronics. Is anyone aware of an easy method with no danger of either? Is taking the secondary coil connections off OK with the ignition control unit?

disconnect the tiny small wires from the ign. coils and put a bit of tape around the ends to insure they can arch to ground.

With no primary power the coil can't spark.

regards, Ibj....

Many thanks for the reply. I'm taking this to indicate there's no risk of damaging ICU? For some reason I have it in my head you're not supposed crank engine without plugs grounded because it can damage "something" but can't remember what or even if this is correct info.

That is correct that you can damage the ignition module if you dont ground the plugs but by disconnectig the coils you isolate the ICU from the source of the damage.
Withiut the plugs grounded you can induce very high voltages into the primary windings of the coils which in turn will fry the final switching transistors in the ICU, but as ibj said make sure the wires are insulated from shorting to the frame or engine as the high current draw can be just as dangerous.

RicK G wrote: by disconnectig the coils you isolate the ICU from the source of the damage.

Thanks for explanation Rick. This is exactly what I was looking for.

For the spray test I'll use extreme caution this time and shrink tube the connectors/zip tie well away from any possible arcing paths.

For any others who ever do this test please take heed from my bad experience:  when you hit the start, fuel pump pressure can instantly pop one or more of the injectors out of the fuel rail and spray the side of the bike and YOU with a large amount of gasoline from the fuel rail. Then ANY source of ignition is all it takes. I was extremely lucky I didn't get sprayed and that I had a dry chem extinguisher. Without it I doubt I could've put this out and I likely would've lost my house when this happened last winter.