Author Topic: safe way to disconnect plugs for compression check  (Read 2597 times)

Offline bizzaro

  • ^ SuperNatural Motobricker
  • Posts: 583
  • co pilot
safe way to disconnect plugs for compression check
« on: July 23, 2016, 12:39:31 PM »
I have always grounded my plugs one at a time with a jump wire to prevent ignition damage?  Is it easier, simpler, and safe to just disconnect the pin connector to the coils?  Then I can just leave the wires hanging instead of putting the plug back in the plug lead and grounding it so the spark has a place to go. 

Or, with the kill switch off, you get no spark at the plug anyway, so is this even a simpler, easier and quicker method to check engine compression?  Just turn on the kill switch,(stopping the ignition), and remove the plugs, then check your compression? And also disconnect the fuel pump so it is not dumping fuel into the cylinder giving false readings?
  • Vermont
  • Current:1994 BMW K1100LT Previous: 1982 Yamaha virago 920,1973 Honda CB550,1976 Yamaha 650 Special
See Ya in the Twisties,
 Bizz

Offline Martin

  • ^ Quintessential Motobricker
  • Posts: 4475
Re: safe way to disconnect plugs for compression check
« Reply #1 on: July 23, 2016, 02:40:46 PM »
I made up a four way earth out of heavy gauge wire, I cut down four screws the same thread as the spark plug nuts and soldered the wire to them  and ran all four wires to a clamp. I can now cater to both types of plugs, my plugs don't require the spark plug nut but a few of my mates bikes do, and he also has a k100. I don't think this will work with the leads that don't have a built in resistance, but you could probably make it with a resistor 5 Ohm built in. RBM might confirm this. If I flip the kill switch on my bike you can't crank it over.
Regards Martin.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline K1300S

  • ^ Quintessential Motobricker
  • Posts: 1293
Re: safe way to disconnect plugs for compression check
« Reply #2 on: July 23, 2016, 07:39:58 PM »
Ground the plugs.
Project Thread "K75s Midlife Refresh"
http://www.motobrick.com/index.php/topic,7810.0.html

Tags: