I would like to compression test a newly acquired motor to have a baseline if I have future problems and to see if the motor is in as good condition as it seems. I have a loaner compression tool. The controls and battery are currently hooked up but there is no safety lanyard on the controls. I removed all 4 spark plugs from the motor along with the airbox cover. I have jumper cables that i can use to jump the starter. My worry is that I dont want to use the key/ignition and possibly fry a coil by loading it. I have 2 18 gauge wires with alligator clips but they dont seem to want to stay in the spark boot. I thought I read that the coils need to be grounded or they could fry themselves. Exactly how can I do this test without using the ignition? Key off and just jump with jump-start wires from the pos+ on the battery directly to the starter lead/post from the solenoid? If so do I need to connect the Neg- to the block somewhere also? Is there any other way because theres a harness real close to the post on the starter. Is there an ignition feed that I can pull from the starter solenoid that feeds voltage to the ignition so I can use the key? Lastly..any suggestions where I can find an OEM repair manual? I tried a Selco on another motor and it was very confusing by different motor sizes and years. I'd like to find something specific to my motor...87 Evinrude 140 VRO E140TLCUA Thanks!!!
There are many different ways to do a compression test. Certain methods will give better readings. If you just want to make sure it has compression within spec, just do one hole at a time. Just throw a rag over the dead wire and make sure it's away from fuel. WOT. Crank it for several revolutions until the needle just pulses and doesn't increase any more. If you find a low hole, then we will go from there... Do a wet compression test, remove adjacent plugs, etc...
