Newb questions on 100HP 72' Johnson

[GLE3]

Picked up a compression tester on the way home from work the other day. It has a screw in fitting with an etched ring at the end to grab on while tightening in to spark plug hole.

Are these things only supposed to be finger tightened?

I ended up only finger tightening and each cylinder read really close to 90 psi on all 4 cylinders on a cold test. I only have a muff and garden hose so I didn't think it was a good idea to warm up the engine to operating temp. Question is: How good is a cold test? Can I assume I would read close to this when warm?

I noticed when I took all the plugs out and was crank testing (for voltage) the bendix on the starter wanted to stay engaged with the flywheel. Could that be considered normal? When I had the tester in the bendix went back down the drive in regular fashion.

Thanks for any help!

 

[Daviet]

Re: Newb questions on 100HP 72' Johnson

I screw my compression tester in finger tight only. Your compression numbers should be OK, has the engine been sitting for a while, the compression might come up some if you decarb the engine. Are you having a running problem or just checking things over? I have seen starters act like yours when there was no plugs in the engine and then worked properly with plugs in.

 

[jerryjerry05]

Re: Newb questions on 100HP 72' Johnson


Bendix staying up is normal.
Cold results are almost identical to hot.
Finger tight.
How many revs did you let the motor turn?
You should let it turn until the guage stops going up.
Very important to have a HOT battery.
You need to ground the plug wires when using the key to turn the motor over(if you did).
You can blow the pack.I rigged up a wire thingy.See pic.

 

[GLE3]

Re: Newb questions on 100HP 72' Johnson

Actually hunting down a voltage drop issue (Just bought and tested/charged new battery).

Decarbing sounds like something I should do.

For each cylinder I held the key to start until I heard 4 or 5 "thumps". Guessing each thump is a rev?

I have a power pack that has a rubber quick connect on it that I disconnected. It has the coil, ignition, sensor wires, and reverse cutoff wiring to it. That would be good enough to protect the pack, right?

Thanks for the ground harness pic.

 

[jerryjerry05]

Re: Newb questions on 100HP 72' Johnson

Unhooking the pack is OK.J

 

[boobie]

Re: Newb questions on 100HP 72' Johnson

jerryjerry, did you say to ground out the plug wires when doing the compression test ??

 

[jerryjerry05]

Re: Newb questions on 100HP 72' Johnson

Yes if your gonna use the key switch to turn the motor.

 

[boobie]

Re: Newb questions on 100HP 72' Johnson

Thank You.