Compression Test - How to disable ignition system?

[iboat2011]

Hello,

On my 1963 28 HP Johnson motor, here is the wiring info:

1)safety switch -> side post of cutout switch -> a small post on the solenoid
2)one cable coming out of Magneto -> a M on the ignition key switch
3)another cable from Magneto -> center post of the cutout switch -> Raised M on ignition key switch.

Can anyone tell me how to wire so I can disable the ignition system while performing compression test on this motor?

Thanks a lot!
Andrew

 

[Davem3]

Re: Compression Test - How to disable ignition system?

just unplug the spark plug wires or cut out the safety switch, i err on the side of caution and unplug the wires just in case...........

 

[iboat2011]

Re: Compression Test - How to disable ignition system?

just unplug the spark plug wires or cut out the safety switch, i err on the side of caution and unplug the wires just in case...........

I tried to disconnect the safety switch from the cutout switch, the starter would not even start any more. Any more sugguestion?

 

[Sureshot]

Re: Compression Test - How to disable ignition system?

Check out this thread:

http://forums.iboats.com/showthread.php?t=524871

You basically use a remote starter switch to crank the engine, leave the key off to disable ignition.

 

[iboat2011]

Re: Compression Test - How to disable ignition system?

Check out this thread:

http://forums.iboats.com/showthread.php?t=524871

You basically use a remote starter switch to crank the engine, leave the key off to disable ignition.

I have read that post and I do not have a remote starter. Can you explain to me how I exactly do(i.e, wiring) "ground the plug leads and jump the starter off the battery. POS to the starter post, NEG lead to a good ground on the motor."?

Thanks a lot!
Andrew

 

[retiredfornow]

Re: Compression Test - How to disable ignition system?

Remove the plugs, put the plug wires back on, take a piece of bare wire and wrap it around the base of the plugs, then wrap the end around a ground somewhere. Just hang them somewhere out of the way.

 

[iboat2011]

Re: Compression Test - How to disable ignition system?

Remove the plugs, put the plug wires back on, take a piece of bare wire and wrap it around the base of the plugs, then wrap the end around a ground somewhere. Just hang them somewhere out of the way.

Just wondering if I can just connect the two M posts on the ignition key switch to disable the ignition while still be able to run the starter. Can anyone confirm?

Thanks a lot!
Andrew

 

[Chris1956]

Re: Compression Test - How to disable ignition system?

Andrew. That motor has a magneto ign system, like an old lawnmower. Remove the spark plugs, and crank the motor to perform the compression test. The ign system will work, but w/o an spark plugs the motor will not fire.

If it were me I would use a jumper wire from the large battery cable on the starter solenoid to the primary winding of the starter solenoid. The primary winding is the small wire that runs to the ign switch. Set the ign switch to off and use the jumper to spin the starter. Second choice is for an auto jumper wire from the battery + pole to the starter connection.

 

[F_R]

Re: Compression Test - How to disable ignition system?

You wrote: "Just wondering if I can just connect the two M posts on the ignition key switch to disable the ignition while still be able to run the starter. Can anyone confirm?"



Yes, that will work, assuming the switch is accessable without a hassle.

The easiest way though is stick something into the spark plug boots and ground that "something" to the block. If you want to be a pro at it, make up a set of two jumper wires with alligator clips on each end. Stick one alligator clip in the plug boot and ground the other end.

Just unplugging the wires and letting them dangle in the open is poor practice. It puts a BIG strain on the coils. On a few ignition systems, it will actually destroy the system. Another danger is fire. You are blowing a combustable fuel mix out those plug holes-----sparks in the area are not a good idea.

 

[JB]

Re: Compression Test - How to disable ignition system?

Just leave the ignition off, iboat 2011.

Look here: http://forums.iboats.com/showthread.php?t=391323