[Jefrsonco]

Does anyone know what the compression should be on a new 1977 140 hp Evinrude? Also the proper way to do a compression check on that motor?thanks.

[emdsapmgr]

Compression should be in the 125 range, and vary no more than 10% between all cylinders. Remove all the plugs before take your readings.

[Jefrsonco]

thanks for the response. When I remove all the plugs do I put the tester in one cyl at a time and have someone crank the eng? Or is there a way to crank it from the engine itself? Thanks.

[rickdb1boat]

Just screw the tester in the plug hole you want to check and crank it over using for about 5 seconds the key switch. The reading will hold on the tester for viewing....

[Brew2]

You can buy a remote starter for $5-$10 at most auto parts places. Just two wires that clip to your starter and push a button. Comes in quite handy if you want to check the spark on your motor and have no helper to turn key for you.As Rick pointed out, not really necessary for the compression check as the reading is maintained until you reset it.Brew

[Tom Scully]

Keep in mind that if you crank it from the key switch you should pull the safety lanyard on the kill switch so.

[Jefrsonco]

Brew, which two leads do I connect on the starter?

[Silvertip]

They are not on the starter. They are on the starte solenoid. Connect one lead to the large terminal that has the positive battery cable on it. Connect the other lead to the small terminal that has the wire on it that comes from the ignition switch. Push the button and the engine will crank. Have at least a small amount of water going to the engine (muffs) so you don't damage the impeller running it dry. (See how handy a service manual would be!)