1989 Johnson 70HP Issues

[HunterIII7]

I have a 1989 70HP Johnson outboard VRO with no oil pump attached.

1) I have been using a mixture 1 pint of oil to every 6 gallons of gas. Is this the correct proportion? The motor does run a bit smoky at idle but as I hit higher RPMs, the smoke seems to be lessened.

2) The motor runs and doesn’t not die on me. At idle it does seem to be running a little rough, like a cylinder is missing every couple times that it fires. At higher RPMs the motor will run smoother for about 5 to 10 seconds then it will seem to miss a cylinder and the exhaust will kick some thicker smoke out. I ran the engine at higher RPMs for about 10 minutes and it kept repeating this cycle. Is this something that I should be concerned about or is this normal for an older engine like this?

 

[coueytwo]

6 gals of gas you need 15.36ozs of oil. so yes you are good at 16 ozs per 6 gals.


Try running seafoam in the gas and see if it clears up.

 

[joereeves]

Comprssion should be approx 100+ psi and even on all cylinders. Is it?

With spark plugs removed, spark should jump a 7/16" gap with a strong blue lightning like flame.... a real SNAP! Does it?

Spark plugs should be Champion QL77JC4 plugs, gapped at either .030 or .040 . Try both settings to check possible performance changes.

 

[HunterIII7]

I used the seafoam and it seamed to have smoothed out the engine. Thanks for the tip!