1981 Mercury 70hp 2 stroke - problem

[ross_larter]

Re: 1981 Mercury 70hp 2 stroke - problem

I have a switchbox and 3 separate coils, i will try swapping out the coil connecting to the fouled plug tommorow.<br />Would a weak spark from a coil breaking down under load cause the plug to foul so much? If I pull the HT lead to the fouled plug (now clean) on tick over the rpm does drop, could the plug fire at tick over but not fire under load due to the coil not giving a big spark under load?

 

[ledgefinder]

Re: 1981 Mercury 70hp 2 stroke - problem

Good question...<br /><br />This is guessing, but I'd pick up two new plugs & see how she runs well with just the plug change. Do the other two plugs look real good?

 

[ross_larter]

Re: 1981 Mercury 70hp 2 stroke - problem

Don't think this is good news.<br />Did an compression test again and here is the reading:<br /><br />top: 25 psi<br />middle: 135 psi<br />bottom: 135 psi<br /><br />If i pore oil in the top cyl the psi goes up to 70 PSI then slowly drops back down.<br /><br />I am thinking piston rings are there any other things it could be (some sort of gasket)? Also how hard is it to change the rings on this engine?<br /><br />ross