6 hp Evinrude ignition?

[growch]

Hi all. Great forum. I have a 1971 6 hp Evinrude twin cyl. It has been a great motor. Started 3rd pull after 3 years in storage. Here's the problem. It idles fine at very, very low rpm. It runs great at full throttle. But in between is where the problem is. As the throttle is in creased it bogs a bit the jumps to higher rpm. Its harder to do in a barrel but in the lake where there's no cavitation and it's under a constant load, when I increase the throttle it will not go full it just runs kind of boggy then wham!, all of a sudden it cuts irratically into high rpm. ??? Points,fuel,?? Totally baffled here. Any thoughts would be appreciated. Thanks

 

[growch]

Re: 6 hp Evinrude ignition?

I think it's ignition - mid throttle is where it's working the hardest. Plus it's the only thing that will suddenly cut in and out.

Fortunately ignition is the easiest to test. First examine the plug wires for any signs of cracks. If they're ok, then set up a test where you can draw a spark from them 3/8" long and test the top and bottom cylinders. This can be as simple as a couple nails driven into a board 3/8" apart, with one grounded to the block and the other with a plug boot on it. Also, you can get real cheap adjustable spark gap testers from discount auto tool stores.

9 times out of 10, the reason a spark will jump say 1/8" but not 3/8" is that the ignition coils arc over. The insulation on the old types tends to crack over time. New coils are better, and cheap. Iboats wants something like $17 for 18-5181. I like that aftermarket coil better than the OEM one.

 

[growch]

Re: 6 hp Evinrude ignition?

Thanks for the input. I take it that a typical coil will jump a spark 3/8". I also am not positive about the correct procedeure to set points if you care to indulge. Meanwhile I'll try your test and see what happens. Thanks again. Much appreciated.




[ quote time=1151277642 user=pmoir uid=17266 fid=28 tid= rid=1]
I think it's ignition - mid throttle is where it's working the hardest. Plus it's the only thing that will suddenly cut in and out.

Fortunately ignition is the easiest to test. First examine the plug wires for any signs of cracks. If they're ok, then set up a test where you can draw a spark from them 3/8" long and test the top and bottom cylinders. This can be as simple as a couple nails driven into a board 3/8" apart, with one grounded to the block and the other with a plug boot on it. Also, you can get real cheap adjustable spark gap testers from discount auto tool stores.

9 times out of 10, the reason a spark will jump say 1/8" but not 3/8" is that the ignition coils arc over. The insulation on the old types tends to crack over time. New coils are better, and cheap. Iboats wants something like $17 for 18-5181. I like that aftermarket coil better than the OEM one.
[/quote]

 

[Paul Moir]

Re: 6 hp Evinrude ignition?

To set the points, adjust them so they open .020" maximum. A .020" feeler gauge should slide through with little resistance but a .022" one shouldn't fit at all. They are opened at their maximum when the key in the crankshaft taper is aligned with the point's rubbing block.

A typical coil with a typical flywheel will produce sparks 7/16" or even longer depending on how precisely the ignition components are set up. Usually with cracks in the insulation, you'll get a healthy snap at .030" (spark plug gap) widths but nothing at all at 1/8".