1972 125hp Evinrude ignition problem?

[tdg]

I have a 1972 125hp Evinrude (125283R) that has a miss at low rpm (idle speed). I runs real strong at high speed. Good compression on all cylinders. It does not seem to be consistant with one cylinder. I've tried a few different plugs but the ones that run the best are the L77JC4. We pulled the flywheel and inspected and cleaned the stator and rotor. There was quite a bit of carbon built up and it appeared it had been arching, but there was no change once it was put back together.

I'm at a loss. Does anyone have any thoughts on more troubleshooting? I hate to just start changing parts to see what fixes it. I figured maybe try a new coil to begin with.

Any help is appreciated.... Thanks

 

[Will Bark]

Re: 1972 125hp Evinrude ignition problem?

Get a spark tester at he auto parts house and test for a bright blue spark that will jump 1/4 to 7/16"; if you have an inductive timing light that will tell if all cylinders are firing on low speed.

 

[tdg]

Re: 1972 125hp Evinrude ignition problem?

I'll pick up a tester tonight. So I'm guessing if I can't get that kind of spark out of it you agree the first and most economical part to try would be the coil?