1978 115 evinrude comp. loss

[Rodlite85]

I have a 1978 115 motor. Checked compression before i bought it back in the fall. All cylinders were 110-115. I've ran it several times this year with no troubles or problems. Time before last that i took it out, I lost fire on one cylinder. I replaced coil, then found that it was the power pack had one channel not firing in it. Replaced that. Took the boat out this last time and it ran rough for a moment, then cleared out and ran fine for about 30 mins. It seemed to only be runnin on 2 or 3 cylinders after that. I got it home, ran a compression test, and both bottom cylinders have no compression. Reed plate looks fine, Cylinders dont seem to have any scarring. Also, starter doesn't turn motor over as fast the past few times i've had it out. Any help?

[115johnson78]

How much compression on the cyl.? If just a few psi lower the try to decarbon it. If it is down around 40-70 psi then pull the heads and have a look. As for the starter check all of your conectiions.

[Rodlite85]

I have since then removed the exhuast plate and heads. Pistons are trashed. Thanks for the help though