1997 Johnson SPL 90 won't plane

My 97 johnson SPL 90 loses power intermittently. Carbs are clean. Compression approx 115psi. New Plugs. Cleaned the recirc valves. Ran tuner in the engine last week. It helped with the idle. It ran fine for most of the trip Saturday until I began back. I could not get it on plane. It didn't have a noticeable miss or cut out. It was just a reduced power. The reduced power level was consistent. It did not hunt or fluctuate. I pulled the cover off in the water and removed each plug wire individually and would throttle up with each removed. A miss was noticeable and it would run worse with each wire removed. When I got home I checked the plugs. Three were clean. One plug had some varnish. It was not wet. I decided to pull a head. I am very concerned with the amount of piston to cylinder spacing I found. I could measure approx .030 between piston and cylinder and there was a little scoring. The engine doesn't seem noisy. It has good power most of the time. Could the piston slack cause a power drop like this?

Re: 1997 Johnson SPL 90 won't plane

I have the exact same motor and had the same thing happen a couple of weeks ago. Ran great all day, then wouldnt start to head home. Choked it and it started, then didnt want to plain. Wouldnt hardly idle long enough to put on the trailer. I had a bad primer bulb. Replaced it and it runs like new. If your Compression is 115 psi on that cyl, then that probably is not your issue. Was there metal shavings? Since your tearing into it, you may want to go ahead and adress it if needed.

Re: 1997 Johnson SPL 90 won't plane

What your describing sounds like a fuel problem. How old is the fuel you have. If you had some that sat over the winter and just added to it that may be your problem. Try adding a bottle of Seafoam to your fuel and run it dry. Or dump the fuel in to your old lawnmower and use a fresh tank of fuel.
As for piston to cylinder clearance, don't take anybodys word for it, get a manual. Printed specs are the only ones to trust. Unforutnatly too many people "know better" and will tell you what they use. May not be the same application as yours.