Johnson 15hp Four Stroke

[neckman]

My 1995 Johnson 15 hp 4 stroke sounds like it is popping back thru carb slightly while at high throttle. The motor seems to run ok but the noise concerns me. Any feedback on this type motor is appreciated. I am wondering if I should have bought a Honda.

 

[JB]

Re: Johnson 15hp Four Stroke

Hmmmm. When 4 strokes do that it usually indicates a problem somewhere in the valve train.<br /><br />Get a Service Manual. Much less expensive than getting someone else to look into it at $65 an hour.<br /><br />Good luck.

 

[neckman]

Re: Johnson 15hp Four Stroke

I did take off valve cover and adjusted valves and checked for broken springs. I also ran it with cover off and everything looks to be working as it is supposed to.

 

[DJ]

Re: Johnson 15hp Four Stroke

Neckman,<br /><br />Your "popping' may be just misfiring.<br /> <br />Do you have a timing light? <br /><br />If so, attach it to each plug wire and run the engine. Do you see a steady pattern on both plug wires?

 

[Boatist]

Re: Johnson 15hp Four Stroke

I hope it is just a bad plug or a plug gaped to wide, but when I was looking at that engine did have several dealers tell me most of the of the warranet repairs were for rocker arms. Also they did shut down the production line one time for something to do with carberator bolts.<br />That was the engine I wanted but since I have a 75 15 HP two stroke Johnson and have seen all the plug fouling problem the engines had before they redesigned the head I figured I would wait for them to get the bugs out. I would still like to get that engine if they start it up and get the bugs out. At last years boat show only 4 strokes Johnson or Evinrude was selling was made by Suzuki. I still hope their parent company get's their act together and start building 4 Strokes. I will probably never buy another two stroke. All ready several likes out here you can not run a 2 stroke in.<br />I wish you the best of luck and hope you will let us know what you find.

 

[JB]

Re: Johnson 15hp Four Stroke

Hi, Neckman.<br /><br />The valve train looks okay? Time for a compression check. <br /><br />You might have a burned valve or your cam drive belt might have jumped a notch.<br /><br />I haven't heard of this sort of problem with the OMC-made 4 strokes. My '96 9.9 Johnny 4 stroke runs like a Swiss watch.<br /><br />Let us know what you find, even if it is nothing.

 

[neckman]

Re: Johnson 15hp Four Stroke

I did have a problem with the rocker arm adjusting screw backing off but I fixed the problem. The valves are all adjusted to specs. now. How do you set timing on this motor?

 

[Frank Martin]

Re: Johnson 15hp Four Stroke

rev limiter will make that type of sound are you sure you are not under proped ?? check it out with a shop tach . PS; Honda will do the same thing if under proped this will save the engine .

 

[neckman]

Re: Johnson 15hp Four Stroke

I am running a 9x11 prop on a 14ft aluminum westcoaster. I did try a 9.5x10 and there seemed to be more of the noise. Maybe the motor is doing what it is supposed to do.