1978 85hp johnson need advise

solidwaste

Petty Officer 2nd Class
Joined
Jul 12, 2005
Messages
106
I have the afore mention 1978 85hp went out today...Engine starts right no problems idles great rms look good idle and at high rev 5000-5500rpms not in gear..Put it in gear motor idles fine ad gas and nothin 7mph max and less than 2000 rpms..Last time I took boat out was the first time with this motor ran like this for a little while than took off like crazy top speed was around 33mph on gps..Didnt happen again after the first time.. Now today ran like crap all day while I was out...nevr broke 2000rpms any help would be apreciated thanks..
 
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DJ

Guest
Re: 1978 85hp johnson need advise

Solid,<br /><br />A two stroke engine will easily rev to 5500 out of gear on two cylinders, out of four.<br /><br />DON'T do that, unless you want to buy a new engine.<br /><br />You are not running on all four cylinders. Probably ignition. First off, find out what cylinders are dead by removing plug wires-one at a time- and watch RPM drop.
 

solidwaste

Petty Officer 2nd Class
Joined
Jul 12, 2005
Messages
106
Re: 1978 85hp johnson need advise

ok so runing engine in drum in idle pull off one spark pug wire at a time until rpms drop? if they dont drop that would indicate what a bad coil?
 
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DJ

Guest
Re: 1978 85hp johnson need advise

Possibly. Or bad plug, low compression, etc. THat's a place to start.
 

solidwaste

Petty Officer 2nd Class
Joined
Jul 12, 2005
Messages
106
Re: 1978 85hp johnson need advise

Thanks DJ went to the store bought spark tester..Came back home pulled cover off to see nothin but the plug for the two right spark plugs not plugged in..God Im so stupid I sure hope I didnt do any damage to the engine..Checked all four wires all have good spark now..Engine started right up sounded like it should now for another trip tp the lake to test and maybe try fishin instead of lookin like a fool with engine cover off..Thanks for help DJ..
 
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