1978 9.9 hp.johnson

[dude11]

Morning fellows;I just picked up a 1078 9.9 johnson model # 1078RM & have a few questions.Does anyone have the specs.such as adjustments,compression numbers,type of plugs,etc. or an owners manual?It seems to run fairly well,I just want to dial it in so to speak.thax,Dude11

 

[TwoRivers]

Dude, I picked up a 77 9.9 Johnson just a few weeks ago. Got a manual on Ebay for $25.
From the manual: Spark Plugs: Champion L77J4 or AC M40FFX , gap at 0.40 inches (1.0 mm)
No ignition timing to set. If the wires are connected correctly the timing is OK.
Probably the only thing besides plugs to dial it in is to clean and adjust the carb while out on the water.
Good luck
rob

 

[dude11]

TwoRivers,,have you ck'ed to see about compression?I have a 76 6hp.Johnson & the plugs are Cham.B65 or J6J?But were set @ .030..Wonder if the difference in yrs.between ours is that critical?

 

[racerone]

???-----The 76 motor has a conventional magneto with points / condensers / coils.-----The 78 has an electronic ignition system , no points / condensers.-----The 2 systems are totally different !

 

[raczekp1]

if powerhead can produce 90 ps/cylinder, it means good running motor and its worth to invest some money

 

[raczekp1]

if powerhead can produce more than 90 ps/cylinder, it means good running motor and its worth to invest some money

 

[tomhath]

A small tachometer doesn't cost much. That motor should run about 5000 RPM wide open on a lightly loaded boat. If it can do that it's good.

 

[TwoRivers]

TwoRivers,,have you ck'ed to see about compression?I have a 76 6hp.Johnson & the plugs are Cham.B65 or J6J?But were set @ .030..Wonder if the difference in yrs.between ours is that critical?

Like Racer said, they went to a different ignition system in 77. Your 78 should be the same as my 77. So set the plugs at 0.040 inches (1.0 mm).
I haven't checked compression in mine yet. I can tell it has compression just by the way it turns. It was sitting for 15 years before I got it. Going to give it a little love this winter: new impeller, plugs, gear oil, carb clean.
good luck
rob

 

[dude11]

???-----The 76 motor has a conventional magneto with points / condensers / coils.-----The 78 has an electronic ignition system , no points / condensers.-----The 2 systems are totally different !

Thax for the info,I knew the ign.was total different .I was refering the different setting & type of plugs.I would think you get the best performance with the correct plugs & settings.So if anyone has that info----I'd love to have it.

 

[dude11]

TwoRivers,Do you have a way of posting pics.?Reason is I got a idle adj.screw the side of case,that goes to squat,,just a bolt in it.I'll post a pic.later.thax

 

[racerone]

That " idle adjusting screw " does not go anywhere.--------------If you look at it closely you will see that it is an idle stop screw.-----Allows the operator to set his favourite idle speed without stalling the motor.

 

[steelespike]

My 89 aftermarket manual indicates 5000 to 6000 rpm range. Lightly loaded should be propped for the upper end of range for best overall performance.

 

[AlTn]

champion QL77JC4 gapped at .040" for the plugs...google Leeroy's Ramblings 9.9/15 hp. Maintenance and Repair for a wealth of info on this series..as well many youtube vids of this series exist

 

[dude11]

That " idle adjusting screw " does not go anywhere.--------------If you look at it closely you will see that it is an idle stop screw.-----Allows the operator to set his favourite idle speed without stalling the motor.

You would think so,,lol.Look @ pics.there's just a bolt in the hole..

 

[dude11]

champion QL77JC4 gapped at .040" for the plugs...google Leeroy's Ramblings 9.9/15 hp. Maintenance and Repair for a wealth of info on this series..as well many youtube vids of this series exist

Thax for the info,I'll ck him out.BTW I can't seem to post pic.??

 

[dude11]

Well thank you Mr.AItn...I ck'ed out Leeroys,,wow!! Your right tons of info.Seems the adj.I was talking about has nothing tod do with carb.setting,appears to be for trolling at a preferred speed.TwoRivers,,your are on with type of plug & setting.Thax guys for all your help.

 

[dude11]

I just tried again (posting pic.) no dice??Anybody else having tro.?

 

[racerone]

????---Post # 11 seems to indicate something.