98 Johnson 50 H.P spark plug gap

[joshk84]

I'm going to put some NGK plugs in and i wanted to ensure the gap is correct. Also, the motor is oil injected and do you guys recommend a specific brand of oil?? Currently ive got just regular johnson brand. 1 more thing do you guys know of a good repair book and/or website i can refer to if i have to tear into the motor?? Thanks.

 

[JB]

Re: 98 Johnson 50 H.P spark plug gap

Hi, Josh.

Welcome to iboats.

First: Use Champion plugs. I think it takes QL77JC4 or L77JC4 gapped at .030". If I am wrong F_R will correct that. That engine was designed to use Champion plugs. It will work best with what it was designed to use.

Next: Any TC-W3 certified outboard oil will do just fine. If you choose a synthetic you will get less smoke and less carbon buildup. Some are even biodegradable, which is environmentally friendly.

Finally, get the Factory Service Manual rather than an aftermarket. If iboats doesn't have it, www.kencook.com or www.outboardbooks.com do.

 

[tashasdaddy]

Re: 98 Johnson 50 H.P spark plug gap

i run QL77JC4 in my 40 and 50 hp motors, but this is what the chart says.
40, 48, 50 (2-Cylinder) 1989 - 2001 QL78YC (see note 3) .030. 3. On ALL VRO/OMS equipped motors the "QL" supressor plug is recommended.

source: http://www.boatsetup.com/SparkPlugChart.pdf