1998 Johnson 120hp (Spark plug gap settings)

[mjsigns]

Anyone have he gap setting for the plugs on a 1989 Johnson 120hp? The engine model #J120TLETS.<br /><br />Thanks in advance.<br /><br />MJ

 

[bubbakat]

Re: 1998 Johnson 120hp (Spark plug gap settings)

The book says 30 but I gap mine at 40 and it keeps fouling down. That way I can go thru no wake zones worry free or troll with it.<br /><br />champion plug QL77JC4 or you can use QL16V surface gap plugs<br />BTW that is a 1993 model you have there

 

[seahorse5]

Re: 1998 Johnson 120hp (Spark plug gap settings)

Years back the then OMC changed the recommended plug for that motor to the extended nose QL78YC gapped at .030". It worked a lot better at low speeds and is very foul resistant. The factory says that as the plug gap wears from use, when it reaches around .045", the RFI emitted can trigger false VRO warning signals and possibly make the '88 and later motors go into SLOW mode.

 

[mjsigns]

Re: 1998 Johnson 120hp (Spark plug gap settings)

Thanks Bubbakat & Seahorse!<br />your feedback is appreciated.<br /><br />Mj