Spark Plug Question

[refractory148]

I have a 1998 25HP Johnson Model # J25RECB. Currently has Champion QL77J4C plugs. I am going to decarb and replace plugs. Are these the proper plugs for this engine? Mostly running at cruising speed, little or no trolling. 14 ft. Alum. jon boat. Also what gap? Thanks in advance.

 

[OBJ]

Re: Spark Plug Question

Yep....those will work just fine. Just a little FYI...the alternate plug is a QL16V which I believe is a surface gap. If I remember right, the book said these could be used if a lot of sustained WOT operations was done. But I think the QL77J4C should do ya' just fine.

 

[ob]

Re: Spark Plug Question

Your 25 takes the QL77JC4 gapped at .030".QL82C is also optional.

 

[ezeke]

Re: Spark Plug Question

Try here: Spark plug chart WEB SITE

 

[MicroBoat]

Re: Spark Plug Question

I know Johhny/rudes call for Champion plugs, but some of my fishing buddies use the NGK equivalent<br />saying that they won't "load up" on ya as bad at trolling speed because they tend to run hotter.<br />Any truth to this?

 

[ob]

Re: Spark Plug Question

There might be.If you do a lot of trolling lots of folks gap the QL77JC4s at .040" instead of .030" and say that they don't foul as much.

 

[Ralphy]

Re: Spark Plug Question

Not trying to hijack the thread, but could there be any adverse effects from increasing the gap??