1973 25 hp Evinrude.... HELP

[soccerdan90]

I just traded a guy my jet ski for his 16 ft flat bottom boat and this 25 hp outboard. He gave me some cash on top so it was a pretty good deal. Anyways I was in the process of changing spark plugs and making sure the correct ones were installed. Well the ones on it are Champions J6C, on sparkplugs.com it says they should be J8C, and on another chart it says it should be J4C. I have no idea what to use. The motor barely runs and the spark plugs are so fouled that it could be the problem. I want to install the proper plugs so that I can rule that out or possibly fix it. Could having the wrong size plug cause me permanent damage? Thanks in advance.

 

[shawnfish]

if you can find an owners manual online it will tell you the proper plug. i do know my motor(80 johnson 25, rude/johnsons are the same) the whole motor was designed around the spark plug, wich is a champion(not sure off hand of model). so getting the right plug in ur rude will make it run better than one thats not recomended by the manufacturer...

 

[soccerdan90]

Thanks. Where can I find an owners manual. I have looked with no success.

 

[shawnfish]

Thanks. Where can I find an owners manual. I have looked with no success.

go to ebay and you should be able to find one there, and marineengine.com. i know they have them...

 

[user 6672]

Yours are J8C..

Taken from Champions site..

https://www.championsparkplugs.com/results_appOther.asp?otherMotiveID=12194&mfid=2

 

[soccerdan90]

Thank you very much!!!!

 

[shawnfish]

Yours are J8C..

Taken from Champions site..

https://www.championsparkplugs.com/results_appOther.asp?otherMotiveID=12194&mfid=2

i would not go off the info on that site, i put my motor in the search and it came up with a different plug than what my owners and service manual say to use for best performance....

 

[shawnfish]

and also that is not an OFFICIAL champion site, go to federal mogul for the official site

 

[baseball_guy_99]

I have a '75 25hp Johnson. Mine is supposed to run on J4C...but I run it with J6C.

 

[shawnfish]

I have a '75 25hp Johnson. Mine is supposed to run on J4C...but I run it with J6C.

for best performance use only the OMC recomended plug wich your motor/ignition is designed for, if you are using the wrong plug and put the correct plug in you will notice a difference in how much better your motor runs and idles....

 

[soccerdan90]

So J4C? I am so confused.

 

[shawnfish]

So J4C? I am so confused.

marineengines.com has your owners and service manual...

25.00 for owners and 36.00 for service....... both are the factory and not aftermarket.


i would use wichever one OMC recomends....plug that is.

 

[crazymanme2]

Remember soccerdan90 that motor has points #-o (.020 gap)

 

[soccerdan90]

Remember soccerdan90 that motor has points #-o (.020 gap)

Umm.... How do I check the points. Lol. I am completely new to outboard engines. Could you direct me to doing this myself?

 

[Hanr3]

Setting points are similar to adjusting the gap on a spark plug. You will need feeler gages or similar tool.

 

[crazymanme2]

Setting points are similar to adjusting the gap on a spark plug. You will need feeler gages or similar tool.

You will need a steering wheel puller & correct bolts to put in flywheel to pull,unless your flywheel has a slot to adjust the points through.

 

[txneal]

I have a 1973 25hp Evinrude and the service manual for it. Manual says Champion spark plug UJ4J, gap .030

 

[soccerdan90]

I put in the proper plugs and she starts on first pull. Thanks guys!