1990 Evinrude 90Hp VRO spark plugs

[ronaldjamesh]

My 90HP VRO engine starts a little hard, idles rough and dies when cold. It runs reasonably well when warmed up. I was going to replace the spark plugs but have not been able to confirm the correct updated spark plug recommendation for this engine.
I use this boat mostly at medium to high speed. Have not done any trolling yet. Previous owner trolled a lot.
It had NGK7HS-10 plugs in it when I purchased it a couple years ago. The charts I have found show Champion QL77JC4 as the best with the QL82C as a substitute.
If you cross these Champion & NGK plugs back and forth they do not match up. The fuels now are different from back in 1990 when these engines where manufactured.
I would like to purchase the BEST quality and proper heat range plug for this application.
I crossed the Champion QL77JC4 on sparkplugs.com and the Denso Iridium IWF27 plug is shown as the Premium Plug.
Any recommendations would be much appreciated.

 

[DJ]

Re: 1990 Evinrude 90Hp VRO spark plugs

NGK's and Denso's are fine for Japanese engines. I recommend them for those engines. They work. I would NOT put Champ's in a Yamaha or a Suzuki.

OMC's (John/Rude) DON't like them.

I am NOT a Champion fan but they work wonders in an OMC. They JUST DO.

Think about it. The engineers that designed the outboard had a certain specification in mind. OMC went to Champion and stated their design intent. Champion met it.

Any other plug is "reverse engineered" which is never exact. I ALWAYS go with what the OEM recommended.

 

[emdsapmgr]

Re: 1990 Evinrude 90Hp VRO spark plugs

Agree with DJ's comments. Go with the QL77JC4 plugs. They'll work fine. Make sure the choke solenoid is working properly and that the feeder hoses are not cracked for cold starting. Double check the idle speed-it should idle between 650-750 when in gear, floating in the water. If it is too low, it will die out. If you have rough idling when cold as well as warmed up, you may want to overhaul the carbs, paying special attention to the dedicated idle circuits in the upper carb bodies.

 

[DJ]

Re: 1990 Evinrude 90Hp VRO spark plugs

I suspect there are other issues but we correct-one at a time.

 

[yoster]

Re: 1990 Evinrude 90Hp VRO spark plugs

I just switched out the NGK's in my 1997 115 rude for the recommended QL78YC plugs, and I kind of regret it. Honestly, despite what everyone has said here, the NGK's ran better (and they weren't the recommended suppressor type either, they were the BPR7HS plugs).

My biggest concern though is the quality of champion. I bought 4 brand-new plugs and right off the bat it looked like they were made in some 3rd world country or something. I also found a metal WASHER stuck down around the electrode in one of them. Had I not dug it out that could have done some nice damage to my engine!

They're running fine, it's not that it's making the engine run BAD, it's just that the old NGK's that had been in there for many years ran absolutely just as good.

I guess we should always caveat spark plug recommendations with, "you're 'mileage' may vary"

I would personally recommend the suppressor-version of the NGK plug. Can't remember the model number off the top of my head.. BZ-something I believe.

 

[DJ]

Re: 1990 Evinrude 90Hp VRO spark plugs

Yoster,

Everyone has an opinion.

Some will never buy an OEM product. Why-unknown.

Some go with OEM only-ME.

We all have our experiences.

I am suggesting, to this poster, that we start with what is known. We go from there.

 

[ronaldjamesh]

Re: 1990 Evinrude 90Hp VRO spark plugs

Sorry for the late response. This was my first post on this Forum and i thought I was going to receive email notification to any replies. I will try the Champs and see how they do. I appreciate all the comments and the spec's on the idle etc.
I will let you know how everything works out. Thanks again!