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Hotter Plugs in a 2 Stroke - Problem?
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Author:  DougT01 [ Wed Sep 02, 2015 8:54 am ]
Post subject:  Hotter Plugs in a 2 Stroke - Problem?

Hi guys, a quick question.

2003 Johnson 90hp 2 stroke

By mistake I got an 8 pack of Champion QL87YC plugs versus QL78YC.
The higher 87 number is a hotter plug.

Everything else about the plug is identical.

Is it a problem to run these hotter plugs? I'd obviously like to use them if possible, but don't want to do any damage.

I was wondering if these hotter plugs could affect the lubrication in the cylinders or not enough to matter.

Best regards,
Doug

Author:  DougT01 [ Wed Sep 02, 2015 9:48 am ]
Post subject:  Re: Hotter Plugs in a 2 Stroke - Problem?

Trying to research this answer, I found mixed results.
When I called a local Johnson mechanic, his answer was simply to use what the manual called for.
I finally got a hold of Evenrude Tech support and they said these 87's may be a little to hot for my engine and could cause premature firing.

Now I have an 8 pack of the 78's on order. Better to waste $25 worth of plugs than to do some damage.

I wish they would have been ok for a limited period of time :-(

FYI,
Doug

Author:  278TheNiseeII [ Wed Sep 02, 2015 4:34 pm ]
Post subject:  Re: Hotter Plugs in a 2 Stroke - Problem?

I would not use them. Hotter plug can easily lead to pre detonation which will burn a hole in the top of the piston. I have seen this before.

Author:  DougT01 [ Wed Sep 02, 2015 5:15 pm ]
Post subject:  Re: Hotter Plugs in a 2 Stroke - Problem?

278TheNiseeII wrote:
I would not use them. Hotter plug can easily lead to pre detonation which will burn a hole in the top of the piston. I have seen this before.


Thanks Goldfish,

I already ordered the correct ones and I'll try to give these away.

Not worth $25 to damage the engine.

Best regards,
Doug

Author:  LouC [ Wed Sep 02, 2015 8:45 pm ]
Post subject:  Re: Hotter Plugs in a 2 Stroke - Problem?

You made the right decision, hotter plugs in a 2 stroke could be a bad thing, especially if the fuel mix was a bit on the lean side. They usually have too hot combustion chamber issues, not too cold.

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