From: "Finn Lassen finn.lassen@verizon.net" <flyrotary@lancaironline.net>
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Subject: Re: [FlyRotary] Re: AR2592 gap
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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Date: Thu, 25 May 2023 16:45:30 -0400
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On 5/25/2023 2:58 PM, Charlie England ceengland7@gmail.com wrote:
> On 5/25/2023 8:13 AM, Finn Lassen finn.lassen@verizon.net wrote:
>> For those of you who use the AR2592 spark plug in the Renesis, do you 
>> use the 0.6mm gap the plug comes with? I bought 8 of them some years 
>> ago.
>>
>> I've been using the stock plugs (RE7A and RE9B) for maybe 100 hours 
>> by now. Experienced a brief 200 RPM drop on last takeoff. Wondering 
>> if it's time to change plugs. Or re-gap the stock plugs to what?
>>
>> What can I learn by looking at plugs?
>>
>> Best way to clean them?
>>
>> Finn
> Since no one else is jumping in...
>
> I don't remember ever swapping plugs in either of the RX7s I used to 
> own, but based on general info for IC engines, the general appearance 
> of the 1st and 3rd look to me like they're running way too hot.  
> Here's one site about 'reading' plugs:
> https://www.lazerhelmets.com/lean-spark-plug-chart/
>
> At $5-$6 each, it's hard for me to justify cleaning/gapping an old 
> worn plug, especially if it looks pretty rough.
>
> Charlie
>

Not sure I'm seeing the same thing as you in that chart. Actual plugs 
are darker than in the picture.

1st and 3rd are the leading plugs. Wonder if the small hole for the 
trailing plugs causes them to have less crud.

Also that crud makes me wonder if I should mix less oil. Still using 
about 1oz/gal. I think that Tracy mentioned using less for the Renesis. 
But then he's using a 50/50 mixture of MMO and 2 stroke oil.

I was going to replace them with the AR2592 but then got thinking about 
correct gapping.

Finn