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Plug Gap


GrassStripFlyBoy

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I replaced the spark plugs this summer and when searching around the forum then I noticed some posts about gap distance depending on summer / winter temps.  How many people are adjusting gap for seasonal change?  I'm doing condition inspection first of Oct now, so would be a time I could tighten them up a tick if need be.  Thoughts?

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8 hours ago, WmInce said:

Reason?

.024" is the minimum gap, and the gap will always grow with use. This is of course for the old style NGK spark plugs. If you have the new style plugs you are not supposed to gap them, simply measure and replace. They call for replacement at 200 hours, so I suspect that they will never go past their wear limit.

https://legacy.rotaxowner.com/si_tb_info/serviceinfo/si-912-027.pdf

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New style Rotax double electrode plugs specs:

INSPECTION OF SPARK PLUGS
Visual check Inspect all spark plugs for mechanical damage.
Electrode gap NOTE
Inspect the electrode gap also on new spark plugs before installation.
Electrode gap
New Wear limit
0.8 - 0.9 mm (0.031 - 0.035 in) 1.1 mm (0.043 in

 

This  is the one you're asking about. .023 - .027. I pick .025 just because it's in the middle. Don't start at .027 because the gap will only get wider. The plugs right out of the box are .030 and need to be gapped down.

NGK DCPR8E plugs:

13.2.2) Inspection of spark plugs
Heat range Check heat range and adjust electrode gap correspondingly.
Visual check Inspect all spark plugs for mechanical damage.
Electrode gap
Wear limit
0,6 - 0,7 mm (0.023 - 0.027 in) 0,9 mm (0.035 in)

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24 minutes ago, Mike Koerner said:

Hmmm.

I usually just bang mine on the floor. If I don't bang them enough, I bang them again. If I bang them too much, I unbend them with a pliers.

I usually go through about 4 cycles like this on the first plug... then use the rest right out of the box.

Mike Koerner

 

Haha! That is some funny stuff!

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4 hours ago, gogogo888 said:

And remember to torque it at 20NM.

Plus don't forget to use the correct silicone heat paste on the threads of the spark plug. I remember from school that they said if you use regular anti seize that you stand a good chance of pulling the threads out of the cylinder head. I suspect they were talking about the Champion ant seize.

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Regular anti seize is old school tradition. Hard to get some people to advance with the times. All anti seize ever did was help stop thread galling and fight off any corrosion. The silicone based thermal paste we use not only does that, but it's big claim to fame is it transfers about 40F - 50F from the plugs to the head. This helps stave off preignition that regular anti seize can't do. Our paste is used in the electronics industry to to transfer heat. I have switched several certified aircraft pilots away from the anti seize.

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