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Rotax 503 Spark Plug question

Posted: Mon Dec 21, 2015 8:19 pm
by swartkat
Hi guys,

today I changed my spark plugs on my Rotax 503.

There is some "petrol and 2-stroke oil" left.

engine hours: 669.5 hours
last change of plugs: 47 hours according to logbook
Mixture is okay: 20L & 500ml Oil (Engen Super Outboard TC-W3)
EGT 510-540 deg.
CGT not fitted

Normally the plugs should be dry and brown from my understanding.

The rotax is build-in the upside down configuration (windlass 503). Can this cause the build-up?

Any ideas? Till now there was no anomaly in regards of power & reliability...

cheers swartkat