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Tuning the DCDI 503

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rvsimons

New Member
Joined
Apr 28, 2014
Messages
2
Location
Post Falls, Idaho
I have an Avid Flyer with an inverted 503 Rotax DCDI engine with a 2.58 to 1 gear reduction. I'm running a 67 inch two blade adjustable Prop which I just installed. I'm having issues in the mid range. I changed the main jets and needle positions several times. The engine runs perfect above 6000 rpm with smooth running, stable temps and RPM. If I pull the RPM's down below 5800 it will not hold RPM and will fluctuate as much as 400 rpm. This problem started when I replaced the prop from a fixed to an adjustable pitch. The old blade only turning 6250 static and 6550 max. I am now running 6350 static and 6750 max. Temps above 6000 are 1050/1050 EGT and 300/250 CHT. Anything below 5800 the temps wander a bit but nothing in the critical range.

Something tell me this prop is not jiving with this setup. The engine seemed to act better with a bit more load on it. I've considered adding a degree of pitch to see what happens.

Any advice would be appreciated. Feel free to call me at (509) 599-9477 or email me at [email protected] Aviation related only please.

Thanks
Vance
Post Falls, Idaho
 
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