High Idle on Rotax 912

H. Paul Shuch is a Light Sport Repairman with Maintenance ratings for airplanes, gliders, weight shift control, and powered parachutes, as well as an independent Rotax Maintenance Technician at the Heavy Maintenance level. He holds a PhD in Air Transportation Engineering from the University of California, and serves as Director of Maintenance for AvSport of Lock Haven.

Moderator: drseti

Post Reply
BrianL99
Posts: 314
Joined: Mon Jun 16, 2014 7:23 pm

High Idle on Rotax 912

Post by BrianL99 »

My Sting has been in the shop for 4 months ... it went in for an oil & filter change, but that's another story.

I pulled it out of the hangar today, to fly. Idle is at 2100 RPM's, with the throttle all the way back. Checked the RPM's on the EFIS, the
standard Tach & with a Laser Tach ... it's definitely idling at 2100.

NOTHING having to do with the Carburetor or linkage was touched.

Anyone have any ideas?

Thanks
User avatar
FastEddieB
Posts: 2880
Joined: Wed Jan 07, 2009 9:33 pm
Location: Lenoir City, TN/Mineral Bluff, GA

Re: High Idle on Rotax 912

Post by FastEddieB »

First thing I would examine is the routing of both the throttle and "choke" cables.

Have someone run both controls through their full ranges and make sure both are moving to both stop.

If you've already checked that, not sure.
Fast Eddie B.
Sky Arrow 600 E-LSA • N467SA
CFI, CFII, CFIME
[email protected]
roger lee
Posts: 807
Joined: Tue Dec 08, 2009 11:47 am
Location: Tucson, Az. Ryan Airfield (KRYN)

Re: High Idle on Rotax 912

Post by roger lee »

It could be a couple of things and sitting for those long periods can make things stick. It could be a choke slightly open and not closed all the way, carb piston (slide) gummy and sticking a tad from sitting, during the work someone impacted the throttle or choke cables throwing them out of position. You won't know a lot unless you do a carb sync and get that info. Unless you do this to help diagnose all you can do is guess and waist a ton of time and effort. Check the couple of items above then put the carbs on a set of gauges and not an electronic sync device. You can't diagnose with those. That's why I never use them.

There is a simple answer here and you just need to look at the simple things and don't look for complicated problems that aren't there.
Roger Lee
Tucson, Az.
LSRM-A, Rotax Instructor & Rotax IRC
(520) 574-1080 (Home) Try Home First.
(520) 349-7056 (Cell)
Post Reply