Why can't the Rotax 912 be on idle when on the ground?

[drseti]

There's a new blog item just posted to Rotax-owner.com that deals with the question of low idle speed and engine roughness. See:

http://rotax-owner.com/index.php?option ... Itemid=349

[roger lee]

Right off the R.O.A.N. website:


Rotax Blog
Wednesday, 30 March 2011 19:08
Engine Roughness at Low RPM
Written by Rotax-Owner.com

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There are several factors that can cause or influence engine roughness, especially at lower RPM's.
A rough running engine can sometimes be a combination of several contributing factors.
One cause of Low RPM roughness can be a gearbox with low spring pack tension (or a "loose" gearbox).

Keep in mind that even though the Rotax Operator's Manual for the 912 and 914 series does allow for a minimum idle of 1400RPM, it is recommended to keep the RPM a little higher to reduce roughness and engine wear. 1800 - 2000 RPM is a good place to set your idle. Prolonged idling at low RPM's can cause accelerated wear in gearbox components, which can cause increased engine roughness. Low idling and rough running can also cause wear in other components such as carburetors. Worn carburetors can cause engine roughness - it can become a wicked cycle. Therefore, proper maintenance of the gearbox is important.