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Europa-List: 914 Too lean at 115%??

Subject: Europa-List: 914 Too lean at 115%??
From: Ronald J. Parigoris <rparigor@suffolk.lib.ny.us>
Date: Mon, 7 Mar 2005 13:10:41

I have been reading on plenty of Rotax 914 technical information. I read through
changes in the airbox.

When running motor at 100% power or below, the carburetor float bowls are vented
to
the airbox in such a way that the float bowls are seeing airbox pressure. Now 
when
you apply over 100% power, there is a 3 way solenoid that opens and in fact 
plumbs
the float bowls to an area in the airbox that is receiving impact pressure, thus
applies more than airbox pressure to the float bowls and makes the motor run 
richer.
OK I understand and like this.

On earlier airboxes Rotax wants you to adjust the impact nipple to a position 
that
will not allow the motor to run too lean. They instruct you to measure the 
Carbon
Monoxide on all cylinders and they want you to adjust the lowest cylinder by 
turning
the impact nipple till you get to between 4 and 6 % CO.

I understand what they are trying to accomplish, find the lean cylinder and make
sure it is not too lean..

How do you measure in flight carbon Monoxide? Can you somehow substitute EGT for
it??

The new style impact nipple supposedly comes installed in a optimum position and
Rotax says no need to mess with it, unless you modify the intake tract. Then you
need to monitor CO and make sure nobody is too lean.

OK I have a Intercooler, that is going to modify intake tract, how do I measure?

Thx.
Sincerely
Ron Parigoris

BTW seeing just how adding more pressure over airbox richens mixture, applying
less
pressure would lean it. A controlled leak with a needle valve and EGT for higher
altitude ops?




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