Can't get ROTAX 277 to idle
-C.EASTLUND
Here's the situation:
We have a 277 newly rebuilt by Green Sky Adventures, (well,
as of late last year) on a Falcon Ultralight.
We can get the engine to run, as long as we stay above 2300 rpm.
The manual says to adjust idle after doing the 1-hour breakin
cycle. The idle did get better after break-in, but 2300 is still
too high. We ran through the idle adjust procedure, but neither the
air mixture screw nor the idle speed screw seems to have
any effect.
We checked the float & jet, but didn't find any obstructions.
Any suggestions (other than get the CPS catalogue - we have it)?
Chris Eastlund
Dan Grunloh
c...@globe1.ho.att.com (-C.EASTLUND) writes:
> We have a 277 newly rebuilt by Green Sky Adventures, (well,
> as of late last year) on a Falcon Ultralight.
>
> We can get the engine to run, as long as we stay above 2300 rpm.
> The manual says to adjust idle after doing the 1-hour breakin
> cycle. The idle did get better after break-in, but 2300 is still
> too high. We ran through the idle adjust procedure, but neither the
> air mixture screw nor the idle speed screw seems to have
> any effect.
>
effect if the idle speed screw is set too high.
2300 RPM is not bad for the Rotax 277. If you have the gearbox
and not a belt drive, you will find anything much lower will
shake the airframe bad enough to blur your vision. ;-)
The little single cylinder 277 has a very long stroke, and
high compression so it doesn't want to idle very slow. Mine
will run as low as 1900 but it shakes terribly at 2100-2200.
I like the static RPM to be a bit low because in flight, it
will turn even faster due to windmilling effect. If it's
too high you can never get to zero thrust and your landings
and rollouts may tend to be longer.
The 277 is a great little engine, but not if you want a
smooth low idle. But, that's not really important for the
flying part. Set it the best you can, and go fly.
--Dan (gru...@uiuc.edu)
ransom@roboben
:
: Here's the situation:
:
: We have a 277 newly rebuilt by Green Sky Adventures, (well,
: as of late last year) on a Falcon Ultralight.
:
: We can get the engine to run, as long as we stay above 2300 rpm.
: The manual says to adjust idle after doing the 1-hour breakin
: cycle. The idle did get better after break-in, but 2300 is still
: too high. We ran through the idle adjust procedure, but neither the
: air mixture screw nor the idle speed screw seems to have
: any effect.
: We checked the float & jet, but didn't find any obstructions.
When I first played w/ my 447 I found that no where in the manual
(or in CPS Care and Feeding for that matter) did it say which direction
the idle mixture screw made idle lean (or rich). Naturally, me and
Murphy tried the wrong way first. Turns out that screwing it in
makes the idle richer, i.e. it cuts off the idle air leak. From the
factory my 447 idle was too rich. I now sit happy w/ it turned out
just a hair under 1/2 turn. I'm at sea level (usually :) )
Except for the fact that you are idling a tad high, give it some
choke when it starts to die. If it seems to like that, try richer
idle.
--
--------|--------
Ben Ransom (*)
UCD Mechanical Engineering Dept. o o
bwra...@ucdavis.edu, (916)752-1834
Stephen Redmond
: In article <DAss2...@nntpa.cb.att.com>
: c...@globe1.ho.att.com (-C.EASTLUND) writes:
:
: > We have a 277 newly rebuilt by Green Sky Adventures, (well,
: > as of late last year) on a Falcon Ultralight.
: >
: > We can get the engine to run, as long as we stay above 2300 rpm.
: > The manual says to adjust idle after doing the 1-hour breakin
: > cycle. The idle did get better after break-in, but 2300 is still
: > too high. We ran through the idle adjust procedure, but neither the
: > air mixture screw nor the idle speed screw seems to have
: > any effect.
: >
:
: effect if the idle speed screw is set too high.
:
: 2300 RPM is not bad for the Rotax 277. If you have the gearbox
: and not a belt drive, you will find anything much lower will
: shake the airframe bad enough to blur your vision. ;-)
:
: The little single cylinder 277 has a very long stroke, and
: high compression so it doesn't want to idle very slow. Mine
: will run as low as 1900 but it shakes terribly at 2100-2200.
:
: I like the static RPM to be a bit low because in flight, it
: will turn even faster due to windmilling effect. If it's
: too high you can never get to zero thrust and your landings
: and rollouts may tend to be longer.
:
: The 277 is a great little engine, but not if you want a
: smooth low idle. But, that's not really important for the
: flying part. Set it the best you can, and go fly.
:
: --Dan (gru...@uiuc.edu)
My Rotax 277 idles down to 1000 RPM and doesn't shake the airframe badly,
but maybe that's because of a good set of Lord mounts. 1000 RPM is
unnecessarily low -- but it does actually have the capability.
Have you checked your idle jet size? It may be the wrong size for your
conditions and altitude. You'll need to open the float chamber, and remove
the idle jet to see the number stamped on it, then check it against the
reccomendations printed in (for example) the LEAF catalog. Another
possibility is the float level might be off, it needs to be exactly right.
If you have an old carb, the idle modification may not be present -- this
consists of a filed notch in the front of the carbeuretor slide to let in
a little more air at idle (again, see the alerts in the LEAF catalog).
Make sure you have a clean air filter. Finally, move the enricher valve
slightly (it's called the choke on the carb, but it's actually an
enricher) if this improves things a little, your problem is not enough
air, if it makes things worse the idle is too lean. This can help pinpoint
the problem. Check your intake manifold for leaks, and all carb gaskets
and O-rings. Check the top of your float needle for pits or wear under a
magnifying glass. Anyway, *something* is causing your problem, and it's
always best to pay attention. Rotax did not design and manufacture an
engine that would not idle if properly adjusted.
An engine that dies at idle is obviously a hazzard in flight. Hope this
helps. Let us know what you find.
Steve
--
| STEVE REDMOND : Naval Architect: Sarasota, : Liveaboard : T100SE laptop
| el...@cris.com : Artist : Florida : Houseboat : Amiga 500
Dan Grunloh
El...@cris.com (Stephen Redmond) writes:
>Dan Grunloh (GRU...@vmd.cso.uiuc.edu) wrote:
>: c...@globe1.ho.att.com (-C.EASTLUND) writes:
>:
>: > We can get the engine to run, as long as we stay above 2300 rpm.
>: 2300 RPM is not bad for the Rotax 277. If you have the gearbox
>: and not a belt drive, you will find anything much lower will
>: shake the airframe bad enough to blur your vision. ;-)
>My Rotax 277 idles down to 1000 RPM and doesn't shake the airframe badly,
>but maybe that's because of a good set of Lord mounts. 1000 RPM is
>unnecessarily low -- but it does actually have the capability.
He's right about the mounts. My 277 is on stiff mounts, just
above my feet where the rudder pedals pass the vibration
through my legs all the way to my brain where I'm sitting.
>An engine that dies at idle is obviously a hazzard in flight.
on approach BEFORE you have the runway made. I believe in
trying to minimize use of full idle while actually in flight.
The engine runs too cool and the spark plug may foul on a long
decsent. ~
For the first flight with a new or rebuilt engine I would
avoid use of full idle entirely. You may find that it has
changed since you took off and now it has suddenly become
very quiet up front. It's better to leave a little power
on almost all the way to the landing. Then check it to
see if it has changed AFTER the first fight. I learned
that the hard way.
--Dan (gru...@uiuc.edu) I hear that racing airplanes
sometimes had their engines bolted directly to the firewall.
iflyk...@gmail.com
I’m wondering about the updated slide modification with an idle notch on the front of the slide. Has anyone ever tried making their own notch on the slide?
Thanks,
Dan in Chattanooga
Tukan Trike