Today's Message Index:
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1. 09:08 AM - Re: Low RPM on Takeoff??? (FLYaDIVE)
2. 12:39 PM - Re: Low RPM on Takeoff??? (Roger Lee)
3. 08:11 PM - Re: Low RPM on Takeoff??? (tmitton)
Message 1
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| Subject: | Re: Low RPM on Takeoff??? |
Sounds like a STUCK VALVE or STUCK RINGS.
Or a Temperature issue with the Mags. Temperature required to expand
something.
Either way it is a ROTAX... What else would you expect!
Barry
I am looking for a Zenith 601 with a Continental O-200 or Lycoming O-235
On Mon, Aug 4, 2014 at 8:11 PM, tmitton <tmitton99@gmail.com> wrote:
>
> Recently my 912ULS engine started only going to 5000rpm on takeoff with
> full throttle.
>
> Previously it always went directly to 5500rpm or so upon application of
> full power. Now it only goes above 5000rpm once it has been flying for a
> few minutes. Once flying it will still go to 5500+ even in a climb so it
> isn't like it is just the climbing load on take off that is holding it back.
>
> No changes have been made to the engine so I don't know what would cause
> the RPM drop. It is enough that takes offs now need 1000+ feet where as
> before 500-600ft was enough. There is definitely a noticeable difference.
>
> I have checked the carburetor linkages - full throw to the stops there.
> Drained the gas in case it was old and replaced it with fresh new gas - no
> change. Tried it with half a tank of 100LL to give it an octane boost - no
> change. Checked the spark plugs - still clean after only 25hrs of use.
> Nothing stuck on the rads. Oil topped up.
>
> So - any idea as to what might cause the drop in rpm?
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=427986#427986
>
>
Message 2
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| Subject: | Re: Low RPM on Takeoff??? |
5000 rpm on take off would equate to approximately 5600 rpm WOT flat and level.
That should be about where you want to be for the average person.
If the compression test is normal (I expect it to be) and the carbs sync up well,
the mag drops are fairly equal and temps are all still what they used to be
then it could be your rpm gauge. If rpms were to really fall off that much then
there has to be changes going on somewhere else. You don't loose 500 rpm with
no other affects.
If you have an air leak that should show up by syncing the carbs (do this at 3500
rpm) or by spraying some starting fluid around the intake manifold and carb
sockets and if the rpm jumps up you have a leak.
Check the prop blades for equal pitch. If you can find nothing then rte-pitch the
prop and see where that takes you.
I have to ask.
Are you sure about your numbers?
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center - Heavy Maint. Rated
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=428172#428172
Message 3
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| Subject: | Re: Low RPM on Takeoff??? |
Positive about the numbers. Re-torqued all the prop bolts to spec (fixed pitch,
wooden prop) and nothing changed. Still 5000rpm WOT on the ground, 5500+rpm WOT
in the air. This sounds like good numbers but it WAS 5400+rpm WOT on the ground
last week!
Might try the starting fluid spray around the carbs next and see what happens.
Thanks,
Todd
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=428192#428192
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