Today's Message Index:
----------------------
1. 05:08 AM - Re: Replacing throttle return springs (Thom Riddle)
2. 05:29 AM - Re: Replacing throttle return springs (Thom Riddle)
3. 07:03 AM - Re: Re: carb balancing (rlborger)
4. 07:11 AM - Re: Replacing throttle return springs (Roger Lee)
5. 07:19 AM - Re: carb balancing (Roger Lee)
6. 09:04 AM - Re: Re: Replacing throttle return springs (Dave Austin)
7. 10:46 AM - Re: Re: Replacing throttle return springs (Paul McAllister)
8. 11:22 AM - replacing throttle return springs (Fergus Kyle)
9. 12:04 PM - Re: Replacing throttle return springs (Thom Riddle)
10. 04:54 PM - Engine Vibration (Gtblu)
11. 06:02 PM - Re: Engine Vibration (Thilo Kind)
12. 06:03 PM - Re: Engine Vibration (Thilo Kind)
13. 06:54 PM - Re: Engine Vibration (Gtblu)
14. 07:56 PM - Re: Engine Vibration ()
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| Subject: | Re: Replacing throttle return springs |
I keep hearing many folks on this list saying that 1800 rpm is minimum recommended
idle speed for the 9 series Rotax engines. Can someone show me in the Rotax
Documentation (not Lockwood) where it says that? The reason I ask is that the
attached file is a snapshot from my 912S Installation Manual.
As you can plainly see it says IDLE SPEED AROUND 1400 RPM. I'm going to piss off
some folks here with my next statement. If you can't get yours to idle smoothly
at less than 1800 rpm, perhaps you ought to have a professional mechanic do
it for you, because something may be amiss in your procedure or your engine.
As the owner operator of your airplane, you are entitled to set your idle speed
at anything you want. If you are happy with 1800, then so be it, but don't tell
me THE MINIMUM RECOMMENDED IDLE SPEED is different from what the Rotax Installation
Manual says unless you can document that in another Rotax Document.
--------
Thom in Buffalo
N221FA Allegro 2000 912UL
N197BG FS1/447
--------------------
Believe nothing, no matter where you read it or who has said it, not even if I
have said it, unless it agrees with your own reason and your own common sense.
- Buddha
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=154975#154975
Attachments:
http://forums.matronics.com//files/idle_speed_540.jpg
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| Subject: | Re: Replacing throttle return springs |
Paul,
I'm glad to hear that you are able to get your engine to idle at less than 1800
rpm. I was beginning to think that I was some sort of real world evil wizard
like my alter ego, Lord Voldermort of Harry Potter fame. do not archive
--------
Thom Riddle
N221FA Allegro 2000 912UL
N197BG FS1/447
--------------------
Believe nothing, no matter where you read it or who has said it, not even if I
have said it, unless it agrees with your own reason and your own common sense.
- Buddha
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=154978#154978
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| Subject: | Re: carb balancing |
Paul,
Having read your comments and gone through a Google search, reading
the posted comments, I'm convinced. I'll order one.
Now, which set of fittings are needed for the Rotax? Standard? BMW?
5mm? 6mm?
Thanks...
Good building and great flying,
Bob Borger
Europa Kit #A221 N914XL, XS Mono, Intercooled 914, Airmaster C/S
http://www.europaowners.org/N914XL
(90%) tail kit done, wings closed, cockpit module installed, pitch
system in, landing gear frame in, rudder system in, outrigger mod in,
Fuselage Top on, lift/drag/flap pins in, wing incidence set, tie bar
in, flap drive in, Mod 70 done. Baggage bay in. Flaps & Main Gear
complete. Mod 72 complete. Instrument panel complete, except for
testing. Rotax 914 installed (for the 3rd time). Airmaster Prop
installed. Electrical complete, except for testing. Fuel system
complete except for testing. Working in - 32 Tail, 34 Door Latches &
35 Doors, 37 Interior & Finishing. Airmaster arrived 29 Sep 05.
Seat arrived from Oregon Aero. E04 interior kit has arrived and is
being installed.
3705 Lynchburg Dr.
Corinth, TX 76208
Home: 940-497-2123
Cel: 817-992-1117
On Dec 29, 2007, at 9:14 PM, Paul McAllister wrote:
>
> Hi all,
>
> I just wanted to share my experience with carburettor balancing. I
> purchased the vacuum gaauges from Lockwood aviation, but for some
> reason I was never able to get them balanced nicely. In particular
> I would find I had a vibration in the range of 3200 ~ 3500 RPM.
>
> Any how I purchased a TwinMax carburettor balancer. This thing is
> awesome, it has variable sensitivity and I can get them nuts on
> using this thing. I am able to idle my 914T ar 1500 RPM nicely.
> It makes quite a difference to my Europa during the landing phase.
> If you google TwinMax you can find several suppliers. Tryhttp://
> www.adventuremotogear.com/twinmax.mgi?mgiToken=29HJXUUF
>
> Cheers, Paul
>
> N378PJ
> http://www.europa.net.nz/363/index.html
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| Subject: | Re: Replacing throttle return springs |
Hi Thom,
You are right the manual does say that. Yes you can get it to idle at those lower
rpm's, but the reason Rotax teaches in their schools to idle around the 1800
mark is for the protection of the gearbox and other parts effected by vibration.
Because the 100hp has more compression than the 80 hp engine at low rpm's
it bangs away at the gearbox and the mating parts inside including the overload
clutch. No matter what the engine will idle smoother at 1800. The chance of
losing and engine at idle on approach is much higher at 1400 rpm settings also.
Those are the reasons, not that you can't make it idle at 1400 it's the higher
compression hammering and chugging along on the parts with the 100hp because
of the good compression. You may never have an issue at 1400, but later down
the line you may have to do more service work sooner than the other guy on your
gearbox.
You can prove this to yourself using a dial indicator. Set it up against the outside
area around the gearbox (so the motion will be left to right) and let the
engine idle at 1400 and then do it again and let the engine idle at 1800. The
dial indicator will have less impact and movement at 1800. A big factor in this
vibration is as Thom has pointed out that the carbs must be properly synced.
I have posted a picture of a gage set on this forum. It is a liquid filled calibrated
set you can put together for about $55 and it is very easy to work with.
I Have talked many many people through a carb balance over the phone and you
are welcome to call any time.
520-574-1080 in Tucson, Az.
A carb balance should take less than 30 min. after you have done it once. It is
not something to be afraid of it is relatively easy once you understand what
certain things do when you turn a screw or cable.
--------
Roger Lee
Tucson, Az.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=154986#154986
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| Subject: | Re: carb balancing |
Hi Thom,
You are right the manual does say that. Yes you can get it to idle at those lower
rpm's, but the reason Rotax teaches in their schools to idle around the 1800
mark is for the protection of the gearbox and other parts effected by vibration.
Because the 100hp has more compression than the 80 hp engine at low rpm's
it bangs away at the gearbox and the mating parts inside including the overload
clutch. No matter what the engine will idle smoother at 1800. The chance of
losing and engine at idle on approach is much higher at 1400 rpm settings also.
Those are the reasons, not that you can't make it idle at 1400 it's the higher
compression hammering and chugging along on the parts with the 100hp because
of the good compression. You may never have an issue at 1400, but later down
the line you may have to do more service work sooner than the other guy on your
gearbox.
You can prove this to yourself using a dial indicator. Set it up against the outside
area around the gearbox (so the motion will be left to right) and let the
engine idle at 1400 and then do it again and let the engine idle at 1800. The
dial indicator will have less impact and movement at 1800. A big factor in this
vibration is as Thom has pointed out that the carbs must be properly synced.
I have posted a picture of a gage set on this forum. It is a liquid filled calibrated
set you can put together for about $55 and it is very easy to work with.
I Have talked many many people through a carb balance over the phone and you
are welcome to call any time. You don't need to spend a lot of money on a balancing
system, but just understand what is going on when you do certain things.
Each person likes different instruments and tools.
520-574-1080 in Tucson, Az.
A carb balance should take less than 30 min. after you have done it once. It is
not something to be afraid of it is relatively easy once you understand what
certain things do when you turn a screw or cable.
--------
Roger Lee
Tucson, Az.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=154987#154987
Attachments:
http://forums.matronics.com//files/carb_sync_1501_140.jpg
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| Subject: | Re: Replacing throttle return springs |
Thom,
Please don't piss us off.
Dave Austin 601HDS - 912, Spitfire Mk VIII
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| Subject: | Re: Replacing throttle return springs |
Hi Thom,
I should add a few other comments. My engine is a 914T and if I understand it
correctly it has the same compression ratio as the 80HP engines, so my experience
might not be relevant for the 912S.
The other experience I can share is that although my idle is set in the 1500 ~
1600 range, I typically see 2200 RPM on short final with the throttle closed due
to the windmill effect, so I can say (for my aircraft at least) that a lower
idle speed is unlikely to result in an engine stoppage.
The other pratice I have adopted is to once I have exited the runway is to set
my throttle to 1800 RPM for taxi.
Just as an FYI, with careful adjustment I can get the idle down lower, but as others
have mentioned it really sounds like "rattle and roll" going on under the
cowling so its probably not a great idea.
BTW, I am still trying to debug my loss of boost at altitude, but is way too cold
to work in the hanger at the moment.
Cheers, Paul
Be a better friend, newshound, and
know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ
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| Subject: | replacing throttle return springs |
Thom -
I was interested in your approach/landing thoughts (and figured you
for Air Force training, way back), and agree with all your thinking BUT am
unsure of the 912 characteristics - so put this in for thoughts.
We were always taught two final processes:
1 Always give the engine a quick burst to keep 'er warm on final and
ready for overshoot,
2 Always throttle off during the approach to hear if the warning horn
indicates gear not locked down.
This may not apply to Rotax (not flying yet) so might be redundant
and perhaps the gearhorn is equally unnecessary. Just a thought.
Cheers, Ferg
Message 9
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| Subject: | Re: Replacing throttle return springs |
Ferg,
If the Rotax 9 series engine has its idle speed set appropriately (fill the rpm
you prefer) and the carbs are synchronized well, and there are no other problems
with the engine, then the engine will be ready for full power in prep for
a go-around or balked landing, without "blipping" the throttle occasionally on
final. In my opinion there are two reasons for this. One the automatic mixture
control (alt. compensating) feature of the Bing 64 carbs precludes over-rich
running and fowling of the plugs due to prolonged idle speed operation. The second
reason is that the heads are liquid-cooled so the engine does not normally
experience wide temperature swings over short time periods when gliding at
idle speed. These features (and others) make the Rotax 9 series engines superior
to (but more complex than) the 50's and 60's vintage Lycoming, Continental,
Franklin etc. air cooled aircraft engines.
--------
Thom Riddle
N221FA Allegro 2000 912UL
N197BG FS1/447
--------------------
Believe nothing, no matter where you read it or who has said it, not even if I
have said it, unless it agrees with your own reason and your own common sense.
- Buddha
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=155025#155025
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| Subject: | Engine Vibration |
Hello Listers and Happy New Year.
Many users of Rotax 912 uls Engines talk of vibration between abut 4400 and 5000
revs which you get used to after a while. However the top end of that vibration
is now creeping up to 5300 revs. Its incredible consistant even to the point
of the vibration stopping if extra load is put on like a turn or up elevator.
It feels to me similar to bearing float of the crankshaft in a vehicle, but
is more obvious in the air especially those magical early mornings with no turbulance.
This engine has been recently split and a new sprag clutch put in (100 hours ago)
but bearings were checked and not replaced. The engne has done 729 hours in
a Slepcev Storch and runs very sweetly above this moving revs line, currently
about 5300 rpm.
It has always run with a little noticable vibration on bothe left and right when
doing a mag check. ( Left and right is not entirely accurate as the plugs that
operate on each switch are shared top and bottom left and right.
I will check plugs, carby sync, carby's generally, air filters, prop alignment
but before I started I thought I'd put this out there for others experience on
engine vibration. Its not violent, but its very noticable on a still day especially
increasing revs from rough to smooth and as it is changing in nature I
need to asses it a little more meticulously.
Any thoughts?
all the best for 2008
regards
Geoff Bell
--------
Slepcev Storch
912 uls 731 hours
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=155064#155064
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| Subject: | Re: Engine Vibration |
Hi Geoff,
sounds to me like a prop issue - you should check angle on the blades. Been there
myself...
Good luck
Thilo
-------- Original-Nachricht --------
> Datum: Sun, 30 Dec 2007 16:52:05 -0800
> Von: "Gtblu" <gtbjbell@gmail.com>
> An: rotaxengines-list@matronics.com
> Betreff: RotaxEngines-List: Engine Vibration
>
> Hello Listers and Happy New Year.
>
> Many users of Rotax 912 uls Engines talk of vibration between abut 4400
> and 5000 revs which you get used to after a while. However the top end of
> that vibration is now creeping up to 5300 revs. Its incredible consistant even
> to the point of the vibration stopping if extra load is put on like a
> turn or up elevator. It feels to me similar to bearing float of the crankshaft
> in a vehicle, but is more obvious in the air especially those magical
> early mornings with no turbulance.
>
> This engine has been recently split and a new sprag clutch put in (100
> hours ago) but bearings were checked and not replaced. The engne has done 729
> hours in a Slepcev Storch and runs very sweetly above this moving revs
> line, currently about 5300 rpm.
> It has always run with a little noticable vibration on bothe left and
> right when doing a mag check. ( Left and right is not entirely accurate as the
> plugs that operate on each switch are shared top and bottom left and right.
>
> I will check plugs, carby sync, carby's generally, air filters, prop
> alignment but before I started I thought I'd put this out there for others
> experience on engine vibration. Its not violent, but its very noticable on a
> still day especially increasing revs from rough to smooth and as it is
> changing in nature I need to asses it a little more meticulously.
>
> Any thoughts?
>
> all the best for 2008
> regards
> Geoff Bell
>
> --------
> Slepcev Storch
> 912 uls 731 hours
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=155064#155064
>
>
>
>
>
>
>
>
>
--
Psssst! Schon vom neuen GMX MultiMessenger gehrt?
Der kann`s mit allen: http://www.gmx.net/de/go/multimessenger?did=10
Message 12
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| Subject: | Re: Engine Vibration |
Hi Geoff,
sounds to me like a prop issue - you should check angle on the blades. Been there
myself...
Good luck
Thilo
-------- Original-Nachricht --------
> Datum: Sun, 30 Dec 2007 16:52:05 -0800
> Von: "Gtblu" <gtbjbell@gmail.com>
> An: rotaxengines-list@matronics.com
> Betreff: RotaxEngines-List: Engine Vibration
>
> Hello Listers and Happy New Year.
>
> Many users of Rotax 912 uls Engines talk of vibration between abut 4400
> and 5000 revs which you get used to after a while. However the top end of
> that vibration is now creeping up to 5300 revs. Its incredible consistant even
> to the point of the vibration stopping if extra load is put on like a
> turn or up elevator. It feels to me similar to bearing float of the crankshaft
> in a vehicle, but is more obvious in the air especially those magical
> early mornings with no turbulance.
>
> This engine has been recently split and a new sprag clutch put in (100
> hours ago) but bearings were checked and not replaced. The engne has done 729
> hours in a Slepcev Storch and runs very sweetly above this moving revs
> line, currently about 5300 rpm.
> It has always run with a little noticable vibration on bothe left and
> right when doing a mag check. ( Left and right is not entirely accurate as the
> plugs that operate on each switch are shared top and bottom left and right.
>
> I will check plugs, carby sync, carby's generally, air filters, prop
> alignment but before I started I thought I'd put this out there for others
> experience on engine vibration. Its not violent, but its very noticable on a
> still day especially increasing revs from rough to smooth and as it is
> changing in nature I need to asses it a little more meticulously.
>
> Any thoughts?
>
> all the best for 2008
> regards
> Geoff Bell
>
> --------
> Slepcev Storch
> 912 uls 731 hours
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=155064#155064
>
>
>
>
>
>
>
>
>
--
Psssst! Schon vom neuen GMX MultiMessenger gehrt?
Der kann`s mit allen: http://www.gmx.net/de/go/multimessenger?did=10
Message 13
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| Subject: | Re: Engine Vibration |
Thanks Thilo, Yes for it to change so quickly (within two weeks) suggests dirty
prop maybe, lots of insects at the moment due to wet warm weather.
Thanks.
regards
Gt
--------
Slepcev Storch
912 uls 731 hours
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=155097#155097
Message 14
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| Subject: | Re: Engine Vibration |
Hello Geoff.
Happy New Year to you.
Do you have an IVO Prop on your Slepcev Storch?
I had this problem on my Kolb ultralight, which was caused be a faulty
prop. There was no way to adjust the propeller, it was balanced and tracked
perfectly, but nothing worked. Finally sent the prop to Ivo for
replacement. Problem solved.
Just a thought.
Best regards,
Johann G.
Iceland.
Zenith 701.
On Sun, 30 Dec 2007 16:52:05 -0800, "Gtblu" <gtbjbell@gmail.com> wrote:
>
> Hello Listers and Happy New Year.
>
> Many users of Rotax 912 uls Engines talk of vibration between abut 4400
> and 5000 revs which you get used to after a while. However the top end of
> that vibration is now creeping up to 5300 revs. Its incredible consistant
> even to the point of the vibration stopping if extra load is put on like
> a turn or up elevator. It feels to me similar to bearing float of the
> crankshaft in a vehicle, but is more obvious in the air especially those
> magical early mornings with no turbulance.
>
> This engine has been recently split and a new sprag clutch put in (100
> hours ago) but bearings were checked and not replaced. The engne has done
> 729 hours in a Slepcev Storch and runs very sweetly above this moving
revs
> line, currently about 5300 rpm.
> It has always run with a little noticable vibration on bothe left and
> right when doing a mag check. ( Left and right is not entirely accurate
as
> the plugs that operate on each switch are shared top and bottom left and
> right.
>
> I will check plugs, carby sync, carby's generally, air filters, prop
> alignment but before I started I thought I'd put this out there for
others
> experience on engine vibration. Its not violent, but its very noticable
on
> a still day especially increasing revs from rough to smooth and as it is
> changing in nature I need to asses it a little more meticulously.
>
> Any thoughts?
>
> all the best for 2008
> regards
> Geoff Bell
>
> --------
> Slepcev Storch
> 912 uls 731 hours
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=155064#155064
>
>
>
>
>
>
>
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