Today's Message Index:
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1. 04:59 AM - Re: Re: Rough Running 912 (Ken Ryan)
2. 05:24 AM - Re: Re: Rough Running 912 (Ken Ryan)
3. 05:44 AM - Re: Re: Rough Running 912 (bjones@dmv.com)
4. 06:24 AM - Re: Rough Running 912 (lucien)
5. 06:45 AM - Re: Re: Rough Running 912 (Ken Ryan)
6. 08:24 AM - Re: Rough Running 912 (Roger Lee)
7. 09:49 AM - Re: Rough Running 912 (moosepileit)
8. 11:54 AM - Re: Rough Running 912 (lucien)
9. 12:33 PM - Re: Rough Running 912 (moosepileit)
10. 01:18 PM - Re: Rough Running 912 (Roger Lee)
11. 02:04 PM - Re: Re: Rough Running 912 (Hugh McKay)
12. 02:59 PM - Re: Rough Running 912 (lucien)
13. 03:48 PM - Re: Rough Running 912 (Roger Lee)
14. 04:44 PM - Re: Re: Rough Running 912 (Richard Girard)
15. 06:23 PM - Re: Rough Running 912 (lucien)
Message 1
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| Subject: | Re: Rough Running 912 |
I could easily be taking off at sea level and then flying to over 14000.
Ken Ryan
Anchorage, Alaska
On Tue, Dec 14, 2010 at 6:11 PM, lucien <lstavenhagen@hotmail.com> wrote:
> lstavenhagen@hotmail.com>
>
>
> kenryan wrote:
> > So all of this talk of changing needle positions based on altitude has me
> wondering. What if you want to fly from sea-level to high altitude? What
> then???
> >
> > Ken Ryan
> > Anchorage, Alaska
> >
>
>
> You shouldn't have to change anything. I live at 7000' MSL (northern NM)
> and fly usually up to 9999' MSL, even on local messing-around flights. My
> carbs still have the factory jetting and they compensate fairly well. Mine
> run a bit rich at low power settings (i.e. between 2000 and 3000 or so on
> the ground or during approaches) and it's going to idle rich also (if you
> use the factory 1.5 turns on the idle needle). But at full power it still
> leans out fairly well, giving EGT's in the 1250 to 1350F range.
>
> So shouldn't be a problem...
>
> LS
>
> --------
> LS
> Titan II SS
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=323383#323383
>
>
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| Subject: | Re: Rough Running 912 |
That example was for flying from a base of 7000 to 9000. I'm talking more
about flying from sea level to about 14,000. Same answer?
On Tue, Dec 14, 2010 at 8:27 PM, Roger Lee <ssadiver1@yahoo.com> wrote:
>
> I'm with Lucien. leave it alone. You will be a little rich for that flight,
> but so what it will fly just fine. Making a permanent needle adjustment
> should mean you are more or less permanently at altitude.
>
> --------
> Roger Lee
> Tucson, Az.
> Light Sport Repairman - Maintenance Rated
> Rotax Repair Center
> Home 520-574-1080 TRY HOME FIRST
> Cell 520-349-7056
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=323400#323400
>
>
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| Subject: | Re: Rough Running 912 |
My home bases are at sea level in Florida Keys and adjacent to Chesapeake
Bay but have flown over Grand Canyon, and around the South West Rockies up
to about 10,000 plus a trip Md to Fl at about 10,000 and have not noticed
any engine roughness in an early s/n 912. Can't remember going to 14,000
feet though.
BJ
KF IV N154K
> That example was for flying from a base of 7000 to 9000. I'm talking more
> about flying from sea level to about 14,000. Same answer?
>
>
> On Tue, Dec 14, 2010 at 8:27 PM, Roger Lee <ssadiver1@yahoo.com> wrote:
>
>> <ssadiver1@yahoo.com>
>>
>> I'm with Lucien. leave it alone. You will be a little rich for that
>> flight,
>> but so what it will fly just fine. Making a permanent needle adjustment
>> should mean you are more or less permanently at altitude.
>>
>> --------
>> Roger Lee
>> Tucson, Az.
>> Light Sport Repairman - Maintenance Rated
>> Rotax Repair Center
>> Home 520-574-1080 TRY HOME FIRST
>> Cell 520-349-7056
>>
>>
>>
>>
>> Read this topic online here:
>>
>> http://forums.matronics.com/viewtopic.php?p=323400#323400
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
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| Subject: | Re: Rough Running 912 |
kenryan wrote:
> I could easily be taking off at sea level and then flying to over 14000.
>
> Ken Ryan
> Anchorage, Alaska
>
>
I still think you'll be ok. By the time you get up there, you're going to be mostly
wide open all the time anyway so the carbs should compensate pretty well.
I've flown mine at density altitudes approaching 12,000' MSL without any visible
running problems.
I would make sure that you have the carb vent lines installed correctly first (i.e.
going into the aircleaners or airbox). The carbs really do go rich at higher
altitudes if the vent lines are just hanging out in the breeze and that could
cause problems that high up.
LS
--------
LS
Titan II SS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=323419#323419
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| Subject: | Re: Rough Running 912 |
Thanks for the inputs!
On Wed, Dec 15, 2010 at 8:21 AM, lucien <lstavenhagen@hotmail.com> wrote:
> lstavenhagen@hotmail.com>
>
>
> kenryan wrote:
> > I could easily be taking off at sea level and then flying to over 14000.
> >
> > Ken Ryan
> > Anchorage, Alaska
> >
> >
>
>
> I still think you'll be ok. By the time you get up there, you're going to
> be mostly wide open all the time anyway so the carbs should compensate
> pretty well. I've flown mine at density altitudes approaching 12,000' MSL
> without any visible running problems.
>
> I would make sure that you have the carb vent lines installed correctly
> first (i.e. going into the aircleaners or airbox). The carbs really do go
> rich at higher altitudes if the vent lines are just hanging out in the
> breeze and that could cause problems that high up.
>
> LS
>
> --------
> LS
> Titan II SS
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=323419#323419
>
>
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| Subject: | Re: Rough Running 912 |
Ok, I didn't want to post this, but for the sake of no one messing with their engine
here goes. I have friends that have been to 18'K + with their 912ULS and
the clip at number 3. Leave your clips alone and your engine will take you any
where you want to go.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=323436#323436
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| Subject: | Re: Rough Running 912 |
Roger,
For the case of sea level to 14k'- I agree, CLIP #3, the standard for the 80HP
Rotax UL. My experience moving from 5k' to sea level proved that out.
You might want to look at the HACMAN for the case of going up high, less than $200
for the install, assuming you didn't need to send out the carbs for the tapping
setup.
Now, My carb vents are just tucked in the bales from the float bowl. I have the
K&N filters, both pancakes, one per side, oriented properly. Should I tap into
the back plastic and run the carb vents back to the air filters? Does anyone
have a picture of this? It would look just like running the vents to the
air inlet manifold on the ROTAX 912s that use a plenum/manifold connected to
both carbs.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=323446#323446
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| Subject: | Re: Rough Running 912 |
moosepileit wrote:
>
> Now, My carb vents are just tucked in the bales from the float bowl. I have
the K&N filters, both pancakes, one per side, oriented properly. Should I tap
into the back plastic and run the carb vents back to the air filters? Does anyone
have a picture of this? It would look just like running the vents to the
air inlet manifold on the ROTAX 912s that use a plenum/manifold connected to
both carbs.
I'd definitely fix this before flying at high altitudes. Soon as I can get out
to the hangar with my camera, I'll take some pictures of how I did mine.
Basically, you can get a brass double-barbed fitting at Lowes or somewhere (1/8"
IIRC), the fitting with barbs on each end and a disc in the center. I.e. looks
like
then, drill a hole in the back panel of the air filter (remove for this and clean
out the scrap rubber completely). Push the barb in till it bottoms out at the
disk. Push the carb vent line over the other end of the barb and you're done....
I have the big flat Rotax K&N's which makes this easy.
But I'll try to get some pics of what I have...
LS
--------
LS
Titan II SS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=323459#323459
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| Subject: | Re: Rough Running 912 |
Lucien, thanks! I was fine cruising at 9500' msl w/ OAT about 32F/freezing. Your
description is great, thanks. I don't think she'll be getting above a couple
thousand feet for a while, EGT is 1400 WOT down low now and takeoff.
It makes sense to have the carbs as equal as possible, which does not include 2
vent hoses randomly in the airflow, even just tucked against the carb bowl holders/bails.
So, with this setup, is there any use for carb drip trays? I don't need them for
heat isolation and the carbs can't drip onto my exhaust in my kitfox...
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=323465#323465
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| Subject: | Re: Rough Running 912 |
Howdy Moose,
The vent lines need to be in the same general area so they pick up the same pressure
to balance the carbs and if the engine were to shake hard for any reason
sometimes you can get some fuel down them and that's why you don't want the vent
lines on top of an exhaust and having a drip tray under them can help. The
drip trays aren't there for the vent lines usually, but for things like a leaking
float bowl gasket which can be common. I always keep a couple of float bowl
gaskets lying around. Easy to replace. The drip trays provide a barrier between
any fuel that comes out of a carb which is usually right above the exhaust.
I would leave them alone. If you're flying you won't know the carbs are leaking
until after you're on the ground and for many of us you won't know unless
you pull the cowl.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=323469#323469
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| Subject: | Re: Rough Running 912 |
Roger,
What is your take on Lucien's idea of running the carb vent lines back into
the air filters on a 912 UL?
Hugh McKay
-----Original Message-----
From: Roger Lee
Sent: Wednesday, December 15, 2010 4:15 PM
Subject: RotaxEngines-List: Re: Rough Running 912
Howdy Moose,
The vent lines need to be in the same general area so they pick up the same
pressure to balance the carbs and if the engine were to shake hard for any
reason sometimes you can get some fuel down them and that's why you don't
want the vent lines on top of an exhaust and having a drip tray under them
can help. The drip trays aren't there for the vent lines usually, but for
things like a leaking float bowl gasket which can be common. I always keep a
couple of float bowl gaskets lying around. Easy to replace. The drip trays
provide a barrier between any fuel that comes out of a carb which is usually
right above the exhaust. I would leave them alone. If you're flying you
won't know the carbs are leaking until after you're on the ground and for
many of us you won't know unless you pull the cowl.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=323469#323469
Message 12
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| Subject: | Re: Rough Running 912 |
hgmckay wrote:
> Roger,
>
> What is your take on Lucien's idea of running the carb vent lines back into
> the air filters on a 912 UL?
>
> Hugh McKay
>
> --
For what it's worth, I didn't make this up. This requirement on the vent lines
is in the installation manual for the 912 series.
There's a diagram in there showing the lines being routed to nipples on the airbox
for illustration purposes, but without the box you kind of have to invent
your method.
Like I said, at my altitude my carbs definitely ran too rich before the fix (EGTs
in the 1100's !) so I'm convinced! ;)
LS
--------
LS
Titan II SS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=323481#323481
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| Subject: | Re: Rough Running 912 |
Rotax likes them run into a common area like an airbox with the same pressure gradient
going to each carb. If you had let's say one large filter then the lines
running in there would be better than into two separate filters. While his
is certainly better than many and by no means bad the best would be to put them
out of all air streams and setup to a common point. There could be a possible
air pressure difference between two carbs, probably small, that could change
things slightly. It might be from maybe someone over oiling one filter compared
to the other with a K&N or the way the engine is set up under a cowl. Nothing
wrong with his setup and there are worse things done to vent lines out there,
but if you wanted to tweak it a little better a common airbox is better.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=323488#323488
Message 14
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| Subject: | Re: Rough Running 912 |
Lucien, I wasn't in on the discussion on the Kolb forum, but I took the time
to read Section 15 and 16 of the installation manual and what it says is
that the carb vents must be routed to a vacuum and ram air free zone. The
air box supplies this, the air filter does not. Letting them just hang,
secured by the float bowl bale is a perfectly acceptable option.
Rick Girard
On Wed, Dec 15, 2010 at 4:57 PM, lucien <lstavenhagen@hotmail.com> wrote:
> lstavenhagen@hotmail.com>
>
>
> hgmckay wrote:
> > Roger,
> >
> > What is your take on Lucien's idea of running the carb vent lines back
> into
> > the air filters on a 912 UL?
> >
> > Hugh McKay
> >
> > --
>
>
> For what it's worth, I didn't make this up. This requirement on the vent
> lines is in the installation manual for the 912 series.
>
> There's a diagram in there showing the lines being routed to nipples on the
> airbox for illustration purposes, but without the box you kind of have to
> invent your method.
>
> Like I said, at my altitude my carbs definitely ran too rich before the fix
> (EGTs in the 1100's !) so I'm convinced! ;)
>
> LS
>
> --------
> LS
> Titan II SS
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=323481#323481
>
>
--
Zulu Delta
Kolb Mk IIIC
582 Gray head
4.00 C gearbox
3 blade WD
Thanks, Homer GBYM
It is not bigotry to be certain we are right; but it is bigotry to be unable
to imagine how we might possibly have gone wrong.
- G.K. Chesterton
Message 15
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| Subject: | Re: Rough Running 912 |
rickofudall wrote:
> Lucien, I wasn't in on the discussion on the Kolb forum, but I took the time
to read Section 15 and 16 of the installation manual and what it says is that
the carb vents must be routed to a vacuum and ram air free zone. The air box supplies
this, the air filter does not. Letting them just hang, secured by the
float bowl bale is a perfectly acceptable option.
>
> Rick Girard
>
Not at my altitudes it isn't. Fortunately 15.1 does clarify the issue a bit - it
also says:
"Pressure differences between intake pressure and pressure in the carburetor chambers
may lead to engine malfunction due to incorrect fuel supply."
That effectively means the vent lines should be at the same atmospheric pressure
(or in the same atmosphere) as the venturis. There is a pressure difference,
tho pretty small, between the outside of the airfilter and the inside. So, if
you have the choice, the lines really need to be routed to the inside. If you
have the airbox, the requirement is very clear, with the diagram, etc.
Now, the interesting thing is it doesn't really show up at sea level. My plane
was originally in Nebraska; the mixture was fine down there with EGT's up to about
1400 with the lines run down the sides into the bales in the usual way. I
guess the effect isn't that significant there. So it's normally not a problem
and the carbs still compensate pretty well.
But when I got it up here after the ferry mission there was a BIG difference -
my EGT's were barely out of the 1100's. And the plugs were starting to get fuel
fouled after about the first 20 hours or so after getting it here. I later learned
about the correct placement of the lines and after the mod that put the
mixture back to practically normal. My EGT's run about 1250 to 1350, a lot closer
to where they should be. Still slightly rich but definitely about the expected
temps for my altitudes and no more fouled plugs.
So in my view, it really is something you want to comply with if you fly at high
altitudes. At sea level, yeah, it's probably not that big of a deal....
LS
--------
LS
Titan II SS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=323500#323500
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