Today's Message Index:
----------------------
1. 02:28 AM - Re: Re: Rejetting a 914 during Winter? (R Holder)
2. 06:08 AM - Re: Rejetting a 914 during Winter? (Thom Riddle)
3. 06:12 AM - Re: Rejetting a 914 during Winter? (rampil)
4. 06:25 AM - Re: Rejetting a 914 during Winter? (Roger Lee)
5. 06:35 AM - Re: Rejetting a 914 during Winter? (Roger Lee)
6. 06:57 AM - Re: Rejetting a 914 during Winter? (Thom Riddle)
7. 07:04 AM - Re: Re: Rejetting a 914 during Winter? (Noel Loveys)
8. 07:14 AM - Re: Re: Rejetting a 914 during Winter? (LarryMcFarland)
9. 07:27 AM - Re: Rejetting a 914 during Winter? (Thom Riddle)
10. 08:09 AM - Re: Rejetting a 914 during Winter? (rampil)
11. 08:09 AM - Re: Re: Rejetting a 914 during Winter? (Noel Loveys)
12. 08:18 AM - Re: Rejetting a 914 during Winter? (Thom Riddle)
13. 09:17 AM - Re: Rejetting a 914 during Winter? (darinh)
14. 10:22 AM - Re: Rejetting a 914 during Winter? (rampil)
15. 10:56 AM - Re: Rejetting a 914 during Winter? (Gilles Thesee)
16. 05:43 PM - Re: Rejetting a 914 during Winter? (Roger Lee)
17. 06:03 PM - Serial number location - Rotax 914 (Paul McAllister)
Message 1
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| Subject: | Re: Rejetting a 914 during Winter? |
darinh wrote:
> Thanks for the post but I have an Airmasters CS prop so
> that is not the issue. It is not a problem with load
> on the prop, rather when it hits the top 10% of
> throttle, it runs a bit rough as though it is jetted
> wrong.
> My understanding is that the main jet controls the top
> end and the engine is smooth as silk through the the
> range from idle to approximately 90% throttle then is
> runs rough so this is why I was thinking it may have
> something to do with the main jetting.
> -------- Darin Hawkes Series 7 914 Turbo Kaysville,
> Utah
Rotaxes are designed to run with the jets that come with
them. I am sure Rotax would say that there is never any
need to change the jetting for winter, or high altitude.
One possibility for a missfire at high power is that the
fuel flow is not sufficient. Have you checked your fuel
flows and your filters ? Does it run better with both fuel
pumps on ?
Richard Holder
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| Subject: | Re: Rejetting a 914 during Winter? |
What do your EGTs telling you?
--------
Thom Riddle
N1208P RANS S6S, Tailwheel, 912UL
N197BG FS1/447
--------------------
It is by universal misunderstanding that all agree. For if, by ill luck, people
understood each other, they would never agree.
- Charles Baudelaire
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=223509#223509
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| Subject: | Re: Rejetting a 914 during Winter? |
Lucian and Ivan,
Happy New Year.
Just a note on the Bings:
There is no evidence that these carbs do ANY altitude compensation.
Not anywhere on the web that I have found. Certainly not in my
flight testing, not in the Diamond Katana DV-20 manual both of
which show that the fuel flow actually increases with altitude.
You might also note that Rotax has ceased claiming altitude compensation
in all their more recent literature.
If you want to respond, please enclose actual data, not hand waving.
I put up the data from the DV-20 and my own tests several months ago.
I have also spoken to Rotax and Kodiak technical people and they do not
deny these observations. Ah well, flying at 8000' will cost you
more fuel than at 4000'. Maybe the wind will be better ;-)
--------
Ira N224XS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=223511#223511
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| Subject: | Re: Rejetting a 914 during Winter? |
You haven't mentioned making sure the carbs have been synced lately? Even if they
have been and it was before the really cold temps I would do it again to eliminate
the possibility. It should not be a jetting issue. We need to look at
differential diagnoses.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Service Center
520-574-1080
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=223513#223513
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| Subject: | Re: Rejetting a 914 during Winter? |
Hi Lucian,
They have to be pressure compensating because there is no direct cable attached
to the carb slide and the holes that are drilled in the carbs allow for pressure
differential on top of the carb to be different from the carb throat and the
pressure differential is what moves the slide up and down. With altitude and
throttle position changes come pressure changes.
I like the word pressure over altitude.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Service Center
520-574-1080
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=223517#223517
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| Subject: | Re: Rejetting a 914 during Winter? |
Rampil,
A Katana DA-20A (80 hp Rotax 912 A or F, 80 hp not 100 hp) flight manual can be
found at
http://www.diamondaircraft.com/library/16/10/DA20-A1-AFM-inc-Rev17.pdf
In this document the charts, tables and data indicate a constant fuel consumption
rate for a given % power with no indication of variation with density altitude.
--------
Thom Riddle
N1208P RANS S6S, Tailwheel, 912UL
N197BG FS1/447
--------------------
It is by universal misunderstanding that all agree. For if, by ill luck, people
understood each other, they would never agree.
- Charles Baudelaire
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=223522#223522
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| Subject: | Re: Rejetting a 914 during Winter? |
First of all the 912 is a four stroke engine so the pitch of the prop won't
affect to any great degree the mixture of the engine. Thinning the prop
will allow it to pass through the air easier so you will be able to develop
take off horsepower. You don't want to thin it too much because the extra
oxygen in the air will also allow your engine to develop more horsepower
while of course burning more fuel.
Noel
-----Original Message-----
From: owner-rotaxengines-list-server@matronics.com
[mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of Ivan
Sent: Wednesday, January 07, 2009 11:06 PM
Subject: Re: RotaxEngines-List: Re: Rejetting a 914 during Winter?
Why are we flattening the prop pitch? Are we doing this for better climb or
are we doing this for mixture control with the Bing altitude compensating
carburetor having a needle to control the mixture rather than a mixture
control? I thought flattening the prop will make it run leaner and we want
to richen up things a bit for the winter? I am confused about something.
Ivan
----- Original Message -----
From: "Roger Lee" <ssadiver1@yahoo.com>
Sent: Wednesday, January 07, 2009 6:57 PM
Subject: RotaxEngines-List: Re: Rejetting a 914 during Winter?
>
> Don't worry about the jetting. Re-pitch the prop. You will loose 100-125
> engine rpm due to the colder denser winter air verses the warmer summer
> air with the prop. We do it in Tucson all the time. The summer temps are
> 90 F + and the winter mornings are 32-40F. You will run better. Take out
> approximately 1/2 degree to pick up another 100 rpm.
>
> --------
> Roger Lee
> Tucson, Az.
> Light Sport Repairman - Maintenance Rated
> Rotax Service Center
> 520-574-1080
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=223466#223466
>
>
>
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| Subject: | Re: Rejetting a 914 during Winter? |
Hi Thom,
The EGTs should provide exhaust gas temps that indicate the lean or
richness of the mixture at various rpm
and altitude. The Bings compensate for lower pressure at altitude and
my EGTs also reflect that as well.
The EGT is a very reliable diagnostic and I wouldn't be without it.
Larry McFarland 601HDS at www.macsmachine.com
Thom Riddle wrote:
>
> What do your EGTs telling you?
>
> --------
> Thom Riddle
> N1208P RANS S6S, Tailwheel, 912UL
> N197BG FS1/447
>
>
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| Subject: | Re: Rejetting a 914 during Winter? |
Larry,
Yes, I know and that is why I was asking the original poster what his EGTs were
telling him about rich/lean condition.
http://riddletr.googlepages.com/a%26pmechanix
--------
Thom Riddle
N1208P RANS S6S, Tailwheel, 912UL
N197BG FS1/447
--------------------
It is by universal misunderstanding that all agree. For if, by ill luck, people
understood each other, they would never agree.
- Charles Baudelaire
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=223531#223531
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| Subject: | Re: Rejetting a 914 during Winter? |
Hi Thom,
Happy New Year.
We went through this several months ago. You posted a 912/DA20
POH and I posted the DV20912S.
http://forums.matronics.com/download.php?id=8745 for your convenience
That plus Eric, Kerry, and Phil have all agreed with my data from my
tests. Sorry. Just install a floscan, read it and weep. :-(
--------
Ira N224XS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=223539#223539
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| Subject: | Re: Rejetting a 914 during Winter? |
A problem, well known to racers, is the octane rating of the fuel... if the
octane rating is below spec, then the engine will run very rough at high
rpm. This can actually be very damaging to the engine. I'd check with a
Rotax shop before trying any of the octane boosters available and in ther
meantime only buy high octane fuel from high volume gas stations. They have
the freshest fuel.
Another slight possibility is you are over revving your engine. You may
also want to check the calibration of your tachometer. I haven't heard any
discussions on the reliability of the 912 tach. but there is always a first
time.
Noel
Rotaxes are designed to run with the jets that come with
them. I am sure Rotax would say that there is never any
need to change the jetting for winter, or high altitude.
One possibility for a missfire at high power is that the
fuel flow is not sufficient. Have you checked your fuel
flows and your filters ? Does it run better with both fuel
pumps on ?
Richard Holder
Message 12
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| Subject: | Re: Rejetting a 914 during Winter? |
Rampil,
I didn't say you were incorrect, just showing different documentation from the
same source, Diamond Aircraft. I don't have a fuel flow meter so I can't do what
you suggest. I wish I did have one and may add one some day.
I have not noticed any meaningful difference in EGTs from sea level density altitude
to 12,000' DA on our 912UL as long as I keep the engine above 4500 rpm.
I know this does not say anything about actual fuel flow but it does say that
the automatic mixture adjustment with changes in DA is working well, which is
my first priority.
--------
Thom Riddle
N1208P RANS S6S, Tailwheel, 912UL
N197BG FS1/447
--------------------
It is by universal misunderstanding that all agree. For if, by ill luck, people
understood each other, they would never agree.
- Charles Baudelaire
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=223543#223543
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| Subject: | Re: Rejetting a 914 during Winter? |
Wow, a whole bunch of post since last night! First of all, the issue I am having
really has nothing to do with calibration of my tach since the engine is running
rough at full throttle...if it was smooth and still not generating the RPM
it should, I would suspect the tach but this is not the issue.
I use only Premium fuel from a station that has fairly high traffic and the fuel
is 100% ethanol free. Having said this, I don't think any station has a huge
demand for premium fuel due to the prices and most cars are fine with the mid-grade
stuff.
Anyone know why Rotax would jet the two carbs differently?
Roger,
I have synched them again a couple times. I think I mentioned this in a earlier
post but I am only getting the misfire or "bump" on the left carb. I will PM
you with additional information.
--------
Darin Hawkes
Series 7
914 Turbo
Kaysville, Utah
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=223552#223552
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| Subject: | Re: Rejetting a 914 during Winter? |
Hi Thom,
This spring I need to do my Commercial long cross country. Buffalo
is just far enough from my base to qualify. Maybe you can take a ride
with me and see what I am talking about.
PS: In science there is an important precept which goes:
Absence of Evidence is Not Evidence of Absence.
If Diamond did not report measurements in the DA manual, that is not
positive proof that they measured no changes. (It would be hard to
believe that the Bings are absolutely perfect in compensation over such a
wide altitude range anyway, something no one claims)
Europa XS 912uls BMA EFIS/2 VFR/IFR Day/Night
--------
Ira N224XS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=223566#223566
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| Subject: | Re: Rejetting a 914 during Winter? |
Darin,
Just found your post.
>
> Does anyone rejet their 914 (or 912) during winter?
We don't.
Our 914 airplane was flown without any problem between - 14Celsius and
+ 38Celsius, and from zero foot density altitude up to FL 145.
We usually run at 31"/5000 rpm, and FF is a little lower at altitude,
which I wonder may be due to bubbling in the fuel lines, and a slightly
lower output.
> Can any of you engine gurus tell me if this may be the source of my slightly
diminished engine performance? Also, one last thing that makes me think the engine
is running a bit rich is that if I land at a small strip and shut down right
after landing,
We are based on a 2000' airstrip, but never shut down without one minute
or so idling for the well-being of the turbo .
Best regards,
--
Gilles
http://contrails.free.fr
Message 16
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| Subject: | Re: Rejetting a 914 during Winter? |
Hi Darin,
If you have exhausted the fuel/carb issue then it's time to think electrical which
can make it seem like a fuel issue. What makes you pretty sure it's fuel/carb?
It could even be a ground on the ignition system or a chafed wire.
Float Flyr,
I agree the prop pitch is a balance of specific performance characteristics that
each person wants to achieve from their engine or plane. Most want it balanced
between cruise, climb and fuel economy. The the average person with a 912,
5500 engine rpm works well and is suggested by Rotax.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Service Center
520-574-1080
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=223634#223634
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| Subject: | Serial number location - Rotax 914 |
Hi All,
I am actually posting a question that- I did know the answer to (once).
I went out to the hanger tonight to get the s/n off my engine and I thought
it was the number stamped on the rear casing, port side near the ignition
trigger sensors.- The reason I am now doubting this number is that when I
went the ROAN site it stated that the numbers are typically 7 digits, I co
uld only find 6 digits.
So, the question is,- is the 6 digit number the right one, should I be lo
oking somewhere else, or did I simply miss a digit.
Thanks,- Paul
=0A=0A=0A
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