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needles for 447

 
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tc1917(at)hughes.net
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PostPosted: Sun Jul 22, 2007 2:12 am    Post subject: needles for 447 Reply with quote

I just want to add my two cents worth. back a few years ago, I flew a
regular standard 447 on an original firestar. flew it for just about seven
years and three engines. had a lot of trouble with mid range and idling so
I replaced the needle with one I had (dont remember where I got it). It was
a number 11G2 (for a 582) worked great. smoothed out the idle and brought
everything in line where it should be. I believe if I remember correct
(yeah, that might work), it put it around 1080 egt and kept it right fine in
the cht marks, from 250 to 275 or so. at least that is my memory. it
seemed to work for all the engines and they were good runners. just worth
l.5 cents probably. ted cowan, alabama. slingshot driver. p.s. I supposed
there will be those out there that say it wont work, but what the heck, it
is only a needle!!


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Joined: 29 May 2006
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Location: Jordan Valley, Or

PostPosted: Sun Jul 22, 2007 8:59 am    Post subject: needles for 447 Reply with quote

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Thom Riddle



Joined: 10 Jan 2006
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Location: Buffalo, NY, USA (9G0)

PostPosted: Mon Jul 23, 2007 2:58 am    Post subject: Re: needles for 447 Reply with quote

Thanks for the needle solutions for your cases. Following is what I did yesterday.

I re-pitched the prop again, this time such that I am getting 6450 rpm at full throttle level flight.... just right. I then flew for 2.3 hours with two stops en-route. The EGTs were running around 1100 +/- 25 during 5500-5800 rpm cruise with no problems in that range. BUT the needle clip is in the #4 (richest) position. Below 5500 rpm the engine is still unstable with RPM varying all over the place.

After the flight I checked the plugs and they are about right. I removed the carb and took it apart. All the jets and the jet needle are per Rotax spec and in good condition with less than 70 hours on engine. The float levels are perfect too.

Today I plan to order a slightly richer needle jet (2.72 vs current 2.70) and one each of the two jet needles that you guys stated solved your problems. With three new pieces the combinations of possible parts is quite large. I'll test them each one at a time and then in various combinations, if needed. In each case I'll put the clip back in the #2 position to begin with.

I'll let you know what finally works for me (I hope).


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PostPosted: Mon Jul 23, 2007 9:09 pm    Post subject: needles for 447 Reply with quote

Thom, You say the engine only has 70 hours on it, but you don't give its actual age. Is it a new engine run at the national average 30 to 50 hours a year or an older engine that spent some time as a hangar ornament? Is the 70 hours since factory new or since rebuild?
The reason I ask is this, the symptoms you describe are a mixture going leaner at higher engine vacuum. The further you get from WOT the worse the problem becomes.
It' s beginning to sound like an air leak somewhere in the intake system.
How is the idle range set? Is the idle air adjustment near the factory setting (.5 turns out for 447, 1 turn out for 447DC? The idle mixture circuit bleeds into the lower midrange. If you richen up the idle, do you see any changes in the middle and high midrange cruise where the anomalous leaning begins. Have you inspected and greased all the rubber fittings to make sure there are no cracks or delaminations. How is the condition of the crank seals?
That's just some of the things I can think of off the top of my head.
Something just does not add up for a 70 hour engine to require radical jetting changes.

Rick

On 7/23/07, Thom Riddle <riddletr(at)gmail.com (riddletr(at)gmail.com)> wrote:[quote] --> Kolb-List message posted by: "Thom Riddle" <riddletr(at)gmail.com (riddletr(at)gmail.com)>

Thanks for the needle solutions for your cases. Following is what I did yesterday.

I re-pitched the prop again, this time such that I am getting 6450 rpm at full throttle level flight.... just right. I then flew for 2.3 hours with two stops en-route. The EGTs were running around 1100 +/- 25 during 5500-5800 rpm cruise with no problems in that range. BUT the needle clip is in the #4 (richest) position. Below 5500 rpm the engine is still unstable with RPM varying all over the place.

After the flight I checked the plugs and they are about right. I removed the carb and took it apart. All the jets and the jet needle are per Rotax spec and in good condition with less than 70 hours on engine. The float levels are perfect too.

Today I plan to order a slightly richer needle jet (2.72 vs current 2.70) and one each of the two jet needles that you guys stated solved your problems. With three new pieces the combinations of possible parts is quite large. I'll test them each one at a time and then in various combinations, if needed. In each case I'll put the clip back in the #2 position to begin with.

I'll let you know what finally works for me (I hope).

--------
Thom in Buffalo
N197BG FS1/447

--------------------
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PostPosted: Tue Jul 24, 2007 2:47 am    Post subject: Re: needles for 447 Reply with quote

Rick,

The engine was new last year and is immaculately clean, no seal leaks.

The only range in which the EGTs are high is the mid-range. At the moment, with the clip in the #4 (richest position) the EGTs are around 1100 +/-25 at cruise. They are fine at idle and low throttle settings and WOT. I have not done an exhaustive intake leak test but will be looking into that while waiting for my jets and needles to arrive. I'm also going to mark on the throttle at 1/4, 1/2, 3/4 positions so I can get an idea of where the problem is occurring in terms of throttle position, not just RPM range. The biggest problem now is that I can't get it to hold a stable RPM below 5,500.

When I got the FS the airscrew was back out a lot more than .5 as the Rotax manual recommends. I re-set it to stock and it would not run so I backed it out to where it was and it runs fine at low speed and idle. The idle speed was set rather low so I bumped it up to get about 2150 rpm when warm. When cold it is a good bit less than 2,000 rpm so I have to add throttle to keep the gearbox happy. If I set the idle speed for 2,000 rpm cold, then when warm it will be really revving and require brakes to stay still on the ramp.


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PostPosted: Tue Jul 24, 2007 6:47 am    Post subject: needles for 447 Reply with quote

If you are considering trying different jet needles, you can find more
information on how different needles may change the mixture in a
graph in the CPS catalog. The Maintenance Tips article number 11,
"Tuning the Bing Carburetor - Understanding the Mid-Range Circuit" has
a lot of detail that may interest you.

Vince Nicely

Thom Riddle wrote:

Quote:


Thanks for the needle solutions for your cases. Following is what I did yesterday.

I re-pitched the prop again, this time such that I am getting 6450 rpm at full throttle level flight.... just right. I then flew for 2.3 hours with two stops en-route. The EGTs were running around 1100 +/- 25 during 5500-5800 rpm cruise with no problems in that range. BUT the needle clip is in the #4 (richest) position. Below 5500 rpm the engine is still unstable with RPM varying all over the place.

After the flight I checked the plugs and they are about right. I removed the carb and took it apart. All the jets and the jet needle are per Rotax spec and in good condition with less than 70 hours on engine. The float levels are perfect too.

Today I plan to order a slightly richer needle jet (2.72 vs current 2.70) and one each of the two jet needles that you guys stated solved your problems. With three new pieces the combinations of possible parts is quite large. I'll test them each one at a time and then in various combinations, if needed. In each case I'll put the clip back in the #2 position to begin with.

I'll let you know what finally works for me (I hope).

--------
Thom in Buffalo
N197BG FS1/447




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PostPosted: Tue Jul 24, 2007 7:42 am    Post subject: Re: needles for 447 Reply with quote

Thanks Vince, I'm familiar with that graph. Though it is hard to read, a straight edge along the line for a particular jet needle helps clarify it.

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PostPosted: Tue Jul 24, 2007 12:09 pm    Post subject: needles for 447 Reply with quote

Thom, Had a customer and his son here a few minutes ago and John, the son, described a problem virtually word for word of what you are experiencing with his single carb 503. The solution, credited to someone at South Mississippi was to increase the pitch of the prop to achieve about 6200 at WOT in flight. He said the CHT's came up and the EGT's came right down.
At least I offer cheap ideas to try.Smile

Rick

On 7/24/07, Vince Nicely <vincenic1(at)earthlink.net (vincenic1(at)earthlink.net) > wrote:
Quote:
--> Kolb-List message posted by: Vince Nicely < vincenic1(at)earthlink.net (vincenic1(at)earthlink.net)>

If you are considering trying different jet needles, you can find more
information on how different needles may change the mixture in a
graph in the CPS catalog. The Maintenance Tips article number 11,
"Tuning the Bing Carburetor - Understanding the Mid-Range Circuit" has
a lot of detail that may interest you.

Vince Nicely

Thom Riddle wrote:

Quote:
--> Kolb-List message posted by: "Thom Riddle" < riddletr(at)gmail.com (riddletr(at)gmail.com)>

Thanks for the needle solutions for your cases. Following is what I did yesterday.

I re-pitched the prop again, this time such that I am getting 6450 rpm at full throttle level flight.... just right. I then flew for 2.3 hours with two stops en-route. The EGTs were running around 1100 +/- 25 during 5500-5800 rpm cruise with no problems in that range. BUT the needle clip is in the #4 (richest) position. Below 5500 rpm the engine is still unstable with RPM varying all over the place.

After the flight I checked the plugs and they are about right. I removed the carb and took it apart. All the jets and the jet needle are per Rotax spec and in good condition with less than 70 hours on engine. The float levels are perfect too.

Today I plan to order a slightly richer needle jet (2.72 vs current 2.70) and one each of the two jet needles that you guys stated solved your problems. With three new pieces the combinations of possible parts is quite large. I'll test them each one at a time and then in various combinations, if needed. In each case I'll put the clip back in the #2 position to begin with.


--
Rick Girard
"Ya'll drop on in"
takes on a whole new meaning
when you live at the airport. [quote][b]


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PostPosted: Tue Jul 24, 2007 5:58 pm    Post subject: Re: needles for 447 Reply with quote

Rick,
I already did that but then the engine rpm instability below 5500 rpm was made worse. At 6450 WOT rpm the EGTs are around 1100 +/25 at cruise which is much better than before the changes made so far, but the engine rpm instability below 5500 is still present. I'm awaiting new jets and needles to see if I can find a combination that solves all the problems.


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Thom Riddle



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PostPosted: Mon Jul 30, 2007 9:51 am    Post subject: Re: needles for 447 Reply with quote

FOREWARNING - Long Post

I finally got a chance to do some more testing and jet changes. Before changing anything, I decided this morning to find out what rpms equated to carb. piston/slide position. I marked the throttle cable at 5 equally spaced points. Idle, WOT, and three intermediate equally spaced places. So now I have 4 approx. equal regions marked. I'll number the points from 1-5 with idle being #1.

As it turns out, at WOT (#5) the piston/slide is well up inside the cylinder and the next point marked (#4) was exactly where the bottom of the piston just cleared the top of the air intake. This means that at throttle openings between #4 and #5 no more air is being pumped (assuming same rpm) than at WOT (#5) but more fuel is coming in because the jet needle continues to be withdrawn from the needle jet thus making the fuel passage larger. It seems to me that, THIS, not the size of the main jet, is why the EGTs go down at WOT. The main jet is an ultimate limiting factor but not the whole enchilada. BTW, at WOT I was seeing 6600 rpm this morning in the cool weather when last time I flew in a good bit warmer weather, I was getting 6450 rpm with the identical setup. More about OAT in a moment.

At #4 throttle position I was seeing around 6300 rpm and about 1100F EGTs +/- 25 or so. Remember this is with the stock jetting and needles but the clip in the lowest(richest) position. In the next leaner position I was getting over 1200F.

At #3 position I was seeing anywhere from 5500-5800 rpm and EGTs about the same as in #4 position. This position equates to a piston/slide position of about 2/3rds open.

I suspected I would not be able to get rpm stability below this point but went ahead and reduced throttle anyway and at the #2 position I was seeing 4800 rpm and it was STABLE with EGTs about 1050-1100F. #2 position is when the piston is about 1/3rd or perhaps a little more open. 4800 rpm with the current prop pitch is the slowest engine rpm I can hold in level flight. I was surprised and mystified at the rpm stability because I had not seen this before nor had I seen EGTs this low at this engine speed. After flying for a total of about an hour I landed.

After a rest it was beginning to warm up a good bit so I took off for another flight to confirm the engine stability. At the higher OATs the engine was no longer stable below 5500 rpm and adding the enricher did NOT help but hindered the engine running.

I landed and changed the jet from 2.70 (stock) to 2.72 and moved the clip up to the next leaner position (#3) instead of #4. I took off and things were looking pretty good and the rpm stability at 4800 was back and EGTs around 1050-1000F. I landed and changed the jet from 2.72 to 2.74.

Now the EGTs were way up to 1200F and the instability was back. This makes no sense to me at all since the 2.74 is supposed to be richer than the 2.72 which is supposed to be richer than the 2.70. I changed back to the 2.72 jet and #3 clip position on the stock (15K2) needle and put the airplane away for the day. The thermals were knocking me about too much.

I'm not finished testing yet but have come to some conclusions thus far.

1) I'm beginning to doubt the EGT readings on the EIS. I did not check the plugs after this morning's test flights so I need to do that before concluding the EGTs are wrong.
2) This 447 sure is finicky, much more so than the 377 I had.
3) The OAT seems to make a big difference in engine stability at lower than 5500 rpm with a given jet setup.

Next step will be to change the needles from stock (15K2) to 15E5U and 11G2 which were fixes for others with finicky 447s. If I can't get it to run right at various OATs without changing jets for every 20 degrees F of temp change, then I will be thinking seriously about the manual mixture control I've read about for the Bing 54s. If I end up doing this then I'll jet for rich and lean as I need it manually.

Thanks for any more input you might have.

Thom the Experimenter


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Richard Pike



Joined: 09 Jan 2006
Posts: 1671
Location: Blountville, Tennessee

PostPosted: Mon Jul 30, 2007 10:19 am    Post subject: needles for 447 Reply with quote

Excellent post, it is great to get something that you can really chew on and
think about.
Reference your idea for the manual mixture control: years ago a friend had a
Hummer with a Zenoah 250 that used a Mikuni pumper carb. Since the high
speed needle on the carb was on the pilot's side of everything, we took a
short stub of fuel hose and safety wired it to the needle for a u-joint,
then stuck a long dowel into the hose and made an extension that ran all the
way to the cockpit. Labeled the directions of twist "rich" and "lean", his
goal was to keep his EGT gauge at 1100. Never had an engine failure, and he
really liked it.

Richard Pike
MKIII N420P (420ldPoops)

From: "Thom Riddle" <riddletr(at)gmail.com>
To: <kolb-list(at)matronics.com>
Sent: Monday, July 30, 2007 1:51 PM
Subject: Re: needles for 447
Quote:


FOREWARNING - Long Post

I finally got a chance to do some more testing and jet changes. Before
changing anything, I decided this morning to find out what rpms equated to
carb. piston/slide position. I marked the throttle cable at 5 equally
spaced points. Idle, WOT, and three intermediate equally spaced places. So
now I have 4 approx. equal regions marked. I'll number the points from 1-5
with idle being #1.

As it turns out, at WOT (#5) the piston/slide is well up inside the
cylinder and the next point marked (#4) was exactly where the bottom of
the piston just cleared the top of the air intake. This means that at
throttle openings between #4 and #5 no more air is being pumped (assuming
same rpm) than at WOT (#5) but more fuel is coming in because the jet
needle continues to be withdrawn from the needle jet thus making the fuel
passage larger. It seems to me that, THIS, not the size of the main jet,
is why the EGTs go down at WOT. The main jet is an ultimate limiting
factor but not the whole enchilada. BTW, at WOT I was seeing 6600 rpm this
morning in the cool weather when last time I flew in a good bit warmer
weather, I was getting 6450 rpm with the identical setup. More about OAT
in a moment.

At #4 throttle position I was seeing around 6300 rpm and about 1100F EGTs
+/- 25 or so. Remember this is with the stock jetting and needles but the
clip in the lowest(richest) position. In the next leaner position I was
getting over 1200F.

At #3 position I was seeing anywhere from 5500-5800 rpm and EGTs about
the same as in #4 position. This position equates to a piston/slide
position of about 2/3rds open.

I suspected I would not be able to get rpm stability below this point but
went ahead and reduced throttle anyway and at the #2 position I was seeing
4800 rpm and it was STABLE with EGTs about 1050-1100F. #2 position is when
the piston is about 1/3rd or perhaps a little more open. 4800 rpm with the
current prop pitch is the slowest engine rpm I can hold in level flight.
I was surprised and mystified at the rpm stability because I had not seen
this before nor had I seen EGTs this low at this engine speed. After
flying for a total of about an hour I landed.

After a rest it was beginning to warm up a good bit so I took off for
another flight to confirm the engine stability. At the higher OATs the
engine was no longer stable below 5500 rpm and adding the enricher did NOT
help but hindered the engine running.

I landed and changed the jet from 2.70 (stock) to 2.72 and moved the clip
up to the next leaner position (#3) instead of #4. I took off and things
were looking pretty good and the rpm stability at 4800 was back and EGTs
around 1050-1000F. I landed and changed the jet from 2.72 to 2.74.

Now the EGTs were way up to 1200F and the instability was back. This makes
no sense to me at all since the 2.74 is supposed to be richer than the
2.72 which is supposed to be richer than the 2.70. I changed back to the
2.72 jet and #3 clip position on the stock (15K2) needle and put the
airplane away for the day. The thermals were knocking me about too much.

I'm not finished testing yet but have come to some conclusions thus far.

1) I'm beginning to doubt the EGT readings on the EIS. I did not check the
plugs after this morning's test flights so I need to do that before
concluding the EGTs are wrong.
2) This 447 sure is finicky, much more so than the 377 I had.
3) The OAT seems to make a big difference in engine stability at lower
than 5500 rpm with a given jet setup.

Next step will be to change the needles from stock (15K2) to 15E5U and
11G2 which were fixes for others with finicky 447s. If I can't get it to
run right at various OATs without changing jets for every 20 degrees F of
temp change, then I will be thinking seriously about the manual mixture
control I've read about for the Bing 54s. If I end up doing this then I'll
jet for rich and lean as I need it manually.

Thanks for any more input you might have.

Thom the Experimenter


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http://forums.matronics.com/viewtopic.php?p=126383#126383




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Thom Riddle



Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

PostPosted: Mon Jul 30, 2007 10:43 am    Post subject: Re: needles for 447 Reply with quote

Richard,

Thanks for your comments on the "home-made" manual mixture control. I'm sure it works fine but I'm not quite that much of an experimenter so if I can't get satisfactory results with jet/needle changes I'm looking at the one that Greenskyadventures sells. I don't want the automatic HACman, just the manual one. For those who have not seen this, here is a link
Manual Mixture Control for Bing 54

http://www.greenskyadventures.com/bing/manualMixPrelease.htm

Automatic Altitude Compensating Mixture Control

http://www.greenskyadventures.com/bing/hacinstall.htm


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jb92563



Joined: 23 Mar 2007
Posts: 314
Location: Southern California

PostPosted: Mon Jul 30, 2007 11:21 am    Post subject: Re: needles for 447 Reply with quote

After reading all the posts I cant help but think that due to the instability there has to be a leak somewhere on the carb/intake side.

Im not familiar with the 447's but perhaps there is an intake leak at a gasket or a crack in an extension, or even something wrong in the carb.

Everytime I have ever experienced erratic engine speeds its because the fuel/air mixture is varying outside of normal throttle control.....airleak, bubbles, restrictions (ie dirt particles in carb)

How far is your fuel pickup height from the carb height? Using Fuel pump?

Crank pressure to fuel pump leaks, fuel pump leaks (hole in fuel pump diaphram)

Just some more ideas to check out.

Ray


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PostPosted: Mon Jul 30, 2007 12:13 pm    Post subject: needles for 447 Reply with quote

Ray,

I can't help but think you're onto something that is a distinct
possibility. In my experience with working with carburator problems, an
erratic behaving carb MIGHT have something other than jets and needles that
are causing the problem(s).

As I am always led to believe, when you find the "culprit" you will want
to kick yourself for overlooking the obvious. That's not suggest that Thom
hasn't checked the obvious, but at this point, with the engine rpm and temps
seemingly all over the place, I would take a step back and reccommend the
following;

1) Insure the gages are accurate and are functioning properly.

2) Spray carb-cleaner around the base and sides of the carb, while the
engine is running, watching for any increase in rpms (indicating an air
leak) (Build a carb throat inlet extension, if you have to, to make sure no
vapors get sucked down the carb, giving you a false reading.)

It sounds as though Thom is on top of things, with all the testing
and what-not he's doing, but I kind of get the impression the high egt temps
sound like a leak, too.

FWIW, Mike in SW
Utah


Quote:
From: "jb92563" <jb92563(at)yahoo.com>
Reply-To: kolb-list(at)matronics.com
To: kolb-list(at)matronics.com
Subject: Re: needles for 447
Date: Mon, 30 Jul 2007 12:21:47 -0700



After reading all the posts I cant help but think that due to the
instability there has to be a leak somewhere on the carb/intake side.

Im not familiar with the 447's but perhaps there is an intake leak at a
gasket or a crack in an extension, or even something wrong in the carb.

Everytime I have ever experienced erratic engine speeds its because the
fuel/air mixture is varying outside of normal throttle control.....airleak,
bubbles, restrictions (ie dirt particles in carb)

How far is your fuel pickup height from the carb height? Using Fuel pump?

Crank pressure to fuel pump leaks, fuel pump leaks (hole in fuel pump
diaphram)

Just some more ideas to check out.

Ray

--------
Ray
Riverside County, CA

Do Not Archive


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Wade Lawicki



Joined: 27 May 2007
Posts: 31
Location: Nashville Tn.

PostPosted: Tue Jul 31, 2007 2:10 pm    Post subject: Re: needles for 447 Reply with quote

Thom,
We at our hanger keep a set of new single egt and cht gauges on hand just to verify that the ones installed are accurate!!! they are notorious for being up to 400 degrees off!!! I have chased my tail more than once only to find it is the gauge and nothing mechanical. Its worth the effort to out rule it first.
Fly Safe,
Wade


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JetPilot



Joined: 10 Jan 2006
Posts: 1246

PostPosted: Wed Aug 01, 2007 7:12 am    Post subject: Re: needles for 447 Reply with quote

I also fly with a Rotax 447, and it is rock solid stable at any RPM. I can set it at 4700 and it will run there all day long, never any of the surging or other problems mentioned by Thomas. EGT and CHT are fine no matter what RPM I run the engine at.

It really sounds like a carb probem, or something more serious than just needle settings Thomas. Check all other possibilities, you will probably be kicking yourself for doing all this methodical testing of different needles and jets just to find out it did not matter because of an air leak or other problem.

Mike


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