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Carb jet changes

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Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Thu Nov 01, 2007 1:09 pm Post subject: Carb jet changes

I had an interesting week working on the Bing carb on my serial #2062  

Jabiru 2200A engine. I had been running the engine with the cowl off,  

and I noticed that fuel was going up the clear tube that is the carb  

bowl vent. I assumed that this was a temporary overflow of fuel and  

it would soon be gone with the engine running, but it was not.  

However,  revving  the engine got rid of the fuel in that line.  

Finally, I closed the main fuel valve, and shut the engine off. I  

then took the incoming air hose off the carb, and about a half-cup of  

fuel gushed out. This led me to believe that the float needle was  

leaking...DUH!  It turned out to be exactly that. I ordered a new  

needle and seat, and a #40 idle jet. The reason for ordering the jet  

was I had read others' comments that the #40 jet took care of their  

idling problems. With the new needle and seat in place, and #40 jet  

too, the engine ran great, and I could get the idle down to below  

900, and it was smooth. Later on, I decide to test the old #45 jet,  

so I reinstalled it, and the engine ran great with that (original)  

jet. So my major problem was with the float needle and seat, and  

nothing else. Amazingly, I have had this bad idle problem for some  

time now, and it's been a leaking needle and seat all along. I had  

been just learning to deal with the rough idle.



Along with curing the rough idle, I no longer have to shut the main  

fuel valve off 30 seconds before I shut the engine down. I thought by  

doing this, I was lowering the fuel level in the float bowl, and  

thereby keeping the carb from "boiling over", but I was just using up  

the excess fuel that was already (probably) laying in the inlet air  

hose.

Lynn Matteson

Grass Lake, Michigan

Kitfox IV Speedster  w/Jabiru 2200

flying w/420+ hrs

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Peter H

Joined: 20 Mar 2007
Posts: 197

Posted: Thu Nov 01, 2007 5:02 pm Post subject: Carb jet changes

Lynn

I found with the J3300 that the needle seat supplied is 2.25mm and according

to Bing engineers is meant for gravity feed. Anything above 2500RPM and it

ran over rich.

I replaced that seat with the 1.5mm seat recommended by Bing and that cured

rich running all the way to WOT and EGT was within recommended range

although hotter, but if I turned on the electric boost pump even this 1.5mm

seat leaked and caused a big increase in fuel consumption. I discussed with

Jabiru engineers and they confirmed policy to run with the over size seat to

cool the engine and it "works" OK up to 2700 RPM and is "safe" above that

with consumption up to 40LPH.

I am now using TBI and have total control of mixture full range.

Peter H



--

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Thu Nov 01, 2007 5:49 pm Post subject: Carb jet changes

Hi Peter-

I have an electric boost pump, but only use it to insure fuel at the  

carb after any work done, or to check for carb leakage, like I found  

this week. A test pilot turned it on while landing a year ago (not  

knowing any better) and the engine quit. Without the electric pump,  

and with only the mechanical Jabiru pump operating while engine is  

running, the gauge reads 2 lbs. pressure, and all seems to be fine.



I should note that when I first got the plane up after the changes,  

it was running hotter on the right-hand 2 cylinders. I rotated the  

carb according to the "old wives tale", that is rotate the top of the  

carb towards the cool, rich side, and that helped. I then rotated it  

again, a little more this time, and the cylinders are within 60-70° F  

of one another, for most of the operating range...certainly where it  

operates the most, at cruising speed. Having had the plenum chamber  

and carb off last week I can see how this works. If the carb is  

rotated, the spray pattern will change in respect to the divider that  

is situated inside the plenum chamber. Apparently if the carb top is  

rotated towards the cool side, the spray pattern is divided more  

toward the hot, lean side, and the temps between the two sides become  

closer together. At least that's what I've been able to observe.



It's late at night and my memory is fading...what's TBI? A type of  

carb, I'm assuming? I'm just not recalling....



Lynn Matteson

Grass Lake, Michigan

Kitfox IV Speedster  w/Jabiru 2200

flying w/420+ hrs



On Nov 1, 2007, at 9:01 PM, Peter Harris wrote:



[quote] 

 <peterjfharris(at)bigpond.com>



 Lynn

 I found with the J3300 that the needle seat supplied is 2.25mm and  

 according

 to Bing engineers is meant for gravity feed. Anything above 2500RPM  

 and it

 ran over rich.

 I replaced that seat with the 1.5mm seat recommended by Bing and  

 that cured

 rich running all the way to WOT and EGT was within recommended range

 although hotter, but if I turned on the electric boost pump even  

 this 1.5mm

 seat leaked and caused a big increase in fuel consumption. I  

 discussed with

 Jabiru engineers and they confirmed policy to run with the over  

 size seat to

 cool the engine and it "works" OK up to 2700 RPM and is "safe"  

 above that

 with consumption up to 40LPH.

 I am now using TBI and have total control of mixture full range.

 Peter H



 --

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Peter H

Joined: 20 Mar 2007
Posts: 197

Posted: Thu Nov 01, 2007 7:49 pm Post subject: Carb jet changes

Lynn

By TBI I mean throttle body fuel injection. I have a 45mm throttle body with

two injectors.

Rotating the carb. means that the partly opened butterfly is directing the

air/fuel flow to one side or the other and this affects mixture rich or lean

each side of the plenum.

With the throttle body I have it mounted so the butterfly axis is horizontal

and the problem does not arise.

Peter H



--

dredmoody(at)cox.net
Guest

Posted: Fri Nov 02, 2007 5:20 am Post subject: Carb jet changes

Actually, according to Pete Krotje, rotating the top of the carb toward the cool side works because it moves the jet, which is on the bottom of the carb throat, toward the hot side. The Bottom of the intake stream where the jet is spewing fuel, tends to be the richer area in the intake stream going inmto the plenum. Moving that rich segment of the intake flow to the hot (lean) side richens the mixture for the cylinders on that side.



At least that's what I was taught.



Dred



---- Peter Harris <peterjfharris(at)bigpond.com> wrote: 

[quote] 

 

 Lynn

 By TBI I mean throttle body fuel injection. I have a 45mm throttle body with

 two injectors.

 Rotating the carb. means that the partly opened butterfly is directing the

 air/fuel flow to one side or the other and this affects mixture rich or lean

 each side of the plenum.

 With the throttle body I have it mounted so the butterfly axis is horizontal

 and the problem does not arise.

 Peter H

 

 --

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Fri Nov 02, 2007 10:34 am Post subject: Carb jet changes

Excellent, Dred. That's the way I had it figured out, and now that I  

see the divider inside the plenum, it makes more sense to me WHY the  

rotation of the carb works.



Lynn



On Nov 2, 2007, at 9:19 AM, <dredmoody(at)cox.net> wrote:



[quote] 



 Actually, according to Pete Krotje, rotating the top of the carb  

 toward the cool side works because it moves the jet, which is on  

 the bottom of the carb throat, toward the hot side. The Bottom of  

 the intake stream where the jet is spewing fuel, tends to be the  

 richer area in the intake stream going inmto the plenum. Moving  

 that rich segment of the intake flow to the hot (lean) side richens  

 the mixture for the cylinders on that side.



 At least that's what I was taught.



 Dred



 ---- Peter Harris <peterjfharris(at)bigpond.com> wrote:

> 

> <peterjfharris(at)bigpond.com>

>

> Lynn

> By TBI I mean throttle body fuel injection. I have a 45mm throttle  

> body with

> two injectors.

> Rotating the carb. means that the partly opened butterfly is  

> directing the

> air/fuel flow to one side or the other and this affects mixture  

> rich or lean

> each side of the plenum.

> With the throttle body I have it mounted so the butterfly axis is  

> horizontal

> and the problem does not arise.

> Peter H

>

> --

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

avidflyer01

Joined: 07 Jun 2007
Posts: 9

Posted: Thu Nov 08, 2007 9:12 pm Post subject: Re: Carb jet changes

Lynn,I also noticed that if I remove the SCAT tube which connects the carb to the air filter, there is some petrol sitting there (if the engine has just been running); I also experience some troubles as to idle, if I reduce power to around 800rpm the engine will progressively start slowing down and will eventually quit after some 30-45secs (as it occasionally does on final if I don't baby it with throttle). exhaust is definitely sooty in spite of high EGT in flight.



I will try putting a new idle/seat; it sounds surprising, though, because I would expect to find a puddle of gas under the plane if left with a valve open - which is not the case in my plane.



martin

avid flyer STOL HH w/Jab2200

Peter H

Joined: 20 Mar 2007
Posts: 197

Posted: Thu Nov 08, 2007 11:34 pm Post subject: Carb jet changes

Martin,

1.	The needle valve seat supplied is 2.25mm meant for gravity feed and

Bing specify a 1.5mm seat for pump feed. The 2.25mm seat leaks under pump

pressure causing an excessive rich mixture but this normally is worse at the

higher throttle settings. 

2.	When throttle is reduced quickly some excess unused fuel runs back

down the induction tubes and floods through the top of the carby. and into

the scat.

 

Peter H



--

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Sat Nov 10, 2007 9:45 pm Post subject: Carb jet changes

Martin-

Are you really using SCAT hose directly to the carb? My instructions  

warned against that, as the engine wants a nice smooth flow of air,  

for the last 4 inches at least. The air must flow smoothly into the  

carb because the two air sensor ports need a smooth and equal flow in  

order to operate properly...or so the instructions say.



Your idle problems sound just *exactly* like mine did before I  

installed the newer, and smaller, float needle and seat. Now I can  

fly the plane, land, taxi to wherever on the field, and shut the  

engine off....no more having to shut off the main fuel valve a  

certain amount of time before I shut the engine down...no more  

worrying about whether it will start when hot...just no more treating  

the engine differently. Hell, with the engine operating like this, I  

could rent it out as a training plane...NOT!



Maybe your leak was not as great as mine, Martin, or it evaporates  

quickly (no puddle under yours). My rubber air hose to my carb, for  

the carb incoming air, is a piece of truck radiator hose, and unless  

it had a long-standing pool of gas sitting in it, would not leak any  

fuel until it rotted away.



Lynn Matteson

Grass Lake, Michigan

Kitfox IV Speedster  w/Jabiru 2200

flying w/420+ hrs

On Nov 9, 2007, at 12:12 AM, avidflyer01 wrote:



 	  Quote: 	
		   

 <vegayacht(at)club.fr>



 Lynn,I also noticed that if I remove the SCAT tube which connects  

 the carb to the air filter, there is some petrol sitting there (if  

 the engine has just been running); I also experience some troubles  

 as to idle, if I reduce power to around 800rpm the engine will  

 progressively start slowing down and will eventually quit after  

 some 30-45secs (as it occasionally does on final if I don't baby it  

 with throttle). exhaust is definitely sooty in spite of high EGT in  

 flight.



 I will try putting a new idle/seat; it sounds surprising, though,  

 because I would expect to find a puddle of gas under the plane if  

 left with a valve open - which is not the case in my plane.



 martin

 avid flyer STOL HH w/Jab2200





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=144710#144710

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

avidflyer01

Joined: 07 Jun 2007
Posts: 9

Posted: Sun Nov 11, 2007 12:18 am Post subject: Re: Carb jet changes/SCAT hose to carb

Lynn, I was also warned against the use of scat hose; My initial setup that dit not include airbox   (had only 90Â°elbow from truck radiator hose and conical air filter on it) worked fine. Then I decided to mount the airbox - I think  Avids have less room between carb intake and firewall (70mm) compared to Kitfoxes and my rubber elbow would not fit any longer.

So I went for a scat hose, just to try, and it actually works fine (I also flew with carb intake simply open, I don't see any noticable diffrence in power, smoothness, or EGT.

of course it is very difficult to put a scat on the narrow flange of the carb and tighten the clamp without having it slide off. But if you achieve it correctly, it works.

I am at present making an epoxy "cobra head" to have a firm fit to the carb and a smooth air transition.

martin

Jim Ballenger

Joined: 12 Jan 2006
Posts: 18
Location: Virginia Beach, Virginia

Posted: Sun Nov 11, 2007 2:37 am Post subject: Carb jet changes

Lynn

I read your story in the Sport Pilot.  Great job.

Jim Ballenger

Sonex 760 TD / Jabiru 2200

Virginia Beach, VA

---

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Sun Nov 11, 2007 4:25 am Post subject: Carb jet changes

Thanks, Jim. I had a lot of fun doing the article and it brought back  

a lot of memories of building the plane...which of course wasn't all  

that long ago.



Lynn Matteson

Grass Lake, Michigan

Kitfox IV Speedster  w/Jabiru 2200

flying w/420+ hrs

do not archive

On Nov 11, 2007, at 5:36 AM, Jim Ballenger wrote:



 	  Quote: 	
		   

 <ulpilot(at)cavtel.net>



 Lynn

 I read your story in the Sport Pilot.  Great job.

 Jim Ballenger

 Sonex 760 TD / Jabiru 2200

 Virginia Beach, VA

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Sun Nov 11, 2007 4:33 am Post subject: Carb jet changes

Martin-

I was thinking about making a fiberglass "cobra head," because of the  

closeness of my installation, then I found the radiator hose  

solution. The hose of so stiff that it's a bear to get on the carb,  

but when on it works just fine...nice smooth transition from the  

airbox, through about 4" of SCAT, then into about 6" of the curved  

radiator hose, which is vertical to the carb.



Lynn Matteson

Grass Lake, Michigan

Kitfox IV Speedster  w/Jabiru 2200

flying w/420+ hrs

do not archive

On Nov 11, 2007, at 3:18 AM, avidflyer01 wrote:



 	  Quote: 	
		   

 <vegayacht(at)club.fr>



 Lynn, I was also warned against the use of scat hose; My initial  

 setup that dit not include airbox   (had only 90Â°elbow from truck  

 radiator hose and conical air filter on it) worked fine. Then I  

 decided to mount the airbox - I think  Avids have less room between  

 carb intake and firewall (70mm) compared to Kitfoxes and my rubber  

 elbow would not fit any longer.

 So I went for a scat hose, just to try, and it actually works fine  

 (I also flew with carb intake simply open, I don't see any  

 noticable diffrence in power, smoothness, or EGT.

 of course it is very difficult to put a scat on the narrow flange  

 of the carb and tighten the clamp without having it slide off. But  

 if you achieve it correctly, it works.

 I am at present making an epoxy "cobra head" to have a firm fit to  

 the carb and a smooth air transition.

 martin





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=145018#145018

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

ElleryWeld(at)aol.com
Guest

Posted: Sun Nov 11, 2007 5:34 am Post subject: Carb jet changes

Yes great story Lynn  Kinda reminds me of my self from Radio controlled to Real wings 

  

 That Jab is a really nice engine Just installed one on a Plane for a Guy  cant wait to hear it run 

  

   Ellery in Maine 

 do not archive





  [quote][b]

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Sun Nov 11, 2007 7:26 am Post subject: Carb jet changes

Thanks Ellery-



By the way, I'm not responsible for the picture captions about the  

"cordless iron" or the one about the "aluminum of the wing from  

rusting."  : )

Lynn Matteson

Grass Lake, Michigan

Kitfox IV Speedster  w/Jabiru 2200

flying w/420+ hrs

do not archive

On Nov 11, 2007, at 8:33 AM, ElleryWeld(at)aol.com wrote:



 	  Quote: 	
		   Yes great story Lynn  Kinda reminds me of my self from Radio  

 controlled to Real wings



 That Jab is a really nice engine Just installed one on a Plane for  

 a Guy  cant wait to hear it run



   Ellery in Maine

 do not archive



 www.matronics.com/Navigator?JabiruEngine-List _- 

 ============================================================

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

agbeyer(at)sbcglobal.net
Guest

Posted: Sun Nov 11, 2007 8:05 am Post subject: Carb jet changes

Here are some pics of the intake elbow I made.

  

 Zodiac 601HDS, 3300 Jabiru (350 Hrs.)

 Al from Oshkosh

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Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Sun Nov 11, 2007 2:33 pm Post subject: Carb jet changes

I see that you have the air inlet tube coming in from the side. This  

is what I was warned against, both in the workshop at Sun 'n' Fun and  

in reading the instruction "manual." They say the airflow should come  

in from below or above, not from the side, as coming from the side  

sends different signals to the two air sensor ports in the top of the  

carb throat. But with 350 hours on yours, it must be working well.  

I've got ~435 on mine and it works well. I guess that's why we  

experiment.



Lynn Matteson

Grass Lake, Michigan

Kitfox IV Speedster  w/Jabiru 2200

flying w/420+ hrs



On Nov 11, 2007, at 11:04 AM, ALAN BEYER wrote:



[quote] Here are some pics of the intake elbow I made.



 Zodiac 601HDS, 3300 Jabiru (350 Hrs.)

 Al from Oshkosh



 ---

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

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