Matronics Email Lists :: View topic

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Carburetor

Matronics Email Lists Forum Index -> Zenith-List

View previous topic :: View next topic

Author Message

BobbyPaulk(at)comcast.net
Guest

Posted: Tue Nov 04, 2008 12:16 pm Post subject: Carburetor

List,

my 3300 Jab idles fairly good at 800 ~ 900 Rpm when i crack the throttle off 

idle at about 1050 to 1300 it will puff black smoke. at 1500 rpm it will smooth 

out. 

has any one changed jets or needle to fix the idle and low end mixture.

i think if i change the needle jet to a smaller size then it would run too lean 

at cruise.

this would call for a change in needle configuration. 

i gotta do something. any help would be appreciated.



bobby

N131BP

601 XL

- The Matronics Zenith-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Zenith-List

crvsecretary

Joined: 18 Mar 2007
Posts: 38
Location: Naugatuck, CT

Posted: Wed Nov 05, 2008 1:03 pm Post subject: Carburetor

Hello Bobby:

    

   Although I am FAR from an expert on Bing CV (constant velocity) carbs, i can attempt to explain the theory of what is happening....

    

   At idle you are running exclusively through the idle circuit.  As you crack open the throttle, there are transition circuits that come into play.  When you get to 1500 you are running "on the needle" that sticks through the main jet, efffectively closing off the size of the main jet fuel flow until the needle retracts....from 3/4 throttle to wide open you're on the main jet only.

    

   Transition circuit problems are very difficult to diagnose.  Sounds like you are running very rich through this circuit.  I would recommend a note to Jabiru USA - Pete knows these things better than anyone.  The other source of information is "The Carb Doctor" 

 http://www.bingcarburetor.com/

 who is the official importer of Bing carbs and parts here in the USA.  The manual is worth every penny.  It's been a long time since I had to access this info, but every owner of an old BMW "airhead" motorcycle has had to deal with these carbs at least once !!

    

   After some thought...check your float height.  If it is set too high that would cause a rich running engine.....

    

   Good Luck

    

   Tracy Smith

   N458XL reserved

   610XL

   Do Not Archive

    

    

   

  

   	  Quote: 	
		   	  Quote: 	
		  

Time: 12:16:34 PM PST US

From: BobbyPaulk(at)comcast.net (BobbyPaulk(at)comcast.net)

Subject: Carburetor



List,

my 3300 Jab idles fairly good at 800 ~ 900 Rpm when i crack the throttle off 

idle at about 1050 to 1300 it will puff black smoke. at 1500 rpm it will smooth



out. 

has any one changed jets or needle to fix the idle and low end mixture.

i think if i change the needle jet to a smaller size then it would run too lean



at cruise.

this would call for a change in needle configuration. 

i gotta do something. any help would be appreciated.



bobby

N131BP

601 XL  	
	


   [quote] [b]

- The Matronics Zenith-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Zenith-List

_________________
Zenith 601XL N458XL (reserved)
Naugatuck, CT
Tail Complete; working on wings

hills(at)sunflower.com
Guest

Posted: Thu Nov 06, 2008 5:32 pm Post subject: Carburetor

Bobby;  

   

Contact Bing, they have a manual that will help you tune the carb and pick replacement jets.  

   

Roger  

   

         

  

From: owner-zenith-list-server(at)matronics.com [mailto:owner-zenith-list-server(at)matronics.com] On Behalf Of crvsecretary(at)aol.com

 Sent: Wednesday, November 05, 2008 3:02 PM

 To: zenith-list(at)matronics.com

 Subject: Carburetor  

  

     

Hello Bobby:  

    

   

    

Although I am FAR from an expert on Bing CV (constant velocity) carbs, i can attempt to explain the theory of what is happening....  

    

   

    

At idle you are running exclusively through the idle circuit.  As you crack open the throttle, there are transition circuits that come into play.  When you get to 1500 you are running "on the needle" that sticks through the main jet, efffectively closing off the size of the main jet fuel flow until the needle retracts....from 3/4 throttle to wide open you're on the main jet only.  

    

   

    

Transition circuit problems are very difficult to diagnose.  Sounds like you are running very rich through this circuit.  I would recommend a note to Jabiru USA - Pete knows these things better than anyone.  The other source of information is "The Carb Doctor" 

 http://www.bingcarburetor.com/

 who is the official importer of Bing carbs and parts here in the USA.  The manual is worth every penny.  It's been a long time since I had to access this info, but every owner of an old BMW "airhead" motorcycle has had to deal with these carbs at least once !!  

    

   

    

After some thought...check your float height.  If it is set too high that would cause a rich running engine.....  

    

   

    

Good Luck  

    

   

    

Tracy Smith  

    

N458XL reserved  

    

610XL  

    

Do Not Archive  

    

   

    

   

    



    

   	  Quote: 	
		   	  Quote: 	
		   Time: 12:16:34 PM PST USFrom: BobbyPaulk(at)comcast.netSubject: Carburetor   List,my 3300 Jab idles fairly good at 800 ~ 900 Rpm when i crack the throttle off idle at about 1050 to 1300 it will puff black smoke. at 1500 rpm it will smoothTime: 12:16:34 PM PST US 	
0 	  Quote: 	
		  Time: 12:16:34 PM PST US 	
1 	  Quote: 	
		  Time: 12:16:34 PM PST US 	
2 	  Quote: 	
		  Time: 12:16:34 PM PST US 	
3 	  Quote: 	
		  Time: 12:16:34 PM PST US 	
4 	  Quote: 	
		  Time: 12:16:34 PM PST US 	
5 	  Quote: 	
		  Time: 12:16:34 PM PST US 	
6 	  Quote: 	
		  Time: 12:16:34 PM PST US 	
7 	  Quote: 	
		  Time: 12:16:34 PM PST US 	
8 	  Quote: 	
		  Time: 12:16:34 PM PST US 	
9 	  Quote: 	
		  From: BobbyPaulk(at)comcast.net 	
0 	  Quote: 	
		  From: BobbyPaulk(at)comcast.net 	
1 	
  

    	  Quote: 	
		   From: BobbyPaulk(at)comcast.net 	
2 	  Quote: 	
		  From: BobbyPaulk(at)comcast.net 	
3 	  Quote: 	
		  From: BobbyPaulk(at)comcast.net 	
4 	  Quote: 	
		  From: BobbyPaulk(at)comcast.net 	
5 	  Quote: 	
		  From: BobbyPaulk(at)comcast.net 	
6 	  Quote: 	
		  From: BobbyPaulk(at)comcast.net 	
7 	  Quote: 	
		  From: BobbyPaulk(at)comcast.net 	
8 	  Quote: 	
		  From: BobbyPaulk(at)comcast.net 	
9 	  Quote: 	
		  Subject: Carburetor 	
0 	  Quote: 	
		  Subject: Carburetor 	
1 	  Quote: 	
		  Subject: Carburetor 	
2 	  Quote: 	
		  Subject: Carburetor 	
3 	  Quote: 	
		  Subject: Carburetor 	
4 	  Quote: 	
		  Subject: Carburetor 	
5 	  Quote: 	
		  Subject: Carburetor 	
6 	  Quote: 	
		  Subject: Carburetor 	
7 	  Quote: 	
		  Subject: Carburetor 	
8 	  Quote: 	
		  Subject: Carburetor 	
9 	  Quote: 	
		   	
0 	  Quote: 	
		   	
1 	  Quote: 	
		   	
2 	  Quote: 	
		   	
3 	  Quote: 	
		   	
4 	  Quote: 	
		   	
5

        [quote][b]

- The Matronics Zenith-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Zenith-List

Display posts from previous:

	Matronics Email Lists Forum Index -> Zenith-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum