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cristalclear13

Joined: 19 Sep 2007
Posts: 363
Location: Southeast Georgia

Posted: Wed Dec 10, 2008 2:39 pm Post subject: choke or primer

Hi all.  I got the mouse nest out of my tube, cleaned up the corrosion, finished my annual inspection and re-mounted my Rotax after Gerry Olenik from Green Sky Adventures did some maintenance on it for me.  I have seen several brag on him so I will also brag.  He did a great job, was very knowledgeable and helpful.



With the help of a friend we determined that my choke has not been closing all the way.  If I manually move the cable back where it splits into the two cables it'll close and run fine.  My friend suggested doing away with the choke and just using a priming system.  I've gotten used to the choke and am thinking perhaps I could just replace the cables.



P.S. Gave my dad a quick ride around the pattern and he LOVED it of course.  What fun!

_________________
Cristal Waters
Kolb Mark II Twinstar Rotax 503 DCSI Sept 2007 - sold Sept 2012
Private Pilot Aug 2008
ELSA Repairman for N193Y April 2008
Rotax 2 stroke maintenance April 2009

Arty Trost

Joined: 25 May 2006
Posts: 203
Location: Sandy, Oregon

Posted: Wed Dec 10, 2008 9:17 pm Post subject: choke or primer

Hi Cristal,



I removed the choke on my 503 a few years ago and have been using just the primer, without any difficulty.  However, I did read somewhere that you can troubleshoot your engine via the choke (don't remember the details) so am not sure if I did the wisest thing - although, as I said, it's been fine for several years and several hundred hours without it.  



Arty Trost

Sandy, Oregon

Maxair Drifter



www.LessonsFromTheEdge.com



"Life's a daring adventure or nothing"

                      Helen Keller



"I refuse to tip toe through life just to arrive safely at death."

--- On Wed, 12/10/08, cristalclear13 <cristalclearwaters(at)gmail.com> wrote:



 	  Quote: 	
		   From: cristalclear13 <cristalclearwaters(at)gmail.com>

 Subject: choke or primer

 To: kolb-list(at)matronics.com

 Date: Wednesday, December 10, 2008, 2:39 PM

 

 "cristalclear13"

 <cristalclearwaters(at)gmail.com>

 

 Hi all.  I got the mouse nest out of my tube, cleaned up

 the corrosion, finished my annual inspection and re-mounted

 my Rotax after Gerry Olenik from Green Sky Adventures did

 some maintenance on it for me.  I have seen several brag on

 him so I will also brag.  He did a great job, was very

 knowledgeable and helpful.

 

 With the help of a friend we determined that my choke has

 not been closing all the way.  If I manually move the cable

 back where it splits into the two cables it'll close and

 run fine.  My friend suggested doing away with the choke and

 just using a priming system.  I've gotten used to the

 choke and am thinking perhaps I could just replace the

 cables.

 

 P.S. Gave my dad a quick ride around the pattern and he

 LOVED it of course.  What fun!

 

 --------

 Cristal Waters

 Kolb Mark II Twinstar

 Rotax 503 DCSI

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p 18755#218755

ropermike

Joined: 28 Aug 2006
Posts: 40
Location: West Texas, South Mississippi

Posted: Thu Dec 11, 2008 5:47 am Post subject: Re: choke or primer

I have farmed and ranched for 28 years and dealt with a lot of troublesome small gas engines. I have kept a lot of those engines running (momentarily) using the choke, at least, I can determine if the problem is fuel starvation....  If my 503 ever starts coughing and running rough during flight, one option would be is to choke the engine slightly. It might work and get you to a safe landing spot. You can also diagnose fuel mixture problems with it....You may be able to do the same thing with the primer but I havnt tried it.....Just my thoughts on the matter.

_________________
The next best thing to playing and winning is playing and losing!...Mike Hillger

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Thu Dec 11, 2008 7:13 am Post subject: Re: choke or primer

 	  ropermike wrote: 	
		  I have farmed and ranched for 28 years and dealt with a lot of troublesome small gas engines. I have kept a lot of those engines running (momentarily) using the choke, at least, I can determine if the problem is fuel starvation....  If my 503 ever starts coughing and running rough during flight, one option would be is to choke the engine slightly. It might work and get you to a safe landing spot. You can also diagnose fuel mixture problems with it....You may be able to do the same thing with the primer but I havnt tried it.....Just my thoughts on the matter. 	




You can with the primer and it's the same troubleshooting process. You can hit the primer with the engine running to enrichen the mixture in the same way as activating the chokes.



The primer is the way to go. The cost is just the extra small tubing you have to run to the carburettors, the plunger and the fuel pickup, but it eliminates the cabling and etc. associated with the chokes. The primer generally leads to quicker starting as well, one shot of gas and usually the motor starts on the first pull of the rope....



LS

_________________
LS
Titan II SS

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Thu Dec 11, 2008 7:38 am Post subject: choke or primer

You can hit the primer with the engine running to enrichen the mixture in 

the same way as activating the chokes.

 >

 	  Quote: 	
		   LS


	


Lucien:



I can't find my chokes.  Don't think I have them on Bing carbs, two or four 

stroke.



john h

mkIII - Waiting on the snow, soon as New Orleans and St Francisville, LA, 

finish with it.  John B:  Got your snow shovel handy?

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Thu Dec 11, 2008 8:12 am Post subject: Re: choke or primer

 	  John Hauck wrote: 	
		  



Lucien:



I can't find my chokes.  Don't think I have them on Bing carbs, two or four 

stroke.



john h

mkIII - Waiting on the snow, soon as New Orleans and St Francisville, LA, 

finish with it.  John B:  Got your snow shovel handy? 	




Er, you are kidding, right? .



Technically, our bings have enrichener circuits instead of the chokes of yore that just had a butterfly that closed off the venturi.



I have to admit to not having had much trouble with the enricheners on the 2-stroke bings. The original builder of my FSII used them and after I bought the plane I never saw the need to eliminate it in favor of a primer. That engine had the clutch, tho, so it was a lot easier to start anyway...



My 912uls fires up fairly quickly with the enricheners unless it's really cold. The system works pretty good...



LS

_________________
LS
Titan II SS

Arksey(at)aol.com
Guest

Posted: Thu Dec 11, 2008 8:20 am Post subject: choke or primer

Hi Cristal,

 I think i would fix the enrichener's  what you called the  choke. On my firestar with the 503 i disabled the enrichener's and use a primer  and it starts and works fine. But some of the primers including the one I am  using is of poor construction and not up to general aviation standards, I had to  replace my primer as the old one was leaking a that meant to me it could be  causing a air leak which you do not want in the suction line on your gas line.  So if I was to do it again I would use the enrichener's (choke) and not the  primer for that reason and because engine temps are so critical on a 2 cly in  case of high temps one could use the enricher to lower the temps until the  problem was cured. So i would rebuild the enrichener's and make sure they were  closing correctly. just my 2 cents worth...    jim  SWAN

    

  

 do not  archive

jim swan FS ll 503

michigan



Make your life easier with all your friends, email, and favorite lcom40vanity&ncid=emlcntaolcom00000010">Try it now.

zeprep251(at)aol.com
Guest

Posted: Thu Dec 11, 2008 8:55 am Post subject: choke or primer

In cold weather the 503 required 4 hard pulls to light off with enrichener only.With 1 full shot of prime and enrichener,it fired and stayed running on the first pull.Even in mild weather that was the case.On the Firestar,the primer was located on the fuel pump mounting angle below the pump,which required only a few inches of primer line but was obviously out of reach from the cockpit,but the enrichener was right where it was in the plans, above and slightly behind your left shoulder.There are some good reasons to keep all your options open in my opinion.

              Welcome  to Fla.Nielsons 

 

   

 

   

 

 --

beauford

Joined: 25 Apr 2007
Posts: 127
Location: Brandon, FL

Posted: Thu Dec 11, 2008 9:31 am Post subject: choke or primer

On the Bing enrichment circuit:

  

 The small enrichment piston which is raised by either a lever  on the carb, or by a cable to a remote

 "choke" lever has a small nitrile rubber insert set in a  cavity in the base.  The rubber insert will gradually 

 deteriorate and deform with age, thereby allowing additional  (excessive) fuel to leak through the enrichment circuit and dump into the  engine.  

  

 This occurs gradually over many hours and  may not be detected until excessive carbon shows up in the top end

 of the engine, possibly causing stuck rings and  potentially serious problems.

  

 Some of you Listers may recall Beauford's fun with this  problem in the Nazi 447 a few years back...  In my ignorance about what was  happening, I ended up chasing back and forth with metering  rod adjustments, jetting changes,

 fouled plugs, etc.... I had repeatedly checked the  enrichment piston's function, verifying that it was bottoming into the seat  properly...the problem was that the rubber insert had receded up into the base  of the thing and I did not notice it. because it looked fine...the rubber  was not obviously cracked or split.

  

 Long story, short...   The guys over at Lockwood  took one look and immediately diagnosed the  problem...said that they had seen a number of Rotax 2-strokes trashed  with this... and that the Bing enrichment piston ought to be replacd every 2  years or so as a matter of routine maintenance....especially with PREMIXED fuel  which attacked the nitrile faster than straight gas...  One can only wonder  what the ethanol is doing to these things.  As I recall, the part  cost under $10....   which was certainly substantially less than  the two new pistons I had to buy after the carbon had seized the  rings...

  

 I now keep an extra enrichment piston on hand...

  

 ...worth what ye paid fer it...

  

 beauford

 FF-076

 Brandon, FL

  

  

  

  

 [quote]   ---

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Thu Dec 11, 2008 3:38 pm Post subject: choke or primer

> Technically, our bings have enrichener circuits instead of the chokes of 

yore that just had a butterfly that closed off the venturi.

 	  Quote: 	
		  

 I have to admit to not having had much trouble with the enricheners on the 

 2-stroke bings. The original builder of my FSII used them and after I 

 bought the plane I never saw the need to eliminate it in favor of a 

 primer. That engine had the clutch, tho, so it was a lot easier to start 

 anyway...



 My 912uls fires up fairly quickly with the enricheners unless it's really 

 cold. The system works pretty good...



 LS


	




Lucien:



Yes, they call them chokes because that is what they do.



Enricheners work on the same principle as the primer.  There is an enricher 

well and enricher jet located in the float bowl.  Important to insure the 

throttle is on the idle stop.  Enricher full open.  When the engine turns 

over, it sucks in the charge of fuel stored in the enricher well.  From 

there on the engine is running off the enricher circuit through the enricher 

jet.



If operated correctly, the enricher system on Bing carbs works well for two 

and four stroke Rotax engines.  I have operated the 912 series engines in 

the Arctic at temps well below freezing with success.  It also takes a hot 

battery to turn the engine over to start.



Big problem with the two stroke Bings is the plunger style system they use 

to control the enricher.  After they get some age on them, they will leak, 

causing an over rich condition without the operator realizing it.  It is an 

easy fix to remove and replace with new parts to correct the problem.



I prefer the enricher over primer.  Primers introduce more plumbing, 

carrying fuel, especially in the area of the cockpit.



Take care,



john h

mkIII

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Thu Dec 11, 2008 4:06 pm Post subject: Re: choke or primer

 	  John Hauck wrote: 	
		  

	




Lucien:



Yes, they call them chokes because that is what they do.



Enricheners work on the same principle as the primer.  There is an enricher 

well and enricher jet located in the float bowl.  Important to insure the 

throttle is on the idle stop.  Enricher full open.  When the engine turns 

over, it sucks in the charge of fuel stored in the enricher well.  From 

there on the engine is running off the enricher circuit through the enricher 

jet.



If operated correctly, the enricher system on Bing carbs works well for two 

and four stroke Rotax engines.  I have operated the 912 series engines in 

the Arctic at temps well below freezing with success.  It also takes a hot 

battery to turn the engine over to start.



Big problem with the two stroke Bings is the plunger style system they use 

to control the enricher.  After they get some age on them, they will leak, 

causing an over rich condition without the operator realizing it.  It is an 

easy fix to remove and replace with new parts to correct the problem.



I prefer the enricher over primer.  Primers introduce more plumbing, 

carrying fuel, especially in the area of the cockpit.



Take care,



john h

mkIII[/quote]



A bit of trivia on the enrichener for parties..... If you need to replace a float bowl, be sure to order the jet as well or save the old jet from the old bowl. Just ordering the bowl and you get the bowl with no jet in it. 



The enrichener circuit works WAY too well without the jet. You can probably guess why I know this but I'm not going to admit anything anyway......



In any case, I've used both the primer system and the stock enrichener systems for many years and both are very trouble free and work very well. 



The only concern I've ever had with the primer is a leaking primer plunger. This can result in extra gas getting into the carburettors just like when the rubber stoppers fail on the 2-stroke carbs.



Which I use simply depends on which is easier to deal with on that particular plane.



On the 912 the enricheners are the only choice, I believe. Mine work perfectly so far even in temps as low as 10F.......



LS

_________________
LS
Titan II SS

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Thu Dec 11, 2008 6:22 pm Post subject: choke or primer

This discussion of the choke (enrichener) raises an interesting question.



As others have pointed out, the enrichener is sometimes used as a 

diagnostic tool, to see if the engine's running lean (or correct it if it 

is).  However, the enrichener also supposedly is only effective near 

idle... so will it have any significant effect at cruise or max throttle?



I have a plunger primer and it works great, but I've considered adding a 

remote cable to the choke for inflight emergency or diagnostic use... now 

I'm not so sure...



-Dana

--

  We are sorry, you have reached an imaginary number.

Please rotate your phone ninety degrees and try again.

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Thu Dec 11, 2008 6:58 pm Post subject: choke or primer

> However, the enrichener also supposedly is only effective near

 	  Quote: 	
		   idle... so will it have any significant effect at cruise or max throttle?

  >
	


 	  Quote: 	
		   -Dana


	




Dana:



The primary reason for starting the engine with the throttle closed is to 

have maximum suction to pull the initial charge out of the enrichener well. 

If the throttle is opened above idle, on start up, it doesn't do a good job 

of scavenging the fuel out of the well.



At cruise rpm, if the enrichener is opened, there is more than enough 

suction to pull the charge out of the well, then run richer from the extra 

fuel being drawn from the enrichener jet.



Clear as mud, huh?



john h

mkIII

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Thu Dec 11, 2008 7:18 pm Post subject: choke or primer

At 09:57 PM 12/11/2008, John Hauck wrote:



 	  Quote: 	
		  At cruise rpm, if the enrichener is opened, there is more than enough 

suction to pull the charge out of the well, then run richer from the extra 

fuel being drawn from the enrichener jet.



Clear as mud, huh?


	


Quite clear... I should have thought of that.



-Dana (brain dead tonight trying to fix a Vista printing problem...)

--

  Please return stewardess to original upright position.

zeprep251(at)aol.com
Guest

Posted: Fri Dec 12, 2008 4:21 am Post subject: choke or primer

the enrichener works at any engine speed

 

   

 

   

 

 --

cristalclear13

Joined: 19 Sep 2007
Posts: 363
Location: Southeast Georgia

Posted: Tue Dec 16, 2008 7:16 am Post subject: Re: choke or primer

 	  Quote: 	
		   [quote="beauford"]On the Bing enrichment circuit:

  

 The small enrichment piston which is raised by either a lever  on the carb, or by a cable to a remote

 "choke" lever has a small nitrile rubber insert set in a  cavity in the base.  The rubber insert will gradually 

 deteriorate and deform with age, thereby allowing additional  (excessive) fuel to leak through the enrichment circuit and dump into the  engine.  

  

 This occurs gradually over many hours and  may not be detected until excessive carbon shows up in the top end

 of the engine, possibly causing stuck rings and  potentially serious problems.

  

 Some of you Listers may recall Beauford's fun with this  problem in the Nazi 447 a few years back...  In my ignorance about what was  happening, I ended up chasing back and forth with metering  rod adjustments, jetting changes,

 fouled plugs, etc.... I had repeatedly checked the  enrichment piston's function, verifying that it was bottoming into the seat  properly...the problem was that the rubber insert had receded up into the base  of the thing and I did not notice it. because it looked fine...the rubber  was not obviously cracked or split.

  

 Long story, short...   The guys over at Lockwood  took one look and immediately diagnosed the  problem...said that they had seen a number of Rotax 2-strokes trashed  with this... and that the Bing enrichment piston ought to be replacd every 2  years or so as a matter of routine maintenance....especially with PREMIXED fuel  which attacked the nitrile faster than straight gas...  One can only wonder  what the ethanol is doing to these things.  As I recall, the part  cost under $10....   which was certainly substantially less than  the two new pistons I had to buy after the carbon had seized the  rings...

  

 I now keep an extra enrichment piston on hand...

  

 ...worth what ye paid fer it...

  

 beauford

 FF-076

 Brandon, FL

  

  

  

  

  --- 	




Beauford,

Is there a website or article in the CPS catalogue that talks about replacing the parts you are talking about (or did you just get the information by word of mouth from Lockwood)?  I would like to read more about it.  Can you look at your old receipts and tell me what part(s) I would need to order?



All,

We got my choke cables working correctly now.  The choke wasn't stuck on...it was never opened.  There was a washer (that prevented the cable housing from sliding into the metal tube) that hadn't been replaced when we put everything back together.  (But this doesn't help me solve the mystery of the excessive smoking when we first started it up...but that could be another thread on the forum.)



Thanks for everyone's input and advice.

_________________
Cristal Waters
Kolb Mark II Twinstar Rotax 503 DCSI Sept 2007 - sold Sept 2012
Private Pilot Aug 2008
ELSA Repairman for N193Y April 2008
Rotax 2 stroke maintenance April 2009

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Tue Dec 16, 2008 7:31 am Post subject: choke or primer

(But this doesn't help me solve the mystery of the excessive smoking when 

we first started it up...but that could be another thread on the forum.)

 > --------

 	  Quote: 	
		   Cristal Waters


	




Cristal:



Two strokes tend to load up with excessive oil in the crank case when run 

slowly for long periods of time.  As soon as rpm is increased, it will clear 

it out, along with a lot of smoke.



Another reason not to let a two stroke idle any longer than necessary. 

Another reason the run a two stroke in the power band and not lug them down 

at lower rpm.



john h

mkIII

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

williamtsullivan(at)att.n
Guest

Posted: Tue Dec 16, 2008 7:43 am Post subject: choke or primer

John- Considering that taxiing and parking may involve low engine speeds, what would be an appropriate shut-down procedure?

  

                                           Bill Sullivan

 [quote][b]

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Tue Dec 16, 2008 8:23 am Post subject: choke or primer

Bill:

  

 I don't know.

  

 I'd keep low engine speeds to a minimum  though.

  

 What does your operators manual say?

  

 john h

 mkIII

  

  

 [quote]    

                               John- Considering that taxiing and parking may involve low          engine speeds, what would be an appropriate shut-down procedure?

          

                                                            Bill Sullivan

 	  Quote: 	
		   	
[b]

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

williamtsullivan(at)att.n
Guest

Posted: Tue Dec 16, 2008 9:16 am Post subject: choke or primer

John- I didn't look it up.  I thought maybe you had some tricks.  Mine used to load up, presumably because of the extended low rpm running time.  I am going to have mine overhauled before re-installing, as I don't know the true hours on it.

  

                                                   Bill Sullivan 

                                                   Windsor Locks, Ct.

  39 degrees at noon, 61 yesterday

  

 do not archive

 [quote][b]

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