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Carburetor Troubles on 912Ul

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jimmieblackwell(at)sbcglo
Guest

Posted: Fri Aug 04, 2006 9:14 am Post subject: Carburetor Troubles on 912Ul

Wanted to check and find out if any of you are having or had trouble keeping the Bing carbs on the 912 UL.

   

  One of my carbs works part way out of the rubber flange after the engine runs about 15 minutes and would fall off were it not for the retaining springs.

   

  These are some of the things I have done and noted:

   

  -  My rubber flanges are the new type with the 8mm spacer, part # 267 788.

   

  -  Engine is running smooth, but checked for carb balance anyway and they are well

     balanced.

   

  -  After taking the carb off I noted that the inside of the rubber flange has

     two places where the rubber material is missing, about the size of a match head and 

     several other much smaller areas where rubber material is missing.

   

   -  My thought was that perhaps the metal part of the carb that fits into the rubber flange

     had a rough spot that rubbed on the rubber flange.  Not the case, the metal part of 

     the carb that fits into the rubber flange is smooth, no burrs.

   

  -  Both of my rubber flanges were put on new about a year ago.

   

  At $87.00 apiece it seems to me that these rubber flanges should last longer.  Would appreciate any ideas from you folks.

   

  Jimmie

FLIER(at)sbcglobal.net
Guest

Posted: Fri Aug 04, 2006 9:55 am Post subject: Carburetor Troubles on 912Ul

Are those the stiff rubber (aftermarket I believe) 

flanges Jimmie?



If so, I'm surprised you're having any trouble as 

I've been running mine now for years.  If not, you 

need to switch over.



Regards,



Ted



--- Original Message ---

list(at)matronics.com>



 	  Quote: 	
		  Wanted to check and find out if any of you are 

having or had trouble keeping the Bing carbs on the 
	


912 UL.

 	  Quote: 	
		     

  One of my carbs works part way out of the rubber 

flange after the engine runs about 15 minutes and 
	


would fall off were it not for the retaining springs.

 	  Quote: 	
		     

  These are some of the things I have done and noted:

   

  -  My rubber flanges are the new type with the 8mm 

spacer, part # 267 788.
	


 	  Quote: 	
		     

  -  Engine is running smooth, but checked for carb 

balance anyway and they are well
	


 	  Quote: 	
		       balanced.

   

  -  After taking the carb off I noted that the 

inside of the rubber flange has
	


 	  Quote: 	
		       two places where the rubber material is 

missing, about the size of a match head and 
	


 	  Quote: 	
		       several other much smaller areas where rubber 

material is missing.
	


 	  Quote: 	
		     

  -  My thought was that perhaps the metal part of 

the carb that fits into the rubber flange
	


 	  Quote: 	
		       had a rough spot that rubbed on the rubber 

flange.  Not the case, the metal part of 
	


 	  Quote: 	
		       the carb that fits into the rubber flange is 

smooth, no burrs.
	


 	  Quote: 	
		     

  -  Both of my rubber flanges were put on new about 

a year ago.
	


 	  Quote: 	
		     

  At $87.00 apiece it seems to me that these rubber 

flanges should last longer.  Would appreciate any 
	


ideas from you folks.

 	  Quote: 	
		     

  Jimmie

mike
Guest

Posted: Fri Aug 04, 2006 10:17 am Post subject: Re: Carburetor Troubles on 912Ul

actually he said they were the rotax newer ones, they are bad in my opinion, I've tried them and didn't like them.  I now use the aftermarket ones, been on there over 300 hrs with no problems.

jimmieblackwell(at)sbcglo
Guest

Posted: Fri Aug 04, 2006 11:04 am Post subject: Carburetor Troubles on 912Ul

They are the stiffer ones and I think are impregnated with kevlar.  

   

  I did just discover one possible cause.  My carb has two retaining springs, one on each side.  They do not have the spring on top of the carb that attaches to the balancing tube.  Do you have this top spring?



flier <FLIER(at)sbcglobal.net> wrote:

  [quote]--> Kitfox-List message posted by: "flier" 



Are those the stiff rubber (aftermarket I believe) 

flanges Jimmie?



If so, I'm surprised you're having any trouble as 

I've been running mine now for years. If not, you 

need to switch over.



Regards,



Ted



--- Original Message ---

list(at)matronics.com>



 	  Quote: 	
		  Wanted to check and find out if any of you are 

having or had trouble keeping the Bing carbs on the  
	


912 UL.

 	  Quote: 	
		   

 One of my carbs works part way out of the rubber 

flange after the engine runs about 15 minutes and 
	


would fall off were it not for the retaining springs.

 	  Quote: 	
		   

 These are some of the things I have done and noted:

 

 - My rubber flanges are the new type with the 8mm 

spacer, part # 267 788.
	


 	  Quote: 	
		   

 - Engine is running smooth, but checked for carb 

balance anyway and they are well
	


 	  Quote: 	
		   balanced.

 

 - After taking the carb off I noted that the 

inside of the rubber flange has
	


 	  Quote: 	
		   two places where the rubber material is 

missing, about the size of a match head and 
	


 	  Quote: 	
		   several other much smaller areas where rubber 

material is missing.
	


 	  Quote: 	
		   

 - My thought was that perhaps the metal part of 

the carb that fits into the rubber flange
	


 	  Quote: 	
		   had a rough spot that rubbed on the rubber 

flange. Not the case, the metal part of 
	


[quote] the carb that fits into

jimmieblackwell(at)sbcglo
Guest

Posted: Fri Aug 04, 2006 11:08 am Post subject: Carburetor Troubles on 912Ul

When you say, "aftermarket", do you mean a rubber flange that is different from the ones that Rotax sells and has the 8mm spacer or a flange that someone other than Rotax sells?  If someone other than Rotax sells them they may be a lot cheaper.

   

   

  Thanks

   

  Jimmie



kitfoxmike <kitfoxmike(at)yahoo.com> wrote:

  [quote]--> Kitfox-List message posted by: "kitfoxmike" 



actually he said they were the rotax newer ones, they are bad in my opinion, I've tried them and didn't like them. I now use the aftermarket ones, been on there over 300 hrs with no problems.



--------

kitfoxmike

kitfox4 1200 912ul speedster

http://www.frappr.com/kitfoxmike

rv7 wingkit

reserved 287RV





Read this topic online

mike
Guest

Posted: Fri Aug 04, 2006 11:13 am Post subject: Re: Carburetor Troubles on 912Ul

I think they are mekuni(spelling) and they are much cheaper.

barry(at)pgtc.com
Guest

Posted: Fri Aug 04, 2006 12:55 pm Post subject: Carburetor Troubles on 912Ul

Jimmy, I am surprised you are having this problem0 with the 912 UL.  I have a 912 ULS and went through a lot of problem with0 the shaking at start up and shut down of the engine.  It was really  violent.  I sent the gearbox to Lockwood for them to tighten the sprag0 clutch and this greatly reduced the shaking.  The 912 ULS tended to shake0 more than the other 912's and of course it is exagerated because the carbs are0 further away from the center of the engine than in other0 applications.

  

 I also bought rubber flanges from a motorcyle0 shop.  They ordered them from a catlog.  Remember, BMW used Bing0 carburettors - don't know if they still do.  They were less than half0 the cost from Lockwood.

  

 These things together solved the problem. 0 About 200 hours now and no more carburettors coming loose or tearing of the0 rubber flanges.

  

 I guess this is what others are calling aftermarket0 but I think they were exactly the same as Rotax supplies.

 [quote]   ---

jimmieblackwell(at)sbcglo
Guest

Posted: Fri Aug 04, 2006 2:50 pm Post subject: Carburetor Troubles on 912Ul

Thank you for the information on BMW's.  I think we all expect to pay a premium to enjoy our hobby of flying, but in my opinion Rotax is starting to gouge us to hard.  

   

  For example, the rubber flange for the bing carb connection is shown in the latest Lockwood catalog as $44.00.  Yet when I priced it today the cost to us has more doubled to $95.00.  With the trouble I have been having lately I am starting to think Jabiru.



Barry West <barry(at)pgtc.com> wrote:

  [quote]        Jimmy, I am surprised you are having this problem with the 912 UL.  I have a 912 ULS and went through a lot of problem with the shaking at start up and shut down of the engine.  It was really violent.  I sent the  gearbox to Lockwood for them to tighten the sprag clutch and this greatly reduced the shaking.  The 912 ULS tended to shake more than the other 912's and of course it is exagerated because the carbs are further away from the center of the engine than in other applications.

   

  I also bought rubber flanges from a motorcyle shop.  They ordered them from a catlog.  Remember, BMW used Bing carburettors - don't know if they still do.  They were less than half the cost from Lockwood.

   

  These things together solved the problem.  About 200 hours now and no more carburettors coming loose or tearing of the rubber flanges.

   

  I guess this is what others are calling aftermarket but I think  they were exactly the same as Rotax supplies.

  [quote]  ---

runwayrex(at)juno.com
Guest

Posted: Fri Aug 04, 2006 3:04 pm Post subject: Carburetor Troubles on 912Ul

Hi Guys, 

  This thread ran a month or two ago. I have a part number for "aftermarket" flanges that are used on Sea Doo snowmobile engines. Mine have been on for years and work fine. Cost? Less than $10 each! 

Rex in Michigan



-- Jimmie Blackwell <jimmieblackwell(at)sbcglobal.net> wrote:

 Thank you for the information on BMW's.  I think we all expect to pay a premium to enjoy our hobby of flying, but in my opinion Rotax is starting to gouge us to hard.  

  

 For example, the rubber flange for the bing carb connection is shown in the latest Lockwood catalog as $44.00.  Yet when I priced it today the cost to us has more doubled to $95.00.  With the trouble I have been having lately I am starting to think Jabiru.



Barry West <barry(at)pgtc.com> wrote:

 [quote]  Jimmy, I am surprised you are having this problem with the 912 UL.  I have a 912 ULS and went through a lot of problem with the shaking at start up and shut down of the engine.  It was really violent.  I sent the gearbox to Lockwood for them to tighten the sprag clutch and this greatly reduced the shaking.  The 912 ULS tended to shake more than the other 912's and of course it is exagerated because the carbs are further away from the center of the engine than in other applications.

  

 I also bought rubber flanges from a motorcyle shop.  They ordered them from a catlog.  Remember, BMW used Bing carburettors - don't know if they still do.  They were less than half the cost from Lockwood.

  

 These things together solved the problem.  About 200 hours now and no more carburettors coming loose or tearing of the rubber flanges.

  

 I guess this is what others are calling aftermarket but I think they were exactly the same as Rotax supplies.

 [quote] ---

flier(at)sbcglobal.net
Guest

Posted: Fri Aug 04, 2006 5:36 pm Post subject: Carburetor Troubles on 912Ul

I0 safety wired the top of my carbs long ago.  Drilled a small hole in the web0 on the carb and put a few (slack) loops of wire around it and the balance tube0 fitting on both sides just in case.  However, with that said, the carbs0 won't come out of the stiffer aftermarket sockets even without the0 wire...

 [quote]   --

kingjohne(at)adelphia.net
Guest

Posted: Mon Aug 07, 2006 5:36 pm Post subject: Carburetor Troubles on 912Ul

Jimmie,

 

 The springs on each side of the carbs were provided by SkyStar as part of the firewall kit.  The one spring on the top of the carbs is a Rotax provided part and can be ordered through Lockwood.

  	  Quote: 	
		  -- 

John King 

Warrenton, VA 	
 

 Jimmie Blackwell wrote:

  	  Quote: 	
		     They are the stiffer ones and I think are impregnated with kevlar.  

    

   I did just discover one possible cause.  My carb has two retaining springs, one on each side.  They do not have the spring on top of the carb that attaches to the balancing tube.  Do you have this top spring?

jimmieblackwell(at)sbcglo
Guest

Posted: Mon Aug 07, 2006 5:55 pm Post subject: Carburetor Troubles on 912Ul

Hope to have two top springs plus new rubber flange in the mail tomorrow.  Sure hope that fixes the problem.

   

  Thanks John

   

  Jimmie



John King <kingjohne(at)adelphia.net> wrote:

   	  Quote: 	
		  Jimmie,



The springs on each side of the carbs were provided by SkyStar as part of the firewall kit.  The one spring on the top of the carbs is a Rotax provided part and can be ordered through Lockwood.

 	  Quote: 	
		  --   John King   Warrenton, VA 	


Jimmie Blackwell wrote:

   	  Quote: 	
		    They are the stiffer ones and I think are impregnated with kevlar.  

   

  I did just discover one possible cause.  My carb has two retaining springs, one on  each side.  They do not have the spring on top of the carb that attaches to the balancing tube.  Do you have this top spring?

Lynn Matteson

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

Posted: Tue Aug 08, 2006 9:33 am Post subject: Carburetor Troubles on 912Ul

Hey Jimmie, are you any closer to thinking about the Jabiru? Not to 

make light of your situation, but with only ONE carb to fall off......: 

)



Lynn

Kitfox IV...Jabiru 2200

On Friday, August 4, 2006, at 03:07  PM, Jimmie Blackwell wrote:



 	  Quote: 	
		   When you say, "aftermarket", do you mean a rubber flange that is 

 different from the ones that Rotax sells and has the 8mm spacer or a 

 flange that someone other than Rotax sells?  If someone other than 

 Rotax sells them they may be a lot cheaper.

  

  

 Thanks

  

 Jimmie

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

gjfpilot(at)yahoo.com
Guest

Posted: Tue Aug 08, 2006 1:38 pm Post subject: Carburetor Troubles on 912Ul

Jimmie,

  I posted a question and an idea to the list a while

back concerning the 912 carbs shaking off but got

little feedback. I had the idea of making a pair of

brackets that would bolt to the top of the cylinder

heads on each side that go rearward bending under the

carb bowl and back up to a ring that would support the

back of the carburetor.  These brackets would bolt to

the spare threaded hole on the top of each cylinder

head. As far as I can tell, there is nothing that this

threaded hole will be used for on my Classic IV (still

building).  For as little weight as they would add, it

would sure give me piece of mind that the carbs aren’t

going to fall off after takeoff.  I still plan on

using Clint Bazzill’s method of startup and shutdown.

Has anyone else thought of doing this or has done

this? 

Grant Fluent

Newcastle, NE

Classic IV 912S  

--- Jimmie Blackwell <jimmieblackwell(at)sbcglobal.net>

wrote:



 	  Quote: 	
		   Hope to have two top springs plus new rubber flange

 in the mail tomorrow.  Sure hope that fixes the

 problem.

    

   Thanks John

    

   Jimmie

 

 John King <kingjohne(at)adelphia.net> wrote:

   Jimmie,

 

 The springs on each side of the carbs were provided

 by SkyStar as part of the firewall kit.  The one

 spring on the top of the carbs is a Rotax provided

 part and can be ordered through Lockwood.

 

 --   John King   Warrenton, VA

 

 Jimmie Blackwell wrote:

     They are the stiffer ones and I think are

 impregnated with kevlar.  

    

   I did just discover one possible cause.  My carb

 has two retaining springs, one on each side.  They

 do not have the spring on top of the carb that

 attaches to the balancing tube.  Do you have this

 top spring?

pulsair(at)mindspring.com
Guest

Posted: Tue Aug 08, 2006 4:18 pm Post subject: Carburetor Troubles on 912Ul

Grant,

Stick with the orignal design of the Rotax. Something else is going on. Is 

your prop properly balanced and pitched? Are you using the latest sockets 

(check the part numbers)? Have you talked to a Rotax tech? Jeff Classic IV 

912UL

---

gjfpilot(at)yahoo.com
Guest

Posted: Tue Aug 08, 2006 7:49 pm Post subject: Carburetor Troubles on 912Ul

Jeff,

  Thanks for your reply. My Classic IV is not flying

yet but I'm trying to plan ahead. With all of the

reports of carbs falling off, it will probably happen

to me too until I get everything fine tuned. What I

was planning on doing was making a simple bracket for

each side that would fasten to the clamp at the air

filters so the carb couldn't wiggle up and down in the

socket. I agree with you about sticking to original

designs. I feel that one of the main reasons people

have trouble losing the carbs is due to the swapped

manifolds not being a Rotax design. It's really too

bad that the engine mount requires the manifold

relocation. I have shortened my engine mount bushings

to the Skystar recommended length so hopefully that

should help. Also, the engine is new enough that it

came from the factory with the slipper clutch. 

Grant Fluent

Newcastle, NE

Classic IV 912S

  



--- jeff puls <pulsair(at)mindspring.com> wrote:



[quote] 

 <pulsair(at)mindspring.com>

 

 Grant,

 Stick with the orignal design of the Rotax.

 Something else is going on. Is 

 your prop properly balanced and pitched? Are you

 using the latest sockets 

 (check the part numbers)? Have you talked to a Rotax

 tech? Jeff Classic IV 

 912UL

 ---

jimmieblackwell(at)sbcglo
Guest

Posted: Tue Aug 08, 2006 11:44 pm Post subject: Carburetor Troubles on 912Ul

I talked to Lockwood aviation and the Tech said that the real problem was that we Kitfoxers turn the intake manifold around which puts the carb in a position to be more vulnerable to shaking.  That does not help us much because as far as I know we do not have a choice about swapping the intake manifolds.

   

  I believe the real problem is a material defect in the newest rubber flanges.  Soon as I get my replacement rubber flanges installed I am sending the old one (which is less than a year old) to Phil Lockwood and ask him to examine the pitting inside this rubber flange.

   

  It would probably be a good idea for anyone who has the new type rubber flanges, (that is the type with the 8mm spacer, Rotax part # 267788), to check in side for signs of pitting.

   

  Jimmie



jeff puls <pulsair(at)mindspring.com> wrote:

  [quote]--> Kitfox-List message posted by: "jeff puls" 



Grant,

Stick with the orignal design of the Rotax. Something else is going on. Is 

your prop properly balanced and pitched? Are you using the latest sockets 

(check the part numbers)? Have you talked to a Rotax tech? Jeff Classic IV 

912UL

---

pulsair(at)mindspring.com
Guest

Posted: Wed Aug 09, 2006 4:37 pm Post subject: Carburetor Troubles on 912Ul

Grant,

The slipper clutch will help. I have not lost a socket but I am cautious. I 

have a rough running engine when I retard the throttle going through about 

3400 rpm. Never could get it out. The engine has never so much as hiccupped. 

It is great at high rpm. Are you making your brackets out of stainless 

steel? Jeff

---

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