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

Throttle springs

Matronics Email Lists Forum Index -> RotaxEngines-List

View previous topic :: View next topic

Author Message

Jim Feldmann

Joined: 01 Sep 2008
Posts: 54
Location: Burbank, CA

Posted: Wed Oct 08, 2008 9:29 am Post subject: Throttle springs

Hi:



I'm new here, having just purchased a Kitfox IV Speedster with a Rotax 912UL.  



The throttle springs are set to open the throttle in the event of a linkage failure.  OK, but the springs are so strong that they pull the cable right past the ratchet in a vernier throttle.  I'm using a collet type throttle, but as soon as I loosen the collet, the springs try to pull the throttle out of my hand.



Is there a lighter spring available?  What have you done and where did you get the springs?



Jim Feldmann

Kitfox IV Speedster

912UL  N629JB

rlborger(at)mac.com
Guest

Posted: Wed Oct 08, 2008 9:46 am Post subject: Throttle springs

Jim,



I don't have a Kitfox (darn nice airplanes, BTW), I have a Europa.  But, I'd replace the throttle linkage system before I'd replace the throttle springs.  Find a throttle handle/linkage with adjustable friction.  



Just my 2 cents.  I'm sure there will be opposing suggestions.



Bob Borger

Europa XS Monowheel, Standard Wings, Intercooled Rotax 914, Airmaster C/S prop.

99.9% complete.  Chasing gremlins in the audio panel wiring.

http://www.europaowners.org/N914XL

 

On Wednesday, October 08, 2008, at 12:29PM, "Jim Feldmann" <feldesign(at)earthlink.net> wrote:

 	  Quote: 	
		  



Hi:



I'm new here, having just purchased a Kitfox IV Speedster with a Rotax 912UL.  



The throttle springs are set to open the throttle in the event of a linkage failure.  OK, but the springs are so strong that they pull the cable right past the ratchet in a vernier throttle.  I'm using a collet type throttle, but as soon as I loosen the collet, the springs try to pull the throttle out of my hand.



Is there a lighter spring available?  What have you done and where did you get the springs?



Jim Feldmann

Kitfox IV Speedster

912UL  N629JB





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p 7924#207924

Jim Feldmann

Joined: 01 Sep 2008
Posts: 54
Location: Burbank, CA

Posted: Wed Oct 08, 2008 2:40 pm Post subject: Re: Throttle springs

Just got back from the hanger and I took a picture of the linkage I am talking about. It seems like that is an awful lot of spring just to open the throttle in case of a linkage failure. Not sure I would like to see what happens if the linkage only fails on one side either. 



The main problems though are the difficulty in holding a specific throttle setting during approach, and the fact that the throttle creeps open during cruise. 



Jim

DSCF1265.jpg

Description:

This is the right carb. The left is the same.

Filesize:

632.69 KB

Viewed:

326 Time(s)

joeing701(at)internet.is
Guest

Posted: Wed Oct 08, 2008 2:46 pm Post subject: Throttle springs

Hello Jim.



I am flying a Zenith 701 with the same engine. Please never change the  

springs in the carb linkage. It could lead to a major engine power  

loss in a situation when you really need the fast reaction from the  

carbs.

This accident is the direct cause to the change of throttle linkage  

springs. See the link.

http://www.ch601.org/stories/croke_crash.htm



I am using a Vernier throttle cable in my plane with  friction lock.  

It works great and I never have any problems with the spring wanting  

to pull the throttle lever in. I even have another on the right side  

but always make sure that the friction lock on that side is loose.



Hope this helps in your decision making.



Best regards,

Johann G.





 	  Quote: 	
		   

 >



 Hi:



 I'm new here, having just purchased a Kitfox IV Speedster with a  

 Rotax 912UL.



 The throttle springs are set to open the throttle in the event of a  

 linkage failure.  OK, but the springs are so strong that they pull  

 the cable right past the ratchet in a vernier throttle.  I'm using a  

 collet type throttle, but as soon as I loosen the collet, the  

 springs try to pull the throttle out of my hand.



 Is there a lighter spring available?  What have you done and where  

 did you get the springs?



 Jim Feldmann

 Kitfox IV Speedster

 912UL  N629JB





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p 7924#207924

Throttle_system_002.jpg

Description:

Filesize:

107.38 KB

Viewed:

305 Time(s)

daberti(at)sbcglobal.net
Guest

Posted: Wed Oct 08, 2008 2:58 pm Post subject: Throttle springs

Search the Zenith archives for Jon Croke...changing those springs cost him

his 701!  Need I say more?



--

joeing701(at)internet.is
Guest

Posted: Wed Oct 08, 2008 3:02 pm Post subject: Throttle springs

Hello Jim.



I just looked at the spring in your throttle linkage and it looks to  

me that this is not the original Rotax part. I would order new springs  

from a Rotax dealer and see if that does not change the situation.

They look more bulk than the original and also the ones I am using  

have a long straight neck on one end. Take a look.





Top left of photo. Hope you can see the long straight end of the spring.

Regards,

Johann G.



008, at 10:40 PM, Jim Feldmann wrote:



 	  Quote: 	
		   

 >



 Just got back from the hanger and I took a picture of the linkage I  

 am talking about. It seems like that is an awful lot of spring just  

 to open the throttle in case of a linkage failure. Not sure I would  

 like to see what happens if the linkage only fails on one side either.



 The main problems though are the difficulty in holding a specific  

 throttle setting during approach, and the fact that the throttle  

 creeps open during cruise.



 Jim





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p 7971#207971





 Attachments:



 http://forums.matronics.com//files/dscf1265_121.jpg

oil_thermostat.jpg

Description:

Filesize:

140.81 KB

Viewed:

323 Time(s)

Jim Feldmann

Joined: 01 Sep 2008
Posts: 54
Location: Burbank, CA

Posted: Wed Oct 08, 2008 3:11 pm Post subject: Re: Throttle springs

Thanks guys.  I went to the Croke 701crash posting, and it appears that his original springs have a long end also.  So it looks like mine have been replaced.



I will contact Rotax.



Jim

larry(at)macsmachine.com
Guest

Posted: Wed Oct 08, 2008 4:24 pm Post subject: Throttle springs

Jim,

The spring throttle combination is not a good one. I recommend you 

remove the springs, find a linkage to tie the two carbs together and go 

with a solid

wire as do the regular aircraft manufacturer's products.  It takes a bit 

of thought, but it does work.  I did this in my Subaru with two Bings 

and I've had no

problems with the system.  Pulling out the cable and replacing it with a 

1/16th diameter music wire in the cable casing is the beginning and it 

will not bend

in the length of free throw the Bing carb linkage requires, especially 

without the springs.  See links

http://www.macsmachine.com/images/controllinkages/full/throttlewire.gif

http://www.macsmachine.com/images/controllinkages/full/abinghardcablelink.gif

http://www.macsmachine.com/images/controllinkages/full/throttlelink.gif

Realizing the Rotax doesn't have much if any direct access for linkage 

between the carbs, but the person that solves that problem will have 

solved a serious

deficiency in the current design.

Best regards,



Larry McFarland 601HDS at www.macsmachine.com



Jim Feldmann wrote:

 	  Quote: 	
		   



 Just got back from the hanger and I took a picture of the linkage I am talking about. It seems like that is an awful lot of spring just to open the throttle in case of a linkage failure. Not sure I would like to see what happens if the linkage only fails on one side either. 



 The main problems though are the difficulty in holding a specific throttle setting during approach, and the fact that the throttle creeps open during cruise. 



 Jim

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Wed Oct 08, 2008 7:42 pm Post subject: Re: Throttle springs

Hi Jim,



Those are not Rotax springs. Order some new carb linkage springs and enricher /choke springs. The new springs are lighter than what you have. Don't get caught up in the good ol'e boy way of fixing your engine. There is a reason and usually a very well tested reason that Rotax does things a certain way. You thought enough to buy a plane and you want it to keep you in the air without facing any problems now or down the road. Maintain it with the same fore thought.



The push / pull type of throttle will work. Just make sure you use the correct wire and throttle.



Enjoy your plane and your flights.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

Thom Riddle

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

Posted: Thu Oct 09, 2008 3:47 am Post subject: Re: Throttle springs

That picture says it all. That throttle return spring looks a lot like the carb support spring just above it, and as Roger said, that is definitely the wrong spring.



Our RANS S6 has a Vernier throttle with correct Bing throttle return springs and that combination works as designed.

_________________
Thom Riddle
Buffalo, NY (9G0)

Don't worry about old age... it doesn't last very long.
- Anonymous

Jim Feldmann

Joined: 01 Sep 2008
Posts: 54
Location: Burbank, CA

Posted: Thu Oct 09, 2008 7:28 am Post subject: Re: Throttle springs

Thank you all for your help.  I will order the correct throttle and choke springs from Rotax.



Jim

Dick Maddux

Joined: 24 Jun 2008
Posts: 516
Location: Milton, Fl

Posted: Fri Oct 10, 2008 4:07 am Post subject: Throttle springs

Jim,

   Those are not the correct springs for the engine.They look home  made.Get in touch with Lockwood or another vendor to get the correct springs. I  had the same problem with my Kitfox and went from the friction throttle to the  Vernier (new) from Spruce. I can now dial in my throttle settings. I takes some  practice but it works well.

                                                  Dick Maddux

                                                  Kitfox4-1200

                                                  Pensacola,Fl



New MapQuest Local shows what's happening at your destination. Dining, Movies, Events, News & more. Try it out! 

  [quote][b]

Jim Feldmann

Joined: 01 Sep 2008
Posts: 54
Location: Burbank, CA

Posted: Wed Oct 15, 2008 2:41 pm Post subject: Re: Throttle springs

I bought the correct springs from Rotax and installed them. Problem solved. 



Thanks to all for your input. 



Jim

Display posts from previous:

	Matronics Email Lists Forum Index -> RotaxEngines-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