Matronics Email Lists :: View topic - 912 Choke Actuation Problem

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

912 Choke Actuation Problem

Matronics Email Lists Forum Index -> Kitfox-List

View previous topic :: View next topic

Author Message

trevorkebb(at)earthlink.n
Guest

Posted: Sat Feb 03, 2007 5:23 pm Post subject: 912 Choke Actuation Problem

Folks:

  

 A quick question: I have a friend with a completed Classic IV who is  getting close to first engine start. Recently we have been going over his Rotax  912 installation with a fine tooth comb. Today we tackled his cockpit  mounted 'choke' (enrichener) control, which had I noticed is extremely difficult  to pull, and hold, out (choke ON).  It is set up to the right of the  throttle and has quite a small knob. Skystar supplied. At first I suspected  his cable routing or binding in the cables but they sure looked alright, with  relatively gentle bends to each carb. Next we disconnected the choke lever  return springs at each carb. MUCH easier but still not baby-smooth. Then we  disconnected the cables from the choke levers on the carbs. The levers are free  and not binding in any way.

  

 We buttoned it all back up, adjusted the throws so each lever is being  pulled equally through its entire stroke, attached the springs and, man, that  choke control seems to take 50+lbs or more of force to actuate. Those 2  little return springs add up to powerful resistance. In fact, my friend  cannot pull it out and needs to grab it with a wrench. I am pretty beefy and I  can pull it out but it seems like way too much effort to do so and too much  effort to hold it out. Part of the problem is the very small knob on the control  supplied by Skystar. If it were the size of a ping-pong ball it would be much  easier.

  

 Since his basic installation seems sound, done and modified per  Skystar, and no individual items in the system seem to be binding, it got  me wondering if others have run into the same problem. Do you need to be a  gorilla to actuate the choke? Anything to suggest or a modification to make? How  do you 912 drivers handle starting with the right hand all taken up straining at  the choke? 

  

 Any ideas would be greatly appreciated.

  

 Robert Beck

  

 Go Bears!

   [quote][b]

lcfitt(at)sbcglobal.net
Guest

Posted: Sat Feb 03, 2007 6:36 pm Post subject: 912 Choke Actuation Problem

Hey, what's this go Bears stuff - just kidding.



The choke is a tough one.  I'll tell you what I did.  First, I drilled a 

hole throught the base of the knob and threadded a key ring through that.  A 

finger through the ring gives a much better purchase.  Another thing I did 

was to take a piece of Nylaflow tubing - some really fine stuff and slit it 

with a Dremel type cut off wheel and threaded it into the bent tubes with 

the unslit - good side toward the bend.  All in all the ring was the hand 

saver.



Lowell



---

davestapa(at)juno.com
Guest

Posted: Sat Feb 03, 2007 6:42 pm Post subject: 912 Choke Actuation Problem

Robert, I had the same problem. Finally disconnected it all and use the

primer system. Works well. Only thing I could figure was the cable was

sitting on the shelf for a few years.



C. David Estapa

Woodstock, GA

N97DE S5TD



Do not archive

trevorkebb(at)earthlink.n
Guest

Posted: Sun Feb 04, 2007 6:10 am Post subject: 912 Choke Actuation Problem

Thanks, Lowell, the keyring idea appeals to my friend. I take it from your 

post that this is a common problem, just 'the way things are' with the 912 

choke. That gives a sense of relief.



The Nylaflow tubing in the bent tubes is another good idea, takes away a bit 

of the friction, right? Like the nylon tubing in the V brake bent tubes of 

my mountain bike. One question: why did the tubing need to be slit? To 

reduce its diameter so it would fit?



Robert Beck



Go Bears means 'go polar bears in your fight for survival in the frigid 

north'.



Do not archive

[quote] Hey, what's this go Bears stuff - just kidding.



 The choke is a tough one.  I'll tell you what I did.  First, I drilled a 

 hole throught the base of the knob and threadded a key ring through that. 

 A finger through the ring gives a much better purchase.  Another thing I 

 did was to take a piece of Nylaflow tubing - some really fine stuff and 

 slit it with a Dremel type cut off wheel and threaded it into the bent 

 tubes with the unslit - good side toward the bend.  All in all the ring 

 was the hand saver.



 Lowell



 ---

lcfitt(at)sbcglobal.net
Guest

Posted: Sun Feb 04, 2007 8:01 am Post subject: 912 Choke Actuation Problem

One more thing I forgot.  I used a length of black vinyl tubing threaded 

over the keyring to match the black.  I canit recall if it was a left over 

piece of the tubing used for the pitot tube line or some drip irrigation 

tubing.



Lowell

---

Nick(at)Scholtes1.com
Guest

Posted: Sun Feb 04, 2007 8:14 am Post subject: 912 Choke Actuation Problem

Robert,



I've had this exact problem many times before (although not specifically on a 912, as I'm a KitFox newbie!), but on other cable-actuated systems.  The problem of where the cable is very hard to actuate, but when you take it apart everything seems very smooth and easy-to-operate.  



Often, and to my surprise, lubing the cable fixes the problem, even  though the cable operates "smoothly" when it's disconnected.  Best thing I can figure is that when the cable isn't connected, it sees no friction from rubbing on the sides of the sheath, but when it's under tension it gets pulled hard against the side of the sheath, and the friction starts.  The amount of friction that can be seen under this scenario, as you point out, can be really huge.



There are several ways to apply lubricant, a pressure lube system is a good choice.  There are also several lubes to choose.  I've tried many of them, from WD-40 to specially supplied "Cable Lubricant with Graphite" to "Dri-Slide" to a lube that comes out very thin and liquidy and then that solidifies into a grease.  Many, especially the ones labeled specially for cable application, seem to work poorly, in my experience.  Also, in my experience (your mileage may vary) is that a thin penetrating lube like WD-40 will work really well, for a few days, and then it seems to "go away".  The best success I've found is to use this specialized stuff that I get from McMaster that sprays out of the can really thin and watery, and then later sets up into a grease.  But, the grease is actually kinda' sticky, so then at that point follow it up with a shot of WD-40 down the pressure luber, and the cable will perform great for years. If you want the specifics of where to get the special grease stuff, let me know.



Best,



Nick

Jim Shumaker

Joined: 09 Jan 2006
Posts: 106

Posted: Sun Feb 04, 2007 9:18 am Post subject: 912 Choke Actuation Problem

You might check the brass cable holder piston in the handle.  I found that one of the slots was not cut deep enough and was causing a binding.  This changed the pull required from impossible to very firm.

  

 Jim Shumaker

 ---

_________________
Jim Shumaker

MichaelGibbs(at)cox.net
Guest

Posted: Sun Feb 04, 2007 10:43 am Post subject: 912 Choke Actuation Problem

Robert,



I found the force required to pull the enrichment valve on my 912S 

surprisingly high also.  In my Model IV-1200, though, I had the 

throttle mounted on my center console and the enrichment valve handle 

(also on the console) was actually a lever of sorts that allowed me 

to pull it a lot easier.



Your description of the force required doesn't surprise me.



Mike G.

N728KF

kitfoxmike

Joined: 05 Dec 2006
Posts: 373

Posted: Sun Feb 04, 2007 11:12 am Post subject: Re: 912 Choke Actuation Problem

You will be better off getting the new stile choke cable and hooking up both carbs.  I had the old stile and it too was hard to pull, the new stile is stiff also, but it now starts better with both carbs choking.

trevorkebb(at)earthlink.n
Guest

Posted: Sun Feb 04, 2007 12:20 pm Post subject: 912 Choke Actuation Problem

Thanks to ALL who replied to my question on the 912 choke. All good, sound 

advice and my friend and I will look into all of the suggestions: lubing, 

modifying the slot in the control, attaching a key ring, nylon tubing 

inserts, etc, etc.



Boo-Hee, good advice!



Robert Beck



Do Not Archive

Bill Willyard

Joined: 10 Jan 2006
Posts: 34
Location: Grandville, Michigan U.S.A.

Posted: Sun Feb 04, 2007 2:29 pm Post subject: 912 Choke Actuation Problem

Robert, I made a larger diameter knob, still pulls very firm but fingers  don't hurt anymore.

  

 Good Luck.

  

 DO NOT ARCHIVE    

  [quote][b]

_________________
Bill Willyard
Classic IV 912UL

Display posts from previous:

	Matronics Email Lists Forum Index -> Kitfox-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