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My 912 is still not happy--

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sdemeyer

Joined: 31 Jul 2009
Posts: 45

Posted: Mon Mar 15, 2010 6:24 am Post subject: My 912 is still not happy--

Hi Guys,



I'm out of ideas on why my 912UL continues to run rough in midrange between 2000 and 3500 RPM. I've rebuilt the carbs, I've sent the carbs in and had them gone through again, I've replaced the entire ignition system including modules,coils,trigger coils and stator, spark plug wires, plug boots and spark plugs. I've balanced the carbs several times with my carbemate. Compression is good in all cylinders - 80/87. 



When I say rough running, I mean the engine shakes and misfires quite noticeably between 2000 and 3500 RPM.



Any suggestions on what to check next would be quite helpful!

Thanks

Scott

blackmore(at)platinum.ca
Guest

Posted: Mon Mar 15, 2010 8:23 am Post subject: My 912 is still not happy--

Bad fuel, sticky / bent valves that clutch thing that was recently talked about. Cracked porcelain on plug,plugged fuel line/filter/pump? Mag switch /mag,bad ground, put an old fashioned scanner in it to see what the spark is doing  

 Chris 

  

 [i]----

litesellme(at)yahoo.com
Guest

Posted: Mon Mar 15, 2010 1:20 pm Post subject: My 912 is still not happy--

Too rich on the bottom end or timing pulled too much. Leaning out my bottom end tends to smoothen out rough idles. If you fauled your plugs you will get this too. Are you burning oil? If it runs good with new plugs, then bad later on, you need an overhaul.

Jason

Connected by MOTOBLUR™ on T-Mobile





-----Original message-----

[quote]From: sdemeyer <scottsr1100rt(at)yahoo.com>

To: rotaxengines-list(at)matronics.com

Sent: Mon, Mar 15, 2010 14:35:53 GMT+00:00

Subject: RotaxEngines-List: My 912 is still not happy--

Brian Davies

Joined: 10 Jan 2006
Posts: 124
Location: uk

Posted: Mon Mar 15, 2010 2:00 pm Post subject: My 912 is still not happy--

Hi Scott, what does the carb balancer show when the engine is misbehaving?

This can often be caused by one throttle cable sticking but this should show

up as an imbalance at that rpm.



Regards



Brian Davies

Europa XS with 912ULS 



--

Ollie Washburn

Joined: 10 Jan 2006
Posts: 56
Location: Central Florida

Posted: Mon Mar 15, 2010 2:04 pm Post subject: My 912 is still not happy--

My 912ULS also runs rough in that range however there is no time I fly in that range so I just pass through it and go flying. 650+ hrs.Ollie



On Mon, Mar 15, 2010 at 10:24 AM, sdemeyer <scottsr1100rt(at)yahoo.com (scottsr1100rt(at)yahoo.com)> wrote:

 [quote]--> RotaxEngines-List message posted by: "sdemeyer" <scottsr1100rt(at)yahoo.com (scottsr1100rt(at)yahoo.com)>

  

 Hi Guys,

 

 I'm out of ideas on why my 912UL continues to run rough in midrange between 2000 and 3500 RPM. I've rebuilt the carbs, I've sent the carbs in and had them gone through again, I've replaced the entire ignition system including modules,coils,trigger coils and stator, spark plug wires, plug boots and spark plugs. I've balanced the carbs several times with my carbemate. Compression is good in all cylinders - 80/87.

  

 When I say rough running, I mean the engine shakes and misfires quite noticeably between 2000 and 3500 RPM.

 

 Any suggestions on what to check next would be quite helpful!

 

 

 Thanks

 Scott

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=290350#290350

 

 

 

 

 

 

 

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 le, List Admin.

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 [b]

_________________
Ollie RV6-A & Rans S7S
Central FL

pchristensen10(at)austin.
Guest

Posted: Mon Mar 15, 2010 2:56 pm Post subject: My 912 is still not happy--

My plane has a rough range too but when I pull on carb  heat it smoothes out.

  

 Pete

  

 [quote]   ---

b.carl@sympatico.ca

Joined: 20 May 2008
Posts: 77

Posted: Mon Mar 15, 2010 6:16 pm Post subject: My 912 is still not happy--

Scott.

Stop the engine in the range where it is missing, don't touch the throttle 

or choke controls, check to see if the control levers on your carbs are in 

sync. If not pull on them to see if they are binding. If they move restart 

the engine to see if this correct the problem.

Also, the engine moves slightly when under load, depening on your throttle 

setup this could cause the carb to loose their sync. Long shots but you 

appear desperate.

Carl

---

cfrhoads(at)yahoo.com
Guest

Posted: Tue Mar 16, 2010 1:05 pm Post subject: My 912 is still not happy--

Scott,

  

 Your problem sounds very similar to the one I had.  After I had done everything else that I could think of I sent both carbs off and had them rebuilt.  I tried to balance the carbs with the electronic balancer, but I still had the mid range problem.  Afterwards I changed my carb choke linkage so that I could choke each carb independently, it became apparent that one of the carbs was running lean in mid range.  I watched the new Rotax video on how to adjust the mid range circuit, the metering rod.  This is a very simple thing to do and it solved the problem.

  

 Good Luck,

 Chuck Rhoads

 A100

--- On Mon, 3/15/10, Carl <b.carl(at)sympatico.ca> wrote:



 [quote]

From: Carl <b.carl(at)sympatico.ca>

Subject: Re: My 912 is still not happy--

To: rotaxengines-list(at)matronics.com

Date: Monday, March 15, 2010, 3:50 PM



 --> RotaxEngines-List message posted by: "Carl" <b.carl(at)sympatico.ca (b.carl(at)sympatico.ca)>



Scott.

Stop the engine in the range where it is missing, don't touch the throttle or choke controls, check to see if the control levers on your carbs are in sync. If not pull on them to see if they are binding. If they move restart the engine to see if this correct the problem.

Also, the engine moves slightly when under load, depening on your throttle setup this could cause the carb to loose their sync. Long shots but you appear desperate.

Carl

---

Jim Feldmann

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

Posted: Tue Mar 16, 2010 1:12 pm Post subject: Re: My 912 is still not happy--

The enriching circuits (chokes) on the left and right carbs are mirror images of each other.  When I first got my 912 someone had reversed them, which made them "off" at idle and "on" everywhere else.  This caused all kinds of tuning problems, and missing and shaking at low rpm was one of the symptoms.



I also rebuilt the carbs without finding that problem.  I think Dean Vogel was the one who finally told me to check for it.  After I put the chokes on the correct carb and reset the carbs to the factory settings the engine ran as smooth as silk.

_________________
Jim Feldmann
Kitfox IV Speedster / 912 lost to prop failure
Building a Kitfox 5 Voyager

sdemeyer

Joined: 31 Jul 2009
Posts: 45

Posted: Tue Mar 16, 2010 1:53 pm Post subject: Re: My 912 is still not happy--

Wow, thanks for all the suggestions!  I replaced the throttle cable towards the beginning of this issue, but that did not help. Sheesh, there are not too many parts left to replace! I'll check the needle and maybe raise it a notch. My EGT is running 1500 which is OK but on the warm side. The engine supposedly has about 450 hours, although I'm a little skeptical about this. I saw quite a lot of deposits on the valve stems, while looking into the exhaust  ports so maybe I have a valve problem.

grahamsingleton(at)btinte
Guest

Posted: Tue Mar 16, 2010 3:46 pm Post subject: My 912 is still not happy--

balance the carbs with a proper vacuum gauge set up. It makes an enormous difference. 

Graham

From: sdemeyer <scottsr1100rt(at)yahoo.com>

To: rotaxengines-list(at)matronics.com

Sent: Tuesday, 16 March, 2010 21:53:03

Subject: RotaxEngines-List: Re: My 912 is still not happy--

--> RotaxEngines-List message posted by: "sdemeyer" <scottsr1100rt(at)yahoo.com (scottsr1100rt(at)yahoo.com)>

Wow, thanks for all the suggestions!  I replaced the throttle cable towards the beginning of this issue, but that did not help. Sheesh, there are not too many parts left to replace! I'll check the needle and maybe raise it a notch. My EGT is running 1500 which is OK but on the warm side. The engine supposedly has about 450 hours, although I'm a little skeptical about this. I saw quite a lot of deposits on the valve stems, while looking into the exhaust  ports so maybe I have a valve problem.

Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=290514#290514

http://www.matronics.com/Navigator?Rotsp;              - MATRONICS WEB FORUMS -

=   -->   [quote][b]

Dick Maddux

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

Posted: Wed Mar 17, 2010 6:37 am Post subject: My 912 is still not happy--

Scott,

  Here are some other ideas you can ponder. A few months ago my engine was pretty rough when decelerating thru 4000 rpm to about 2800 rpm for landing.Like you,I synched everything so I just lived with it. I had an interest in a Kiev prop so I bought one. I removed my Warp and installed the Kiev for flight tests. I had it on and off for about 4 hours of flying. I readjusted the pitch each time to try and get the best performance. Alas, it did not work out . I could not get even my old cruise speed so I went back to my Warp.(sold the Kiev) One thing I did notice was that thru the mid range the engine was smooth as silk with the Kiev ! (as it was overall..what a nice prop )! 

  I put the Warp back on and there was that rough mid range again (it has since abated) 

  Perhaps the prop might contribute to the problem? I think the choke idea the guys brought up is certainly valid. I don't have a choke only a primer. My chokes are wired closed.

  My old nemis,diseling on shutdown (prop turns backwards about 3 revolutions) has cropped up again. I have fresh premium no alcohol fuel in my tanks too. I guess I will pour in some Octane booster and see if that stops it. I shouldn't have opened my mouth...the other shoe fell!

  Man, this is a full time job for me keeping this engine running good. I sure am glad I am retired and like engines!

  Good luck to you Scott and please keep us informed! Your problem will probably be mine tomorrow.

                                                   Dick Maddux

                                                   Kitfox 4-1200

                                                   Rotax 912UL

                                                   Milton,Fl

 PS; I had the wrong Kiev prop on my plane it turns out.The wrong one was sent. Soooo I will probably give it another try. I sure loved it !!!

  [quote][b]

Ollie Washburn

Joined: 10 Jan 2006
Posts: 56
Location: Central Florida

Posted: Wed Mar 17, 2010 9:45 am Post subject: My 912 is still not happy--

 I have 660 hrs. on my 912ULS and the only thing I have ever done is sync. the carbs, change plugs a couple of times and change oil (at) 50 hrs. Gearbox was changed (at) 250 hrs. for SB about bad metal in gears which mine had. 



Ollie



On Wed, Mar 17, 2010 at 10:32 AM,  <Catz631(at)aol.com (Catz631(at)aol.com)> wrote:

[quote]     Scott,

  Here are some other ideas you can ponder. A few months ago my engine was pretty rough when decelerating thru 4000 rpm to about 2800 rpm for landing.Like you,I synched everything so I just lived with it. I had an interest in a Kiev prop so I bought one. I removed my Warp and installed the Kiev for flight tests. I had it on and off for about 4 hours of flying. I readjusted the pitch each time to try and get the best performance. Alas, it did not work out . I could not get even my old cruise speed so I went back to my Warp.(sold the Kiev) One thing I did notice was that thru the mid range the engine was smooth as silk with the Kiev ! (as it was overall..what a nice prop )! 

   I put the Warp back on and there was that rough mid range again (it has since abated) 

  Perhaps the prop might contribute to the problem? I think the choke idea the guys brought up is certainly valid. I don't have a choke only a primer. My chokes are wired closed.

  My old nemis,diseling on shutdown (prop turns backwards about 3 revolutions) has cropped up again. I have fresh premium no alcohol fuel in my tanks too. I guess I will pour in some Octane booster and see if that stops it. I shouldn't have opened my mouth...the other shoe fell!

   Man, this is a full time job for me keeping this engine running good. I sure am glad I am retired and like engines!

  Good luck to you Scott and please keep us informed! Your problem will probably be mine tomorrow.

                                                   Dick Maddux

                                                   Kitfox 4-1200

                                                   Rotax 912UL

                                                   Milton,Fl

 PS; I had the wrong Kiev prop on my plane it turns out.The wrong one was sent. Soooo I will probably give it another try. I sure loved it !!!

   	  Quote: 	
		  



ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List

tp://forums.matronics.com

_blank">http://www.matronics.com/contribution



	


[b]

_________________
Ollie RV6-A & Rans S7S
Central FL

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