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912ULS - Rough start & Rough on one magnet

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sidsel.svein(at)oslo.onli
Guest

Posted: Tue Jul 10, 2012 1:18 am Post subject: 912ULS - Rough start & Rough on one magnet

No two symptoms are alike, and I do not find what I am experiencing in the Europa List archives:

 

<![if !supportLists]>-          <![endif]>Cold start with choke, throttle idle:  Instant ignition, VERY rough running for one-two seconds, then smooth (see below, hwr).

<![if !supportLists]>-          <![endif]>Warm start:  No choke, some throttle:  A little rough for one – two seconds, then smooth (see below, hwr).

<![if !supportLists]>-          <![endif]>Magnet check (at) 4 000 rpm:  rpm drops are well within limits, also differential rpm drop (abt 50 rpm).  Hwr, on magnet A it runs a little rough, but not much.  Smooth on B.

 

This happens every time I start up, exactly the same “behavior”, so it is a little difficult to imagine that a poor connection/broken wire strands in the ignition circuit is the cause.  One would in such case expect some variation e.g. in the time it takes to get smooth running, wouldn’t one?

 

I have replaced all the spark plugs.  No improvement, neither re. starting nor magnet check.  The old plugs were all looking good, light greyish-brown colour and no soot deposits.

 

I have checked that choke & throttle on both sides work in sync.

 

The service agent for Scandinavia suggest that this may not have a common cause.  He recommends the following:

 

<![if !supportLists]>-          <![endif]>Install new battery, the 912ULS is a hard one to turn (about time to do this, but I do not think this is the cause). 

<![if !supportLists]>-          <![endif]>Synchronize the carbs (the symptoms began only 4 hours flying time after last synchronization).   May cause the symptoms at mag.check, he says.

<![if !supportLists]>-          <![endif]>Check the ignition wires at the electronic boxes on top of engine and to/on the plugs, with the engine idling.

 

Any other suggestions will be very much appreciated.

 

Regards,

Svein

LN-SKJ

 

  [quote][b]

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Mark Burton

Joined: 10 Jan 2006
Posts: 74

Posted: Tue Jul 10, 2012 2:51 am Post subject: Re: 912ULS - Rough start & Rough on one magnet

Hi Svein,



How about checking the ignition pickup gaps. Perhaps, they are wide enough to make the ignition unreliable at very low RPM (i.e. when starting).



Cheers,



Mark

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kheindl(at)msn.com
Guest

Posted: Tue Jul 10, 2012 3:46 am Post subject: 912ULS - Rough start & Rough on one magnet

Hi Mark,



Sometimes I had the same problem, as if the engine is running on one cylinder.

Where exactly is this ignition pickup point and what should the gap be ?

Cheers,

Karl



 	  Quote: 	
		   Subject: Re: 912ULS - Rough start & Rough on one magnet

 From: markb(at)ordern.com

 Date: Tue, 10 Jul 2012 03:51:14 -0700

 To: europa-list(at)matronics.com

 

 --> Europa-List message posted by: "Mark Burton" <markb(at)ordern.com>

 

 Hi Svein,

 

 How about checking the ignition pickup gaps. Perhaps, they are wide enough to make the ignition unreliable at very low RPM (i.e. when starting).

 

 Cheers,

 

 Mark

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=377848#377848

 

 

 

 

 

 

&gt=========
	


 	  Quote: 	
		   

 

 


	




 		 	   		  

  [quote][b]

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Mark Burton

Joined: 10 Jan 2006
Posts: 74

Posted: Tue Jul 10, 2012 4:15 am Post subject: Re: 912ULS - Rough start & Rough on one magnet

Hi Karl,



Sorry, I can't remember what the min/max gaps should be and I no longer own a Rotax engine but I'm sure someone here can advise you (and the numbers are in the manual).



Cheers,



Mark

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JonSmith

Joined: 21 May 2010
Posts: 110

Posted: Tue Jul 10, 2012 5:19 am Post subject: Re: 912ULS - Rough start & Rough on one magnet

Hi Svein, just a thought - probably not relevant to you but do you have the small starter motor or the larger heavy duty one installed?  It's just that I was having the exact same starting problems that you've described.



I was advised to bin my existing small starter and fit the large one which I did just two weeks ago.  It's early days yet and I'm never one to be naively complacent but so far I'll say cautiously that the results have been startlingly brilliant.  I've only done a few starts with the new starter yet but (fingers crossed) the starting problem has been completely cured.  



I was told that with the old starter the engine can start firing at a low rpm as it can't accelerate it quickly enough for the advanced ignition to kick in and so it remains on retarded ignition.  Especially if there is a bit of wear in the gearbox the prop can end up rocking backwards and forwards between ignition pulses, stopping the engine accelerating further.  The large starter motor in theory turns at the same speed as the small one but has much more torque to accelerate the engine rpm quickly beyond the point where this problem occurs.  ( This explanation is purely what I've been told and certainly not my field of expertise!)



Of course you've probably got the large starter motor already so this would not be relevant apart from I think it's important to be completely confident that your battery and all the battery connections and grounds are in top order.



Cheers, Jon

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_________________
G-TERN
Classic Mono

rlborger(at)mac.com
Guest

Posted: Tue Jul 10, 2012 7:43 pm Post subject: 912ULS - Rough start & Rough on one magnet

Karl,



Rotax Heavy Maintenance Manual, Section 74, 3) Maintenance/Troubleshooting



 Blue skies & tailwinds,

Bob Borger

Europa XS Tri, Rotax 914, Airmaster C/S Prop.

Little Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP

3705 Lynchburg Dr.

Corinth, TX  76208-5331

Cel: 817-992-1117

rlborger(at)mac.com (rlborger(at)mac.com)

 

 

On Jul 10, 2012, at 6:45 AM, Karl Heindl wrote:

Hi Mark,



Sometimes I had the same problem, as if the engine is running on one cylinder.

Where exactly is this ignition pickup point and what should the gap be ?

Cheers,

Karl



                        -Matt Dralle, List Admin.

 	  Quote: 	
		   Subject: Re: 912ULS - Rough start & Rough on one magnet

 From: markb(at)ordern.com (markb(at)ordern.com)

 Date: Tue, 10 Jul 2012 03:51:14 -0700

 To: europa-list(at)matronics.com (europa-list(at)matronics.com)

 

 --> Europa-List message posted by: "Mark Burton" <markb(at)ordern.com (markb(at)ordern.com)>

 

 Hi Svein,

 

 How about checking the ignition pickup gaps. Perhaps, they are wide enough to make the ignition unreliable at very low RPM (i.e. when starting).

 

 Cheers,

 

 Mark


	




 	  Quote: 	
		  http://www.matronics.com/contribution

- The Matronics Europa-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Europa-List

yck.laurens(at)gmail.com
Guest

Posted: Wed Jul 11, 2012 12:41 am Post subject: 912ULS - Rough start & Rough on one magnet

First : change the battery; I had the same pb, and new battery "odissey" solved the problèm



Regards 

yannick LAURENS

F PSCZ



Le 10 juil. 12 à 11:18, Sidsel & Svein Johnsen a écrit :

 	  Quote: 	
		  No two symptoms are alike, and I do not find what I am experiencing in the Europa List archives:

 

-          Cold start with choke, throttle idle:  Instant ignition, VERY rough running for one-two seconds, then smooth (see below, hwr).

-          Warm start:  No choke, some throttle:  A little rough for one – two seconds, then smooth (see below, hwr).

-          Magnet check (at) 4 000 rpm:  rpm drops are well within limits, also differential rpm drop (abt 50 rpm).  Hwr, on magnet A it runs a little rough, but not much.  Smooth on B.

 

This happens every time I start up, exactly the same “behavior”, so it is a little difficult to imagine that a poor connection/broken wire strands in the ignition circuit is the cause.  One would in such case expect some variation e.g. in the time it takes to get smooth running, wouldn’t one?

 

I have replaced all the spark plugs.  No improvement, neither re. starting nor magnet check.  The old plugs were all looking good, light greyish-brown colour and no soot deposits.

 

I have checked that choke & throttle on both sides work in sync.

 

The service agent for Scandinavia suggest that this may not have a common cause.  He recommends the following:

 

-          Install new battery, the 912ULS is a hard one to turn (about time to do this, but I do not think this is the cause).

-          Synchronize the carbs (the symptoms began only 4 hours flying time after last synchronization).   May cause the symptoms at mag.check, he says.

-          Check the ignition wires at the electronic boxes on top of engine and to/on the plugs, with the engine idling.

 

Any other suggestions will be very much appreciated.

 

Regards,

Svein

LN-SKJ

 



 	  Quote: 	
		  



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