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Rotax Tacho

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europa(at)pstewart.f2s.co
Guest

Posted: Tue Oct 28, 2008 10:05 am Post subject: Rotax Tacho

Have just run the engine for the first time (914). All seems well with  

exception of rotax tacho. Advancing  throttle from  'rough running' to  

just smooth, the tacho jumps from <2000rpm to 4000rpm - numbers which  

I just don't believe. Anyone got any thoughts?



Unfortunately the rest of our engine instruments are a BMA EFIS1 which  

doesn't easily support an alternative tacho for the rotax.

Regards



Paul

grahamsingleton(at)btinte
Guest

Posted: Tue Oct 28, 2008 11:01 am Post subject: Rotax Tacho

Paul Stewart wrote:

 	  Quote: 	
		   



 Have just run the engine for the first time (914). All seems well with 

 exception of rotax tacho. Advancing  throttle from  'rough running' to 

 just smooth, the tacho jumps from <2000rpm to 4000rpm - numbers which 

 I just don't believe. Anyone got any thoughts?



 Unfortunately the rest of our engine instruments are a BMA EFIS1 which 

 doesn't easily support an alternative tacho for the rotax.

the calibration seems to varie with the gap of the sense coil, I once 
	


set clearance to the book, (912) above 4000 the reading was full scale. 

Not good those Rotax tachos, we used a Grand Rapids EMI which was perfect.

Graham

acrojim7534(at)YAHOO.COM
Guest

Posted: Tue Oct 28, 2008 4:34 pm Post subject: Rotax Tacho

Paul

  

 I thank Jim Butcher had the same problem. He has the Blue Mtn EFIS and was having  some problems with the tach reading incorrect.

  

 I have not seen any postings from him lately. 

  

 Jim are you still out there ???

  

 Jim Brown



--- On Tue, 10/28/08, Paul Stewart <europa(at)pstewart.f2s.com> wrote:



  	  Quote: 	
		  From: Paul Stewart <europa(at)pstewart.f2s.com>

Subject: Rotax Tacho

To: "europa-list(at)matronics.com" <europa-list(at)matronics.com>

Date: Tuesday, October 28, 2008, 5:48 PM



 	  Quote: 	
		  --> Europa-List message posted by: Paul Stewart

<europa(at)pstewart.f2s.com>



Have just run the engine for the first time (914). All seems well with  

exception of rotax tacho. Advancing  throttle from  'rough running' to 



just smooth, the tacho jumps from <2000rpm to 4000rpm - numbers which  

I just don't believe. Anyone got any thoughts?



Unfortunately the rest of our engine instruments are a BMA EFIS1 which  

doesn't easily support an alternative tacho for the rotax.

Regards



Paul





	
	


          [quote][b]

Brian Davies

Joined: 10 Jan 2006
Posts: 124
Location: uk

Posted: Wed Oct 29, 2008 12:35 am Post subject: Rotax Tacho

Hi Paul,

  

 Common problem on the Rotax tacho- swap the signal leads  over at the connecting plug.  That normally fixes it. If it does not , it  is a tacho change.

  

 Brian Davies



   From: owner-europa-list-server(at)matronics.com  [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of Jim  Brown

Sent: 29 October 2008 00:33

To:  europa-list(at)matronics.com

Subject: Re: Rotax  Tacho

 

                   Paul

        

       I thank Jim Butcher had the same problem. He has the Blue Mtn EFIS        and was having  some problems with the tach reading incorrect.

        

       I have not seen any postings from him lately. 

        

       Jim are you still out there ???

        

       Jim Brown



--- On Tue, 10/28/08, Paul Stewart        <europa(at)pstewart.f2s.com> wrote:



        	  Quote: 	
		  From:          Paul Stewart <europa(at)pstewart.f2s.com>

Subject: Europa-List:          Rotax Tacho

To: "europa-list(at)matronics.com"          <europa-list(at)matronics.com>

Date: Tuesday, October 28, 2008,          5:48 PM



 	  Quote: 	
		  --> Europa-List message posted by: Paul Stewart

<europa(at)pstewart.f2s.com>



Have just run the engine for the first time (914). All seems well with  

exception of rotax tacho. Advancing  throttle from  'rough running' to 



just smooth, the tacho jumps from <2000rpm to 4000rpm - numbers which  

I just don't believe. Anyone got any thoughts?



Unfortunately the rest of our engine instruments are a BMA EFIS1 which  

doesn't easily support an alternative tacho for the rotax.

Regards



Paul





	
	


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No virus found in this incoming message.

Checked  270.8.4/1753 -  Release Date: 28/10/2008 21:20

   [quote][b]

pr(at)dcanderson.myzen.co
Guest

Posted: Wed Oct 29, 2008 1:54 am Post subject: Rotax Tacho

Paul,

    I think that the problem may be that the tacho coil is picking up 

secondary impulses as the speed increases - which accounts for the doubling 

of the reading. The Rotax manual does show a graph of the output from the 

coil which does show secondary impulses. I suggest that a slight increase in 

the gap might cure the problem.

    Modellers use a battery operated gadget which works on the strobe effect 

of the prop to measure the speed of their props. I bought one when I was 

having a similar problem with my tacho, it wasn't very expensive an it did 

reassure me that the engine was not in fact overspeeding.

        Roger (G-BXTD)



---

rparigor(at)suffolk.lib.n
Guest

Posted: Wed Oct 29, 2008 2:10 am Post subject: Rotax Tacho

Hi Paul



I attached a pdf file from Rotax about tachometer troubleshooting.



Ron Parigoris

rparigor(at)suffolk.lib.n
Guest

Posted: Wed Oct 29, 2008 2:22 am Post subject: Rotax Tacho

Hmmmm pdf did not attach.



Go here:

http://www.rotax-owner.com/index.htm



Click:

Education then E-Learning



Click:

Click here to view our current PDF documents

 

Click:

Tachometer Troubleshooting



Ron Parigoris

Visit -  www.EuropaOwners.org

h&jeuropa

Joined: 07 Nov 2006
Posts: 645

Posted: Wed Oct 29, 2008 4:06 am Post subject: Re: Rotax Tacho

Paul & AcroJim



Just a quick update.  We gave up getting our G2 Blue Mountain EFIS to work properly.  Sold it on E Bay and installed GRT Sport and EIS which interfaces to the 914 with no problem.  Tach, fuel flow, temps, pressures, volts & amps all work properly, even when transmitting on the comm radio!! And no interference or noise in the comm radio!



Never did get the BMA tach to work, I think they do have a tach solution with their engine pod.  Our Rotax tach worked fine while we had the BMA system.



Jim Butcher

N241BW  flying again!!



Do not archive

rampil

Joined: 04 May 2007
Posts: 870

Posted: Wed Oct 29, 2008 10:33 am Post subject: Re: Rotax Tacho

Hi All,



When I upgraded from the G3 to the G4 BMA EFIS for my 912ULS,

I took it upon myself to engineer working solutions for the new BMA

Engine Pod.



The Rotax electric tach output was designed to go to a electro-mechanical

panel gauge, like the new UMA Rotax-specific Tach meter.  The UMA

works great (although the RPM>IDLE contact never worked in my unit).

The electrical output of the engine was never designed for talking to a 

digital or analog-to-digital conversion box.  The voltage out of the flywheel

coils exceeds 100v at normal engine speed and the typical high impedance input.



The GRT guys may have spent some time working out a conversion/

protection circuit for their engine monitor.



I have my EFIS read RPM off a hall-effect sensor mounted on the gearbox

next to my prop brushes.  It detects the embedded magnet in the prop

backing plate used by the Airmaster.  The Hall-effect sensor is a stock

item at Westach and it produces nice digital pulses for the BMA Engine

pod. It works like a champ.  There is a small caveat - the Airmaster

guys are not picky about which polarity they embed face up in the prop

plate.  The Westach probe is only sensitive to one polarity, so you need

to check the magnet first, before ordering the sensor.

_________________
Ira N224XS

europa(at)pstewart.f2s.co
Guest

Posted: Wed Oct 29, 2008 11:02 am Post subject: Rotax Tacho

Many thanks to all who responded. A few things to try. Glad to hear  

you're flying again Jim. We're still pressing on with the BMA E1  I  

certainly wouldn't go this way 2nd time round.



Regards

Paul

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