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582 - compression test

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msm_9949(at)yahoo.com
Guest

Posted: Wed Jun 28, 2006 10:13 am Post subject: 582 - compression test

Hello KF listers.

   

  I'm doing my annual condition inspection and one of the items is to check cylinder compression. Is there a recommended technique for the 582 with Ducati CDI? I recall reading that the CDI modules can be fried by cranking the engine with plugs disconnected. Will simply grounding the disconnected plug suffice to prevent damage to modules?

   

  As always, thanks for your assistance.

Marco Menezes

Model 2 582 N99KX

lcfitt(at)sbcglobal.net
Guest

Posted: Wed Jun 28, 2006 1:27 pm Post subject: 582 - compression test

Marco,



With the 912, The recommended technique is to use a differential compression 

testor.  It has of two dials and you attach the unit in the spark plug hole 

and after findind top dead center pressurize to 80 lbs. using the attached 

pressure regulator.  The unit will then read the pressure in the cylinder - 

usually a bit under the 80 lb. reference pressure.  In our manual, it gives 

the acceptable tolerance.



The only hazard is when the piston is not at TDC.  If this is the case, the 

piston will be forced down with the pressure and the prop will turn.



Lowell

---

asq1(at)adelphia.net
Guest

Posted: Wed Jun 28, 2006 2:01 pm Post subject: 582 - compression test

Yes, the prop will turn. VIOLENTLY. Please be careful.   Larry



---

noelloveys(at)yahoo.ca
Guest

Posted: Wed Jun 28, 2006 5:27 pm Post subject: 582 - compression test

Differential testing not only tells you whether or not you have good

compression but will also tell you if you have bad valve seats , which ones

and whether or not you have bad rings.



Set up the diff test and listen for air at the air intake, the exhaust and

the oil filler to tell where the air is escaping.... It is recommended if

you are listening for air to have two people do the test the strongest one

holds the prop at TDC.  I can't see why the diff. test wouldn't work on the

two stroke engines to test the integrity of the piston rings.



Noel



[quote] --

bnn(at)nethere.com
Guest

Posted: Wed Jun 28, 2006 8:36 pm Post subject: 582 - compression test

Funny you should ask. I hope I didn't fry my ignition modules, as I just 

did a compression test for my DAR sign-off on Friday. I did it the old 

fashioned way and came up with 118 psi in each cylinder. As I ran the 

engine after I don't think I fried anything, but I didn't do a mag check. 

I'll try it tomorrow to make sure.



At 11:12 AM 6/28/2006, you wrote:

 	  Quote: 	
		  I'm doing my annual condition inspection and one of the items is to check 

cylinder compression. Is there a recommended technique for the 582 with 

Ducati CDI? I recall reading that the CDI modules can be fried by cranking 

the engine with plugs disconnected. Will simply grounding the disconnected 

plug suffice to prevent damage to modules?


	




Guy Buchanan

K-IV 1200 / 582-C / Warp / 99.9% done, thanks mostly to Bob Ducar.

smokey_bear_40220(at)yaho
Guest

Posted: Thu Jun 29, 2006 8:13 am Post subject: 582 - compression test

Great summary Noel!



Kurt S.



Do not archive



--- Noel Loveys <noelloveys(at)yahoo.ca> wrote:



 	  Quote: 	
		   Differential testing not only tells you whether or

 not you have good

 compression but will also tell you if you have bad

 valve seats , which ones

 and whether or not you have bad rings.

 

 Set up the diff test and listen for air at the air

 intake, the exhaust and

 the oil filler to tell where the air is escaping....

 It is recommended if

 you are listening for air to have two people do the

 test the strongest one

 holds the prop at TDC.  I can't see why the diff.

 test wouldn't work on the

 two stroke engines to test the integrity of the

 piston rings.

 

 Noel


	


__________________________________________________

skyflyte(at)comcast.net
Guest

Posted: Thu Jun 29, 2006 9:03 am Post subject: 582 - compression test

   The differential pressure test is probably not a good idea for a 2 cycle engine.  It doesn't take a lot of pressure in the crankcase to blow out the crankshaft seals.

    Mike

  

 [quote]-------------- Original message -------------- 

From: "Noel Loveys" <noelloveys(at)yahoo.ca> 



[quote] --> Kitfox-List message posted by: "Noel Loveys" 

 

 Differential testing not only tells you whether or not you have good 

 compression but will also tell you if you have bad valve seats , which ones 

 and whether or not you have bad rings. 

 

 Set up the diff test and listen for air at the air intake, the exhaust and 

 the oil filler to tell where the air is escaping.... It is recommended if 

 you are listening for air to have two people do the test the strongest one 

 holds the prop at TDC. I can't see why the diff. test wouldn't work on the 

 two stroke engines to test the integrity of the piston rings. 

 

 Noel 

 

 

 

 > -----Original Mess  age--- -- 

 > From: owner-kitfox-list-server(at)matronics.com 

 > [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of 

 > Lowell Fitt 

 > Sent: Wednesday, June 28, 2006 6:53 PM 

 > To: kitfox-list(at)matronics.com 

 > Subject: Re: 582 - compression test 

 > 

 > 

 > --> Kitfox-List message posted by: "Lowell Fitt" 

 > 

 > 

 > Marco, 

 > 

 > With the 912, The recommended technique is to use a 

 > differential compression 

 > testor. It has of two dials and you attach the unit in the 

 > spark plug hole 

 > and after findind top dead center pressurize to 80 lbs. using 

 > the attached 

 > pressure regulator. The unit will then read the pressure in 

 > the cylinder - 

 > usually a bit under the 80 lb. reference pressure. In our [b]>  > manual, it gives 

 > the acceptable tolerance. 

 > 

 > The only hazard is when the piston is not at TDC. If this is 

 > the case, the 

 > piston will be forced down with the pressure and the prop will turn. 

 > 

 > Lowell 

 > ---

msm_9949(at)yahoo.com
Guest

Posted: Thu Jun 29, 2006 10:58 am Post subject: 582 - compression test

My plan was to do an "old fashioned" test. Pull a plug, insert the comp tester, crank the engine a turn or 2 with mags off, read the gauge, repeat on other cyl.. But back to my original question: Does anyone know of I have to take any special precautions to keep from ruining my CDI modules?

  Hey Bob Robertson, are you following this thread?

skyflyte(at)comcast.net wrote:

  [quote]     The differential pressure test is probably not a good idea for a 2 cycle engine.  It doesn't take a lot of pressure in the crankcase to blow out the crankshaft seals.

     Mike

  [quote]-------------- Original message -------------- 

From: "Noel Loveys"  <noelloveys(at)yahoo.ca> 

[quote] --> Kitfox-List message posted by: "Noel Loveys" 

 Differential testing not only tells you whether or not you have good 

 compression but will also tell you if you have bad valve seats , which ones 

 and whether or not you have bad rings. 

 Set up the diff test and listen for air at the air intake, the exhaust and 

 the oil filler to tell where the air is escaping.... It is recommended if 

 you are listening for air to have two people do the test the strongest one 

 holds the prop at TDC. I can't see why the diff. test wouldn't work on the 

 two stroke engines to test the integrity of the piston rings. 

 Noel 

 > -----Original Mess age--- -- 

 > From: owner-kitfox-list-server(at)matronics.com 

 > [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of 

  > Lowell Fitt 

 > Sent: Wednesday, June 28, 2006 6:53 PM 

 > To: kitfox-list(at)matronics.com 

 > Subject: Re: 582 - compression test 

 > 

 > 

 > --> Kitfox-List message posted by: "Lowell Fitt" 

 > 

 > 

 > Marco, 

 > 

 > With the 912, The recommended technique is to use a 

 > differential compression 

 > testor. It has of two dials and you attach the unit in the 

 > spark plug hole 

 > and after findind top dead center pressurize to 80 lbs. using 

 > the attached 

 > pressure regulator. The unit will then read the pressure in 

 > the cylinder - 

 > usually a bit under the 80 lb. reference pressure. In our [b]> > manual, it gives 

 > the acceptable tolerance. 

 > 

 > The only hazard is when the piston is not at  TDC. If this is 

 > the case, the 

 > piston will be forced down with the pressure and the prop will turn. 

 > 

 > Lowell 

 > ---

dave(at)cfisher.com
Guest

Posted: Thu Jun 29, 2006 12:29 pm Post subject: 582 - compression test

Marcos,

  

 Good question and I would say that if you know your  mags ground out then with both mags off you should have no spark to damage the  Ducati igntion. 

  

  

 Dave

 [quote]   ---

rexjan(at)bigpond.com
Guest

Posted: Thu Jun 29, 2006 4:37 pm Post subject: 582 - compression test

I have made about 20 CDI's in my time so I can  enlighten you as to what goes on.  If you don't have that spark gap when  you create a spark you get a very high voltage build up and the solid state  components in the modules might well fail. Then again they may not but it's  certainly not a good idea to temp fate.  When an ignition module fires it  builds up voltage until it is high enough to jump the plug gap and then the  energy is dissipated. With no plug gap to jump the voltage keeps building to a  very high figure. Shorting the plug lead to ground [ the cylinder head or  whatever ] will also stop the build up but may overload the module. The right  idea is to have the plug lead connected to the plug and the body of the plug  grounded. A plug usually fires around 25,000 volts but if the lead is left  floating in mid air the voltage may well go to 100,000 with CDI. [ Capacitor  Discharge Ignition ]

                                                                                                                       Rex Shaw.

noelloveys(at)yahoo.ca
Guest

Posted: Fri Jun 30, 2006 1:27 pm Post subject: 582 - compression test

The diff test is done with the  piston at TDC.  Even in a poor cylinder any air passing the compression  ring would just leak out the exhaust port without pressurizing the crankcase at  all.

  

  

 

Noel [quote]   

   --

noelloveys(at)yahoo.ca
Guest

Posted: Fri Jun 30, 2006 1:42 pm Post subject: 582 - compression test

Don't bother with the "old  fashioned test"  There are too many variables.  Temperature of the  rings... Temperature of the cylinders..... speed the starter can crank the  engine.   Worst lying SOBs I've ever seen!

  

  

 

Noel [quote]   

   --

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