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Cuyuna engine failure

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mark.shimei(at)gmail.com
Guest

Posted: Tue Jun 01, 2010 8:23 am Post subject: Cuyuna engine failure

Im hoping John H  will chime in with a LOT of info,and whoever else has had a  Cuyuna.

  

 I was flying  along,4600rpm,1150EGT,260CHT, 74degree at 1500'.....when it happened........I  have 80+ hours with no problems over the last 15  months.

  

 Got a slow power  reduction,EGT dropped,CHT went down to 200. Engine went to idle but never  quit,landed at airport. Was barely able to taxi back to hangar.Checked for ice  and fuel blockage...none.

  

 Plugs were tan,both  almost the same .Pulled carb off,didnt find anything.

  

 Ran it up on ground  to 6000,seemed to run fine.

  

 Flew it a day  later,only got 5500 instead of the usual 6000 at take off,front cylinder ran  70deg hotter than the rear(they normally run 20-30 difference max at  takeoff),EGT was normal.Landed Ok,now what??

  

 I know there is a  few out there that know ins and outs on keeping this engine running for MANY  hours.

  

 Im up for ANY type  of info/theories

  

 Mark in  Florida

  

  

  

   [quote][b]

by0ung(at)brigham.net
Guest

Posted: Tue Jun 01, 2010 9:25 am Post subject: Cuyuna engine failure

Im hoping John H will chime in with a LOT of info,and whoever else has had a Cuyuna.  

   

I was flying along,4600rpm,1150EGT,260CHT, 74degree at 1500'.....when it happened........I have 80+ hours with no problems over the last 15 months.  

   

Got a slow power reduction,EGT dropped,CHT went down to 200. Engine went to idle but never quit,landed at airport. Was barely able to taxi back to hangar.Checked for ice and fuel blockage...none.  

   

Plugs were tan,both almost the same .Pulled carb off,didnt find anything.  

   

Ran it up on ground to 6000,seemed to run fine.  

   

Flew it a day later,only got 5500 instead of the usual 6000 at take off,front cylinder ran 70deg hotter than the rear(they normally run 20-30 difference max at takeoff),EGT was normal.Landed Ok,now what??  

   

I know there is a few out there that know ins and outs on keeping this engine running for MANY hours.  

   

Im up for ANY type of info/theories  

   

Mark in Florida  

 	  Quote: 	
		  >>>>>>>>>>>>>>>>>>>>>>   

   
	


How long after shutoff did you check for carb ice.   If it were more than a couple minuets.  It may have already melted.    

   

Not sure why lower rpm in next takeoff,    you said egt temps was normal on landing were rpm’s ok ????  

   

Had you drained float bowls before next takeoff?  

   

You said  the temp was 74 deg f  and humidity????  

   

You said front was 70 deg hotter than rear.     Was the front 70 deg hotter than normal???    or was the rear 70 deg colder than normal???   

   

Boyd Young  

MMIII  

       [quote][b]

rlaird

Joined: 10 Jan 2006
Posts: 373
Location: Houston

Posted: Tue Jun 01, 2010 9:42 am Post subject: Cuyuna engine failure

I had similar symptoms with a Rotax 447... After suffering with it for a few

weeks, decided it was a fuel delivery problem (even though all other tests,

as yours, looked okay).  Once I simplified and replaced my fuel lines, the

problem went away.  I also got rid of anything with check valves in it

(except for the Facet).



  -- Robert



On Tue, Jun 1, 2010 at 12:22 PM, b young <by0ung(at)brigham.net> wrote:



[quote]  Im hoping John H will chime in with a LOT of info,and whoever else has

 had a Cuyuna.



 I was flying along,4600rpm,1150EGT,260CHT, 74degree at 1500'.....when it

 happened........I have 80+ hours with no problems over the last 15 months

_________________
~~~~~~~~~~~~~~~~~~~
Robert Laird
formerly: MkIIIc w/ 912ULS & Gyrobee
current: Autogyro Cavalon w/ 914ULS
Houston, TX area
http://www.Texas-Flyer.com

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Tue Jun 01, 2010 10:07 am Post subject: Cuyuna engine failure

Mark/Gang:

  

 If it was me, I'd pull the engine down and insure  the rings are not stuck or trying to stick, and/or a piston was not scored or  scuffed.

  

 Two strokes are experts at suckering us into  believing they are healthy, just prior to seizure.  I have been suckered  several times over the years.

  

 There are many other things that could be your  engines problems.

  

 john h

 [quote]   ---

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

lhaggerty(at)tampabay.rr.
Guest

Posted: Tue Jun 01, 2010 10:43 am Post subject: Cuyuna engine failure

Fuel pump rebuild kit is a goo idea.   Pete

 [quote]   ---

The BaronVonEvil

Joined: 23 Jun 2006
Posts: 76
Location: Walla Walla, WA.

Posted: Tue Jun 01, 2010 1:40 pm Post subject: Cuyuna engine failure

Hi Mark,

  

 The first thing I would check is the compression of  each cylinder. They should be pretty close to the same amount, within 5 to 10  psi of each other. Should the values be beyond those then there is a possibility  of a scored cylinder or stuck or broken rings. 

  

 The rings can be checked by removing the exhaust to  expose the pistons and you can carefully prod/poke each ring with a popsicle  stick to check that they are floating and not stuck. The exhaust side of the  rings are the most vulnerable due to the heat they are exposed to.

  

 If your engine is okay then you start check for  fuel issues and or air leaks/ fuel leaks that could restrict power  output.

  

 Good luck with your engine and please tell us what  you found/ and the solution(s) to your engine problem.

  

 Best Regards,

 Carlos G

 AKA 

 BaronVonEvil.

 [quote]   ---

lcottrell

Joined: 29 May 2006
Posts: 1494
Location: Jordan Valley, Or

Posted: Tue Jun 01, 2010 6:02 pm Post subject: Cuyuna engine failure

I had some of the same problem and found that it was a  brand new squeeze bulb. It would run up on the ground, but pooped out under  load.

 Larry

  

 Note: If you forward this email, please delete the forwarding history,  which includes my email address.

 [quote]   ---

_________________
do not archive

Mrikio

Joined: 02 Nov 2009
Posts: 4

Posted: Tue Jun 01, 2010 8:11 pm Post subject: Re: Cuyuna engine failure

I forgot to add the following:



I pulled the exhaust,pushed on the rings,everything was the same as it was 50 hours ago.Stuck a light in the cylinder,looks great,no scoring or hot spots



Fuel bulb is next,along with compression(how much?)



My cylinder base gasket has been leaking a little,takes a few hours to get some residue around the flange. Dont think  it is an issue,hasnt worsened in 30+hours



It starts with 1-2 pulls,just using the lever choke.That hasn't changed either.

_________________
Mark R
Kolb Modified US Cuyuna UL2 60+hrs
Kolb Twinstar,503,12hrs
Phantom, Kaw 440 250hrs
SE-5A UL 3 hrs
Eipper Quick, Chrysler power Bee 8hrs
PA28-140...350hrs

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Wed Jun 02, 2010 3:15 am Post subject: Cuyuna engine failure

At 12:11 AM 6/2/2010, Mrikio wrote:



 

  	  Quote: 	
		  My cylinder base gasket has been leaking a little,takes a few hours to get some residue around the flange. Dont think  it is an issue,hasnt worsened in 30+hours 	


 That's a big no-no.  ANY air leak in a 2-stroke engine is bad news!  That would explain the hot cylinder, and in the worse case could cause a seizure.  Cuyuna base bolts tend to loosen, and unfortunately the Kolb mount design makes it impossible to get at them.  You need to remove the engine mount bolt (I use straps to keep it more or less in place) and retorque the cylinder base bolts.



 The power loss may be a different issue, though.  It sounds like carb ice, and has happened to me, too, but on another occasion I experienced a similar power loss but quicker.  I never was 100% certain, but I believe it was the carb float needle, allowing the engine to flood (I had also noticed some fuel on the floor of my trailer under the engine, but dismissed it).



 -Dana

 --

      [quote][b]

Mrikio

Joined: 02 Nov 2009
Posts: 4

Posted: Wed Jun 02, 2010 8:31 am Post subject: Re: Cuyuna engine failure

OK........  Think its solved



To answer a previous post the cyl temps were 60-70 deg higher than normal,but not over the limit.I reduced throttle when I heard a power reduction and that dropped the temps more.I know from experience,when an engine stops,or wants to,full throttle will often kill it . A little power has helped me to find a better place to land 3 times so far.



Fuel system checked out fine,from tank pickup to the carb. My system is probably the simplest out there..worked flawlessly on my phantom for 7yrs,200+hrs.



A friend was helping me pull it down the other day,he said he checked the bottom of the bowl....I decided to check it again.  Scraped the bottom of the cap that screws on the bottom of the bowl.....HHHUUMMM   found a piece of dead grass 1/4" long and about .020 in diameter. 



It was curved on the inside edge of the cap,and the same color. I can see why it was missed,when it dislodged,I thought the cap was flaking aluminum. It was hidden VERY well,but this time I dried the bowl out.

I suspect carb ice also,and now that I remember,I reduced the throttle as soon as there was a problem,then tried to advance it to see if it was just loaded up.



Flew it again today(TUES) for 30 min....same normal temps.At cruise,CHTs were 260 .255 EGT was about 1200 or so.



The fix?? the grass must have come up the vent tubes,so I will put a screen over them.(I fly out of grass,some of it gets a little high.)



Also checked the torque on the cyl bolts...they are good.



I thought John H would have a list of things for me to check,since he has a lot of time on them.



Thanks to the list members who helped.....flying again,still working on the GENERAC conversion....

_________________
Mark R
Kolb Modified US Cuyuna UL2 60+hrs
Kolb Twinstar,503,12hrs
Phantom, Kaw 440 250hrs
SE-5A UL 3 hrs
Eipper Quick, Chrysler power Bee 8hrs
PA28-140...350hrs

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Wed Jun 02, 2010 9:21 am Post subject: Cuyuna engine failure

> I thought John H would have a list of things for me to check,since he has 

a lot of time on them.

 	  Quote: 	
		  

 Thanks to the list members who helped.....flying again,still working on 

 the GENERAC conversion....



 --------

 Mark R


	




Mark R/Gang:



Sorry to have disappointed you, although I did respond with what I would 

have done if it was my problem.



Actually, the way I solved all my two stroke problems was to buy my first 

912UL in 1994.



To make the attached photos Kolb related, this is what the average Kolb 

builder/pilot looks like.



john h - 3 weeks into rehab

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_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

Mrikio

Joined: 02 Nov 2009
Posts: 4

Posted: Thu Jun 03, 2010 9:41 am Post subject: Re: Cuyuna engine failure

THAT LOOKS PAINFUL!!!        



GET WELL    



The 912 would be a little much for the Ultrastar  



Thats why Im working on the Generac....

_________________
Mark R
Kolb Modified US Cuyuna UL2 60+hrs
Kolb Twinstar,503,12hrs
Phantom, Kaw 440 250hrs
SE-5A UL 3 hrs
Eipper Quick, Chrysler power Bee 8hrs
PA28-140...350hrs

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