---------------------------------------------------------- RotaxEngines-List Digest Archive --- Total Messages Posted Sun 05/30/10: 14 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:54 AM - 912UL turning backwards on shutdown (Catz631@aol.com) 2. 05:38 AM - Re: 912UL turning backwards on shutdown (dave) 3. 05:41 AM - Re: 912UL turning backwards on shutdown (Dave Fisher) 4. 05:44 AM - Re: 912UL turning backwards on shutdown (Richard Girard) 5. 06:30 AM - Re: 912UL turning backwards on shutdown (dave) 6. 06:36 AM - Re: 912UL turning backwards on shutdown (Roger Lee) 7. 06:41 AM - Re: 912 oil purge proceedure (Roger Lee) 8. 06:48 AM - Re: 912UL turning backwards on shutdown (Noel Loveys) 9. 07:12 AM - Re: 912UL turning backwards on shutdown (Scott DeMeyer) 10. 07:21 AM - Re: Re: 912UL turning backwards on shutdown (Noel Loveys) 11. 10:08 AM - Re: Re: 912UL turning backwards on shutdown (Noel Loveys) 12. 10:23 AM - Re: 912UL turning backwards on shutdown (Noel Loveys) 13. 11:13 AM - Re: 912UL turning backwards on shutdown (rparigoris) 14. 12:02 PM - Re: 912UL turning backwards on shutdown (Roger Lee) ________________________________ Message 1 _____________________________________ Time: 04:54:57 AM PST US From: Catz631@aol.com Subject: RotaxEngines-List: 912UL turning backwards on shutdown Well, my old nemesis is back with a vengeance! Yesterday was a very hot (96degree) , muggy,lousy,typical Florida summer day. So why not go fly. I did and after shutting my engine down it slung itself backwards at least 5-10 engine revolutions (not blades) If I would have turned the mags back on, and the jugs didn't blow I betI I could have backed into my parking spot! Everyone that saw this was amazed. They have never seen an engine do this. It has done this too me before about 5 times but never turned backwards that many revolutions. Now I do realize that I am the ONLY person in the world that has had this problem (verified by calls to tech reps at Lockwood and LEAF) but I would like this to stop. It's beginning to give me the RA (red ass) I only mention this again on this forum to see if some of you gurus agree with me on the procedure I will follow from here. I plan on getting an oil sample today and sending it off for analysis for metal to see if there is any cam damage from collapsed lifters. As I understand it turning the engine backwards could ingest air into the lifters thus causing one or more to collapse thus causing scuffing of the cam lobes (ie:metal) I have performed the valve lifter check after each of these events and at no time in the past have the clearances been greater than 20 thousands which according to the bulletin would indicate air in the lifters. The oil filter has always been free of metal also. After this last event at an outlying field, I restarted the engine, the oil pressure fluctuated a little bit at idle (as it always does since I have had the airplane) normal rpm produced steady oil pressure so I flew the aircraft back home (10 minutes) Today I might do another check for air in the lifters but I am sure if any was there, it is gone due to the 10-15 minutes of flight time home. I believe the major causes of this problem are, old premium fuel (over30 days as I was on vacation) high outside temps and the fixed engine ignition timing is off somewhat. I had added octane booster to the fuel as this has helped in the past but probably not added enough. I have borescopped the engine cylinders and they seem relatively free of carbon (250 hrstt engine) Any ideas? I am running a Warp drive prop. I have even thought of going back to the Kiev prop. It is about a pound lighter than the Warp. It,s momentum would be less than the Warp. Maybe that would do it. Mystery! Thanks, Dick Maddux Kitfox 4 Milton,Fl ________________________________ Message 2 _____________________________________ Time: 05:38:29 AM PST US Subject: RotaxEngines-List: Re: 912UL turning backwards on shutdown From: "dave" Dick, Are you using avgas or auto premium ? Sounds like pre ignition-- since you likley do not have a mixtue cut off try shutting off the fuel vakve at shut down. 912 UL will run fine on auto regular 87 grade --with or without ethanol. Acutally you might want to run a tank of ethanol regular gas through it and see if that helps. Although many armchair captains will say bal bla bla about ethanol Rtoax does infact recoment the use of it up to 10%. Also who says that premium is always premium gas at the pumps. I VERY rarely use premium if ever on Rotax 2 stroke and 912 UL . 912 S yes preium auto fuel only. NO avgas. Just in from 1.5 flight on ethanol gas -- I am over 1000 hours onethanl gas no personally without a gitch so far. :) -------- Rotax Dealer, Ontario Canada http://www.cfisher.com/ Awesome *New Forum * http://rotaxaircraft.com/forum/ Realtime Kitfox movies to separate the internet chatter from the truth http://www.youtube.com/profile_videos?user=kitfoxflyer Read this topic online here: http://forums.matronics.com/viewtopic.php?p=299344#299344 ________________________________ Message 3 _____________________________________ Time: 05:41:03 AM PST US From: "Dave Fisher" Subject: Re: RotaxEngines-List: 912UL turning backwards on shutdown Dick, Are you using avgas or auto premium ? Sounds like pre ignition-- since you likley do not have a mixtue cut off try shutting off the fuel vakve at shut down. 912 UL will run fine on auto regular 87 grade --with or without ethanol. Acutally you might want to run a tank of ethanol regular gas through it and see if that helps. Although many armchair captains will say bal bla bla about ethanol Rtoax does infact recoment the use of it up to 10%. Also who says that premium is always premium gas at the pumps. I VERY rarely use premium if ever on Rotax 2 stroke and 912 UL . 912 S yes preium auto fuel only. NO avgas. Just in from 1.5 flight on ethanol gas -- I am over 1000 hours onethanl gas no personally without a gitch so far. :) ----- Original Message ----- From: Catz631@aol.com To: rotaxengines-list@matronics.com Sent: Sunday, May 30, 2010 7:54 AM Subject: RotaxEngines-List: 912UL turning backwards on shutdown Well, my old nemesis is back with a vengeance! Yesterday was a very hot (96degree) , muggy,lousy,typical Florida summer day. So why not go fly. I did and after shutting my engine down it slung itself backwards at least 5-10 engine revolutions (not blades) If I would have turned the mags back on, and the jugs didn't blow I betI I could have backed into my parking spot! Everyone that saw this was amazed. They have never seen an engine do this. It has done this too me before about 5 times but never turned backwards that many revolutions. Now I do realize that I am the ONLY person in the world that has had this problem (verified by calls to tech reps at Lockwood and LEAF) but I would like this to stop. It's beginning to give me the RA (red ass) I only mention this again on this forum to see if some of you gurus agree with me on the procedure I will follow from here. I plan on getting an oil sample today and sending it off for analysis for metal to see if there is any cam damage from collapsed lifters. As I understand it turning the engine backwards could ingest air into the lifters thus causing one or more to collapse thus causing scuffing of the cam lobes (ie:metal) I have performed the valve lifter check after each of these events and at no time in the past have the clearances been greater than 20 thousands which according to the bulletin would indicate air in the lifters. The oil filter has always been free of metal also. After this last event at an outlying field, I restarted the engine, the oil pressure fluctuated a little bit at idle (as it always does since I have had the airplane) normal rpm produced steady oil pressure so I flew the aircraft back home (10 minutes) Today I might do another check for air in the lifters but I am sure if any was there, it is gone due to the 10-15 minutes of flight time home. I believe the major causes of this problem are, old premium fuel (over30 days as I was on vacation) high outside temps and the fixed engine ignition timing is off somewhat. I had added octane booster to the fuel as this has helped in the past but probably not added enough. I have borescopped the engine cylinders and they seem relatively free of carbon (250 hrstt engine) Any ideas? I am running a Warp drive prop. I have even thought of going back to the Kiev prop. It is about a pound lighter than the Warp. It,s momentum would be less than the Warp. Maybe that would do it. Mystery! Thanks, Dick Maddux Kitfox 4 Milton,Fl ________________________________ Message 4 _____________________________________ Time: 05:44:45 AM PST US Subject: Re: RotaxEngines-List: 912UL turning backwards on shutdown From: Richard Girard Dick, Try dropping your idle speed so that you have to set it manually. That way you can be sure the throttle is completely closed when you shut off the mags. Check for fuel leaking into the engine through the starting carburetor, too. For the weather you're having you might want to try one range colder spark plug, also. Have you looked into the combustion chamber with a bore scope to make sure there isn't any sort of carbon build up that could cause detonation? Be sure and burp your engine after one of these run on events. VW's (the old air cooled models) started doing this when they were leaned out for emissions control in the late 60's. It was solved by putting a solenoid and plunger over the main jet that choked off the fuel supply completely. When the solenoid failed ("Volkswagen does it again" was their advertising slogan at the time) you just let the clutch out with the tranny engaged so the engine didn't run on. Of course you don't have that option. :-} Rick Girard On Sun, May 30, 2010 at 6:54 AM, wrote: > Well, my old nemesis is back with a vengeance! Yesterday was a very hot > (96degree) , muggy,lousy,typical Florida summer day. So why not go fly. I > did and after shutting my engine down it slung itself backwards at least > 5-10 engine revolutions (not blades) If I would have turned the mags back > on, and the jugs didn't blow I betI I could have backed into my parking > spot! Everyone that saw this was amazed. They have never seen an engine do > this. It has done this too me before about 5 times but never turned > backwards that many revolutions. > Now I do realize that I am the ONLY person in the world that has had this > problem (verified by calls to tech reps at Lockwood and LEAF) but I would > like this to stop. It's beginning to give me the RA (red ass) > I only mention this again on this forum to see if some of you gurus agree > with me on the procedure I will follow from here. I plan on getting an oil > sample today and sending it off for analysis for metal to see if there is > any cam damage from collapsed lifters. As I understand it turning the engine > backwards could ingest air into the lifters thus causing one or more to > collapse thus causing scuffing of the cam lobes (ie:metal) > I have performed the valve lifter check after each of these events and at > no time in the past have the clearances been greater than 20 thousands which > according to the bulletin would indicate air in the lifters. The oil filter > has always been free of metal also. > After this last event at an outlying field, I restarted the engine, the > oil pressure fluctuated a little bit at idle (as it always does since I have > had the airplane) normal rpm produced steady oil pressure so I flew the > aircraft back home (10 minutes) Today I might do another check for air in > the lifters but I am sure if any was there, it is gone due to the 10-15 > minutes of flight time home. > I believe the major causes of this problem are, old premium fuel (over30 > days as I was on vacation) high outside temps and the fixed engine ignition > timing is off somewhat. I had added octane booster to the fuel as this has > helped in the past but probably not added enough. > I have borescopped the engine cylinders and they seem relatively free of > carbon (250 hrstt engine) > Any ideas? > I am running a Warp drive prop. I have even thought of going back to the > Kiev prop. It is about a pound lighter than the Warp. It,s momentum would be > less than the Warp. Maybe that would do it. Mystery! > Thanks, > Dick Maddux > Kitfox 4 > Milton,Fl > > * > > * > > ________________________________ Message 5 _____________________________________ Time: 06:30:48 AM PST US Subject: RotaxEngines-List: Re: 912UL turning backwards on shutdown From: "dave" dropping idle speed sounds good but will add to gear box wear dramatically. Most carburated auto added the solenoid in the 70s as they were higher compression engines . -------- Rotax Dealer, Ontario Canada http://www.cfisher.com/ Awesome *New Forum * http://rotaxaircraft.com/forum/ Realtime Kitfox movies to separate the internet chatter from the truth http://www.youtube.com/profile_videos?user=kitfoxflyer Read this topic online here: http://forums.matronics.com/viewtopic.php?p=299354#299354 ________________________________ Message 6 _____________________________________ Time: 06:36:22 AM PST US Subject: RotaxEngines-List: Re: 912UL turning backwards on shutdown From: "Roger Lee" Hi Dick, Sorry to hear your having this problem. I think I would be getting a little on the RA side too. If you know the carbs are balanced and the idle is set to 1700-1800 rpm then I would dump your fuel (all of it) and try some 100LL and see if that makes a difference. It really could be old fuel and a badly reduced octane number. My first guess if the idle and carb balance is good is a fuel issue. After you try a normal shut down with 100LL, which I hope works, then try shutting off one mag for 10-15 seconds then turn the last one off, but use the 100LL first to see if it makes any difference. -------- Roger Lee Tucson, Az. Light Sport Repairman - Maintenance Rated Rotax Repair Center 520-574-1080 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=299356#299356 ________________________________ Message 7 _____________________________________ Time: 06:41:52 AM PST US Subject: RotaxEngines-List: Re: 912 oil purge proceedure From: "Roger Lee" Hi Ross, Most of the time when people are having oil pressure issues it is the oil pressure sending unit or a bad ground. It usually is not really an engine oil pressure problem. That's why I advise most people to put a mechanical gauge in line and double check the real pressure and it will usually tell you right away what the problem is. Glad it worked out. -------- Roger Lee Tucson, Az. Light Sport Repairman - Maintenance Rated Rotax Repair Center 520-574-1080 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=299358#299358 ________________________________ Message 8 _____________________________________ Time: 06:48:42 AM PST US From: "Noel Loveys" Subject: RE: RotaxEngines-List: 912UL turning backwards on shutdown Dick: Perhaps the thing to do is to shut off your fuel and starve the engine. Similar to what they do with certified engines. It may take a few minutes to refill the float bowl to restart though. In the meantime it sure sounds to me like your engine is running a bit too hot while taxiing and when you cut the ignition head temps cause pre-ignition... enough to spin the engine backward. Perhaps a minute or so at a fast idle before shutting down the engine will help. Noel From: owner-rotaxengines-list-server@matronics.com [mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of Catz631@aol.com Sent: May 30, 2010 9:24 AM Subject: RotaxEngines-List: 912UL turning backwards on shutdown Well, my old nemesis is back with a vengeance! Yesterday was a very hot (96degree) , muggy,lousy,typical Florida summer day. So why not go fly. I did and after shutting my engine down it slung itself backwards at least 5-10 engine revolutions (not blades) If I would have turned the mags back on, and the jugs didn't blow I betI I could have backed into my parking spot! Everyone that saw this was amazed. They have never seen an engine do this. It has done this too me before about 5 times but never turned backwards that many revolutions. Now I do realize that I am the ONLY person in the world that has had this problem (verified by calls to tech reps at Lockwood and LEAF) but I would like this to stop. It's beginning to give me the RA (red ass) I only mention this again on this forum to see if some of you gurus agree with me on the procedure I will follow from here. I plan on getting an oil sample today and sending it off for analysis for metal to see if there is any cam damage from collapsed lifters. As I understand it turning the engine backwards could ingest air into the lifters thus causing one or more to collapse thus causing scuffing of the cam lobes (ie:metal) I have performed the valve lifter check after each of these events and at no time in the past have the clearances been greater than 20 thousands which according to the bulletin would indicate air in the lifters. The oil filter has always been free of metal also. After this last event at an outlying field, I restarted the engine, the oil pressure fluctuated a little bit at idle (as it always does since I have had the airplane) normal rpm produced steady oil pressure so I flew the aircraft back home (10 minutes) Today I might do another check for air in the lifters but I am sure if any was there, it is gone due to the 10-15 minutes of flight time home. I believe the major causes of this problem are, old premium fuel (over30 days as I was on vacation) high outside temps and the fixed engine ignition timing is off somewhat. I had added octane booster to the fuel as this has helped in the past but probably not added enough. I have borescopped the engine cylinders and they seem relatively free of carbon (250 hrstt engine) Any ideas? I am running a Warp drive prop. I have even thought of going back to the Kiev prop. It is about a pound lighter than the Warp. It,s momentum would be less than the Warp. Maybe that would do it. Mystery! Thanks, Dick Maddux Kitfox 4 Milton,Fl ________________________________ Message 9 _____________________________________ Time: 07:12:37 AM PST US From: Scott DeMeyer Subject: RE: RotaxEngines-List: 912UL turning backwards on shutdown I would not do this. A while back I had a P lead break and the only way to shut down was to turn the fuel off. After five minutes one carb ran out of gas before the other and it REALLY ran bad for another minute until the oth er carb ran out of fuel. The motor shook so bad I was worried about it rema ining attached to the mount. In fact, shortly after that is when I found a large crack in my engine mount. Scott --- On Sun, 5/30/10, Noel Loveys wrote: From: Noel Loveys Subject: RE: RotaxEngines-List: 912UL turning backwards on shutdown =0A=0A=0A =0A =0A=0A=0A=0A=0A=0A=0ADick: =0A=0A - =0A=0APerhaps the thing to do is to=0Ashut off your fuel and starve the engine.- Similar to what they do with=0Acertified engines.- It may take a few minutes to refill t he float bowl to=0Arestart though. =0A=0A - =0A=0AIn the meantime it sure =0Asounds to me like your engine is running a bit too hot while taxiing and when=0Ayou cut the ignition head temps cause pre-ignition... enough to spi n the engine=0Abackward.- Perhaps a minute or so at a fast idle before sh utting down the=0Aengine will help. =0A=0A - =0A=0ANoel =0A=0A - =0A=0A =0A=0A=0A=0AFrom:=0Aowner-rotaxengines-list-server@matronics.com=0A[mailto: owner-rotaxengines-list-server@matronics.com] On Behalf Of Catz631@aol.com =0ASent: May 30, 2010 9:24 AM =0ATo: rotaxengines-list@matronics.com =0ASubject: RotaxEngines-List: 912UL turning backwards on shutdown =0A=0A =0A=0A=0A=0A - =0A=0A=0A=0AWell,=0Amy old nemesis is back with a vengeanc e! Yesterday was a very hot=0A(96degree)-, muggy,lousy,typical Florida su mmer day. So why not go fly. I=0Adid and after shutting my engine down it s lung itself backwards at least 5-10=0Aengine revolutions (not blades) If I would have turned the mags back on, and=0Athe jugs didn't blow I betI I-c ould have backed into my parking spot!=0AEveryone that saw this was amazed. They have never seen an engine do this. It=0Ahas done this too me before a bout 5 times but never-turned backwards that=0Amany revolutions. =0A=0A =0A=0A=0A=0A-Now=0AI do realize that I am the ONLY person in the world th at has had this problem=0A(verified by calls to tech reps at Lockwood and L EAF) but I would like this to=0Astop. It's beginning to give me the RA (red ass) =0A=0A=0A=0A=0A=0A-I=0Aonly mention this again on this forum to see if some of you gurus agree with me=0Aon the procedure I will follow from h ere. I plan on getting an oil sample=0Atoday-and sending it off for analy sis for metal-to see if there is=0Aany cam damage from collapsed lifters. As-I understand it turning the=0Aengine backwards could ingest air into the lifters thus causing one or more to=0Acollapse thus causing scuffing of the cam lobes (ie:metal) =0A=0A=0A=0A=0A=0A-I=0Ahave performed the valv e lifter check after each of these events and at no time=0Ain the past-ha ve the clearances been greater than 20 thousands which=0Aaccording to the b ulletin would indicate air in the lifters. The oil filter has=0Aalways been free of metal also. =0A=0A=0A=0A=0A=0A-After=0Athis last event at an out lying field, I restarted the engine, the oil pressure=0Afluctuated a little bit at idle (as it always does since I have had the=0Aairplane) normal rpm produced steady oil pressure so I flew the aircraft back=0Ahome (10 minute s) Today I might do another check for air in the lifters but I=0Aam sure if any was there, it is gone-due to the 10-15 minutes of flight=0Atime home . =0A=0A=0A=0A=0A=0A-I=0Abelieve--the major causes of this problem ar e, old premium fuel=0A(over30 days as I was on vacation) high outside temps and the fixed engine=0Aignition timing is off somewhat. I had added octane booster to the fuel as this=0Ahas helped in the past but probably not adde d-enough. =0A=0A=0A=0A=0A=0A-I=0Ahave borescopped the engine cylinders and they seem relatively free of carbon=0A(250 hrstt engine) =0A=0A=0A=0A =0A=0A-=0AAny ideas? =0A=0A=0A=0A=0A=0A-I=0Aam running a Warp drive pro p. I have even thought of going back to the Kiev=0Aprop. It is about a poun d lighter than the Warp. It,s momentum would be less=0Athan the Warp. Maybe that would do it. Mystery! =0A=0A=0A=0A=0A=0A--------- ------------------------- =0AThanks, =0A=0A=0A=0A=0A=0A--------------- ------------------------- -----=0ADick Maddux =0A=0A=0A=0A=0A=0A--------- ------------------------- -----------=0AKitfox 4 =0A=0A=0A=0A=0A=0A---- ------------------------- ----------------=0AMilton,Fl =0A=0A=0A=0A - -http://www.matronics.com/Navigator?RotaxEngines-Listhttp://forums.ma tronics.comhttp://www.matronics.com/contribution - =0A=0A=0A=0A=0A=0A=0A =0A ________________________________ Message 10 ____________________________________ Time: 07:21:49 AM PST US From: "Noel Loveys" Subject: RE: RotaxEngines-List: Re: 912UL turning backwards on shutdown Check again... I think Rotax actually ALLOWS the use of up to 10% eth. That's a stretch from recommending its use. Ethanol has a RON of 116 and will actually increase the RON of just about any gas available today. That is if you have a source of fresh 99.99% eth to add to your gas. Ethanol will also absorb moisture right out of the air and because it is already in the fuel that's the wrong place for moisture to be. There are several other reasons why I don't like ethanol in fuel and I've gone over those countless times. What Dave says about, is premium actually premium, is a good question. I don't know anyone who has the equipment to do accurate flash testing. I do know that a few years ago the Newfoundland Constabulary was having problems with a factory built hotrod they called a police car. Technicians were sent from GM to find out what was causing the backfiring... after two weeks of building and rebuilding the engine the test results from GM's own lab came back that the fuel was a very low octane... low even for regular fuel. The Constab. then tested all the premium gas sold in the area and found over 50 pumps only one actually had premium fuel in it. Letters went out to all the oil companies and the result of that was one oil company returned a letter saying they would no longer conduct flash tests for the Constabulary. The answer to your problem may be as easy as changing where you buy your gas. If you want to foot the $50 or so bill to have a flash test done on your fuel you may find in fact your supplier is in fact cheating you. If this happens be sure to inform the authorities about what is going on. After all that is fraud. Always buy the freshest gas you can get. Large busy stations have more turn over in fuel so generally have fresher fuel in their tanks. With ethanol, if you must use it, don't let it sit in your plane's tanks for any longer than a day or two. In that time ethanol can evaporate and what doesn't evaporate will absorb some moisture (water) right out of the air. If you have to store ethanol fuel longer than that, store it in a sealed container not in the plane's tanks. Noel -----Original Message----- From: owner-rotaxengines-list-server@matronics.com [mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of dave Sent: May 30, 2010 10:08 AM Subject: RotaxEngines-List: Re: 912UL turning backwards on shutdown Dick, Are you using avgas or auto premium ? Sounds like pre ignition-- since you likley do not have a mixtue cut off try shutting off the fuel vakve at shut down. 912 UL will run fine on auto regular 87 grade --with or without ethanol. Acutally you might want to run a tank of ethanol regular gas through it and see if that helps. Although many armchair captains will say bal bla bla about ethanol Rtoax does infact recoment the use of it up to 10%. Also who says that premium is always premium gas at the pumps. I VERY rarely use premium if ever on Rotax 2 stroke and 912 UL . 912 S yes preium auto fuel only. NO avgas. Just in from 1.5 flight on ethanol gas -- I am over 1000 hours onethanl gas no personally without a gitch so far. :) -------- Rotax Dealer, Ontario Canada http://www.cfisher.com/ Awesome *New Forum * http://rotaxaircraft.com/forum/ Realtime Kitfox movies to separate the internet chatter from the truth http://www.youtube.com/profile_videos?user=kitfoxflyer Read this topic online here: http://forums.matronics.com/viewtopic.php?p=299344#299344 ________________________________ Message 11 ____________________________________ Time: 10:08:42 AM PST US From: "Noel Loveys" Subject: RE: RotaxEngines-List: Re: 912UL turning backwards on shutdown I agree with Dave on this one... AVGAS should only be used as a last alternative and if you really have to use AVGAS then get some lead scavenger to put in it. The idea of having a look with a borescope has lots of merit! Noel -----Original Message----- From: owner-rotaxengines-list-server@matronics.com [mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of Roger Lee Sent: May 30, 2010 11:06 AM Subject: RotaxEngines-List: Re: 912UL turning backwards on shutdown Hi Dick, Sorry to hear your having this problem. I think I would be getting a little on the RA side too. If you know the carbs are balanced and the idle is set to 1700-1800 rpm then I would dump your fuel (all of it) and try some 100LL and see if that makes a difference. It really could be old fuel and a badly reduced octane number. My first guess if the idle and carb balance is good is a fuel issue. After you try a normal shut down with 100LL, which I hope works, then try shutting off one mag for 10-15 seconds then turn the last one off, but use the 100LL first to see if it makes any difference. -------- Roger Lee Tucson, Az. Light Sport Repairman - Maintenance Rated Rotax Repair Center 520-574-1080 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=299356#299356 ________________________________ Message 12 ____________________________________ Time: 10:23:41 AM PST US From: "Noel Loveys" Subject: RE: RotaxEngines-List: 912UL turning backwards on shutdown I never thought about one side running longer than the other side. That pretty well puts paid to the idea of starving the engine. Pulling the enricheners just before shutdown would probably flood the engine but may stop the dieseling by cooling down the combustion chamber. I suspect in warm weather you may have to go to a higher octane fuel to prevent the detonation. The idea of resetting the throttle so you will have a shutdown position sounds ok if and only if you never use that position to idle the engine. I had my idle on my 582 set to around 600 rpm. But I never idled the engine at that speed. The only time I actually pulled the throttle all the way out was when landing. As soon as I was on the water I would increase the throttle to around 1500 or even 2000 wherever the engine ran smoothest. I still think the first thing I would do is buy my gas at a different station..... and probably try high octane gas that flashes at a higher temperature. Noel From: owner-rotaxengines-list-server@matronics.com [mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of Scott DeMeyer Sent: May 30, 2010 11:42 AM Subject: RE: RotaxEngines-List: 912UL turning backwards on shutdown I would not do this. A while back I had a P lead break and the only way to shut down was to turn the fuel off. After five minutes one carb ran out of gas before the other and it REALLY ran bad for another minute until the other carb ran out of fuel. The motor shook so bad I was worried about it remaining attached to the mount. In fact, shortly after that is when I found a large crack in my engine mount. Scott --- On Sun, 5/30/10, Noel Loveys wrote: From: Noel Loveys Subject: RE: RotaxEngines-List: 912UL turning backwards on shutdown Dick: Perhaps the thing to do is to shut off your fuel and starve the engine. Similar to what they do with certified engines. It may take a few minutes to refill the float bowl to restart though. In the meantime it sure sounds to me like your engine is running a bit too hot while taxiing and when you cut the ignition head temps cause pre-ignition... enough to spin the engine backward. Perhaps a minute or so at a fast idle before shutting down the engine will help. Noel From: owner-rotaxengines-list-server@matronics.com [mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of Catz631@aol.com Sent: May 30, 2010 9:24 AM Subject: RotaxEngines-List: 912UL turning backwards on shutdown Well, my old nemesis is back with a vengeance! Yesterday was a very hot (96degree) , muggy,lousy,typical Florida summer day. So why not go fly. I did and after shutting my engine down it slung itself backwards at least 5-10 engine revolutions (not blades) If I would have turned the mags back on, and the jugs didn't blow I betI I could have backed into my parking spot! Everyone that saw this was amazed. They have never seen an engine do this. It has done this too me before about 5 times but never turned backwards that many revolutions. Now I do realize that I am the ONLY person in the world that has had this problem (verified by calls to tech reps at Lockwood and LEAF) but I would like this to stop. It's beginning to give me the RA (red ass) I only mention this again on this forum to see if some of you gurus agree with me on the procedure I will follow from here. I plan on getting an oil sample today and sending it off for analysis for metal to see if there is any cam damage from collapsed lifters. As I understand it turning the engine backwards could ingest air into the lifters thus causing one or more to collapse thus causing scuffing of the cam lobes (ie:metal) I have performed the valve lifter check after each of these events and at no time in the past have the clearances been greater than 20 thousands which according to the bulletin would indicate air in the lifters. The oil filter has always been free of metal also. After this last event at an outlying field, I restarted the engine, the oil pressure fluctuated a little bit at idle (as it always does since I have had the airplane) normal rpm produced steady oil pressure so I flew the aircraft back home (10 minutes) Today I might do another check for air in the lifters but I am sure if any was there, it is gone due to the 10-15 minutes of flight time home. I believe the major causes of this problem are, old premium fuel (over30 days as I was on vacation) high outside temps and the fixed engine ignition timing is off somewhat. I had added octane booster to the fuel as this has helped in the past but probably not added enough. I have borescopped the engine cylinders and they seem relatively free of carbon (250 hrstt engine) Any ideas? I am running a Warp drive prop. I have even thought of going back to the Kiev prop. It is about a pound lighter than the Warp. It,s momentum would be less than the Warp. Maybe that would do it. Mystery! Thanks, Dick Maddux Kitfox 4 Milton,Fl http://www.matronics.com/Navigator?RotaxEngines-List http://forums.matronics.com http://www.matronics.com/contribution http://www.matronics.com/Navigator?RotaxEngines-List http://www.matronics.com/Navigator?RotaxEngines-List http://www.matronics.com/contribution ________________________________ Message 13 ____________________________________ Time: 11:13:00 AM PST US Subject: RotaxEngines-List: Re: 912UL turning backwards on shutdown From: "rparigoris" Hi Dick I had a 1972 Yamaha RT-2 360 single cylinder 2 stroke. Often after a highway ride in hot temps upon shut down it would give a pop and turn backwards. Easy on a bike to deal with, i would just put in gear and stall by letting out clutch. Once after a highway ride on a hot day decided to take a compression test, boy the compression gage didn't like the cylinder firing with full throttle at all! What must have happened is there was a glowing piece of carbon that fired the fuel air mixture. Anyway with your problem: **Give a try engaging the enriching circuit for a little bit before shut down to help cool things off, try both ways, shutting down with enrichment rich, and also after attempt to cool things a bit with enrichment lean **I have heard that high temps of ignition boxes causes inability to shut down engine. Circuit fails with heat but when cooled down begins to work again. With such a wishy washy thing I would imagine you could get it to intermittent fire which is perhaps your problem? Anyway to add a bit of extra cooling to ignition modules? **OK here we go, I think cooling the cylinder heads, pistons and ignition modules before shut down is in order to test. Before shut down point into wind, richen with choke and try 2750 or 3000 rpms for 15 or 20 seconds, idle with choke for 5 or 10 seconds and shut down. Try same but at idle turn off choke. Other stuff: **Too lean is no good upon shutting down if a glowing piece of carbon is your culprit, did you adjust idle mixture? If not give it a go on a hot day, perhaps go just a tad bit richer. **If glowing carbon is problem, give the plane a decarbonization. Best way of course is to pull jugs, but on my 914 I will use water. If you ever had a look at a automobile engine that has a water leak, ain't very hard to find the leak, the cylinder and head is scrubbed clean! I have owned a number of Volvo turbo station wagons, the 1983 with aircooled Garette turbo very similar to 914 turbo. After a gazillion miles they would tend to ping even with high test fuel. No problem, pick a hot summer day, go up a 1 mile not too far from my home hill with full throttle, quick pull over on side street and pour a quart of distilled water through a nipple on manifold. I add water fast enough to begin to kill motor, but increase throttle. I do this till I am about 1/4 throttle and use water injection to keep RPMs ~3,000. I will do this 3 times, first with water, second time with a can of Seafoam (get at most auto parts stores) and third time with water. I only use distilled water. Been doing that since 1983. With Rotax my idea was to try injection in manifold pressure input between cylinders on cross tube. Run a tube back to a safe distance, could probably use a super soaker for water, oil can for Seafoam. **Another thought, Rotax is adamant you use Whacker thermal conductive compound on spark plug threads. I spoke with research guy who tested various compounds and said Whacker is hands down winner. Best use that (I am). I remember filling my brothers Jawa motorcycle carb with model aeroplane fuel, it started and began to scream (way too lean because such a high alcohol content) and when he hit kill switch, nothing, it kept on running till he put in gear and stalled. **Is spark plugs very full of carbon to have a glowing ember and act like a glow plug? **Are spark plugs proper heat range? This is critical. **True that the slower the idle is below 1800RPM the more loading of gearbox. I think I read there is 10 times more loading at idle compared to 5,000 rpm. Having carbs balanced (and mixture adjusted) helps. With a Europa if you have idle set at 1800RPM on ground, you will have a hard time landing any sort of short. Best have idle on ground (stopped) able to get to 1450 (or 1400 even), this way you can land shorter, remember when flying air flowing over prop will increase RPM. Anyway just use throttle to keep 1800 or over on ground, but in your case lowering for shut down will be a good thing. Another thought is when you are doing 2750 or 3000 rpm choke cooling, give a mag check. See if one is either not shutting down or giving a misfire. At this RPM I doubt glowing carbon would cause this. A miss may be overheated or failing ignition module. If you suspect ignition modules, perhaps if easy have someone spray with water mist to cool before shut down and see if that helps. Wait a second, perhaps I remember you have a primer? If you do use that to help cool motor before shut down. Good luck Ron Parigoris Read this topic online here: http://forums.matronics.com/viewtopic.php?p=299382#299382 ________________________________ Message 14 ____________________________________ Time: 12:02:31 PM PST US Subject: RotaxEngines-List: Re: 912UL turning backwards on shutdown From: "Roger Lee" Hi Dick, Are the carbs balanced? The temporary use of 100LL is to determine if it is a poor fuel or Octane issue. Running a few gallons of 100LL will tell you that fairly quickly. If your problem goes away then you know it is nothing else. The 100LL is the easiest and cheapest up front test. Drain the fuel and put in 5 gal. of 100LL and go fly again. If it still happens then don't chase the fuel issue again and look at other things. You need to rule out one issue at a time to make sure you find the problem. This may also be a gearbox issue in part. Does your 912 have an overload clutch and how many hours? I need to do a little more checking, but do the other test first. -------- Roger Lee Tucson, Az. 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