---------------------------------------------------------- RotaxEngines-List Digest Archive --- Total Messages Posted Mon 01/04/10: 9 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:17 AM - Re: Re: Rotax 914 Won't Start (FLYaDIVE) 2. 09:10 AM - Re: Re: Rotax 914 Won't Start (Richard Girard) 3. 10:30 AM - Re: Rotax 914 Won't Start (rampil) 4. 11:11 AM - What happens if you overspeed a 91X? (rparigor@suffolk.lib.ny.us) 5. 11:47 AM - Re: What happens if you overspeed a 91X? (Bob Comperini) 6. 03:54 PM - Re: Re: Rotax 914 Won't Start (FLYaDIVE) 7. 05:19 PM - Re: What happens if you overspeed a 91X? (rampil) 8. 05:27 PM - Re: Re: Rotax 914 Won't Start (Graham Singleton) 9. 06:45 PM - Re: Re: Rotax 914 Won't Start (Richard Girard) ________________________________ Message 1 _____________________________________ Time: 08:17:45 AM PST US Subject: Re: RotaxEngines-List: Re: Rotax 914 Won't Start From: FLYaDIVE Hi Rick: HAPPY NEW YEAR! The procedure is standard for horizontally opposed combustion engines. It is what is being used for both Continental & Lycomming engines. When having a prop balanced it is the first thing checked. I am taking a course on vibration and prop balancing and Chadwick Helmuth and ACES both cover balancing this way. This is done to reduce the amount of balance weight required. Yes, you can balance without doing a static balance but this just helps. It is like balancing tires. Ever see a car with a huge amount of weight required to balance a tire? More than likely they did not place the heavy spot of the tire across from the valve stem. Barry On Thu, Dec 31, 2009 at 10:12 PM, Richard Girard wrote: > Barry, Where did you get this procedure? It's not in any Rotax manual. > > Rick Girard > > On Thu, Dec 31, 2009 at 4:05 PM, FLYaDIVE wrote: > >> Rich: >> >> I asked the same question. The procedure is the same as for direct >> drives. Why you may ask? >> Because the prop has more an effect as the FLYWHEEL having a much larger >> diameter than the gears. >> The procedure is this: >> 1 - Take all safety precautions. >> 2 - Put the prop on with only a few bolts >> 3 - Remove the #1 Cyl Spark Plug. >> 4 - Rotate the prop so #1 piston is TDC on compression stroke. >> 5 - The prop #1 Blade ... Should be at the 1 O'clock position - LQQKing at >> it from the front of the engine. >> 6 - Position and reassemble as required. >> >> Barry >> On Thu, Dec 31, 2009 at 3:54 PM, Richard Girard wrote: >> >>> Barry, Rotax engines run a gearbox of either 2.27 or 2.43 ratio. How >>> exactly are you going to CLOCK it? >>> >>> Rick Girard >>> >>> On Thu, Dec 31, 2009 at 2:32 PM, FLYaDIVE wrote: >>> >>>> Gilles is right 100%! >>>> >>>> You should NEVER run an engine without some form of flywheel. A prop IS >>>> a flywheel. And if your friend ran an engine without a flywheel and is >>>> alive to talk about it he is either lucky or a liar. >>>> An engine run without a flywheel or the proper size flywheel can JUMP >>>> into a RUNAWAY condition and reach RPM's so high the engine will literally >>>> tear itself apart / explode. >>>> >>>> Another question to throw into the pot: Is the prop properly CLOCKED? >>>> If it is not in the correct position you will get rough running and >>>> vibration. >>>> >>>> Barry >>>> >>>> On Thu, Dec 31, 2009 at 2:51 PM, AmphibFlyer < >>>> SeaRey@abstractconcreteworks.com> wrote: >>>> >>>>> >>>>> >>>>> >>>>> Gilles.Thesee(at)ac-greno wrote: >>>>> > Rotax engines have NO flywheel... Running a Rotax without a prop is a >>>>> no-no. >>>>> >>>>> >>>>> Well, you're right, mostly. I shouldn't have said that they do. On the >>>>> other hand, the Heavy Maintenance Manual discusses "flywheel hub" in several >>>>> places (July 01/2008, 74-00-00, page 49, page 117, and page 25). It doesn't >>>>> seem to show a clear diagram of an actual flywheel, though. >>>>> >>>>> Also I should confess that I have never tried to run a 914 without a >>>>> prop and relied on someone else's testimony, which I can't verify right now. >>>>> So maybe it can be done and maybe it can't. >>>>> >>>>> >>>>> >>>>> >>>>> Read this topic online here: >>>>> >>>>> http://forums.matronics.com/viewtopic.php?p=279458#279458 >>>>> >>>>> >>>>> >>>>> >>>>> Attachments: >>>>> >>>>> http://forums.matronics.com//files/scr====== >>>>> >>>>> he Contribution link below to find out more about >>>>> lder's Bookstore >>>>> >>>>> www.buildersbooks.com >>>>> >>>>> href="http://www.howtocrimp.com/" target="_blank">www.howtocrimp.comiption, >>>>> www.matronics.com/Navigator?RotaxEngines-List" target="_blank"> >>>>> http://www.matronics.com/Navigator?RotaxEngines-List >>>>> ronics.com/" target="_blank">http://forums.matronics.com >>>>> ============= >>>>> >>>>> >>>>> >>>>> >>>> * >>>> >>>> _blank">www.aeroelectric.com >>>> >>>> .com" target="_blank">www.buildersbooks.com >>>> >>>> ="_blank">www.homebuilthelp.com >>>> >>>> nk">www.howtocrimp.com >>>> _blank">http://www.matronics.com/contribution >>>> >>>> ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List >>>> >>>> tp://forums.matronics.com >>>> * >>>> >>>> >>> * >>> >>> >>> "_blank">www.aeroelectric.com >>> .com/" target="_blank">www.buildersbooks.com >>> ="_blank">www.homebuilthelp.com >>> >>> ank">www.howtocrimp.com >>> >>> _blank">http://www.matronics.com/contribution >>> >>> ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List >>> >>> ttp://forums.matronics.com >>> * >>> >>> >> * >> >> _blank">www.aeroelectric.com >> .com" target="_blank">www.buildersbooks.com >> ="_blank">www.homebuilthelp.com >> nk">www.howtocrimp.com >> _blank">http://www.matronics.com/contribution >> ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List >> tp://forums.matronics.com >> * >> >> > * > > * > > ________________________________ Message 2 _____________________________________ Time: 09:10:41 AM PST US Subject: Re: RotaxEngines-List: Re: Rotax 914 Won't Start From: Richard Girard Barry, Your mistake here is not recognizing that the 912/914 are GEARED engines. Go to all the trouble to set the prop as you like but the gearing won't bring it back around to that same point for 1071 complete combustion cycles, i.e if you set a very high idle of 2142 RPM the prop would return to your set point once a minute. Lycosaurs are great, but they have so little to do with a Rotax that experience gained with them is virtually useless. Rick On Mon, Jan 4, 2010 at 10:06 AM, FLYaDIVE wrote: > Hi Rick: > > HAPPY NEW YEAR! > > The procedure is standard for horizontally opposed combustion engines. It > is what is being used for both Continental & Lycomming engines. When having > a prop balanced it is the first thing checked. I am taking a course on > vibration and prop balancing and Chadwick Helmuth and ACES both cover > balancing this way. This is done to reduce the amount of balance weight > required. Yes, you can balance without doing a static balance but this just > helps. It is like balancing tires. Ever see a car with a huge amount of > weight required to balance a tire? More than likely they did not place the > heavy spot of the tire across from the valve stem. > > Barry > > On Thu, Dec 31, 2009 at 10:12 PM, Richard Girard wrote: > >> Barry, Where did you get this procedure? It's not in any Rotax manual. >> >> Rick Girard >> >> On Thu, Dec 31, 2009 at 4:05 PM, FLYaDIVE wrote: >> >>> Rich: >>> >>> I asked the same question. The procedure is the same as for direct >>> drives. Why you may ask? >>> Because the prop has more an effect as the FLYWHEEL having a much larger >>> diameter than the gears. >>> The procedure is this: >>> 1 - Take all safety precautions. >>> 2 - Put the prop on with only a few bolts >>> 3 - Remove the #1 Cyl Spark Plug. >>> 4 - Rotate the prop so #1 piston is TDC on compression stroke. >>> 5 - The prop #1 Blade ... Should be at the 1 O'clock position - LQQKing >>> at it from the front of the engine. >>> 6 - Position and reassemble as required. >>> >>> Barry >>> On Thu, Dec 31, 2009 at 3:54 PM, Richard Girard wrote: >>> >>>> Barry, Rotax engines run a gearbox of either 2.27 or 2.43 ratio. How >>>> exactly are you going to CLOCK it? >>>> >>>> Rick Girard >>>> >>>> On Thu, Dec 31, 2009 at 2:32 PM, FLYaDIVE wrote: >>>> >>>>> Gilles is right 100%! >>>>> >>>>> You should NEVER run an engine without some form of flywheel. A prop >>>>> IS a flywheel. And if your friend ran an engine without a flywheel and is >>>>> alive to talk about it he is either lucky or a liar. >>>>> An engine run without a flywheel or the proper size flywheel can JUMP >>>>> into a RUNAWAY condition and reach RPM's so high the engine will literally >>>>> tear itself apart / explode. >>>>> >>>>> Another question to throw into the pot: Is the prop properly CLOCKED? >>>>> If it is not in the correct position you will get rough running and >>>>> vibration. >>>>> >>>>> Barry >>>>> >>>>> On Thu, Dec 31, 2009 at 2:51 PM, AmphibFlyer < >>>>> SeaRey@abstractconcreteworks.com> wrote: >>>>> >>>>>> >>>>>> >>>>>> >>>>>> Gilles.Thesee(at)ac-greno wrote: >>>>>> > Rotax engines have NO flywheel... Running a Rotax without a prop is >>>>>> a no-no. >>>>>> >>>>>> >>>>>> Well, you're right, mostly. I shouldn't have said that they do. On >>>>>> the other hand, the Heavy Maintenance Manual discusses "flywheel hub" in >>>>>> several places (July 01/2008, 74-00-00, page 49, page 117, and page 25). It >>>>>> doesn't seem to show a clear diagram of an actual flywheel, though. >>>>>> >>>>>> Also I should confess that I have never tried to run a 914 without a >>>>>> prop and relied on someone else's testimony, which I can't verify right now. >>>>>> So maybe it can be done and maybe it can't. >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> Read this topic online here: >>>>>> >>>>>> http://forums.matronics.com/viewtopic.php?p=279458#279458 >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> Attachments: >>>>>> >>>>>> http://forums.matronics.com//files/scr====== >>>>>> >>>>>> he Contribution link below to find out more about >>>>>> lder's Bookstore >>>>>> >>>>>> www.buildersbooks.com >>>>>> >>>>>> href="http://www.howtocrimp.com/" target="_blank">www.howtocrimp.comiption, >>>>>> www.matronics.com/Navigator?RotaxEngines-List" target="_blank"> >>>>>> http://www.matronics.com/Navigator?RotaxEngines-List >>>>>> ronics.com/" target="_blank">http://forums.matronics.com >>>>>> ============= >>>>>> >>>>>> >>>>>> >>>>>> >>>>> * >>>>> >>>>> _blank">www.aeroelectric.com >>>>> >>>>> .com" target="_blank">www.buildersbooks.com >>>>> >>>>> ="_blank">www.homebuilthelp.com >>>>> >>>>> nk">www.howtocrimp.com >>>>> _blank">http://www.matronics.com/contribution >>>>> >>>>> ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List >>>>> >>>>> tp://forums.matronics.com >>>>> * >>>>> >>>>> >>>> * >>>> >>>> >>>> "_blank">www.aeroelectric.com >>>> .com/" target="_blank">www.buildersbooks.com >>>> ="_blank">www.homebuilthelp.com >>>> >>>> ank">www.howtocrimp.com >>>> >>>> _blank">http://www.matronics.com/contribution >>>> >>>> ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List >>>> >>>> ttp://forums.matronics.com >>>> * >>>> >>>> >>> * >>> >>> _blank">www.aeroelectric.com >>> .com" target="_blank">www.buildersbooks.com >>> ="_blank">www.homebuilthelp.com >>> nk">www.howtocrimp.com >>> _blank">http://www.matronics.com/contribution >>> ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List >>> tp://forums.matronics.com >>> * >>> >>> >> * >> >> "_blank">www.aeroelectric.com >> .com/" target="_blank">www.buildersbooks.com >> ="_blank">www.homebuilthelp.com >> ank">www.howtocrimp.com >> _blank">http://www.matronics.com/contribution >> ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List >> ttp://forums.matronics.com >> * >> >> > * > > * > > ________________________________ Message 3 _____________________________________ Time: 10:30:55 AM PST US Subject: RotaxEngines-List: Re: Rotax 914 Won't Start From: "rampil" Without a load on the crankshaft/gearbox, a Rotax 900 has several problems, but exploding is not one of the them! what will happen is that above 6000 engine rpm, the speed of the hydraulic valve lifters is inadequate to completely open and close. They essentially float out of synch and get bent out of straight by the cams. Apparently this situation is worsened by what is unfortunately common occurrence: In a rush to try their new $20K investment, some builders too busy to read the manuals try to fire up the engine not only without the prop load, but also without the throttle cable! From the factory, the engine is WOT without a cable pulling it back. The engine goes to above 6000 rpm in a heartbeat and no chance for the operator to react before the engine is damaged. -------- Ira N224XS Read this topic online here: http://forums.matronics.com/viewtopic.php?p=280060#280060 ________________________________ Message 4 _____________________________________ Time: 11:11:48 AM PST US Subject: RotaxEngines-List: What happens if you overspeed a 91X? From: rparigor@suffolk.lib.ny.us Hi Ira I am curious what failure occurs if you overspeed a 91X? You mentioned: "what will happen is that above 6000 engine rpm, the speed of thehydraulic valve lifters is inadequate to completely open and close.They essentially float out of synch and get bent out of straight by the cams." I am not sure what you said, do the hydraulic valve lifters themselves get bent by overspeed? I always assumed that the mass of valve train has more inertia than can be held by the valve springs where the valve lifters are in contact with the cam (valve float)? Then a valve is left opened where it shouldn't be and a piston contacts the valve andbends the valve, and probably also the pushrod? Another question, since the 912S has a different cam grind than the 912 or 914,does overspeed problemsoccur at the same RPM as 912 or 914? Thx. Ron Parigoris ________________________________ Message 5 _____________________________________ Time: 11:47:29 AM PST US From: Bob Comperini Subject: Re: RotaxEngines-List: What happens if you overspeed a 91X? On 11:10 AM 1/4/2010, rparigor@suffolk.lib.ny.us wrote: >Then a valve is left opened where it shouldn't be and a piston contacts the valve and bends the valve, and probably also the pushrod? For what its worth, In the 912 Line maintenance manual (05-50-00, section 3.3), the inspections exceeding max RPMs are addressed. Yes, Pushrods are on the "list" of things to inspect. -- Bob Comperini e-mail: bob@fly-ul.com WWW: http://www.fly-ul.com ________________________________ Message 6 _____________________________________ Time: 03:54:38 PM PST US Subject: Re: RotaxEngines-List: Re: Rotax 914 Won't Start From: FLYaDIVE Rich: OK, you have a student here ... Pull out your books and ruler and start pounding some information into my head. Where does the 1071 come from? How is the math done? Barry On Mon, Jan 4, 2010 at 12:06 PM, Richard Girard wrote: > Barry, Your mistake here is not recognizing that the 912/914 are GEARED > engines. Go to all the trouble to set the prop as you like but the gearing > won't bring it back around to that same point for 1071 complete combustion > cycles, i.e if you set a very high idle of 2142 RPM the prop would return to > your set point once a minute. Lycosaurs are great, but they have so little > to do with a Rotax that experience gained with them is virtually useless. > > Rick > > > On Mon, Jan 4, 2010 at 10:06 AM, FLYaDIVE wrote: > >> Hi Rick: >> >> HAPPY NEW YEAR! >> >> The procedure is standard for horizontally opposed combustion engines. It >> is what is being used for both Continental & Lycomming engines. When having >> a prop balanced it is the first thing checked. I am taking a course on >> vibration and prop balancing and Chadwick Helmuth and ACES both cover >> balancing this way. This is done to reduce the amount of balance weight >> required. Yes, you can balance without doing a static balance but this just >> helps. It is like balancing tires. Ever see a car with a huge amount of >> weight required to balance a tire? More than likely they did not place the >> heavy spot of the tire across from the valve stem. >> >> Barry >> >> On Thu, Dec 31, 2009 at 10:12 PM, Richard Girard wrote: >> >>> Barry, Where did you get this procedure? It's not in any Rotax manual. >>> >>> Rick Girard >>> >>> On Thu, Dec 31, 2009 at 4:05 PM, FLYaDIVE wrote: >>> >>>> Rich: >>>> >>>> I asked the same question. The procedure is the same as for direct >>>> drives. Why you may ask? >>>> Because the prop has more an effect as the FLYWHEEL having a much larger >>>> diameter than the gears. >>>> The procedure is this: >>>> 1 - Take all safety precautions. >>>> 2 - Put the prop on with only a few bolts >>>> 3 - Remove the #1 Cyl Spark Plug. >>>> 4 - Rotate the prop so #1 piston is TDC on compression stroke. >>>> 5 - The prop #1 Blade ... Should be at the 1 O'clock position - LQQKing >>>> at it from the front of the engine. >>>> 6 - Position and reassemble as required. >>>> >>>> Barry >>>> On Thu, Dec 31, 2009 at 3:54 PM, Richard Girard wrote: >>>> >>>>> Barry, Rotax engines run a gearbox of either 2.27 or 2.43 ratio. How >>>>> exactly are you going to CLOCK it? >>>>> >>>>> Rick Girard >>>>> >>>>> On Thu, Dec 31, 2009 at 2:32 PM, FLYaDIVE wrote: >>>>> >>>>>> Gilles is right 100%! >>>>>> >>>>>> You should NEVER run an engine without some form of flywheel. A prop >>>>>> IS a flywheel. And if your friend ran an engine without a flywheel and is >>>>>> alive to talk about it he is either lucky or a liar. >>>>>> An engine run without a flywheel or the proper size flywheel can JUMP >>>>>> into a RUNAWAY condition and reach RPM's so high the engine will literally >>>>>> tear itself apart / explode. >>>>>> >>>>>> Another question to throw into the pot: Is the prop properly >>>>>> CLOCKED? If it is not in the correct position you will get rough running >>>>>> and vibration. >>>>>> >>>>>> Barry >>>>>> >>>>>> On Thu, Dec 31, 2009 at 2:51 PM, AmphibFlyer < >>>>>> SeaRey@abstractconcreteworks.com> wrote: >>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> Gilles.Thesee(at)ac-greno wrote: >>>>>>> > Rotax engines have NO flywheel... Running a Rotax without a prop is >>>>>>> a no-no. >>>>>>> >>>>>>> >>>>>>> Well, you're right, mostly. I shouldn't have said that they do. On >>>>>>> the other hand, the Heavy Maintenance Manual discusses "flywheel hub" in >>>>>>> several places (July 01/2008, 74-00-00, page 49, page 117, and page 25). It >>>>>>> doesn't seem to show a clear diagram of an actual flywheel, though. >>>>>>> >>>>>>> Also I should confess that I have never tried to run a 914 without a >>>>>>> prop and relied on someone else's testimony, which I can't verify right now. >>>>>>> So maybe it can be done and maybe it can't. >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> Read this topic online here: >>>>>>> >>>>>>> http://forums.matronics.com/viewtopic.php?p=279458#279458 >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> Attachments: >>>>>>> >>>>>>> http://forums.matronics.com//files/scr====== >>>>>>> >>>>>>> he Contribution link below to find out more about >>>>>>> lder's Bookstore >>>>>>> >>>>>>> www.buildersbooks.com >>>>>>> >>>>>>> href="http://www.howtocrimp.com/" target="_blank">www.howtocrimp.comiption, >>>>>>> www.matronics.com/Navigator?RotaxEngines-List" target="_blank"> >>>>>>> http://www.matronics.com/Navigator?RotaxEngines-List >>>>>>> ronics.com/" target="_blank">http://forums.matronics.com >>>>>>> ============= >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>> * >>>>>> >>>>>> _blank">www.aeroelectric.com >>>>>> >>>>>> .com" target="_blank">www.buildersbooks.com >>>>>> >>>>>> ="_blank">www.homebuilthelp.com >>>>>> >>>>>> nk">www.howtocrimp.com >>>>>> _blank">http://www.matronics.com/contribution >>>>>> >>>>>> ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List >>>>>> >>>>>> tp://forums.matronics.com >>>>>> * >>>>>> >>>>>> >>>>> * >>>>> >>>>> >>>>> "_blank">www.aeroelectric.com >>>>> .com/" target="_blank">www.buildersbooks.com >>>>> ="_blank">www.homebuilthelp.com >>>>> >>>>> ank">www.howtocrimp.com >>>>> >>>>> _blank">http://www.matronics.com/contribution >>>>> >>>>> ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List >>>>> >>>>> ttp://forums.matronics.com >>>>> * >>>>> >>>>> >>>> * >>>> >>>> _blank">www.aeroelectric.com >>>> .com" target="_blank">www.buildersbooks.com >>>> ="_blank">www.homebuilthelp.com >>>> nk">www.howtocrimp.com >>>> _blank">http://www.matronics.com/contribution >>>> ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List >>>> tp://forums.matronics.com >>>> * >>>> >>>> >>> * >>> >>> "_blank">www.aeroelectric.com >>> .com/" target="_blank">www.buildersbooks.com >>> ="_blank">www.homebuilthelp.com >>> ank">www.howtocrimp.com >>> _blank">http://www.matronics.com/contribution >>> ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List >>> ttp://forums.matronics.com >>> * >>> >>> >> * >> >> ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List >> tp://forums.matronics.com >> _blank">http://www.matronics.com/contribution >> * >> >> > * > > > = > * > > ________________________________ Message 7 _____________________________________ Time: 05:19:34 PM PST US Subject: RotaxEngines-List: Re: What happens if you overspeed a 91X? From: "rampil" Hi Ron, It did not occur to me that the cams are different on the different models. As for different frequency response of the valve train, sounds like a factory question. No one else would have an engine closely instrumented to detect the float and over-sped to destruction. The cams should only be different in amplitude, not angular change. The float is a phenomena of frequency response so it should be a function of spring compliance and push rod inertance. (Hows that for an x engineer) Happy New Year! -------- Ira N224XS Read this topic online here: http://forums.matronics.com/viewtopic.php?p=280131#280131 ________________________________ Message 8 _____________________________________ Time: 05:27:19 PM PST US From: Graham Singleton Subject: Re: RotaxEngines-List: Re: Rotax 914 Won't Start It is pointless "clocking" the prop on a Rotax because the prop will reclock itself continuously as the gearbox steadily alters the relation between prop and crank. Graham On 04/01/2010 16:06, FLYaDIVE wrote: > Hi Rick: > HAPPY NEW YEAR! > > The procedure is standard for horizontally opposed combustion > engines. It is what is being used for both Continental & Lycomming > engines. When having a prop balanced it is the first thing checked. > I am taking a course on vibration and prop balancing and Chadwick > Helmuth and ACES both cover balancing this way. This is done to > reduce the amount of balance weight required. Yes, you can balance > without doing a static balance but this just helps. It is like > balancing tires. Ever see a car with a huge amount of weight > required to balance a tire? More than likely they did not place the > heavy spot of the tire across from the valve stem. > Barry ________________________________ Message 9 _____________________________________ Time: 06:45:18 PM PST US Subject: Re: RotaxEngines-List: Re: Rotax 914 Won't Start From: Richard Girard The crank on the 2.43 ratio gearbox has a 21 tooth gear on the crankshaft and a 51 tooth on the prop shaft. When the crank turns through on complete combustion cycle the 51 tooth gear advances only 42 teeth, roughly 60 degrees less than a full revolution. If you want to look at it in terms of revolutions, for each combustion cycle the crank gear goes around 2 times and the prop shaft gear goes around .82353 times. It was here that Rick went off the rails. The only way I could get back on track was to do it the bonehead way and make a spreadsheet. It turns out that when the crank goes through 17 combustion cycles (34 revolutions of the crank, or 714 teeth) the prop shaft gear has gone around 14 times (714 teeth) at which time the number 1 tooth on booth gears would again be aligned. So, sorry for the original miscalculation, the concept was correct but the math was faulty. Rick On Mon, Jan 4, 2010 at 5:19 PM, FLYaDIVE wrote: > Rich: > > OK, you have a student here ... Pull out your books and ruler and start > pounding some information into my head. > > Where does the 1071 come from? > How is the math done? > > Barry > > On Mon, Jan 4, 2010 at 12:06 PM, Richard Girard wrote: > >> Barry, Your mistake here is not recognizing that the 912/914 are GEARED >> engines. Go to all the trouble to set the prop as you like but the gearing >> won't bring it back around to that same point for 1071 complete combustion >> cycles, i.e if you set a very high idle of 2142 RPM the prop would return to >> your set point once a minute. Lycosaurs are great, but they have so little >> to do with a Rotax that experience gained with them is virtually useless. >> >> Rick >> >> >> On Mon, Jan 4, 2010 at 10:06 AM, FLYaDIVE wrote: >> >>> Hi Rick: >>> >>> HAPPY NEW YEAR! >>> >>> The procedure is standard for horizontally opposed combustion engines. >>> It is what is being used for both Continental & Lycomming engines. When >>> having a prop balanced it is the first thing checked. I am taking a course >>> on vibration and prop balancing and Chadwick Helmuth and ACES both cover >>> balancing this way. This is done to reduce the amount of balance weight >>> required. Yes, you can balance without doing a static balance but this just >>> helps. It is like balancing tires. Ever see a car with a huge amount of >>> weight required to balance a tire? More than likely they did not place the >>> heavy spot of the tire across from the valve stem. >>> >>> Barry >>> >>> On Thu, Dec 31, 2009 at 10:12 PM, Richard Girard wrote: >>> >>>> Barry, Where did you get this procedure? It's not in any Rotax manual. >>>> >>>> Rick Girard >>>> >>>> On Thu, Dec 31, 2009 at 4:05 PM, FLYaDIVE wrote: >>>> >>>>> Rich: >>>>> >>>>> I asked the same question. The procedure is the same as for direct >>>>> drives. Why you may ask? >>>>> Because the prop has more an effect as the FLYWHEEL having a much >>>>> larger diameter than the gears. >>>>> The procedure is this: >>>>> 1 - Take all safety precautions. >>>>> 2 - Put the prop on with only a few bolts >>>>> 3 - Remove the #1 Cyl Spark Plug. >>>>> 4 - Rotate the prop so #1 piston is TDC on compression stroke. >>>>> 5 - The prop #1 Blade ... Should be at the 1 O'clock position - LQQKing >>>>> at it from the front of the engine. >>>>> 6 - Position and reassemble as required. >>>>> >>>>> Barry >>>>> On Thu, Dec 31, 2009 at 3:54 PM, Richard Girard >>>> > wrote: >>>>> >>>>>> Barry, Rotax engines run a gearbox of either 2.27 or 2.43 ratio. >>>>>> How exactly are you going to CLOCK it? >>>>>> >>>>>> Rick Girard >>>>>> >>>>>> On Thu, Dec 31, 2009 at 2:32 PM, FLYaDIVE wrote: >>>>>> >>>>>>> Gilles is right 100%! >>>>>>> >>>>>>> You should NEVER run an engine without some form of flywheel. A prop >>>>>>> IS a flywheel. And if your friend ran an engine without a flywheel and is >>>>>>> alive to talk about it he is either lucky or a liar. >>>>>>> An engine run without a flywheel or the proper size flywheel can JUMP >>>>>>> into a RUNAWAY condition and reach RPM's so high the engine will literally >>>>>>> tear itself apart / explode. >>>>>>> >>>>>>> Another question to throw into the pot: Is the prop properly >>>>>>> CLOCKED? If it is not in the correct position you will get rough running >>>>>>> and vibration. >>>>>>> >>>>>>> Barry >>>>>>> >>>>>>> On Thu, Dec 31, 2009 at 2:51 PM, AmphibFlyer < >>>>>>> SeaRey@abstractconcreteworks.com> wrote: >>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> Gilles.Thesee(at)ac-greno wrote: >>>>>>>> > Rotax engines have NO flywheel... Running a Rotax without a prop >>>>>>>> is a no-no. >>>>>>>> >>>>>>>> >>>>>>>> Well, you're right, mostly. I shouldn't have said that they do. On >>>>>>>> the other hand, the Heavy Maintenance Manual discusses "flywheel hub" in >>>>>>>> several places (July 01/2008, 74-00-00, page 49, page 117, and page 25). It >>>>>>>> doesn't seem to show a clear diagram of an actual flywheel, though. >>>>>>>> >>>>>>>> Also I should confess that I have never tried to run a 914 without a >>>>>>>> prop and relied on someone else's testimony, which I can't verify right now. >>>>>>>> So maybe it can be done and maybe it can't. >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> Read this topic online here: >>>>>>>> >>>>>>>> http://forums.matronics.com/viewtopic.php?p=279458#279458 >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> Attachments: >>>>>>>> >>>>>>>> http://forums.matronics.com//files/scr====== >>>>>>>> >>>>>>>> he Contribution link below to find out more about >>>>>>>> lder's Bookstore >>>>>>>> >>>>>>>> www.buildersbooks.com >>>>>>>> >>>>>>>> href="http://www.howtocrimp.com/" target="_blank"> >>>>>>>> www.howtocrimp.com iption, >>>>>>>> www.matronics.com/Navigator?RotaxEngines-List" target="_blank"> >>>>>>>> http://www.matronics.com/Navigator?RotaxEngines-List >>>>>>>> ronics.com/" target="_blank">http://forums.matronics.com >>>>>>>> ============= >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>> * >>>>>>> >>>>>>> _blank">www.aeroelectric.com >>>>>>> >>>>>>> .com" target="_blank">www.buildersbooks.com >>>>>>> >>>>>>> ="_blank">www.homebuilthelp.com >>>>>>> >>>>>>> nk">www.howtocrimp.com >>>>>>> _blank">http://www.matronics.com/contribution >>>>>>> >>>>>>> ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List >>>>>>> >>>>>>> tp://forums.matronics.com >>>>>>> * >>>>>>> >>>>>>> >>>>>> * >>>>>> >>>>>> >>>>>> "_blank">www.aeroelectric.com >>>>>> .com/" target="_blank">www.buildersbooks.com >>>>>> ="_blank">www.homebuilthelp.com >>>>>> >>>>>> ank">www.howtocrimp.com >>>>>> >>>>>> _blank">http://www.matronics.com/contribution >>>>>> >>>>>> ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List >>>>>> >>>>>> ttp://forums.matronics.com >>>>>> * >>>>>> >>>>>> >>>>> * >>>>> >>>>> _blank">www.aeroelectric.com >>>>> .com" target="_blank">www.buildersbooks.com >>>>> ="_blank">www.homebuilthelp.com >>>>> nk">www.howtocrimp.com >>>>> _blank">http://www.matronics.com/contribution >>>>> ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List >>>>> tp://forums.matronics.com >>>>> * >>>>> >>>>> >>>> * >>>> >>>> "_blank">www.aeroelectric.com >>>> .com/" target="_blank">www.buildersbooks.com >>>> ="_blank">www.homebuilthelp.com >>>> ank">www.howtocrimp.com >>>> _blank">http://www.matronics.com/contribution >>>> ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List >>>> ttp://forums.matronics.com >>>> * >>>> >>>> >>> * >>> >>> >>> ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List >>> tp://forums.matronics.com >>> >>> _blank">http://www.matronics.com/contribution >>> * >>> >>> >> * >> >> >> ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List >> >> ttp://forums.matronics.com >> ======== >> = >> _blank">http://www.matronics.com/contribution >> * >> >> > * > > > * > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message rotaxengines-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/RotaxEngines-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/rotaxengines-list Browse Digests http://www.matronics.com/digest/rotaxengines-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.