---------------------------------------------------------- RotaxEngines-List Digest Archive --- Total Messages Posted Thu 03/12/09: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 11:04 AM - Re: RotaxEngines-List Digest: 1 Msgs - 03/06/09 (Kitfoxkirk) 2. 12:22 PM - Rotax 921ULS rough running(420 hoursTSN) (Malcolm Ferguson) ________________________________ Message 1 _____________________________________ Time: 11:04:40 AM PST US Subject: RotaxEngines-List: Re: RotaxEngines-List Digest: 1 Msgs - 03/06/09 From: Kitfoxkirk I have inspected the inside of the intake manifolds on a Rotax 912UL and found black soot like fine particulate in there. It does wipe off with a rag, so it is not stuck on very hard. Has any other person experience this? Thanks, Kirk On Sat, Mar 7, 2009 at 2:57 AM, RotaxEngines-List Digest Server < rotaxengines-list@matronics.com> wrote: > * > > ================================================= > Online Versions of Today's List Digest Archive > ================================================= > > Today's complete RotaxEngines-List Digest can also be found in either of > the > two Web Links listed below. The .html file includes the Digest formatted > in HTML for viewing with a web browser and features Hyperlinked Indexes > and Message Navigation. The .txt file includes the plain ASCII version > of the RotaxEngines-List Digest and can be viewed with a generic text > editor > such as Notepad or with a web browser. > > HTML Version: > > > http://www.matronics.com/digest/digestview.php?Style=82701&View=html&Chapter 09-03-06&Archive=RotaxEngines > > Text Version: > > > http://www.matronics.com/digest/digestview.php?Style=82701&View=txt&Chapter 09-03-06&Archive=RotaxEngines > > > =============================================== > EMail Version of Today's List Digest Archive > =============================================== > > > ---------------------------------------------------------- > RotaxEngines-List Digest Archive > --- > Total Messages Posted Fri 03/06/09: 1 > ---------------------------------------------------------- > > > Today's Message Index: > ---------------------- > > 1. 07:00 AM - 912 UL for sale (george.mueller@aurora.org) > > > ________________________________ Message 1 > _____________________________________ > > > Time: 07:00:25 AM PST US > Subject: RotaxEngines-List: 912 UL for sale > From: george.mueller@aurora.org > > If anyone is looking at buying an engine, I have a Rotax 912 UL 60 hours > total time since new, plus a Woodcomp Klassic three blade prop 30 hours > total time since new, plus a Rieff rotax engine preheater for sale on > Barnstormers for $14,900. The engine is currently being gone over at the > rotax dealer to make sure it is perfect. > > > George in Milwaukee > > ________________________________ Message 2 _____________________________________ Time: 12:22:55 PM PST US From: "Malcolm Ferguson" Subject: RotaxEngines-List: Rotax 921ULS rough running(420 hoursTSN) Over a period of a couple of months the engine/plane has developed significant vibration that was related to engine revs and was like it was running on 3 and a half cylinders-not actually missing. After much head scratching and all the usual things such as carby balancing, plugs etc. a leak down test was performed with the following results: Cyl 1: 73/80 Cyl 2: 64/80 Cyl 3: 63/80 Cyl 4: 73/80 By listening I determined the intake valves in cyl. 2 and 3 were leaking. Subsequently all 4 heads were removed and sent for service. All 4 intake valves were too badly damaged on their valve seat mating surfaces to be repaired. So 4 new valves. The Rotax mechanic had no explanation for the damage. Have used mostly Mogas premium unleaded. The mechanic said he would expect to see that damage on an engine that had done 1200 hours exclusively on Avgas. No damage to the valve seats in the heads. Talk of sending the valves back to Rotax. I liked the lack of head gaskets. There would be good heat transfer from the top of the cylinder barrels to the heads. The mechanic also suggested that some people had vibration problems at around 3000 revs that could not be cured. It was discovered that the nut holding the small gear(gearbox) on the crankshaft was loose. This proved to be the case on mine. It was well below the required 200nm(146 ft/lb). The serrated bellville washer under the nut was badly worn and was replaced. The nut is supposed to be put on with Loctite. On my engine it appeared that Loctite had been applied after the nut was tensioned up and had wicked in only a couple of threads. I was impressed with the simplicity of the Rotax gearbox and its ease of disassembly. I loved the use of bellville(cupped) washers and shims to get the required torsion in the "dog clutch". After carby disassembly 2 damaged O rings were found on the idle mixture screws, after renewal the idle improved marginally. Engine has always run much smoother on one mag than the other, although rev drop difference between the two was only 30-40 revs at 4000, much less than the roughness indicated. Trigger coils checked and tested okay with an ohm meter. Trigger coil plugs reversed at the ignition modules, but roughness stayed with the same mag circuit eliminating the trigger coils. Then switched plugs that connect the ignition modules to the coils(4 of) and voila the problem changed mag circuits, indicating a problem with 2 coils or their leads and plug caps. Both coils test okay, both primary and secondary circuits. One spark plug cap tested okay until a slight tension was applied, then went open circuit. It was replaced and engine test run. Still the same problem. The ignition modules/coil pack are an absolute dog's breakfast to get at, compact but a terrible design for access. So the saga continues. I have found several major problems I would not have found for a while. Have just priced a coil. Hard to imagine how a tiny little coil could cost more than a set of tyres for my car or a bottle of Australia's premier red wine-a bottle of Penfold Grange(over $500). Incidentally, I priced an ignition module and I could get a one way airline ticket to London for less. So I just need a few days to pluck up the courage to order a new coil then try to work out which coil is crook. On a more serious note the ignition modules are supplied with power from 2 charging coils. The schematic shows 2 seperate wires from the charging coils to the ignition modules. On my engine there is only one wire, jumpered to each module. The failure of that wire at either end results in the loss of both ignition systems, a very serious design flaw and one I'm glad I found. Malcolm Ferguson Esqual, 912ULS, Rospeller CS ------------------------------------------------------------------------------------- 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.