---------------------------------------------------------- RotaxEngines-List Digest Archive --- Total Messages Posted Sat 05/31/08: 7 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:20 AM - Silicone for Spark Plug Threads (michael baker) 2. 06:35 AM - Re: Silicone for Spark Plug Threads (Gilles Thesee) 3. 07:45 AM - Re: Silicone for Spark Plug Threads (ricklach) 4. 09:45 AM - Re: Silicone for Spark Plug Threads () 5. 12:00 PM - Re: Silicone for Spark Plug Threads (LarryMcFarland) 6. 12:38 PM - Re: Silicone for Spark Plug Threads (Duncan & Ami McFadyean) 7. 04:28 PM - Re: Silicone for Spark Plug Threads (Roger Lee) ________________________________ Message 1 _____________________________________ Time: 06:20:31 AM PST US From: michael baker Subject: RotaxEngines-List: Silicone for Spark Plug Threads Rotax service information states that 'the application of a silicone heat conduction compound is necessary as it improves heat transfer between spark plug and cylinder head.' I was wondering what type of silicone do others use and where do you buy it. Also would Champion Spark Plug lube give the same heat transfer. Cheers, Mike. do not archive ________________________________ Message 2 _____________________________________ Time: 06:35:28 AM PST US From: Gilles Thesee Subject: Re: RotaxEngines-List: Silicone for Spark Plug Threads michael baker a crit : > Rotax service information states that 'the application of a silicone > heat conduction compound is necessary as it > improves heat transfer between spark plug and cylinder head.' I was > wondering what type of silicone do others use and where do you buy it. > Also would Champion Spark Plug lube give the same heat transfer. Michael, Good question indeed. Rotax advises the use of a heat transfer compound such as is used for electronic components. The idea is rather odd, since the threads transfer only about 20% of the heat to the cylinder head. So even with a 50% improvement due to compound, heat transfer will increase only 10 %...Not much. Nevertheless, such compound can be purchased from any electronic dealer. The French Rotax dealer sells copper based spark plug lube in lieu of heat transfer compound. It sure helps preventing seizure, but does little toward improving heat transfer...But he says everyone is happy with it, so the actual compound does not matter much, after all. The Rotax don't really need any antiseize compound, since the heads are way cooler than the Lyco/Conti heads. Never experienced any problem with plugs on a Rotax. Some info on Rotax plugs here http://contrails.free.fr/engine_tighten.php Only in French for the moment, sorry. In my opinion, proper cooling is much much more important for engine life than any compound we could use on the plug threads. FWIW, Best regards, -- Gilles http://contrails.free.fr ________________________________ Message 3 _____________________________________ Time: 07:45:31 AM PST US Subject: RotaxEngines-List: Re: Silicone for Spark Plug Threads From: "ricklach" Try Radio Shack, thats where I got mine. Rick Read this topic online here: http://forums.matronics.com/viewtopic.php?p=185613#185613 ________________________________ Message 4 _____________________________________ Time: 09:45:28 AM PST US Subject: Re: RotaxEngines-List: Silicone for Spark Plug Threads From: Hi Michael "I was wondering what type of silicone do others use and where do you buy it." I talked with the guy who did research for Rotax on silicone thermal conductive compound to use on spark plugs. He said hands down winner was what Rotax sells. I forget the name of Mfg. but he said stuff you purchase from Radio Shack or most Electronic supply houses does not fare well. He was on mission to find alternative to what Rotax offers and in smaller quantities. Could not find an acceptable substitute. I was read many names he tested from a quite impressive list. I did read a while back someone in Europe was able to procure form Mfg. direct, think in Germany. I agree with Gilles that proper cooling is paramount, followed very close by not running too lean when you are making some BTUs. Spark plug cooling is a pretty important issue as well. Let the tip of the plug get too hot and it can act like a glow plug and cause detonation. Worst case is preignition that will trash a motor making BTUs in short order. Run too cold and carbon can build up and fouling/misfiring is very likely. The spark plug Mfg. for 914 plugs recommends not using anything on threads at all. That said Rotax recommends their reccomended silicone thermal conductive compound be used. I for one am willing to follow the Rotax suggestion on my engine. The research guy for Rotax said only use what Rotax sells. If by chance I did any testing and found anything I thought was at least as good, please send him a sample he wants to know about it. I for one am willing to listen very close to what the manufacturer and researcher has to say and follow their instructions with my 914. Yes Rotax paste is expensive, one idea is go in with 3 others and each will have a lifetime supply. When the chips are low 50 feet above the end of the runway and all my coolant decides to depart, or just running hot due to a high density altitude and more alcohol than the pump says, I am happy to know that the tip of my plugs are a bit cooler than using nothing or the wrong product. Ron Parigoris BTW if you dig in Rotax documentation, on 914 they want you to do a test to make sure that the leanest cylinder is running rich enough at full power. Their procedure is to measure carbon monoxide. I know of no one including Authorized Rotax Repair facilities who do this. Anyone out there have a machine (like what Eastwood sells) and plumbing to test? ________________________________ Message 5 _____________________________________ Time: 12:00:28 PM PST US From: LarryMcFarland Subject: Re: RotaxEngines-List: Silicone for Spark Plug Threads Hi Guys, Ive a Subaru, but plug issues are common to us. I use no seize which is an anti-lock paste. Its got very good thermal conductive properties and you need not worry about galling threads at some point during removal and reinstall. They need light and sensitive fingers for the initial turn-in and then torque to spec. Not sure of whether it has a silicone base or not. Good luck, Larry McFarland 601HDS at www.macsmachine.com rparigor@suffolk.lib.ny.us wrote: > > Hi Michael > > "I was wondering what type of silicone do others use and where do you buy > it." > > > Ron Parigoris > > ________________________________ Message 6 _____________________________________ Time: 12:38:28 PM PST US From: "Duncan & Ami McFadyean" Subject: Re: RotaxEngines-List: Silicone for Spark Plug Threads Not having the benifit of access to the research/testing done on the alternatives, why would copperslip be inferior? Copper is a far better conductor than the glass (?) used in normal silcone heat sink compounds. Except that the carrier grease probably boils off and its use is frowned upon in automotive cirlces (because excessive use can contaminate catalytic converters). Or has Rotax found the copper to be incompatable with the Nikasil cylinder linings? Duncan McF. ________________________________ Message 7 _____________________________________ Time: 04:28:58 PM PST US Subject: RotaxEngines-List: Re: Silicone for Spark Plug Threads From: "Roger Lee" Hi Guys, Buy your plug paste at Lockwood. They sell a small squeeze tube for about $1.38 that will last 2-3 plug changes. The paste is for the 4 strokes. Don't over apply and don't get it on the plug tip. The plug paste will also help to prevent galling. Do not use anti-seize as it is very different. The transfer heat paste will help keep the plugs operating at their proper heat range. Number one cause for Rotax engine failures whether it be a 4 or 2 stroke engine (especially 2 stroke) is owner/operator changing specs for what Rotax spent hundreds or even millions of dollars for over the years in research and development. They have hundreds of thousands of hours if not millions of hours on engines to prove their theories. The owner operator usually has less than a hundred hours and is willing to spend $100 to change a Rotax design. The Rotax 2 stroke is a very dependable engine so long as you leave it stock and load the engine with the prop correctly. -------- Roger Lee Tucson, Az. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=185666#185666 ------------------------------------------------------------------------------------- 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.