NC Bill Posted April 18, 2011 Report Share Posted April 18, 2011 What's the recommended time between plug replacement? I'm figuring to have the spark plugs inspected and cleaned every 50 hrs and replaced every 100. Is that adequate? Link to comment Share on other sites More sharing options...
Roger Lee Posted April 18, 2011 Report Share Posted April 18, 2011 Hi Bill, This is a small debate and has a few different trains of thought. The Rotax maint manual says up to 200 hrs. which to me and most in the Rotax maint educated community and the Rotax class teaching is senseless. Rotax says to look at them, clean , re-gap and put them back in at 100 hrs. and run up to 200 hrs. I would never go beyond 100 hours before tossing them. They cost around $2.50-$3.00 depending on where you get them. Many, like myself has been taught in a Rotax class that 75 hours is the best place. I change mine and recommend to my clients 75 hrs which came from Eric Tucker that teaches for Rotax. The plug is the "Heart beat" of your engine and the Blood is the oil. Disease of either of these will cause down the road issues, just like smoking does to a human. It won't get you today, but just wait. So to answer your question, you need to make that choice. 100hrs. is not a big issue and it wouldn't bother me personally, anything longer, well? I just checked a set of plugs that had 140 hrs on them and the gap was .035. Too wide. While you are deciding now throw in 100LL verses 91 unleaded. Just love that lead. Do you want to be on top of the maint. curve or on the bottom? p.s. Don't let any mechanic put anti seize on your plug threads. (The gap is .023 - .027) (.027 for warm weather) Link to comment Share on other sites More sharing options...
Jim Posted April 18, 2011 Report Share Posted April 18, 2011 As an engineer, my two cents would be "never reuse a crush gasket". If you pull the plugs to inspect them, put in new ones. The plugs don't cost $25 each and keeping a couple of boxes of them at the hanger is no big deal. Link to comment Share on other sites More sharing options...
NC Bill Posted April 18, 2011 Author Report Share Posted April 18, 2011 Thank you Roger. Will have the plugs changed out tomorrow with the oil change. BTW what should be applied to the plug threads? Link to comment Share on other sites More sharing options...
Roger Lee Posted April 18, 2011 Report Share Posted April 18, 2011 You use a heat or thermal, if you like, conducting paste. It can be purchased form numerous places. Lockwood, CPS http://www.rotaxparts.net/scripts/prodView.asp?idproduct=245 C:\Documents and Settings\User\Desktop\Rotax Manuals\Silicone Heat Transfer Compound.mht Link to comment Share on other sites More sharing options...
Tad Olmsted Posted April 19, 2011 Report Share Posted April 19, 2011 Agreed, the plugs are out at every 100 hr insp. $25.00 is really good piece of mind, especially if you are running AVGAS. In addition, if anti-sieze is used it will pull the threads out of the head. I had this happen when a customer brought in his CT that had been maintained by an "old school" A&P. I was able to chase the threads on 7 out of 8 spark plug holes. Guess what he had to replace???? Link to comment Share on other sites More sharing options...
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