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912s spark plug lifespan?

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  • 912s spark plug lifespan?

    Hello

    I seem to be getting only approx 10 hours out of a set of plugs before she runs rough on one mag & i need to buy a new set. I removed, cleaned and refitted them to no effect.

    I was wondering roughly how many hours other people are getting from theirs, 10 hours seems rather short!

    Also, is there anywhere cheaper to get them from apart from the usual skydrive / P&M? I found the DCPR8E on a couple of motorbike websites but they were no cheaper, one was even dearer if you can believe it!!!

    All comments gratefully received.

  • #2
    912s spark plug lifespan?

    200 hours is the rotax required replacement time ( and at that they are barely worn), if you are having issues at only 10 hours then there is definitely another issue that needs investigating

    Chris
    CT Aviation

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    • #3
      912s spark plug lifespan?

      marc dawson wrote:
      I was wondering roughly how many hours other people are getting from theirs, 10 hours seems rather short!
      Time to measure the coil resistance, and to check all the plug caps. If not you may have the dreaded ignition module problem. Look for shorting or low resistance paths to deck where the HT leads touch, and inspect them along their lengths.

      One coil does two plugs, so any issues on either HT lead run will knock out two cylinders on one mag, as I understand it.

      Rather than replace all plugs, locate the affected mag/ignition module and the affected coil. One mag drives two coils, so eliminates the other two.

      marc dawson wrote: Also, is there anywhere cheaper to get them from apart from the usual skydrive / P&M? I found the DCPR8E on a couple of motorbike websites but they were no cheaper, one was even dearer if you can believe it!!!
      Skydrive pricing on the 8 plugs needed is very keen, whilst they are doing us a good deal we may as well support them.

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      • #4
        912s spark plug lifespan?

        Thank you gents for the replies, but bear with me as I'm mentally slow! If I put a new set of plugs in & it runs fine with 2 nice smooth mag drops, what does that mean?

        This is what happened last time. rough on one mag, new plugs in and nice and smooth. Ten hours later chug chug grumble rough on one mag!

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        • #5
          912s spark plug lifespan?

          marc dawson wrote: Thank you gents for the replies, but bear with me as I'm mentally slow! If I put a new set of plugs in & it runs fine with 2 nice smooth mag drops, what does that mean?
          It means that the spark is of marginal strength and jumps the gap with new plugs but not after a few hours. This could be due to extra resistance in the leads or plug caps.

          Have you checked the gaps and maybe reduced them in line with the advice in the Rotax manual?

          There is other trouble shooting info in the Rotax manual. I have binned one plug cap as it was looking tired and measured higher resistance than the spec.

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          • #6
            912s spark plug lifespan?

            Thanks very much for the advice chaps, I'll look into the suggestions and report back.

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            • #7
              912s spark plug lifespan?

              Hello again. To cut a long story short a new set of leads & plug caps seems to have sorted out this problem. Thank you for all of the replies.

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