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  • #31
    Exhaust Gas Temps

    Nick... If required Procom will make the thermocouple leads any length you wish, normally at no extra charge and have CHT under plug thermocouples of all sizes
    The EGT probe is of smaller diameter than the Rotax probes and from memory protrudes a different length into the manifold. It is spot welded to the stainless jubilee clip so easy to remove the spot weld and make up a sleeved clamp to adjust to the different parameters if needed.... or of course use the Rotax K type probe.

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    • #32
      Exhaust Gas Temps

      Many thanks Wally...amazing whats available these days.
      "When once you have tasted flight...you will forever walk with your eyes turned skywards..."

      https://www.youtube.com/user/nickjaxe/videos.

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      • #33
        Exhaust Gas Temps

        Are you sure the airfilter is un-restricted Phil...you could as a test try running without it.

        If the jets come up as std it maybe worth checking the ignition timing.
        "When once you have tasted flight...you will forever walk with your eyes turned skywards..."

        https://www.youtube.com/user/nickjaxe/videos.

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        • #34
          Exhaust Gas Temps

          Thanks Wally! Very useful gadgets and, like Nick, I've ordered the Thermocouple and Meter for comparison against my fitted gauges....Unbelievable that they're so cheap, especially when they have to be shipped half way around the world to boot!

          I'll also be cleaning and oiling the carb filters soon, although I understood when I bought the aircraft that they had been done very recently. 'Still, no harm in doing them again!

          I also believed that the prop pitch had been set correctly but I checked last weekend and found that three blades were set 3 degrees too fine and the fourth was 5 degrees out(!) so that's the next thing to adjust.....

          Phil.

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          • #35
            Exhaust Gas Temps

            That magnitude of pitch error will bigger everything up!!!!

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            • #36
              Exhaust Gas Temps

              3 deg fine...thats a hell of a lot Phil...its a wonder the EGTs and rpm are not through the roof.

              I cant get over the price of stuff from China either Phil...get it whist you can.
              "When once you have tasted flight...you will forever walk with your eyes turned skywards..."

              https://www.youtube.com/user/nickjaxe/videos.

              Comment


              • #37
                Exhaust Gas Temps

                This is according to the Noise Certificate for the aircraft which states that the pitch should be set at 20 degrees - but 18 degrees is perfectly acceptable for good performance, so I guess you could say that 3 of the blades are only 1 degree out - what surprised me is that the fourth blade was so different to the other three!

                I intend to set all four to 20 degrees, see what effect it has on take-off roll, climb and cruise (and EGTs!) - then assess whether it's worth experimenting with a reduction to 18 degrees..... of course, this might introduce hassle with re-applying for a new noise certificate!

                Doh!

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                • #38
                  Exhaust Gas Temps

                  An awful lot of noise certificates state pitches that are somewhat coarse of the optimum for aircraft and engine, as the manufacturer struggled to get the noise down during his testing. And you shouldn't operate at anything other than the stated figure...
                  Dave

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                  • #39
                    Exhaust Gas Temps

                    Hi all.

                    I've re-set the blade pitch to 20 degrees all round and checked the tracking - well worth while, everything seems a fair bit smoother.

                    The EGTs are now 480/460 so there's still a way to go....next step is to fit 162 main jets instead of 165 to check the effect. The plugs are still dark tan (the rear one a VERY dark tan) so I'm confident that I'm not weakening the mixture too much yet.

                    I'll report back once I've received the new jets and tested them....

                    Phil.

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                    • #40
                      Exhaust Gas Temps

                      Phil,
                      How easy is your machine to start?
                      Has it got points or cdi?
                      As above with the find pitch you had the egt's should have been high - as they weren't (assuming gauging good) then only the jetting and or ignition timing can be the cause. What two stroke oil do you use?
                      You should not be having all this trouble sorting the problem out!

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                      • #41
                        Exhaust Gas Temps

                        Just had another thought - I have an IR 'gun' (very cheap and accurate) point it at the position of the 'EGT sensors and see what reading it gives.
                        It won't of course be what the gauge reads it will be less but it should allow some indication of the 'ball park' accuracy of the sensing system and the temp of the exhaust gas.

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                        • #42
                          Exhaust Gas Temps

                          Hi Paul,

                          My engine is pretty easy to start with my pull cord system, helped by the fact that I've got a primer fitted and Iridium plugs (perhaps the extra efficiency of the plugs are contributing to low EGTs!?). When I first bought her she was a bit of a cow to start until I started tweaking - shortening the pull cord, adjusting the air screws, getting just the 'correct' amount of priming, fitting Iridiums etc. Now it's almost invariably a first-time pull. Yes, I know that Iridium plugs aren't listed as a 'recommended' plug by Rotax but have they even considered them I wonder? They certainly work tremendously well.....I first used them in my Yamaha RD350 motorcycle and was amazed at the easy starting and extra performance they gave. They're expensive of course, but well worth it in my humble opinion. I regularly check the screw-caps for tightness of course.

                          My 582 has dual CDI ignition and I use Castrol TTS. On reflection, maybe the TTS is contributing to the carbon build up since it's aimed at 'performance' two strokes which are stripped down (and de-coked) fairly regularly. I may switch to Castrol Power 1.....it'll be interesting to see the effect, if any. There again, the existing carbon build-up might just be the result of the engine not being de-coked properly before I bought the aircraft (I've only had her for about 20 flying hours)- I'll do a thorough job at the next service, the first one for me on this particular engine.

                          Where abouts are you based out of interest? If I'm flying by one day I might drop in to use your IR gun if I may.....

                          Ciao,

                          Phil.

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                          • #43
                            Exhaust Gas Temps

                            Er Phil, your first post said ...confirmed by the amount of carbon between decokes and you say now that you haven't done a decoke yet? If you are going by what is written in the log (unless the aircraft came from a very reliable source) I would be cautious as to what has actually been done and when. I have had engines and gearboxes apart and can say that people can be economical with the truth (I took a trike suspension to pieces for lubricating, according to the log it had been done at every recommended service interval, yet the r/h/s was bone dry with no signs of grease). Best way forward, in my opinion, is to strip, clean and inspect carbs, gearbox and top end that way you can be certain exactly where you are. Please be extremely careful with the gearbox as I have recently seen an influx of seemingly ok boxes that are damaged internally, needing new gears etc and the logs make no mention of the boxes ever being inspected.

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                            • #44
                              Exhaust Gas Temps

                              Thanks Dominic, good advice, and yes I was going by the log book entries, but It had been re-bored not too long before I bought the aircraft and I hypothesized that it had been set up to run rich whilst it was running in.....hence my desire to check all the jet sizes. Having said that, I can't complain about the power output which is really strong.

                              I haven't had the heads off at all yet but the first time I took the (old) plugs out there was a thick layer of black carbon on them so I'm sure the heads must be the same - or worse. For sure as soon as the warmer weather hits I'll be doing a complete top-end and carb overhaul and taking the gearbox to a professional for servicing.

                              Thanks again,

                              Phil.

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                              • #45
                                Exhaust Gas Temps

                                If you aren't too far away I would gladly give your gearbox a once over.

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