Rotax 582 wet fouling

Discussion in '2-Stroke Aircaft Engines' started by ve3xox, Aug 29, 2013.

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  1. Aug 29, 2013 #1

    ve3xox

    ve3xox

    ve3xox

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    Bought a murphy renegade with an inverted 582 in it a few weeks ago. Uses pre-mix fuel and oil.
    Starting has been a problem. Plugs wet foul and have to be removed and cleaned. Started yesterday first thing and
    run it for 10 minutes and shut down. Went to restart and plugs fouled again. HAve replaced with new plugs and the same.
    Any ideas? thank you Bob
     
  2. Sep 1, 2013 #2

    nickjaxe

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    How about turning off the fuel then let the engine stop when the carbs are empty,

    Then prime up before re starting.
     
  3. Sep 1, 2013 #3

    ve3xox

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    I thought about that. fuel off each tank flows into a header tank under the front cock pit. then to the carbs. So would have to remote the turn off just before the carbs. Wonder how long to run the carbs empty?
    bob
     
  4. Sep 2, 2013 #4

    Doggzilla

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    If you take a look at cars, they have this vaccum control that keeps you from closing the butterfly valve too quickly... because when you cut the air, the vaccum has nowhere to pull from but the fuel needle in the carb...
    You may have noticed that some vehicles shoot flames and pop when you reduce the throttle, that is superheated fuel that has no air to burn, and ignites once it hits the fresh air, or left over partially lean air in the exhaust.
    That fuel comes from closing the butterfly valve, and the lower manifold pressure sucking fuel but no air... Remember that the carb relies on vacuum to supply fuel... low manifold pressure will suck more fuel regardless of if their is air coming with it or not...

    Try opening the throttle immediately after killing the ignition, in order to open the butterfly valve and keep the left over engine inertia from pulling a vacuum off of the closed butterfly valve... and accidentally sucking fuel into the cylinders and fouling the plugs...
    If this works, you have a few options, including adding a carb with two butterfly valves that you can control independently, and simply open the second one will relieve the vacuum, and with no vacuum, the fuel will stop flowing, and the engine will spin down...

    Of course, it could also be that your idle mixture is not working right, and so its releasing way too much during low RPM... which would have a similar issue...

    This is a huge problem with scooters and other simple engines... and can be relieved by being smooth with the throttle... and opening the throttle immediately after killing the ignition...
     
  5. Sep 2, 2013 #5

    C5Engineer

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    My 582 is inverted in my Avid and I have zero issues with fouling even after it sits for a week. Are you using a primer to start it? Priming is critical on mine. Half a shot is the difference between it flooding and firing. I found that if I pull the primer out and get it full and then don't hit it until after it's cranking it helps. What battery and starter are you using? The Ducati ignition needs a really healthy crank to produce a good spark. I've had mine crank and crank before and not fire and as soon as I pulled the cowl and yanked on the rope if fired first pull. I had starting issues until I went from a little dinky motorcycle battery to an Odyessy PC545. Another thing to help with firing while starting is to gap the plugs at the bottom of the range .016".
     
  6. Sep 2, 2013 #6

    rajiv

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    can i make ultralight with bike engines..Engine spec is 2 stroke petrol 98 cc 11.5 HP @7500 Rpm
     
  7. Sep 8, 2013 #7

    Vivianyeisley

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    Hello, One thing that I would recommend is to stop gapping your plugs. Get the Iridum plugs (BR8EIX) and use them right out of the box (DO NOT GAP). You will find that your fowling will stop. I do not even gap normal plugs (BR8ES), because every time I do they foul. Vivian (skip) f yeisley jr
     
  8. Sep 8, 2013 #8

    ve3xox

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    Spoke with a fellow flyer today. He was wondering how I was doing with the renegade. I told him I was having a starting problem. His comment was... "You have a rotax 582 and it's inverted and your plugs are wet fouling.... Right?". I told him yes, and his response was..... "You need a bigger battery." The battery seems to turn the engine but it can not supply enough power to the starter and the ignition system at the same time because the battery does not have the cranking amps. He told me he went through the same trouble a couple years ago and was told to go to a bigger cranking amp battery or jumper the battery on a start. It fixed all his problems. I guess I will give it a try.
     
  9. Sep 9, 2013 #9

    C5Engineer

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    The ignition system on a 582 is completely self contained within the engine. It doesn't use any kind of power from the battery. It DOES however need 300 RPM on the crank to produce a spark. At 299 it sounds like it's turning over plenty fast but it won't fire.
     
  10. Sep 10, 2013 #10

    ve3xox

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    Well interesting day today. Went out to the Renegade and dropped a fresh new set of plugs in her Gaped to 20 thousand. Replaced a couple O rings in the fuel system shut off valves, and fuel her up. I throw the jumper on the battery and to the van and climbed in .... master on, Mags on, Fuel on, Two shoots of primer, CLEAR , and pulled on that switch that has the magic word on it... "START". A whole and behold she fired up. I ran it for 5 or so minutes to bring it to operating temp and shut her down. Now for the test... Will it start again? Master on, Mags On, CLEAR and Start... And away she went AGAIN. So shut down again. Out I jumped and off came the jumper cables. Button down the cowling, Un-tie the horses from her tie down, and here we go.... Master, Mags on, CLEAR, Start and away she went. Purring like a kitten Tiger cub. One more test was to shut down one more time and restart. Away she went again. So out i went for some playing on the runway.... Tomorrow the test continues.
     
  11. Oct 4, 2014 #11

    ve3xox

    ve3xox

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    I got it all figured out..... iridium spark plugs! I installed a set and i have not had a problem since.....
    :)
     

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