Rotax start up issue?

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  • #66083
    Greg Welch
    Participant

    My first thought is that there is a main seal issue on the crank seal behind the gear case.

    When the balance gear went was the gear case still full of oil? I wonder if that seal went and sucked all the oil through the engine causing the balance gear failure in the first place. With the pulse tube off of the gear case you should be able to feel a pretty strong pulse coming out of the engine, if not it is not likely that seal. It is possible to get it out without breaking the bottom end apart, its just kind of a pain.

    Other than that, about all it can be is an issue with the way the lines are hooked up, an issue with the way the gears are installed, or the fuel pump needs a rebuild kit.

    #66084
    JasonMorton
    Participant

    So i double checked my gear alignments and markings all in place and that checks out. My new fluid was still in there which is good and I am getting a pulse pressure from my pulse line port on top of my gear case nipple. My fuel pump was working perfectly before my gears took a crap so im doubtful my fuel pump needs a rebuild kit but i suppose it wouldnt hurt to do it anyways at this point so Ill order one hopefully from Greg. Ill mess with it more tomorrow but new plug gears are all set im getting spark so hopefully the only issue is the fuel getting to the cylinder at this point as i already went through everything on the motor on the bench again tonight and everything is clean clear and looks good up to this point. If anyone has any other ideas please chime in …THANKS!

    #66086
    Greg Welch
    Participant

    So from this point I would attack carb. I would give it a thorough disassembly and cleaning.

    #66085
    Joe Hawley
    Participant

    I agree with Greg, I’ve had a lot of experience with this motor and they’re pretty reliable. Got gas, spark, compression, and the timing is right it’s got to run.
    I’d really look at the fuel pump or carb. Make sure your fuel and vacuum lines to the pump are not sucking air. If you had another pump to try it would be the easiest to change then look at the carb, doesn’t take much dirt to plug them up.

    #66087
    JasonMorton
    Participant

    So i finally figured out my issue today and thought id give you all an update. The issue was i getting low compression still and the fault was a stuck piston ring in the piston groove. Not sealing like it should have so today with the help from Lee@ SBR Motorsports we got it properly diagnosed and fixed with a complete top end rebuild with a new piston and all. Put it back together to test fire her and we have strong compression back and it fired up instantly! So now ill just finish putting a few more things back on and then its ready for more track time 😀

    THANK YOU LEE, GREG AND EVERYONE ELSE THAT CHIMED IN HERE 😀

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