Home Forums TaG Rotax Max Need Help with EVO MAX – Rev-limited to 12,400

This topic contains 5 replies, has 4 voices, and was last updated by  Ambrose Buldo 3 years, 7 months ago.

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  • #52621

    Ambrose Buldo
    Participant

    Getting frustrated by my Rotax with EVO Upgrade kit installed.  I had kit instaled by Rotax dealer.  When I got it, it would not rev past 12,400.  It would just reach that RPM and peak there.  I left it with the shop to address.  Not sure what they did to engine, but when I got it back it rev’ed  to 14,000 RPM.  I think the work order indicated clearing pulse line or installing a valve in the plumbing.

    Today I ran the kart again.  First couple sessions ran fine.  A couple sessions later a lap or two would pop up where the RPMs was again limited.  By the end of the day, maybe  session 7-10, if I ran 10 laps in the session maybe 8 of the laps engine would be limited again.  The Data just show it flat-lining. Its weird as one lap could be fine, the next not and then it is fine again.

    Any suggestions would be appreciated.  This is getting frustrating. We already installed the Crank sensor gasket.

  • #52698

    Josh Buttafoco
    Participant

    Try taking the pill out of the line that goes to the bottom of the powervalve solenoid.  Set the red adjustable spring cap flush with the Powervalve housing.

    We haven’t really had any issue with the upgraded spring/Powervalve routing… But we did come across one kit that the pill had burs blocking the flow of air that ended up with similar symptoms.

    The issue was solved ,with a new pill

  • #56396

    John Ruess
    Participant

    A too rich condition can limit the pull to where it won’t get into the second ignition timing. To test, use enough rear teeth so it can easily rev all the way up on the straight (like 2 or 3 teeth more) and go 2 jet sizes leaner.

  • #56449

    Ambrose Buldo
    Participant

    It took 1/2 a season, but I got the issue resolved. Although my EVO kit supposably had the upgrade to the upgrade, I ordered one anyway. It was probably a combination of things but mostly vibriation.

    1. My seloniod was hard mounted by shop. I put one rubber isolator on it (Kit only can with one). I also relocated the coil so it bounced around less.
    2. It is possible in some bumpy corners the coil may of been making contact with the seat.
    3. I also put a couple rubber washers between where the bracket mounts to the crank-case. That dampened a little more vibriation.
    4. Added the second crank sensor Gasket (Did not resolve the issue)

    I am running without resistrictor pill installed. I found that when I had the pill installed it got sucked about an inch down the black hose and it is a pain to remove. Its a pretty poor design. Intresting in that the dealer said he installed he pill but I could not find it. It has me thinking maybe there already is one stuck in the line.

    Running with 2 ground wires connected, it pulls 14,900 RPM. Next time out going to test back to back with one wire verses two.

    Also I think 14,900 RPM may be on the high side, I may drop a tooth. Can only help with engine longevity. What are you guys targeting for max RPM?

  • #56572

    Rob Kozakowski
    Participant

    Why set a target for max rpm?  It might be different at every track.

    Instead, target minimum lap time – that is always the goal no matter what track.

  • #56573

    Ambrose Buldo
    Participant

    Let me rephrase. Every engine as an operating range to balance performance and durability. Assuming one wants to get 50 hrs between rebuilds, what should top limit of RPM be? The EVO upgrade defnatly allows me to pull higher RPM than I was previously. I’d sacrifice a couple tenths in order to avoid prematurely wear the engine or dramaticially increase likley-hood of failure.

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