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Thread: Low RPM riding and engine noise

  1. #1
    Senior Member Mesozoic's Avatar
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    Low RPM riding and engine noise

    As I've been tuning my '09 1125CR with upgraded exhaust and K&N filter (I've got the AFVs to within 0.5% front and rear), the engine now runs smoothly all the way down to 2000 RPM. While I never go WOT at that low an RPM, the engine makes quite the racket at lower RPMs - mainly below 3000 RPM. Is this normal? It runs smooth and has torque, but it sounds like there's a fair bit of chain slap going on and being new to the Rotax engine I'm unsure whether that's a sign that I need to adjust the valves, replace the chain tensioner guides, or WHY.

  2. #2
    Senior Member BuellyBagger's Avatar
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    I dont have an answer for you question, but any one who might will want to know mileage and previous repair history. just heads up

  3. #3
    Senior Member Mesozoic's Avatar
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    The bike has 17K miles on it, is originally a southern Arizona vehicle (I reside in southern Arizona), and according to the service records has been meticulously maintained throughout it's life. It runs very well, otherwise.

  4. #4
    Senior Member Cooter's Avatar
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    That's an extremely low rpm for that motor and hard on it, it's not a diesel!! It's making noise because it doesn't like it. They were designed to RPM and prefer it so don't be so afraid to spin it up. Not extreme like a I-4, but not a diesel like you're treating it now.

    Red line is red line and anything below it is fine. You will do much more damage to it by lugging it around than using it with some rpm.

    Personally I cruised my CR at 4500-5500 and only went WOT after downshifting. The SX is even higher! It hates anything below 5000 and makes power after 8000.



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