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  1. #1

    900zxi falls off at 3/4 throttle

    A couple weeks ago, I started having issues once I hit 3/4 throttle.

    It seems okay up to that. It gets up to about 6600 RPM if I keep it just below 3/4. Above it the rpms drop off pretty fast.

    I had it set to 1 1/4 low and 3/4 high.

    I changed it the high to 1 turn but I still have the isse.

    Engine and carbs were rebuilt last year. Compression is at 120 on all three cylinders. It running fine a couple weeks ago.

    Any suggestions?
    Anyone have carb setting for a 900 zxi?

  2. #2
    If you haven't already I would check the fuel filter, the pick up in the tank and the tank vent valve.

  3. #3
    Rodsatheart's Avatar
    Join Date
    Nov 2014
    Arkansas SoCal transplant
    Sounds like there might be some crap in the metering circuit of one of the carbs or the inlet filters are restricted a bit.. Did it change at all when you turned them out ? Looks a tad rich on the low speed screws, but if it likes them there, leave em. Have you tried applying the choke a tad to see if that helps ?

  4. #4
    I replaced an external filter outside of the tank and cleaned the small filters in the carbs. I have not pulled the ones in the tank.

    Roddaheart, last weekend I pulled the choke and it seemed to improve. As a result I turned the screws out from 3/4 to 1. I was planning to go to 1 1/4 out today.

    The low end seemed a little week so I turned that out too. I think I may turn them in. It doesnt seem to be loading up but there isnt a lot power.

    The factory settings I found online for the 900 were all over the place but non of them were jver 1 turn out on the high speed screws.

  5. #5
    steve45's Avatar
    Join Date
    Feb 2008
    If it used to run good, then starts running lean, then you either have trash in the fuel system or an air leak. Adjusting the mixture screws is like putting a band-aid on a broken leg.

  6. #6
    I turned in the low screws in to 1 turn and the high out to 1. Started having issue on the low end but high end was a little better.

    I then turned the lows back out to 1 1/4 and the highs out to 1 1/4. It ran pretty good. No issues with flat spots or rpms falling off.

    I think I could turn them out and get a little more out of it but as Steve pointed out there may be an air leak.

    I am thinking I should do a leak down test.

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