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power fading in a ZZR250

Discussion in 'Technical and Troubleshooting Torque' started by Arch-Angel, Jan 19, 2009.

  1. Hi guys, I have an old ZZR250 that doesn't get much use, and want to pass it on to my partner. Having a few issues though, and can't seem to diagnose the problem...
    Any help would be greatly appreciated!!

    Bike: 1991 Kawasaki ZZR 250
    K's: about 18,000
    No modifications, regularly maintained up until I stopped riding it about 18 months ago (brought it back gently though, didn't give it a rough time after it had sat for so long or anything!)

    Problem: Basically it starts out by riding fine. But after a few minutes it starts to feel a little drained for power.
    After around 10 mins you need to start revving it a lot more off a standing start (lights etc) to get it moving.
    After needing more and more revvs to get it going it really starts to feel very lethargic and eventually 'runs out of power'.

    When it stops it cannot be immeadiately restarted, but usually if I just let it sit and then restart it in a few days it doesn't have any troubles starting up.

    I had the tank and hose clamps replaced a few months ago because there was a fuel leak.
    Still seems to have a leak after the above problem happens though - a very constant drip.
    I've taken the tank off and checked the lines but haven't been able to see where the fuel was coming from.

    At first I thought I may have a blocked fuel filter (new tank and all) and that a blockage in it was causing there to be a decrease in the flow of fuel to the point where it was overheating.
    But I've since learned that these ZZR's dont actually HAVE a fuel filter... :cry:

    So I'm kind of at a loss now... any suggestions??
  2. Have you replaced the old fuel? Fuel does have an expiry date.
  3. Not knowing too much about these bikes i dont know if there are any common issues that would cause that problem but I'd start off sorting out the fuel leak and have a good look at the rest of the fuel system, take off the carbs and give them a good clean out/inspection and make sure there is no crap in the tank. If possible add an inline fuel filter. Fresh fuel as the first reply suggests.

    If that doesnt fix it I'd start checking other things, air, fuel, spark!

    Edit: if you left fuel sitting in the carbs for 18 months i'd definately clean them out. I am of the understanding that this is bad, fuel sitting in carbs for long periods can cause problems.
  4. Yeah the tank pretty much leaks out completely when it's left to sit, so I've put new fuel into it a couple of times now...

    I have a feeling there is a very very small perforation in the fuel lines (I didn't replace them when I did the tank) that I can't detect. I might try replacing the lines.

    Will clean the air box and carbs as well.

  5. in order of likelihood
    -tank vent
    -vacuum line to fuel tap
    -fuel lines

    Not just condition, but good seal at the fittings
  6. Do you know if its running rich? That'll make it start really easy, then when it gets warm it'll bog down unless you rev the hell out of it.