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Could it be carb sync? 93 zzr250 kawasaki

Discussion in 'Maintenance and Servicing' at netrider.net.au started by enginewrecker, Apr 23, 2012.

  1. I have a zzr 250 kawasaki 93 model that developed some problems with lurching under load.
    I cleaned the (twin) carbs and it ran well, was really responsive to the throttle and good at idle, for a while. I sounded different to what it had though, almosst a roaring, 'sputtering' sound to the revs when increased.
    After cleaning, rebuilding, I didn't sync the carbs at all and within a month it did the same thing as before, started pulling/ lurching under load. The first symptom I noticed that anything was amiss was the idle speed became too low and it threatened to die at idle.
    I cleaned rebuilt carbs again and it worked well for just one ride of about 15kms then it started to lose power again under load, sputtered and lurched as before.
    Being a beginner I didn't sync the carbs at all and have been reading a bit about this and am wondering if this may be my problem, since each time I rebuild the carbs the bike runs great for a little while then starts with the same symptoms and then rapidly declines.
    Could anyone share their thoughts please?

    1993 zzr 250 kawasaki
    no mods
  2. Same issue with my CBR400 after having the carb cleaned........might take it to the mechanic to get him to sync it and dyno it.
  3. Thanks for the advice.
    I would sink my teeth into the wallet and do the same but I've already eaten it. There's a homemade carb sync tool being mentioned on the net somewhere that I might have to try, in lieu of funds.
  4. Have you drained and flushed your tank? Could be picking up gunk from there, specially if it only lasts 15 lays. Have you cleaned the air filter as well?
  5. I made my own carb synch tool. I picked up a few metres of clear plastic tubing from Bunnings (The size of the tubing depends on the size of the connection points on your bike.) I tied the tubing onto a bit of timber 1.2m or so long with cable ties - you just want something stiff to hold it steady. I filled it with 2 stroke oil about 50cm up each side. It's easiest to suck the oil through and be careful not to get bubbles in the oil. Otherwise leave it to sit until the bubbles rise.

    You can put one way valves in the lines, but I didn't. I was ready to flick the kill switch if one side started sucking madly.

    Then just turn the appropriate screw until both sides of oil stay pretty level.
  6. Thanks a lot for the response, I have drained and flushed the tank and cleaned the air filter too.
    There is one strange factor regarding the air filter that may be an issue though, the air filter doesn't snugly fit the intakes on the carbs. It does seriously leak, but has done since I first got the bike a few years ago and it ran fine like that for a long time.
    Last carb rebuild, I decided to gaffer tape up these leaks and then couldn't get the idle right, so I tore it off and then just managed to get it to idle properly again.
    I figured that whenever it has been serviced previously they've taken into account the gap between filter and carb so I should leave it like that.
  7. Thanks a lot for this. Could you please tell me which part of the carbs the lines connect to and which screws you turned?
  8. If you want a good site check out faq.ninja250.org. the engines are exactly the same as the gpx 250 and the ex250 sold in the states. There is step by step guides on carb balancing there. I'm thinking your issue is probably more mixture related though.....
  9. I agree it sounds like a problem with the right amount of fuel getting through.

    In relation to my bike, the synch ports and details can be found here. It's not the same bike/engine as yours though, so I'd be checking out the site suggested above.
  10. i own a zzr too ...pretty sure i've got a owners manual hidden away on one of my laptops..might be easier to understand the schematics of the bike with it...let me know if you'd like me to forward it on....i'm always keen to hear of both problems and solutions people have with the same type of bike i own/have owned so i'll keep an eye on this thread
  11. Thanks a lot for all the advice.
    I also posted this same question on yahoo answers and someone suggested that it might have something to do with the varnish crud on the inside of the tank from 20 years worth of fuel. The problem is that these new ethanol fuels dissolve the crud and then there's a carb full of gunk again.
    The suggestion to cure this problem was to add an inline fuel filter and to sync the carbs.
    I also had the fortune to speak to the Tasmanian state champion motorcycle mechanic who suggested it might be a petcock problem and to test for that by taking off the tank and gently blowing into the smaller tube for about 30 seconds to see if the flow from the large tube remains consistent and constant.
    Also, he suggested riding the bike and opening the tank when the problem starts to check and see if it might be an obstruction of air flow into the tank, as it has an air hole which can become blocked thus obstructing fuel flow.
    To 87crisis, that offer of a copy of the ever elusive zzr250 manual is very kind and is one that I would very much please like to take you up on. The state reference library here in Tassie haven't got the manual for the zzr (which they are actually supposed to have) so I've been working from diagrams for a zzr600 which is a quad carbied bike. I got one manual from repairmanualclub when that site still worked years ago, but it's actually lacking large portions of each chapter.
    So these are my options;
    1.clean carbs (again)
    2.test petcock
    3.test tank air inlet valve
    4.install inline filter
    5.sync carbies
    6.clean and coat inside of tank to prevent varnish dissolving
    I will keep you all posted on the progress of this endeavor.
  12. bah lost my old copy somehow...only had some half assed supplement...so here's a link i found for the service/repair manual for the 1990-1996 zzr 250 ...i have downloaded it and checked it myself first (needed another copy anyway) and it's all above board...it's in pdf format and about 20MB download


    there's the three preview picture's in the middle of the webpage there...and a very small "download" button just below the pictures...click that...not the open pdf or any other banners.

    hope it helps mate.
  13. Exact same symptoms as my bike. I kept cleaning the carbies, etc. In the end I found a crack in the fuel hose, coming from the tank. Once fixed the issue was gone. So could very well just be that minor issue. Hope it works out.