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ZZR250 Performance issues

Discussion in 'Technical and Troubleshooting Torque' started by trustno1, Aug 8, 2014.

  1. Hey guys :)

    I replaced the carb on my 1990 ZZR250 a couple of weeks ago due to a pretty bad fuel leak from my old carb.
    Since I have had the new carb in my performance has been shocking, I have no "oomph", I can do a 0-60 in about 10 seconds and my acceleration tapers out at about 10k RPM. The little acceleration I do have, Which isnt much at all, occurs at about 6-10k RPM. I am riding with my throttle constantly open to maintain a constant speed most of the time, unless I am going downhill.

    Any ideas what could be the cause and how to fix it?

    Thanks :)
  2. Carb needs a rebuild
  3. thought i would chime in as obviously the above post adds no value to your thread.

    get this looked at immediately as there is a chance you could do damage to your engine if left.

    Was your carb replaced with an OEM carb?

    Is your bike running any performance mods?

    Do you know what jetting is in the carb?

    Was your bike running hot when you did ride it after the carb change?

    Either way pull your spark plugs out and let us know what color the insulator around the centre electrode is. This will tell you if your bike is running lean, rich or A OK.

    Lean - plugs will be black or a very dark color
    if lean locate your fuel screw and turn it out a couple of turns then take for a quick ride, then if improvement shows fine tune it until you are happy. This process is the same if it is rich, just turn the fuel screw the other way.

    Rich - a very ligh color

    Fuel air mixture ok - plugs will be a tan color

    Get your manual out and study up on the carby system. Cheers.
  4. Yep, get a bigger bike. Read just like a 250 to me.

    OK, assuming you had better performance before, is it a new carb or a different second hand one?

    Are you aware you can get kits for carbies? If you had a leak, why didn't you just get a kit?

    If it really is a new carbie, what is it, who sold it to you, did they sell it specifically for your bike?
  5. wouldnt the plugs be black if rich?
  6. Actually, thinking about it, a zzr250 has two carbies. Did you replace both? did you sync them after you replaced it?
  7. right you are, my bad, had to double check what i posted. My apologies for leading anyone down the garden path. Should probably proof read my post before throwing it out there. Cheers.
  8. Lol you had me confused, had to check ;)
  9. I replaced the carb with a second hand OEM from a wrecker bike.


    More or less, More of the less though. I can use google so ill read up on it so I understand your reply :)

    No hotter than usual.

    Ill make some time over the weekend to pull off the tank and check the plugs, Also need to check my thermo too so ill do it all in one hit.

    As I said earlier in this message, Its a second hand OEM from a wrecker.

    I am aware, But the guy I spoke too said that it would cost about the same for a kit and a new carby so I went the later route.

    I replaced the entire carby unit, so yes.
    I didnt sync them, Should I?

    Thanks guys :)
  10. The problem with carbies that have been off the bike for more than a few months is all the rubber dries out and cracks.

    So you usually have to put a kit through them. . . . .

    And yes, you should sync them.

    I think you need to pull your carbies down, thoroughly clean them and have a good look as all the O-rings and seals.

    You might be able to build two good carbies from the 4. Pick the best two needle jets and needles.

    Set float height and the idle jet.

    Then sync them.
  11. The carbs were sitting on the bike with petrol in them, so the rubber should be ok.

    Ill pull them off and take a look today though.

    I have no idea what to look for regarding good needles and jet, so ill take many photos and post here for some opinions :)
  12. #12 trustno1, Aug 9, 2014
    Last edited: Aug 9, 2014
    Hi guys.

    I got one of my spark plugs out, the other one looks like it doesnt want to play nice. Ive attached a photo but other than some slight yellowing(rust?) on the metal and insulator it looks fine.

    I also noticed that one of the pipes leading to the carb from the airbox was half off. Could that be a cause for my issues?

    Attached Files:

  13. Probably not. Sometimes you can get some oddness, but it shouldn't be that bad.
  14. I got my other spark plug out and it had some oil on it, Not a significant amount but enough to make it look black