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GPX250 Loss of power when accelerating.(amongst other probs)

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by loth, Feb 23, 2007.

  1. It all started with some idle problems. Hard to explain but here I go.

    It usually idles at 1.9K or so. When rolling to a stop at the lights, it would go unusually low, like 1K or so, and sometimes die down. It also happens when I rev it up while in neutral, it drops to like 1K and does not want to come up unless I manually rev it slowly to 2K. I also tried another thing - let the clutch out slightly so the bike moves a little, but not enough to stall it. Clutch in... rev stays down.

    When accelerating, I feel like a loss of power. It will not accelerate 'normally', and is not as responsive as before. Sometimes I'm under the impression that it's behaviour is erratic, as in sometimes it would accelerate sharply and sometimes it 'takes some time?'.

    And last but not least, my bike never needed the choke to start. But I tried putting it on just to see what would happen, and it doesn't start at all with it on. Started the bike, and added some choke, it just stalled.

    Thanks for reading and hopefully I'll be able to fix it up without going to the mechanics :]
  2. My first guess would be to check your choke and see that it isn't stuck on...
  3. Actually, adding choke means reducing air flow and increasing fuel delivery. The reason why the bike might be stalling when adding choke is the lack of air.

    This lead me to check the valves. They have little, too little clearance. I was not willing to adjust the valves since I could potentially mess up the bike big time, therefore bringing it to a mechanic's on Wednesday.

    Can anyone tell me if the above makes sense, I'm by no means a pro on bikes.
  4. yeah it does make sense. Generally sounds like an overall tune is in order. The valve adj on those is pretty easy being with adjusters and lock nuts. if they are out then the carb balance is prob out as well and hence some idling issues. Then if going that far a good mechanic will check fuel bowls and float levels (again a piece of cake on those)

    A proper service should see it running much better :)

  5. I just went with the easiest to check first :)

    You can also check spark plugs, valves, carb sync/cleaning. You'ld prolly be better off to set aside a weekend (or a day if your quick) to check the whole bike out.
  6. Btw - I always thought tight valves meant it dies when idling, but runs okay while at speed? Maybe I'm wrong, or maybe its advanced beyond that. Never hurts to check them anyway.
  7. Yes thanks :]

    That's correct Bonkers. Well it might be only one problem of many. :'C
  8. I just did a test. While idling, I added Choke. It eventually stalled.
    Next I did was let it idle, added choke and at the same time added throttle. It then idled with a higher rev while the choke was on.

    Air problems? Tight valves? It sure seems so...