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  • Help?!

    My GPX250 has been giving me trouble lately. I crank it up and ride down the street no problem, then 2-3k's into my ride I give it some throttle and instead of giving me revs it cuts them, like the throttle is chocking the engine, after which the engine cuts out and won't restart. I got the carbs cleaned thinking it might fix the problem but to no avail.

    Anyone have any ideas/thoughts to what might be the problem? and any solutions?


  • #2
    Is the choke stuck?


    • #3
      Sounds like a proper carb clean is in order. What milleage you have will give some indication of what might be wrong. Things to check before you do any carb work are:-

      Fuel valve...if its a vacuum operated one then the diaphragm may be toast.

      Fuel valve filter.

      Tank vacuum vent...try running with the cap unlocked.

      Fuel line...kinked or routed kidding if the B12 I used to own had the line routed slightly upwards the motor would starve.

      If fitted fuel pump...filter or not working good enough.

      If none of these repost and I will walk you through possible carb probs.

      Good luck
      Smoke me a kipper...I'll be home in time for breakfast


      • #4
        Choke is in working order ZedRex, thanks for the input though.

        I'll run through what you've posted BusaSteve when I've got the time (uni can be a pain), but hopefully its one of these otherwise I'm going raging that I paid the shop to clean my carbs and its still acting up.



        • #5
          how long does it normaly take after its stalled to restart it?


          • #6
            Couple hours. I lock and leave it and come back later to try start it up, can usually get it all the way back home. But at the moment I haven't been able to get it running for a day or two.


            • #7
              That really sounds like a blocked float valve.... I had a very similar problem on my B12 except in my case one cylinder would not fire due to low fuel level in the carb bowl. I ended up removing all the bowls....carbs on.... and blowing the float valves clear. It worked and I never had the same thing happen again.
              Smoke me a kipper...I'll be home in time for breakfast


              • #8
                Should fire on one cylinder still (float valve in each carby) if it was a float valve. Doubt both gone?

                Check that petcock is working. Generally have a prime position which allows fuel through when not running. Next time it stops take fuel hose off an make sure its flowing freely (while on prime). If its not then investigate petcock further.

                No inline filter?

                Pretty sure no fuel pump in these. So that shouldn't be the issue.

                Long shot but when it stops check for spark. Spare spark plug comes in handy here.

                Another long one try leaving fuel cap open, this used to cause issues on my old gpz.

                Sent from my HTC Desire using Tapatalk
                Every one has a story.....



                • #9
                  also check your battery. leaving it a few hrs would maybe let it get enough charge to turn the bike over but once its flat u are depending on the alternator for power and if u slow down below 5k or so it will just cut out.


                  • #10
                    Some extra info:

                    While talking to a mate about the problem and brought up that choke is the only thing that gets the bike started and keeps it running; he thought we were onto something. I need full choke to get it running and if I let off it cuts out. Leading to thinking that its more of an air problem with it running too lean, and not so much of a fuel problem (though still very plausible). Maybe a rejet is in order?

                    This completely slipped my mind early, sorry for not adding it.


                    • #11
                      Carbs do not suddenly need a rejet so do not go down that path. The air filter may be so clogged as to cause a problem. As regards one cylinder not running not being the cause... even though my B12 only lost one cylinder it would bog down so much that it became almost imposible to ride. Now this was a four cylinder machine so a twin would be even worse. You may have an intermittant electrical problem but it is vital that you not get too many possible problems on the boil at once. Be methodical, pull the suspected plug and see if it is wet or dry....almost certainly a wet plug indicates an electrical fault whereas a dry one indicates a fuel delivery fault. Once you establish this then look further. Once established a fuel delivery fault can be one or more of a lot of things...esp on carbed bikes so I wont go into what these are until you know which fault it may be.

                      Good luck... and if you need some help I am more than willing to lend a hand.
                      Smoke me a kipper...I'll be home in time for breakfast


                      • #12

                        Hopefully I have some time this weekend to work on it, Ill post updates when i can