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Once hot, running very bad (gsx250f)

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by johny_tas, Feb 26, 2009.

  1. Hey all
    i've been using netrider for about a year now and it's an awesome site.. used it for everything and now i'm 2 days away from my p's test..
    i have an issue with my bike though and was just wondering if anyone had experienced it or something like it before

    So basically the bike runs like a dream when its cold, its smooth and quick... however once the temp gauge gets above say 1/3rd the bike starts to go slower, and needs more revs to get it going..
    Then once the fan has to be used to cool it in like traffic (about 3/4 to hot) the bike runs like absolute shit.. it splutters around, its hard to get going to the point it's just not safe to drive through the city because once it gets this hot it stalls as soon as you take off even with super high revs etc..

    yesterday i was practicing uturns for like 30 minutes for p's test and the fan had to often come on, when i had finished i went to take off and it just died as soon as i started to move.. like impossible to take off without it just stalling as soon as you started moving.. i had to wait like 5 minutes and take off at the speed i was doing uturn's at to get going in which i had to do several runs of this road i was on to cool the bike down to be safe going through traffic..
    you can feel it getting better while your driving fast, and the temp gauge drops.

    Also when starting when you need to use the choke, it must be turned fully on.. if you touch the throttle or move the choke back slightly it does instantly.

    it needs to be serviced that's a given, but that will have to wait a couple of weeks..

    sorry for the long write, and no worries if no one replys.. netrider rocks and a big hello to you all :)
  2. Sounds like it might be running lean - try whipping one of the sparkplugs out and see what the end of it looks like.
  3. I had very similar problems (with the exception of having to use the choke) when my bike was running rich.

    You do have enough water/coolant in the thing, right?

    When riding around in 40+degree heat in traffic recently my bike would get a little bit bogged down when taking off but nothing too bad.

    A few months ago when it was running rich the bike would have struggled to take off after sitting in traffic on a hot day.

    But like jd said, could be running lean also.
  4. Overheating can also be caused by an air pocket in the cooling system - coolant level might seem okay but the engine can still run hot.
    Draining and refilling the system would probably be a good idea, if you don't know when it was done last you should do it anyway.
  5. Get your cooling system checked out, on my Across you would feel a noticable decrease in performance but sounds like yours is going just beyond it.
  6. thanks guys, will replace the coolant today and see if it makes any difference..
    i suspect something is wrong with the fuel anyway considering the choke issue, so it has to be serviced.. it's just im taking my p's this sunday and don't really want to pay the $60 to use one of theirs.

    it is tasmania so i'm only talking like 20degree heat, and one of the issues is that every time you stop your on a hill... so i might be able to make it start extremely slowly on flat ground.. but going up a hill, that same max amount of power i can give it wont be enough to get me going...

  7. Did ya get your P's?
  8. lol, have you seen the stroke of the engine? its tiny. i wouldnt think thats a problem. you need to give it about 4.5k -5k to get going up a hill.

    going up my driveway, if the engine gets below 3k it will bog down and ill have to roll back and try again :LOL:

    and the bike does run hot fairly easily but the fan should be able to bring the temp back down
  9. change to a hotter temp spark plug seems your bike's temp guage is running right i hope u done well on your P's test i done mine recently and i thought my bike was going to over heat so with the sounds of your bike i think the instructor would have sent u home?
  10. Valve clearances closing up when bike heats up.
    Get the bike a thorough service.

    Regards, Andrew.
  11. Try checking your Carb slide holders. Theyre cheap and easy to replace, and my across ran very similar to how you are describing when mine were worn. The bike running better when cold indicates towards running rich, a symptom of worn slide holders.

    More info at http://au.geocities.com/ozcross250/holder.html
  12. Are you sure it's not running time related rather than heat related.

    Try opening the petrol cap next time it starts running rough.