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    • #4679
      Scott
      Member
      • Topics: 1
      • Replies: 5
      Joined:
      Jul 13, 2020
      @sborder92
      Newcastle
      GT125R
      Points: 43

      So I had a GT125 for about 7 years. Loved it, but circumstances changed and I had to sell her. To cut a long story short, 3 years after I sold it I bumped into the guy I sold it to, turns out the bike was dead in his back garden, had been for a year, so I did what anyone else would do and bought it back for pennies as a better option than letting it sit and rot.

      Its been a long and slow road getting her back to her former glory but now I’m nearly there, mechanically she’s perfect again, except one thing… every time I go to start her after leaving to sit for even a day I have to crank the shit out of her to get her to start. I’ve ended up having to get a trickle charger and leaving it plugged in permanently so I can start the bike without killing the battery every time. With my limited knowledge of carbs what I’m assuming is happening is that the float bowls are emptying into the engine while shes sat. If you go back an hour later, she fires straight away again so I know its not a fuel supply issue.

      Yesterday I took the carb off and completely stripped it down. Removed every single part and cleaned everything. The bike had been sat with fuel in for over a year so plenty of gunk and shite came out when I was blasting it with carb cleaner and shop air but she runs perfect so I don’t think anything is blocked, I’m fairly sure its the float bowls running dry.

      My question is, what component should I be looking at to stop this happening? I just don’t know enough about what each individual part of the carb does to know where to look.

      Any help appreciated

    • #4681
      Simon
      Member
      • Topics: 0
      • Replies: 25
      Joined:
      Jul 13, 2020
      @syco
      Kent
      Gt250 f1
      Points: 170

      The float bowl will not empty into the engine, it’s worth draining the tank because you could have water in the system a little in there will cause the problem but when it is moved about it will work that would be the first thing to check.

    • #4682
      Scott
      Member
      • Topics: 1
      • Replies: 5
      Joined:
      Jul 13, 2020
      @sborder92
      Newcastle
      GT125R
      Points: 43

      I don’t think that’s the issue as when I got the bike back I completely stripped everything down, right down to the frame and the tank was drained and rinsed with fuel then dried with compressed air before being put back on. Its only had 5l of fuel put in since then and it hasn’t actually been out of the garage yet. I checked today and the float bowls are definitely emptying somewhere (I opened the drain valves on either side and not a drop came out) but there is no fuel around the carb, under the bike or anywhere like that. If that quantity of fuel (I reckon both bowls hold about 50ml between them) was leaking into my garage and evaporating I’d definitely smell it.

      It just seems strange that I have to crank the engine for a good few minutes to start the bike each day, but once its started once it’ll fire first time if you kill it, or even if you go back a few hours later it only takes a couple of turns to go. When I’m cranking the engine to start I can even hear the engine getting closer as it’ll do nothing for a bit, then it’ll stutter when its starting to get fuel but not enough, then eventually it fires no problem. I’m ready to pull my hair out with it!

    • #4683
      Simon
      Member
      • Topics: 0
      • Replies: 25
      Joined:
      Jul 13, 2020
      @syco
      Kent
      Gt250 f1
      Points: 170

      Could well be the float needles sticking

    • #4684
      Simon
      Member
      • Topics: 0
      • Replies: 25
      Joined:
      Jul 13, 2020
      @syco
      Kent
      Gt250 f1
      Points: 170

      Check the fuel pump is connected the right way as well

    • #4687
      Scott
      Member
      • Topics: 1
      • Replies: 5
      Joined:
      Jul 13, 2020
      @sborder92
      Newcastle
      GT125R
      Points: 43

      When you say float needles do you mean the needles in the slide valve assembly? I was running the bike with no air box/filter so I could see the slide assembly opening and it’s not sticking at all but then I know the needles have been lowered a notch to tune 3/4 throttle response so there’s a chance they might not be closing… Is it the needles that would control fuel flow to the Venturi when throttle is closed? I thought that was pilot jet? But then I suppose on thinking about it that if those needles weren’t seating that fuel could bypass the pilot jets and drain the bowl? But is it likely this would happen on both sides of the carb for both cylinders? If it was happening on one but not the other should the engine start running on one cylinder only? I’m going to record the starting procedure tomorrow and upload so you can see what is happening

    • #4689
      Simon
      Member
      • Topics: 0
      • Replies: 25
      Joined:
      Jul 13, 2020
      @syco
      Kent
      Gt250 f1
      Points: 170

      No in the bottom bowl there are floats which move up & down to control the fuel level these are held in with a small pin they act upon a small needle that allows the fuel in.

    • #4692
      Simon
      Member
      • Topics: 0
      • Replies: 25
      Joined:
      Jul 13, 2020
      @syco
      Kent
      Gt250 f1
      Points: 170

      The first thing to check would be disconnect the fuel pipe from the carbs put it in to a container & crank the bike & see if you are getting fuel

    • #4699
      Scott
      Member
      • Topics: 1
      • Replies: 5
      Joined:
      Jul 13, 2020
      @sborder92
      Newcastle
      GT125R
      Points: 43

      Carb is definitely getting fuel. Float needle valves aren’t the issue as they allow fuel IN to the bowl when the level is low when the bike is running. They should be shut and not allowing any fuel in when the bike isn’t running. The problem is that the fuel that is in the bowl when the engine stops is draining somewhere… After examining the carbs and parts diagrams and following the flow of fuel through the carb the obvious thing to check is the slide needles but I have checked these and they are both seating correctly.

      I just don’t know where to look next.

    • #4710
      Scott
      Member
      • Topics: 1
      • Replies: 5
      Joined:
      Jul 13, 2020
      @sborder92
      Newcastle
      GT125R
      Points: 43

      Carb rebuild kit ordered, new gaskets and valves. Will rebuild carb again and see what happens.

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