Forums 🚥 PIT STOP 🔧 Hyosung Technical Help Bike start’s but revs to 6k after upgrades.

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    • #4974
      Alan McLean
      Member
      • Topics: 7
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      Joined:
      Jul 21, 2020
      @macker
      Orihuela Spain
      Aquila GV125
      Points: 281

      Hi Marcel, after doing all the upgrades, main jets, new coils and cap’s and carb’s stripped and cleaned new fuel lines and vacuum line everything thing went back on today. The bike wouldn’t start initially and took quite a while for it to start it eventually did. The problem is now that when it starts the revs climb to 5.5/6k and no matter what I do with the idle adjustment it has no effect on it.

      Any ideas?

    • #4975
      ♠️ MARCEL
      Administrator
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      @mf448kxn6
      North UK
      GTR
      Points: 4,343

      Hey,

      Since you took the carb apart; the fuel was drained. It takes a few cranks for the fuel to eventually fill the carb bowls then it starts cause the pilot jets dont reach deep enough to start drinking and idling away. Choke speeds things up.

      Revving to 6k is caused by either of these  = manifold leaks , airbox leaks (both airboxes top and right) , loose intake clamps , leaking vacuum port on manifolds , carb not sitting properly , choke cable stuck (?)

      Check choke is fully disengage BY THE CARB itself , check throttle cable and OPERATE THE SWING GATE (where cable slots in) at the carb by hand after disconnecting throttle line.   if revs go down after cables removed , investigate lines or metal assemblies where cables join to carb.

      Hope that helps.

       

      // Meditation doesn't mean you have to sit still....

    • #4977
      Alan McLean
      Member
      • Topics: 7
      • Replies: 15
      Joined:
      Jul 21, 2020
      @macker
      Orihuela Spain
      Aquila GV125
      Points: 281
      1. Hi Marcel, thanks for the info, I think I must have a leak somewhere. I checked both throttle and choke action before trying to start it and they were both operating perfectly. Will have to investigate the manifolds and vacuum lines 😔

    • #4992
      Alan McLean
      Member
      • Topics: 7
      • Replies: 15
      Joined:
      Jul 21, 2020
      @macker
      Orihuela Spain
      Aquila GV125
      Points: 281

      Hi Marcel, I have discovered what the problem was with the bike revving to 6k, the linkage between the two carbs was being fouled by one of the clips on the intake manifold. However after sorting that out I took the bike for a quick ride and was very disappointed, the bike reels exactly the same before doing all the upgrades, new main jets, new coils and plugs etc. The bike feels dead in the lower rev range very little power until the revs get up to about 5000, this is how it was performing prior to changing anything.

      Any ideas or suggestions?

    • #4995
      ♠️ MARCEL
      Administrator
      • Topics: 38
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      Joined:
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      @mf448kxn6
      North UK
      GTR
      Points: 4,343

      Check spark plug and put the picture here front and rear so I see how dark or light the white cones are.

      Also poorer running is a result of the following

      • Valve Clearances
      • Carb float must be 7mm (all 4 floats inside)
      • Slide needle too rich / too lean (this is midrange from 2k to 6k revs)
      • exhaust modified ? (Make exit hole / baffle of exhaust size of a 10p british coin or 2.4cm diameter hole at exhaust => the bigger the hole, the flatter it feels, some pressure needs to stay inside)
      • Coils will do their job but we don’t know how strong the CAPS are (stock caps?)
      • Coils also run a little better when your charge system is better (stator&reg + battery)
      • Clean rear pump.
      • Spray intake boots and airbox with carb cleaner => if revs change, you have a leak

      if you change gears or downshift etc, and bike feels delayed in picking up revs etc,  pilot jets are clogged again.   Don’t play with the fuel mixture screws and leave it OEM.

      // Meditation doesn't mean you have to sit still....

    • #4997
      Alan McLean
      Member
      • Topics: 7
      • Replies: 15
      Joined:
      Jul 21, 2020
      @macker
      Orihuela Spain
      Aquila GV125
      Points: 281

      Hi Marcel, I checked all float levels when I was cleaning the carb’s, standard exhaust, new NGK cap’s supplied by you, and new battery. Slide needle’s set on third ring as per your tutorial. How do you clean the fuel pump? I’ve only ridden the bike once since doing all the upgrades, hope pilot jet’s aren’t still blocked 😔

      Will take the bike out again tomorrow and check the plugs.

      Thanks.

       

       

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