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    • #4665
      Sev
      Member
      • Topics: 1
      • Replies: 1
      Joined:
      Jul 7, 2020
      @seve
      USA
      2008 GV650
      Points: 32

      Hello gentleman,
      I need your help to troubleshoot my 2008 Hyosung GV650 ( carburetor model ). Motorcycle has 1,500 miles. Currently the motorcycle is not running.
      I bought the motorcycle a year ago ( off Craigslist), garage kept, looking good and running okay..
      The day I bought it, I rode it for the whole day, logging like 200 miles, without issues.
      Then I parked it for 6 months in a friend’s shop ( decided to travel).
      After 6 months the motorcycle would start and run but turn itself off after a few seconds or minutes, or when I would rev it, or when the choke would be pulled, or when I would drop it into the 1st gear…sometimes it would make it around the block, but not more then that.
      I figured that I have a carburetor problem.
      I changed the oil and filter and it run a little better, but then the starter solenoid broke, and had it replaced…since then the motorcycle started to act a little weird.
      It would start ( when it wanted to ), so it was time to clean the carbs.
      I stripped the carbs and soaked it in muriatic acid, sprayed carb cleaner, and compressed air.
      The membranes are fine.
      The carbs looked okay, not too dirty, but to my surprise the carbs were setup ( by the previous owner) to run with the air/fuel screw turned in all the way.
      After I cleaned the carbs, adjust the float height and the air/fuel screw the bike still would not start/run without pulling the choke or twisting the gas.
      * One day I filled the carbs and lines with Seafoam and gas and let it stay for a couple of days and to my surprise, the bike would start and run LIKE NEW, I could not believe it ! My excitement faded away 1 hour later and 5 miles down the road…the bike would act up again getting hard to start and/or stay running.. This is what drives me crazy.. the bike would not run good, then use Seafoam and the bike would run good for a short time and then acting up again, all this without touching the carbs or any other component. The bike was running perfect with and without the air box/filter..
      I kept on playing with the carbs and now it would not start at all regardless what I do.
      I will not start even if I spray starting fluid into the carbs.
      Bought a used carb from a gt650 and still no luck ( I had to clean and adjust the “new carb”).
      Compression is at 200 psi both cylinders.
      I have good spark ( I would say).
      I took the coils from a 2009 gv650 EFI – a friend’s bike ( I know they are different..) but same result.
      I installed new spark plugs. The old sparks were black coated in carbon ( the engine was running very rich, black smoke when revved and backfire )
      Bike is stock , factory air filter and exhaust.
      Valves have carbon deposit.
      * When the bike was running the rear cylinder was running 10 degrees hotter then the front cylinder.
      Also I checked for vacuums leaks ( spraying starting fluid around the engine/ carbs / hoses with the engine running, and I couldn’t find any ..

      Could I have a timing / ignition misalignment ?
      I am a little scared to open that engine, but I guess that is what is next..
      I am running out of ideas..

      Any advice would help.
      Thank you

    • #4667
      Simon
      Member
      • Topics: 0
      • Replies: 25
      Joined:
      Jul 7, 2020
      @syco
      Kent
      Gt250 f1
      Points: 170

      It’s got to be a carb issue also change the fuel filter, the problem with unleaded is when it’s left it goes like varnish the only way to really clean the carbs is ultrasonic. I personally would go through the whole fuel system tank everything, I think the gv has a vacuum fuel pump that might be an issue as well.

    • #4670
      Sev
      Member
      • Topics: 1
      • Replies: 1
      Joined:
      Jul 7, 2020
      @seve
      USA
      2008 GV650
      Points: 32

      Hello Simon!

      Thank you for replying!

      I was thinking about this, that’s the reason I got the second carburetor ..

      I think the engine should start/run if I spray starting fluid in the carbs/intake ..but it doesn’t.

      I will clean the carbs again – I don’t have access to an ultrasonic- but I’ll do my best.

      Something tells me that there is something else..last time I rode the bike I heard a ‘clonk’ noise in the gearbox / lower part of the engine just before I returned from my 1 hour glorious riding. The engine was still running after that, but became increasingly harder to start in part because I was playing with the carbs, especially the float height .

      Thank you

    • #4672
      Simon
      Member
      • Topics: 0
      • Replies: 25
      Joined:
      Jul 7, 2020
      @syco
      Kent
      Gt250 f1
      Points: 170

      You need to back track your moves, the bike was running fine when you got it but then it was left for 6 months then problems this is fuel related, the trouble is you have tackled several different things which can make things very difficult to figure out, it’s adjusting the floats that concern me if this is wrong it will flood the engine & it will not start regardless of what you spray into them, take the plugs out & give it a spin over see if anything sprays out. Leave them out for a day to dry the cylinders then go from there. If there’s a spark & compression then it’s fueling the timing cannot really move unless something has broken & believe me you would hear that. I would start at the fuel filter then check the pump then the carbs I would strip & check everything is spot on also that side stand switch can cause a whole lot of pain so ms worth looking at.

    • #4673
      Simon
      Member
      • Topics: 0
      • Replies: 25
      Joined:
      Jul 7, 2020
      @syco
      Kent
      Gt250 f1
      Points: 170

      Edit also make sure the battery is fully charged.

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