Forums 🚥 PIT STOP 🔧 Hyosung Technical Help Occasionally non starting – help needed

This topic contains 6 replies, has 3 voices, and was last updated by  Toby 1 week ago.

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  • #3655

    Toby
    Member
    Joined:
    Jan 2, 2020

    Hi all, I know I’m new to this club and I know that a lot of people don’t like new people asking for help but either way I’ll put this out there in the hope that someone can help.😊

    So, I bought this bike as a spares or repairs and I’m slowly going through the process of putting it back on the road in the hope of having it ready asap. I’ve fixed both front and rear brakes, right handle bar, camshaft bearing (seriously thought I’d bitten off more than I could chew when I finally got it to start up and theirs a mental knock from the top end😂), luckily it was only the bearing and now is smooth, indicators and a few other little bits..

    The only problem I have is when I finally got it to start up is was running quite lumpy so I stripped the carbs down and they were full of muck. As I was in no particular rush at the time so i had the time to leave it in the ultrasonic cleaner to get every little bit of muck out.
    Once it was all cleaned it looked like new 😍put it all back together jets all clean and put back in. After putting it back on the bike with fresh fuel and all the lines cleaned out I couldn’t get it to start :/
    Ive finally got it to start but here’s where the problem is thats got me completely stumped…
    Sometimes it’ll start and sometimes it won’t, when it does start sometimes it’ll take a few turns to start and sometimes it’ll start straight away, and once it has started, sometimes it’ll Rev the nuts off the thing and I’ll have to turn it off and sometimes it’ll idle nice and smooth… I’ve tried running a fuel pipe straight to the carb from the tank to cut out all the vacuum systems to remove the possibility of fuel starvation and no help, it won’t run from the tank but if you shuv a funnel in the end of the fuel pipe going to the carbs and fill it with fuel then it’ll start occasionally…

    Sorry for the long winded explanation but I’m completely stumped on this and wanted to give you as much info as I could think of so that you have a better idea of what is going on. Any help is appreciated at this point :/

    Cheers – Toby

    (plus if I’ve put it in the wrong topic please let me know or if you can, move it to the correct topic 😊thanks again)

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  • #3658

    ♠️ MARCEL
    Administrator
    • Topics: 33
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    Joined:
    Jan 2, 2020
    @mf448kxn6
    Location:
    North UK
    Riding:
    GTR
    Points: 2,996

    Hey,

    Strip the carbs again, remember the brass tube with the tiniest hole, yeah thats the starting ports used for starting the bike,  even compressed air helps blow the holes clean through trust, its very very very small lol.  A single strand of a headphone wire should be able to go in and out.

    Do this with pilot jets, take them out and make sure light shines through the holes.

    Put the carb upside down on table  (floats facing the ceiling) get a ruler and make sure each float is 7mm tall from the edge of the carb bodies or adjust , these control fuel flow so its very crucial or you have too little fuel to begin with (floats closed early)

    Fuel pump at rear  = open its cover, you will see the insides are okay and close it back after clean , it rarely , rarely fails but a bad filter can let particles go to your carb n pump making 2 issues than 1.

    Check that vacumm pipes are sealed good, also the intake system , it will take few annoying cranks to start it if there is even a slightest air leak.   Since you had the carbs off, check that your manifold O rings are okay  (go to /shop at top menu to see what i mean) ,  then we can rule out a leaking intake system causing start related issues and does affect idle big time.

    Clean the spark plugs,  but if they are old or show signs that they are fouling easy , maybe consider new plugs and try again ,     your ignition HT cap will say 7k ohms on your meter with the other meter wire on frame as ground,  suggestive that  your coils are okay

    or coil terminal pin   (spade shape behind coil)  and  frame on your meter will say about 0.6 ohms strong.  (less than 1)  ,  coils are assumed to be okay and should spark just fine  , weak coils affect starting and idling too.

    Hope this info , and welcome .  i probably also covered some things in more depth in other forum topics too.

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

  • #3659

    Toby
    Member
    • Topics: 1
    • Replies: 3
    Joined:
    Jan 2, 2020
    @toby-d
    Location:
    Lincolnshire
    Riding:
    Hyosung gt125r 2007
    Points: 45

    Thanks for all the suggestions Marcel, no idea when I’ll get another chance to take a look given work and family stuff going on but either way I’ll let you know how it all goes.

    Tbh both the coils look quite corroded but they still sent quite a healthy looking spark to the plugs but I’ll go through and check it all out like you said plus all the vacuum pipes and valves ect.

    Hope to be back on the road soon and get you some lovely pictures of my girl all clean and shiny 😍

  • #3662

    ♠️ MARCEL
    Administrator
    • Topics: 33
    • Replies: 232
    Joined:
    Jan 2, 2020
    @mf448kxn6
    Location:
    North UK
    Riding:
    GTR
    Points: 2,996

    Thanks for all the suggestions Marcel, no idea when I’ll get another chance to take a look given work and family stuff going on but either way I’ll let you know how it all goes. Tbh both the coils look quite corroded but they still sent quite a healthy looking spark to the plugs but I’ll go through and check it all out like you said plus all the vacuum pipes and valves ect. Hope to be back on the road soon and get you some lovely pictures of my girl all clean and shiny 😍

    You ain’t too far from me , i may be in Lincs when its warmer, so we may go for a sprint if she is ready  or   meet us in rochdale for march meet 😉  , event details on facebook or ill post info soon on this website over weekend im sure.

    As long you take your time to address each part , we should expect progress , good luck

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

  • #3695

    Toby
    Member
    • Topics: 1
    • Replies: 3
    Joined:
    Jan 2, 2020
    @toby-d
    Location:
    Lincolnshire
    Riding:
    Hyosung gt125r 2007
    Points: 45

    Okay, so sorry for the long gab between updates, due to work and family life just haven’t had time to work on it till today, but I have a massive update!!

    So I have now got the bike starting every time without fail and will happily run for as long you need until you turn it off and doesn’t stall anymore, and the throttle can actually be used now (concidering before I sorted this it would stall the second you touched the throttle😂)

    So it turns out that the owner before me and messed with the mixture screws and they were like way out 😂so i somewhat sorted that to an extent so that it’s now running, unfortunately then ran out of time for today but tomorrow I’ll be back out there again and I’ll balance the carbs and then set both screws and everything to where it should be and then thats then engine done apart from a good service 😍

    She’s so close to being done now it’s unreal just a few more small jobs, which as any of you that work on your own bikes will know they never stay small jobs but either way, should be finished soon then I can finally get back in the road 😫

  • #3696

    Mick
    Member
    • Topics: 3
    • Replies: 5
    Joined:
    Jan 2, 2020
    @daytona675
    Location:
    Uk
    Riding:
    Mainly Triumphs
    Points: 59

    Okay, so sorry for the long gab between updates, due to work and family life just haven’t had time to work on it till today, but I have a massive update!! So I have now got the bike starting every time without fail and will happily run for as long you need until you turn it off and doesn’t stall anymore, and the throttle can actually be used now (concidering before I sorted this it would stall the second you touched the throttle😂) So it turns out that the owner before me and messed with the mixture screws and they were like way out 😂so i somewhat sorted that to an extent so that it’s now running, unfortunately then ran out of time for today but tomorrow I’ll be back out there again and I’ll balance the carbs and then set both screws and everything to where it should be and then thats then engine done apart from a good service 😍 She’s so close to being done now it’s unreal just a few more small jobs, which as any of you that work on your own bikes will know they never stay small jobs but either way, should be finished soon then I can finally get back in the road 😫

    I have just had the same issue. The mixture screws were set as they were from factory… after a carb clean it ran terrible, constantly surging for idle. Spent 45 minutes getting the mixture right and balanced the carbs… runs sweet now.

    The problem is with newer bikes, to meet emission laws carburetors are set so lean its daft. Up the main jets one size and (if you know what you are doing!) Set the mixture correctly. A quick balance if you have vacuum gauges does them a world of good too!

  • #3698

    Toby
    Member
    • Topics: 1
    • Replies: 3
    Joined:
    Jan 2, 2020
    @toby-d
    Location:
    Lincolnshire
    Riding:
    Hyosung gt125r 2007
    Points: 45

    Yeah, I don’t even know what has been done to mine, so much stuff on it had been messed with by the previous owner, but I knew it was going to be a project when I bought it so no suprise really, and yeah I balanced the carbs using the gauges today and reset the mixture to the point that it didn’t seem to be running too rich or lean, (going off of smell and how the engine reacted to different load settings like if it bogged down or anything) haven’t touched the jets personally but god knows if the previous guy had or not and didn’t really think to look while it was apart as I just wanted to get it running 😂.

    But she’s running now, idling happily and starts first time every time so far 😊only problem i have left is that every now and again while it’s idling the revs Will pick up for some unknown reason 😂but if I’m honest at this point I don’t care to much because at least it’s running 😂.

    All that’s left before it goes on the road is just need to sort the indicators, indicator switch, a good engine service, (brake fluid was changed when I sorted the brakes obviously) then a new starter solinoid and I’ll be on my way to the MOT…

    I’ve had this bike for a few months now and I’m so excited to finally have it this close to actually going on the road. I can’t wait to take it out for it’s first ride and so many trips planned for this year of riding 😍. Including hopefully coming along to the meets and meeting the rest of you guys 😉.

    Bring on summer baby!! 🌞😊😍

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