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  1. #1 Sinnis Max 2 (QM125-2V) Carb issues 
    C-Moto Noob
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    Aug 2020
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    Hi Folks.
    I'm new here. Hoping for a bit of advice from you all.
    I Have a 2015 Sinnis Max 2 that's randomly developed a carb problem.
    The bike is completely standard apart from the stupid SAI thing has been removed and the ports plugged up, and the exhaust is a GS125 pattern part.

    I bought it second hand and gave it a thorough service etc. It ran perfectly for a couple of hundred miles, now the revs have started hanging at around 4000.
    It starts fine, idles at around 1300, plug is a good colour if not slightly rich.
    Throttle cable is new and in good condition, no binding at all.
    Carb has been stripped and cleaned 4 times at this point. New o-rings fitted.
    Valve clearances are bang-on.
    It's a mikuni carb, one of those cheap single cable jobs. Jets are standard, 97.5 main and I think 15 idle but can't remember to be honest.

    I've checked for air leaks, all good there. I've tweaked the mixture screw, no joy there. It'currently set to about 1 3/4 turns out which feels about right. Any further out and it starts bogging when I blip the throttle.

    Any ideas,guys? It's my son's first bike and I need it to be safe for him.

    Cheers Folks,
    Thanks very much!
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  2. #2 Re: Sinnis Max 2 (QM125-2V) Carb issues 
    Senior C-Moto Guru humanbeing's Avatar
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    Dec 2008
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    1,509
    BS26? Torn a hole in diaphragm isn't uncommon at all. Quick Chinese solution = Replace it w/ a Fakuni
    https://item.taobao.com/item.htm?id=616677907525
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  3. #3 Re: Sinnis Max 2 (QM125-2V) Carb issues 
    C-Moto Noob
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    Aug 2020
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    United Kingdom
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    Hi Humanbeing.

    It's not a CV carb, it's a cable operated slide job. I stuck a new one on today but still no joy. As soon as I adjust the idle so that it doesn't stall, the revs start hanging at around 4000. Mixture screw doesn't seem to help much. Bearing in mind that the idle screw basically just alters the stop position of the slide, do you think changing the needle height will help? I'm just clutching at straws here ��. Is there anything simple I'm overlooking here? I'm certain it's not the cable.

    Cheers ��
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  4. #4 Re: Sinnis Max 2 (QM125-2V) Carb issues 
    C-Moto Noob
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    Hi, did you manage to solve this?

    I’m having the exact same problem

    Cheers
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  5. #5 Re: Sinnis Max 2 (QM125-2V) Carb issues 
    C-Moto Noob
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    Hi Mate,
    I managed to get it running adequately but it's not perfect. Revs still drop a bit slowly but don't hang anymore. I basically stripped and cleaned the carb again, tried a bunch of different jets but ended up going back to stock. Tried altering needle height but it just made it run like shit so put it back to stock. I cleaned all the mating surfaces, put new o rings and a smear of gasket goo and stuck it back together. I had a blanking plate over the ais port so I took that off, cleaned it all and replaced the gasket. After that I just pissed around with the mixture screw and adjusted the idle speed as I went along. It took ages. Start at around 1.5 turns out and adjust about 1/4 turn each time. Its a case of just getting it running the best you can and living with it, I reckon. Upgrading the carb is probably a really good idea, the stock one is pretty nasty. Best of luck!
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  6. #6 Re: Sinnis Max 2 (QM125-2V) Carb issues 
    C-Moto Noob
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    Mar 2021
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    I think I had the same problem 2 years ago. The issue is the taper on the carb sliding cylinder is slightly rough probably because the tickover has been adjusted and driven into and scratched the slide surface (I now open the throttle slightly before adjusting the tickover). I tried to emery the surface smooth but this did not work, so I cut up a bit of plastic bottle and stuck it on with epoxy to provide a smooth surface so it doesn't stick at 3-4000 RPM. Hope this helps.
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  7. #7 Re: Sinnis Max 2 (QM125-2V) Carb issues 
    C-Moto Noob
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    Hi John
    It's a brand new carb so that's not the issue with mine. I know what you mean though, my old carb had a huge notch on the slide where it hits the throttle stop. I had to file it smooth.

    With regard to the exhaust, I picked up a cheap chinese gs125 knockoff and it fits perfectly. Even the stopper for the centre stand is in the right place. The black paint fell off pretty quickly but the exhaust itself is pretty solid.

    Cheers,
    Dave
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