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Thread: Sportcity One 125 - Very Sluggish.

  1. #1
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    Sportcity One 125 - Very Sluggish.

    I've just put a 2009 Sportcity One 125 together from pieces for my wife, and it is very sluggish. It has about the acceleration as a mates Honda Lead 100, with a top speed of about 90 kmh.

    If I stick my finger into the carby and lift the slide, it revs freely and with noticeable power as compared to letting the vacuum on the CV carb do its work. I can't find any leaks in the vacuum system, and the diaphragm does not have any holes and fits ok.

    I have fitted a new drive belt.

    Q1) If I connect a vacuum guage, what vacuum should I expect under full acceleration?
    Q2) What should I look for in the varispeed drive that may be an issue. Does changing weights make a difference?
    Q3) It has a throttle position sensor, but no efi. Is the scooters performance restricted in some manner?

    Help would be appreciated

    Regards, Greg

  2. #2
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    The Sport City 125 in the US has no TPS unit however we do not have a tiered licensing system that would require restricting a 125cc bike. Since you cobbled it together are you sure that you put the correct carb on it? Is it possible that you have the needle on the diaphragm set too low or that the enrichener is partially plugged or sticking?

    Does the Australian version have a SAS valve and air injection system?

    Check out the carb and air system starting at about page 40 on the parts listing:
    http://www.af1racing.com/store/Scrip...dCategory=2577

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    Quote Originally Posted by Rockynv View Post
    The Sport City 125 in the US has no TPS unit however we do not have a tiered licensing system that would require restricting a 125cc bike. Since you cobbled it together are you sure that you put the correct carb on it? Is it possible that you have the needle on the diaphragm set too low or that the enrichener is partially plugged or sticking?

    Does the Australian version have a SAS valve and air injection system?

    Check out the carb and air system starting at about page 40 on the parts listing:
    http://www.af1racing.com/store/Scrip...dCategory=2577
    Yep, it has the SAS valve.

    Scoot was as OEM when I got it. Carb is correct. just pulled apart by someone to replace a drive belt that doesn't know what they are doing. ( I'm reasonable at working on bikes. Been doing it for almost 50 years, currently have 14 Italian bikes, nothing less than 650, that nobody touches except me. Bad part is i'm a sparky, not a mechanic. These scoots are very different, but serious fun!!!)

    Haven't changed the needle position from oem.
    enrichener? that would be choke in Australia?. it's ok, have done a physical look, and I think a disconnect, not sure. It's not running rich.

    It doesn't seem to want to rev out when riding. But revs like shit when I stick my figure down the throat and lift the slide (on the stand). Almost like the varispeed is not letting it get up to the peaks on the torque/power curves, but is holding the revs down low so the motor can't work.

    It has to be either of, a vacuum issue, a varispeed setup issue, or a legislated restriction????

    I want to put a vacuum guage on to see if the diaphragm is getting enough vacuum. ie leaks. what should I be looking for?

    Regards, Greg

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    It has SAS valve. Bike is OEM, just pulled apart by others. Needle clip not changed, choke system ok.

    What vacuum should I be looking for? I'll t piece and put a guage on.

    New drive belt, but almost like the varispeed is not letting the engine revs get up to meet torque/power peaks

    Regards, Greg

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    Before you even go there start with the basics like adjusting the valve lash, verifying the valve timing, etc.

    When you put the new belt in did you use OEM rollers or aftermarket? How did the ramps in the variator look after you cleaned them and how worn were the variator guides when you replaced them. Hopefully you did not use brake cleaner or any other solvent on the permanently lubricated Oilite bushing in the center of the variator that the boss slides through.

    Was the clutch operating freely and free of belt debris when you inspected it during the belt change and the needle bearings in its center nicely lubed with fresh grease?

    Are you running the stock exhaust or aftermarket? If aftermarket was the carb rejetted to compensate for the change in back pressure? If the bike was tinkered with by others you may have to undo a bit of that to get it right again. No real guarantee that others did not already mess up the clip setting on the needle however before one even goes there you have to ensure valve lash and timing are correct otherwise you'll be redoing the carb if you modify anything there before ensuring that the valves are correct.

  6. #6
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    Quote Originally Posted by Ghwallice View Post
    I've just put a 2009 Sportcity One 125 together from pieces for my wife, and it is very sluggish. It has about the acceleration as a mates Honda Lead 100, with a top speed of about 90 kmh.

    If I stick my finger into the carby and lift the slide, it revs freely and with noticeable power as compared to letting the vacuum on the CV carb do its work. I can't find any leaks in the vacuum system, and the diaphragm does not have any holes and fits ok.

    I have fitted a new drive belt.

    Q1) If I connect a vacuum guage, what vacuum should I expect under full acceleration?
    Q2) What should I look for in the varispeed drive that may be an issue. Does changing weights make a difference?
    Q3) It has a throttle position sensor, but no efi. Is the scooters performance restricted in some manner?

    Help would be appreciated

    Regards, Greg
    vacuum at WOT should be close to zero.

    the brass emuision tube in the carb if it has one is suspect. i would look for vaccuum leaks or make a testor to pressurise it to 30psi or something. get a new sparkplug and upgrade the boot. i would check the valve clearance. clean the idle jet and play with the settings like idle screw and mix screw. try to run the mix screw at factory settings and look for problems.
    --- diploma for engine repair in 2012
    --- custom parts and machining --- porting and polishing
    ------------------------------------------------------------------------
    ---derbi bullet 2006 - piaggio AC - TPR 70CC - giannelli shotV4
    ---1992 lt250r suzuki quadracer - new and improved
    --- complete 2012 wethepeople volta bmx - full sanko seamless chromoly frame/fork/handlebars

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    I've printed the thread out. I'll try and find time to go through it all over the weekend. Thanks!!! Greg

  8. #8
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    Quote Originally Posted by Rockynv View Post
    Before you even go there start with the basics like adjusting the valve lash, verifying the valve timing, etc.

    When you put the new belt in did you use OEM rollers or aftermarket?Did not replace the rollers. How did the ramps in the variator look after you cleaned them and how worn were the variator guides when you replaced them. There did not appear to be wear evident. Hopefully you did not use brake cleaner or any other solvent on the permanently lubricated Oilite bushing in the center of the variator that the boss slides through. I probably cleaned it up with petrol...

    Was the clutch operating freelyIt looked ok and free of belt debris Yeswhen you inspected it during the belt change and the needle bearings in its center nicely lubed with fresh grease? Yes

    Are you running the stock exhaust or aftermarket?Stock If aftermarket was the carb rejetted to compensate for the change in back pressure? If the bike was tinkered with by others you may have to undo a bit of that to get it right again. No real guarantee that others did not already mess up the clip setting on the needle however before one even goes there you have to ensure valve lash will do and timing are correct will do otherwise you'll be redoing the carb if you modify anything there before ensuring that the valves are correct.
    As above in red

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