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Joined: Aug 15, 2013 21:10:13 GMT -5
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Post by zeedhen on Aug 23, 2013 20:00:04 GMT -5
so ive done alot of researching on derestricting the 50cc scooters.....ive opened the cvt case and it appears as though the restrictor there has already been removed and also i checked my cdi box for the pink wire....i have no pink wire but i have one spot on the plug with a missing wire (im assuming the limiter) ive also checked my carb throat and i have a needle with no adjusting tab so i cant increase my fuel air there....only thing ive read that i havent been able to check is the exhaust system to see if there is a restrictor there....even with all these restrictions removed i cant get above 30-32 mph on flatground and 20 uphill (and thats by the speedo so i can only imagine how slow it actually is)......any help or suggestions would be appreciated tons!
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Post by skuttadawg on Aug 24, 2013 1:26:02 GMT -5
First off how many miles are on it ? The pink wire is only for Adley scooters not the common Chinese scoots . The 50s have too small of a main jet to get all of the power out of the engine so we ether install a larger main jet or replace the carb since most have the air/fuel screw covered , no needle clip to adjust its position and I have seen some where the carb bowl is riveted on instead of using screws . How does it run ? Have you done a compression test ? Is the belt stretched out ? Remove the variator weights and weigh them with a digital scale . You can try lighter rollers or sliders which will help on take off , up hill and often top end . Too light and top end will be less since the engine will be redlining at a slower speed . Check and clean the airfilter , as a dirty one will restrict the intake air flow . Make sure the vacuum hoses are all attached . I had a small one pop off on my old 50 and man it really killed the performance . I put on a screw clamp since the factory snap clap came off . Seafoam is a great product that can clean out the fuel system if dirty and also keep it clean . The best way to clean the carb is to remove the bowl and unscrew the idle and main jet to clean with carb cleaner spray or stiff solid strand wire . Im a lucky I can do this with out having to remove the carb . Note look for the drain plug screw on the bottom to release the gas in the bowl before taking it off . Check the intake manifold for cracks or holes since many use a Teflon intake that rots over time . If the valves have not been adjusted it may need them to be done . Plenty of how to videos on adjusting the valves and more on YouTube . The engine must be cold and you will need a valve feeler gauge that has a bend end or bend a flat blade type . Most auto parts stores sell them for 3 bucks . All 4T scooters will need to have this done at least once and my scooter dealer told me many need to be adjusted out of the crate . Harbor Freight has and engine compression gauge kit for 20 dollars which can be handy to have . Here is a great article on derestricting a scooter www.scootnfast.com/scooter/Tuning_mods/De-Restricting.htmSome older scoots have a RPM limited CDI but often they are not limited on some scoots . An aftermarket racing CDI is a 50/50 gamble as many reported no top end gain . Some performance CDIs have an advanced timing curve which can help on the low end . There is at least 4 carbs on the 139QMB engine like listed here www.partsforscooters.com/Street-Scooter-Carburetors-and-Parts . Look up engine and CVT parts for 139QMB ( very common engine used ) instead by your scooters brand or model |
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