Why is my 50cc holding back accelerating? Please shed some light!

[Tim1214]

Hello, I’ve had my kymco super 9 for a little while now, and having ongoing issues with power, I know these things don’t exactly make massive power, but it’s just not as responsive as I’m used to with previous 50cc scooters I’ve owned, ive got 0-15mph takeoff running good, but 15-35mph is so slow. Really hoping someone can shed some light. So far I’ve fitted a de restricted cdi, upjetted to a 90 main jet, fitted a new variator (de restricted) 7g rollers, new clutch, new belt, iridium NHL’s spark plug, and it came fitted with an expansion chamber exhaust. I just want it to exellerate smoothly and quickly, and possibly get 40/45mph to keep up with traffic. Idle is fine, and the fuel/air Screw is turned out about 3-4 turns, I’ve also added 3 small air holes as it was running a bit too rich. Thanks

[CROSSBOLT]

Added 3 small air holes in what? How do you know it is running rich? Asking to find where we need to start.

Karl

[Tim1214]

Added to the air box, the plug was soaked and fuel was backing into the air box. The plug is about the right colour now, slightly black, but not as bad as when I got it, the element is a dark brown colour.

[Mr. Paul]

Theres been so much done to this little bike that I would not know where to start!

[ole two wheels]

It could be that you need to start by plugging the three small holes back up and de-restricting air flow thru the air box. If it is set up right,ie: clean air filter, no blockage in the air inlet, it does not need additional  air hole in the box. Also is it a 2 stroke.? Must be because you don't use an expansion chamber type exhaust on a 4 stroke. Have you checked to see if the carburetor is clean> There is some sort of idle jet and high speed jet in there. Could be that the HS jet is clogged. Make sure the carburetor has an air-tight connection to the intake,ie; good gasket and screws tight. If it has a shutter type choke, make sure it is opened. The fact that it has gas is backing up in the air box, indicates you may have a choke problem If it is an electric choke, try unplugging the wire and see if that helps.  Also check to see if any vacuum lines are off.I hope somewhere in all this info that will locate your problem. A service manual sounds like it is in order. Good luck.

[stuo]

Check the float level. My Vino 50 is a dog from 20mph up because the float level is too low and it takes time to fill and then accelerate to speed. It's a long story as to how it got that way but I'm too lazy to fix it.