My kymco super 9 doesent take high rpm

[Nico Hakala]

I have a brand new 70cc big bore kit from naraku on it and 17.5mm carburator naraku (both are brand new). When i start it it runs well and the idling is good. I can drive it but when it gets to like 30km/h it doesnt go anymore. It doesent take more rpms. Before the install the scooter had been in a garage for 3-4 years and not touched. Anyone have any ideas why this happens?

[CROSSBOLT]

You using the same carburetor?

[Nico Hakala]

Im using a 17.5mm naraku.

[eamartin]

What are the jet sizes?  What is the air filter set-up?

[CROSSBOLT]

Im using a 17.5mm naraku.

Is that the same-as-original-the-one-the-factory-installed when the bike was unmodified? You see, I have no idea what was standard for this model. And I would not know a Naraku if it bit me. Eamartin asked good questions about jets. All the answers you supply will help in solving your problem.

[Nico Hakala]

95 main jet and original air filter.

[eamartin]

Have you tried to removing the air filter element  and running it?

[Nico Hakala]

Yes i have tried that.

[Nico Hakala]

Now it takes high rpm when the tire is off the ground but when i drive it it just goes 30km/h max.

[eamartin]

How did it run before the big bore kit was installed?  What was its' top speed then?  Did it rev okay?  How many kilometers on the bike?

[scooterfan]

Did you the CVT driving system ? Make sure the Variator shaft, bush, and rollers are clean, and the rollers are in good condition. The clutch assembly could have a problem as well.

The reasoning for my comments - I think if the CVT system has a problem at the Variator or clutch (i.e. clutch spring), the driving system could “gear up” too fast and the engine will not have sufficient power to drive the scooter forward.

Just a guess of cause.

[Nico Hakala]

Now it works pretty good. The problem was the exhaust. I replaced it with a leovince hand made tt i think and now it works fine. Just need it to get more fuel. Installing 100-105 main jet.