Hi! i just bought a 08 xtx. Before i tok my first ride i performed a service. (oil,filter,spark plug) The previous owner put on some leovince cans and some mod to the air box. He also changed the front sprocket down to 14 teeth. i dont know if they did enthing to the engine. The problem i have, is that the bike is really jerking on low-mid range throttle when cruising. Something that makes the bike terrible to ride... does anyone experienced simular problem?
The bike got 10000km on it.

Thank you!