I have the one of those bikes here at the house except mine's a 2002. The first thing I would check is to see if its getting ample fuel. They don't need much fuel to run so just make sure it's coming out of the valve ok and let it run into a cup. Another thing to check is the reed valves. You'll probably have to pull the reed block out and make sure none are broken or damaged. They look like petals but made out of real thin metal. They should be closed when you have them out.To get them out you'll have to pull the carb off and the intake boot. While the carb is off take it apart and give it a good cleaning. If you need any specs or diagrams let me know and I'll dig up the book I have for mine and scan what you need to know. Also clean the air filter and spark plug or replace the plug. You can clean the spark arrestor too.
There's about a million things that can cause what you have going on but the ones I would check first is good fuel flow out of the valve, a clean carb that's set up right, clean air filter, good spark plug,good exaust flow, and that the reeds are ok. if it isn't any of those we'll have to go deeper. Just holler.
They do have a restrictor in the exaust so if it's revving up about half way and that's all it will rev before it starts missing and bucking then the restrictor is still in the exaust.
There's about a million things that can cause what you have going on but the ones I would check first is good fuel flow out of the valve, a clean carb that's set up right, clean air filter, good spark plug,good exaust flow, and that the reeds are ok. if it isn't any of those we'll have to go deeper. Just holler.
They do have a restrictor in the exaust so if it's revving up about half way and that's all it will rev before it starts missing and bucking then the restrictor is still in the exaust.