it means its weak there is a fuel shortage somehow,try this take the slide out of the top of the carb and take the cable out of the slide then pull the needle out of the slide you will see a small circlip on it and about 4 slots move the circlip to the lowest slot nearest the pointed end of the needle and out it back in a try it,also make sure the air filter is on properly and it has not leaks or holes drilled in the air box the mixture screw on the carb should be set to 2.5 turns out on this model.
adam bike doctor, July 2010