i have a 110cc pit bike not sure of the make or year bt i know it is made in china. the bike has 4 gears, 1 down and 3 up, the prolem is that when you pull the clutch and put it in 1st gear the bike jearks so i have to rev it and then put the bike in gear, the gear changes without pressing the clutch and sometimes when i change the gear own it goes into neutral it self, can anyone tell me what the problem is please.