Hi I'm new. My first build from Bgf has gone ok. so far I need to get some sealant for the gas line, try to bend the exhaust to fit inside the crank arms, I'm running the Heavy Duty 415 chain to I think a 48t rear wheel sprocket with the stock tensioner and my chain keeps slipping inward every time I start the motor. I have tried to slide it everywhere. thinking about getting a spring tensioner and or a new rear sprocket. Other than that the quality of their kit has been ok. Any suggestions on drive chain tension?