I have seen first hand the damage broken chains and failed primary rubbers do to an engine. so for peace of mind I would consider some hd ones.
If your engine is standard then ok not so much of a concern.
The 'smith honda cr' never actually broke a chain in our 3 year go at the uk championships, but we always used new hd chains when we rebuilt the motor.
But once we started churning out 95hp things really started to let go. Primary rubbers disintegrated, which caused the chains to jump a tooth, which broke one of them, which in turn tore all the teeth off the crank, and also cracked a liner. people have lost cases to broken chains i am told. but this bike is putting out a lot more torque, and that torque is being used all the time, not just a squirt away from the lights, so keep things in perspective.
our first season we used new standard ones, but we also ony had 76 hp and less torque.
