My 71 CB500 has developed a metallic rattle at 5500 rpm. It seems to come from the engine but not sure with all the noise - the 4- 1 pipe isn't very quiet. Could be a loose header pipe maybe??
I have recently removed the carb to replace intake manifold o-rings. They seemed to go back on very well and I'm pretty sure the noise is not coming from the carb. The bike is running better since I replaced the o-rings.
I have had a few issues lately with the engine hesitating between 5-6k rpm....especially in top gear at 60+mph.
Any thoughts?
I'm off to investigate.
