Topic: Would a cb550 exhaust fit a cb650 motor?

[sinister902]

I tried using the search function and could not come up with an answer...... are the head pipes a different diameter between the cb550 and cb650 motors? I'm doing a hybrid motor for my CB550 and I'm trying to find out what I'll have to do for an exhaust.....

[Scott S]

 I once picked up a CB650 4-1 from a junkyard (now long gone) and the pipes were slightly larger in diameter and a tiny bit more widespread. They would, however, fit in my CB500/550 head with a little persuading. I never tried running them on the engine, just checked to see if they'd fit.

 I can't tell you for 100% sure, but I think the 500/550 headers are slightly smaller diameter and maybe a bit tighter spacing. I bet you could make them fit. Not sure how the smaller pipes would effect the powerband.....probably increase low end torque at the expense of high RPM horsepower.
 I've also read that the CB650 head flows really well compared to the 550. I'd be a little concerneda about heat build up.

[sinister902]

thanks for the info Scott! I'm building the hybrid motor based on Paulages thread so I definitely don't want to run too small of an exhaust, so it looks as though I'll be trying to source a cb650 exhaust (I hate the MAC, might have to find some stock head tubes to build something custom).