Honda-SOHC

Sorry if this has been asked before, I've tried 'Search' but i've so far only drawn blanks. Two queries.

Is the oil-pump from a CB650, fitable to a CB550F2 ?

And the same goes for the sump. I have seen this somewhere that this is possible, the proviso being it has to be a particular model CB650, and obviously the pick-up has to be modded to cater for the 650's deeper sump.

The theory about the fluid displacement being greater with a larger piston is valid. However, there are much more important things to consider. Like keeping the calipers' correctly adjusted, using pads with a higher coefficient of friction, using braided hoses, not leaving braking until it's more than too late, etc. etc.

And despite what logic might dictate, a narrow bore master cylinder (MC) piston (bike's stock part) will give a smoother and more  subtle action when a second front disc is fitted.

Sure, the fluid transfer will be less with an 11mm bore compared to one of 16mm, by a little less than a factor of 2.16. but you'll have twice the breaking surface available.

You'll max-out the pressure in the breaking system (and hence breaking force on discs) before you bottom-out the break lever.

Track-day racers often use a "smaller than stock" master cylinder setup on their clutch for similar reasons, but in the opposite sense, i.e. they're feeding-in energy - not dissipating it.

So by fitting a second disc set-up using stock MC, you'll get a smoother braking system - not a stronger one. If you want a sharper braking system, just fit the MC with a larger diameter (say 16mm) and forget about the second disc/caliper/pipes, save weight at the same time.


Does the single disc set-up look as cool as the twin disc? Hell no!