CB900 parts in a CB750

[shadowmoses42]

Hi Guys,

I have a 1980 CB750C I am rebuilding, and while I have the engine open I am curious if it's possible to increase the stroke by using the crankshaft from a cb900f engine. If so, are there any additional parts I would need to make that work? I am boring the cylinders from 62mm stock to 65mm so I can add a Wiseco 823cc piston set but I was curious if I can increase stroke this easily. I'm guessing it's not that simple and I would need longer cylinder sleeves or something of that nature, but I couldn't find a lot online about it.

thanks!

 

[amc49]

Your guess is correct. The 900 cylinder block itself is longer, not just the liners in it. The rods are too. The 750 cases have cylinder spigot holes that are too small for 900 liners. Timing chain longer for longer block, in short not a bolt-on at all. Yet the conventional wisdom spreads that it is.

Oh well.

Be happy with the fact that the super long 900 stroke then makes them super easy to snap rods on, common on the scrapyard motors.