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SOHC.co.uk Forums => CB350/400 => Topic started by: SteveB424 on December 19, 2022, 01:42:25 PM

Title: CB400 Larger Oil Pump Rotor
Post by: SteveB424 on December 19, 2022, 01:42:25 PM

Hello.  A question for those who have fitted a big bore kit and modified the oil pump along with it.  Besides machining a larger inside diameter to accept the larger rotor, where there any tricks to it? 

I'm spicing up my 1975 race bike for next season with a Yoshimura 492 kit and will likely go with a GL1000 oil pump rotor.  An oil cooler will be added also.

Thanks.

Title: Re: CB400 Larger Oil Pump Rotor
Post by: ttr400 on December 22, 2022, 10:33:31 AM

Hi,

The way it is done is not in the diameter but in the rotor thickness.
Yes i think the GL 1000 is the same diameter but thicker, it will need grinding down.
The other rotor choice is from the CB750K....it has 2 rotors one is the same size as the 400 and the other (i think the return rotor) is thicker.....will also need to be ground down. and the pump body machined to fit etc.
I make a larger rotor for the 400 pump, it will give around 33-35% off the top of my head increased oil flow. not pressure.

Kevin