Topic: Oil Pump Rebuild?

[the_col]

Greetings,

I am new to this site and I must say that I have really been helped with all of the sites content for both technical information and inspiration.

I have a 1978 CB 750F (according to the Frame) with a CB 750K8 motor I think (motor sn# CB750E-315XXXX).  I purchased this bike from a motorcycle junk yard that was located in Barstow around 4 or 5 years ago which is no longer there.  The guy had a couple of CB 750's but the one which I selected was the only one with a turning motor.

I dismantled the motor and found the internal components appear at first glance to be in great shape, but when I looked at the lower case close up I found a crack on the chain side of the motor which seems to have been welded and cosmetically cleaned up the exterior case with JB weld.  Any how, when I got down to the oil sump the oil filter screen was covered with grit, a small amount of metal flake, and gasket material.

I decided to take the oil pump apart and in the process I have had a hard time removing the screws for the oil pump housing ( I will need to replace 1), and noticed that a small rubber seal was toasted so I removed it.  Removing this seal was a pain in the ass but being new to this I probably just don't know all the tricks to doing this kind of stuff  .

So now I am trying to locate this seal, or it's part#.  I did a search and found "wet sump" where one of the senior members of this site said that he was looking into ways of rebuilding these oil pumps but no follow up after that.


Thank you,

[kslrr]

Try these guys.  http://www.ttr400.com/   They modify CB750 oil pumps to work in CB350F/CB400F's.  They might know where to get parts.  There is also David Spears Spares and Z1 Enterprises among many vintage parts sources that the guys on this site speak of.

[the_col]

Cool, I will check them out. 

Thank you,

[JLeather]

Does anyone "blueprint" CB750 oil pumps?  I'd like to have one blueprinted to make sure it'll feed enough oil to the turbo kit I wanna install one f these days.

[the_col]

Hopefully this is a better picture of the seal and where it goes.

Thanks for all your help!

[bunghole]

Go to www.Honda-Partsdirect.com  They will have all of the parts listed.  They might also stock the part.  They have great customer service and will contact you if the part is discontinued.

[MoTo-BunnY]

You might also want to consider a brand-new oil pump or used (low mileage) pump, to replace it in its entirety, as the metal internal pieces get worn out (non-rebuildable) and the pump gradually puts out less and less oil pressure (NOT good).

When I first got my bike, with 24,000 miles on it, the oil light would flicker at idle - no matter what the oil level. After reading up on that symptom here on the forums, I picked up a low mileage pump off of feeBay (had like 5000 miles on it) and symptoms vanished. It ALSO really quieted the overall engine racket down, making me realize that my engine was probably being semi-oil starved - yikes!!! 

[ttr400]

At first I thought it might be an O-ring, but it's not. checked a pump i have apart and it's an oil seal. size is 15mm Od x 11mm Id x 3mm thick. you might have luck finding this seal at a seal/oring supplier. There is no part # listed in the parts book that I have.

In case anyone want's to know the smaller of the 2 pump rotors is the same as the one fitted to the CB400F and CB350F.

Kevin