Topic: CB750 Oil Tank Thread Size?

[Jet Pilot]

I'm planning to plumb in an oil cooler using stainless braided hoses, and would like to know the thread type and size of the fittings on the stock CB750 oil tanks.

[mrosso]

I'm interested too. Anyone have the dimensions? Is it an NPT thread?

[voxonda]

I'm interested too. Anyone have the dimensions? Is it an NPT thread?

No, it's metric fine thread. Will look into it but think it was M20x1.5 and M22x1.5.

Will get back!

Cheers, Rob

[voxonda]

Got most of it right! It is M22x1.5 and M24x1.5

Cheers, Rob

[Jet Pilot]

Hi Rob;

Got most of it right! It is M22x1.5 and M24x1.5

Thanks for the information!  Unfortunately I want to use -8 AN size steel braided hose, and the appropriate M22 and M24 hose ends are only available to fit -10 hose.  So, I purchased a used oil tank on eBay, and will braze on -8AN fittings, saving my original tank and hoses just in case I want to return back stock someday. 

Dan

[mrosso]

Is there any way to use -10 hose or is the ID too large for the Honda engine-side fittings?

[Jet Pilot]

Hi;

Is there any way to use -10 hose or is the ID too large for the Honda engine-side fittings?

Yeah, the engine fittings are the problem.
I plan to drill and tap a set of the OEM engine hose fittings to a 1/4 NPT thread, which I think is the largest size that can safely be used.  I have not been able to find 1/4 NPT to -10 AN adapters from any of the major vendors, so I'm going with 1/4 NPT to -8 AN fittings and probably Earl's Ultra Flex 650 hose.  The Ultra Flex hose has an I.D. of 0.536" (13.6mm) which should be fine for the long run up to and back from the cooler on the return, and not overly restrictive.

Dan