CB750K - Oil Cooler adapter - Need some help

[AlixM]

Hello everyone.

I am helping a friend with CB750 he's building and I have some questions about an Oil Cooler.

We picked up this set yesterday at a local swap meet.





There should be a longer bolt that is needed to mount the stock oil filter cover over this adapter to the engine cases.

Anyone have any experience with this set-up?

Will the oil filter bolt from a CB750F work? It looks longer from pictures than the bolt from the "K" models.

Anyone have any pictures of this set up on their bike? Do the hose barbs go at the bottom or the top?

Thank you in advance.

[shinyribs]

I think only the F2 (77-78) engine used the long bolt. My 76 F1 uses the short bolt,too.


The barbs usually go to the bottom,but I dont see why they wouldn't work either way. Putting them off the bottom should make your hose routing easier.

There should be an adapter that holds the oil cooler to the engine,then the filter housing should bolt to that adapter with the stock bolt. Since all that is missing I'm not sure what you would have to come up with now. The longer F2(?) bolt might work.You would just have to find a length on it

Here is a pic of the adapted I was trying to describe. The stock bolt just threads in to it.


We have the same engine adapter. This side goes towards the engine.It seals with the same type o-ring used on the stock filter housing.

[AlixM]

That adapter is what we're missing!

Ok, where do I get one of those now?

Are they a Honda part from another bike?

[TOOLS1]

You should be able to just use the longer F-2,3 bolt. That "adapter looks like it came from a DOHC engine.
TOOLS

[sgtslag]

Without the adapter, unfiltered/un-cooled oil may pass through the gap in the adapter.  Only the lack of filtration is of real concern.  I used a different adapter, added a CB900 Radiator, and an inline Oil Thermostat.  Mine was on my 1979 CB750K, DOHC.  I logged over 3,000(?) miles on it, without issue (72 PSI @ 7,000 RPM, max. oil pressure on the DOHC -- I was told the 900's radiator wasn't designed for that kind of pressure, but it was, and still is, as far as I know, holding up).

As to what to expect, my setup dropped my oil temperature from 250 F, two-up, 60 MPH, for 3+ hours of driving, without the cooling system, to 210 F, with the cooling system online, same load, same speed, but higher air temperatures.  If you can drop your oil temperature to somewhere near 210-212 F, your engine's life will supposedly more than double.  It needs to be at a minimum of 180 F, for the detergent oil to suspend crud, to be caught by the filter; at 210-212 F, it will quickly boil off any water byproducts from the combustion.

As to where to get the adapter, I have a few suggestoins:  swap meets; e-Bay; post a wanted ad on Craigslist.org, too; try visiting local motorcycle junkyards, asking the staff there for it, to save yourself a lot of time.  If you have a SOHC bike, you may not gain much from the oil cooler, as they run their oil a very different way, such that it never gets near 250 F...   Cheers!

[Piute]

  We've spoke on this and other possibilities before
http://honda-cb750-s.456789.n3.nabble.com/CB650-SC-Oil-Cooler-for-CB750-s-td3909678.html
  Maybe something here will help I picked up a few brass washers and hoses / clamps
 to give a nother DRY FIT for possible working order for next oil change witch will be this month also going to Rontell syn T,bit worried cause rocker cover has slight leak and know will get worse,"O"well wont need to oil chaps over winter,not entering any shows yet,they come to parking lot to see my bike.