CB650 SC Oil Cooler for CB750's

[sgtslag]

A member of this forum privately asked me about my oil cooler system I installed on my '79 K model.  After doing some research on BikeBandit.com, comparing O-ring sizes, I discovered that the Oil Filter Housing on both the 1983 CB650 SC's engine, and the Oil Filter Housing on the CB750 K's, use the same O-ring; they also use the same oil filter.  This indicates that the Filter Housings, are identical, and interchangeable.

To boil it down, it is possible to take the Oil Cooling System off of a 1983 CB650 SC engine, and mount it onto a CB750K/C/S engine, as long as you get the long Filter Housing Bolt off of the CB650 SC.  The SC's bolt is longer, and it has a different P/N; this is the linchpin of the adapting process:  I assume the SC's Bolt will be a direct match, for threads, to the CB750 models' Oil Filter Boss, but I have not verified it.

The SC's Oil Cooling system consists of an adapter plate, with fittings for the oil lines which circulate the engine's oil through the radiator, then return it to the filter, and the engine.  The SC Oil Cooling Systems are frequently available on e-Bay for reasonable prices (usually less then $50).  The bolts, however, tend to be less commonly available.  Oil pressure throughout the Cooling System, will be the same as the oil pressure within the engine:  max. oil pressure, as per the FSM, is 72 PSI @ 7.000 RPM, for the 1979 CB750K.  I do not know the max. oil pressure on the SC engine, but it likely is very similar, which means there is no risk of excessive pressures.  My CB900C Radiator has performed flawlessly, on my CB750K, for over a year, and 5,000+ miles, without any leaks, bulges, or other issues.  I was advised that the CB900C systems were not designed for this much pressure, but that has proven to be untrue.

To install the SC's cooling system, remove the 750's Filter Housing, install the SC's adapter plate, and radiator (fashion a mounting assembly out of aluminum bar stock, two U-bolts to secure it to the frame down tubes, behind the front wheel, and some nylon locking nuts, to secure the mounting plate to the fork tubes).  Use the Filter Housing Bolt from the SC, to secure the whole to the engine.

This will circulate all of the engine's oil through the radiator, for cooling, as long as the engine is running.  Without an Oil Cooler, the CB750's will run their oils at around 250 F, at highway speeds.  With an Oil Cooling System, the engine oil will run at an average of 210 F, with an ambient air temperature of 80 F.  For faster warm-up's, and better thermal control, an oil thermostat can be inserted into the oil lines, between the radiator, and the adapter.  Installing an Oil Cooling system, will extend the life of the engine's seals, gaskets, and other components, extending the life of the engine, overall.

When performing an oil/filter change, add the same amount of oil, as per the FSM.  The Oil Cooling System's volume is small enough that it will not require additional oil be added to the engine.  Filters should be replaced with each oil change.  The two, large, O-rings (89 x 4.5), should be changed each time, as usual (note that only one, large O-ring, is typically included with the new Filter, so extra O-rings should be ordered, in advance, from a supplier such as BikeBandit.com).

If I had known that the SC's Oil Cooling System could be adapted to the CB750's this easily, it would have saved me a very great deal of time, as well as one-half of the cost of my system, adapted from a CB900C's system...  Cheers!

[Piute]

                            Oil cooler is next on my list for large buy $$$

        Spotted this
                                http://www.ebay.com/itm/320827370872?item=320827370872&viewitem=&vxp=mtr
        sent "E" asked if would fit whats yo thought
        I'm thinking just get it from"X" IF in stk.
46.55 free ship. ?

[sgtslag]

The seller states that it will not fit a Honda CB650 SC, which uses the same cartridge filter, as the CB750K's...  My guess is, "No, it won't work," but I am not certain.  It will depend on whether the center bolt will reach into the existing Filter Boss, and snug against the engine block.  My gut feeling is that the CB650 SC would be a better option, and you could get a complete system for the same price as this adapter.  Best of luck, whatever you choose.  Cheers!

[Piute]

 
.
1 of the prob. I'm having is that it's A 77 F2 S.S.,Most don't work ??
So I'm thinking it has the longer bolt then the rest
                             Ya notice the plate(extra fins) in the back it comes off with the cap

              Sorry bad pic but do the rest of 750s have this extra 3/4" plate thought I read It's new for 77

http://www.bikebandit.com/houseofmotorcycles/1977-honda-750-super-sport-cb750f/o/m151839#sch403072
                                              Now I see lots of differance ,THX

[TOOLS1]

It will not bolt onto the CB 750. The CB 750 has a protrusion that the bolt goes into. This creats a space between the case, and the adapter. However my buddy, and I are working on this problem right now. He is wanting to adapt a DOHC oil cooler/filter can onto his CB 750, and I want to use a remote oil filter on Mortal Vindication. I picked up a length of 4" X 1/2" wall aluminum pipe, and we are having spacers made. They will have the grove, for the o-ring on the case side, and a flat on the adapter side.
TOOLS

[Piute]

                                    The F2 has A spacer / collar the others don't
                                         Notice Bandit ? my prev.post

                                           # 9: - COLLAR  581148  Enter 0-99     $22.05

[TOOLS1]

I thought the F-2 came with an oil cooler. That spacer looks just like the one I have on the Toolmatic.
TOOLS

[Piute]

                                                              1977 A

http://www.bikebandit.com/houseofmotorcycles/1977-honda-cb750a-hondamatic/o/m14720#sch403058

                                                             1976 A
http://www.bikebandit.com/houseofmotorcycles/1976-honda-cb750a-hondamatic/o/m143639#sch401532

[shinyribs]

Not to sound rude or stupid,but are oil coolers really needed? I just recently put an oil temp gauge on my bike.It is reading oil temp from where the factory put the oil temp switch,so it should be in a good location.I have checked my gauge against two infrared thermometers and it reads about 15 degrees F off. Anyway,my oil temps seem to run hotter on the highway vs in town.I didnt expect that but suppose it's all RPM related.But my bike has yet to run over 160 degrees F(175-ish on the gauge). Maybe I'm doing something wrong...again.

[sgtslag]

The spacer you refer to, is that the Oil Filter Boss?  The Oil Filter Boss is the hollow, threaded tube, which the filter housing Bolt screws into.  The Oil Filter Boss screws into the block.  For my adapter to fit, I had to cut off 1/4" of the Oil Filter Boss, to allow my adapter plate to snug up, and seal against, the block.  I used a cut-off wheel on my moto-tool to remove the 1/4", then I used a grinder to smooth the edges.

Here is a schematic showing the Oil Filter Boss on my 1979 CB750K:

http://www.bikebandit.com/houseofmotorcycles/1979-honda-cb750k/o/m2001#sch16784 (#14, the Bolt is #13)

The 1983 CB650 SC's oil cooler, and adapter plate, appears to be a direct bolt-on, which is why I recommend that over an after-market adapter made for the CB750's.  Besides that, some folks are currently selling the whole oil cooler unit, on e-Bay, for around $30 -- little, to no, modifications required.

Shiny, if your oil is that cool, then, No, you don't need a Cooler.  Mine read 250 F, at highway speeds, consistently, for 3 hours of riding, which is the thermal limit of dino oil, before it breaks down into carbon sludge.  Mine is a DOHC, which may run hotter, for whatever reason.  The best thing to do, is what you have done:  put a temperature gauge on it first, to check to see what temperatures your particular engine is running at.  If it is consistently at 240+ F, then a Cooler is a very good idea; if it is at, or below, 210 F, then you don't need a Cooler (mine consistently runs at 210 F, with the Cooler circuit running, in town, and on the highways).

Also, it depends on the air temperature:  if the air is cooler than 60 F, your engine oil will be much cooler; my oil won't reach minimum operating temperature of 180 F, if the air is cooler than 60 F (even with 90% of the oil bypassing the Cooler, due to the Thermostat, it still can't warm up).  In air temperatures of 80 F, or higher, my oil heats up to 250 F, without the Cooler; it only reaches 210 F, in air temperatures of 90 F, with the Cooler running.  Cheers!

[TOOLS1]

Well thanks sarg!!!! I did not know that thing screwed in. I just learned something! That is the part that is giving us trouble. The Toolmatic has had an adapter off an F model, and an oil cooler put on it already. I had a tuff time getting the lines to seal. If I ever have a problem with them again, I am going to have braided stainless steel lines made up.
Also I think the reason Shiny's oil temp is lower then your DOHC is because your oil is in the case, and his is in a tank hanging off the side of the bike.
TOOLS

[Piute]

   If I remember right there are no threads and is the same thickness as that base plate

    I need an oil cooler ,bags, fairing, my fat ,pulling a trailer
  Going over mountains at 6-7 k feet,AND it get hummid as  here,
   into Tex / mex/cal. 100s easy in summer,
  All my bikes had coolers and front crash guards that I cover in morn and cold season blocks the wind for legs but also the engine.Of course oil covers .
   
    I've seen the 1s I wont but there all chrome plated (  )witch holds the heat so does coatings,The plate for the lines is what I wont now .well after I get the bike running / back together N legal.Ins.

[shinyribs]

Thanks for the insight Sarge.Good call on the tank Tools.I imagine that would make a big difference. I guess the true test will be once the temps get hotter. Hottest I've rode with the gauge was in the mid 80's.

[TOOLS1]

I just noticed the parts diagram Sarg posted was, for a DOHC. I just checked, and the SOHC does not have a removable fitting, so it is back to the machine shop.
TOOLS

[sgtslag]

Here are two things I used to seal my system, after 'the usual suspects' failed:

http://www.bing.com/shopping/permatex-high-temperature-thread-sealant-59235/p/FD1622A375806E1A5006?q=permatex+hydraulic+sealant&lpq=permatex%20hydraulic%20sealant&FORM=HURE  Hydraulic Thread Sealer  (PTFE Tape/Teflon Tape/Plummer's Tape always leaked, within a few hours, no matter how many layers I wrapped around the threads on the hose barbs...)

http://www.bing.com/images/search?q=T-bolt+clamp&view=detail&id=CFDE77FEDA693C61D4F2B7373F10C2DEBF185677&first=0  T-bolt Clamps -- worm drive clamps won't withstand the high pressure (72 PSI, max., in my DOHC; I tried using two, and even three, worm drive clamps, next to each other, but they could not hold the pressure)

I may have to write that one on my calendar, Tools.  

It is rare that you don't know some detail about these bikes.  Your expertise keeps this place worthwhile, along with the collective expertise available.  Without some extremely knowledgeable folks, like you, Luke, and many others, it would be a lot more challenging to mine this site for needed information.  Cheers, to you, and everyone else who is willing to share their knowledge, and experiences, with us all!


---------------------------------------------------------------
Part Deux:

I know Lockhart made complete cooling systems, which included adapter plates, for the SOHC's.  Did they have the adapter with walls to make it stand off from the SOHC's non-removable Filter Boss?  The Lockhart adapters I have seen on e-Bay, seem a bit thick, so maybe that is how they did it?  There is plenty of space between the OEM filter housing, and the front tire, so clearance is not an issue, if you push the filter housing forward a couple of inches, with an adapter plate.

[Piute]

sgtslag ;"

  ""  It is rare that you don't know some detail about these bikes.  Your expertise keeps this place worthwhile, along with the collective expertise available.  Without some extremely knowledgeable folks, like you, Luke, and many others, it would be a lot more challenging to mine this site for needed information.  Cheers, to you, and everyone else who is willing to share their knowledge, and experiences, with us all!   ""
                                                   Yes thank you all ,You to srg.
                                                                 

  See parts needed here ,I was looking 750,
http://www.cmsnl.com/honda-cb650sc-1984-nighthawk-650-usa_model7227/partslist/E++01.html

[Piute]

                                                         
                             Bought this  35.bucks        Well IF can't make work sure some-1 will

[TOOLS1]

$35.00 Great deal!! My buddy paid $75.00. for his at the salvage yard on Hwy 50. I could not believe he did not leave it on the counter, and walk out. I am having some spacers machined to adapt it to his K-3.
TOOLS

[Piute]

http://www.bikebandit.com/houseofmotorcycles/1984-honda-night-hawk-650-cb650sc/o/m151719#sch400589
http://www.bikebandit.com/houseofmotorcycles/1977-honda-750-super-sport-cb750f/o/m151839#sch403072
 
                                               use Bike Bandits OEM spec.
                                             
    O.K. looking at both specs  84 650sc    side by side         with 77 750f
                     
                         main bolt   581221 650 smaller houseing    581110
                     valve check    581240       same                    581240
            spring valve check   581241       same                     581241
          pin spring setting      581242       same                     581242
                   bigg spring      581099       same                     581099
                             filter     581064       same                     581064

                                                    bigg"O" ring 89x4.5

          So what ya think can I just swap out the rear plate and remove ? spacer.
           need to see inside SC plate fo flow desgn
          this is cool learning alot all over this putter

  With all even the K being the same any switch should be easy for all Tanks again srg/ tools

[sgtslag]

If the adapter, with the hoses attached, is the same OD as the filter housing on the 750, yes, they will swap, and seal properly.  As long as they are the same diameter (both OD, and ID), on the adapter plate, and the filter housing, they will mate, and seal.

Check the center hole on the adpater, also.  The front and back of the adapter plate need to be sealed from each other, or oil will not flow through the Radiator.  I could not tell if the CB650 SC used a different Oil Filter Boss, or not.

[EDIT (06-27-12):  There is a hole in the adapter plate; this will allow only some, not all, of the oil to circulate through the radiator, while the rest goes to the filter, un-cooled; I suspect it also lowers the pressure within the radiator, but I could be wrong.]  This 7-row Radiator will shed a lot of heat.  Try it for a while, and see how your oil temperatures run.  If it takes a very long time to warm it up to 180 F (minimum operating temperature at which the oil will begin to suspend crud within itself, to be captured by the filter), you may want to install an oil thermostat, which will bypass the Radiator until the oil reaches 180 F.  I used the Perma-Cool thermostat (20 GPM flow rate; will withstand up to 200 PSI; available on e-Bay, for $59 + $9 S/H:  auction link.  Keep us posted.  Cheers!