Author Topic: Oil Cooler for CB750 (Read 21008 times)

wiskey · « **Reply #25 on:** May 13, 2014, 07:59:28 AM »

Quote from: PeWe on May 13, 2014, 07:51:20 AM

- Do you use a thermostat?
Or did you get high temperature direct due to the 836 High CR kit and less need for thermostat? Like me..

I have searched more about this and found that a Setrab cooler with 7 rows Type 107 (210mm wide in total) is a common choice.
I have thoughts about a 10 row version Type 110, no thermostat. Thermostat should be in the adapter to avoid something hitting into the engine case, cylinder.

I did not use a thermostat as I only ride during summer months. I believe mine is a 9 or 10 row I can't remember.

PeWe · « **Reply #26 on:** May 13, 2014, 09:00:42 AM »

Spring/Summer/Autumn for me... mostly 10-25C (50-80F)
Maybe no risk for too cool. Vaporating out the water and fuel is important.

I have an old ugly thermostat that is still available from Mocal (I think thermostat switching temp is 84C). I can use if the cooler cool too much. Or reduce the flow in hoses.
http://www.demon-tweeks.co.uk/motorsport/oil-coolers-accessories/mocal-oil-stat

Edit: I have just ordered a Setrab type 110 from a Swedish site. Strange to order Swedish product outside Sweden

and 45 degree adapters
http://www.ebay.co.uk/itm/360706376879?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

and steel braided hose
http://www.ebay.co.uk/itm/310428906379?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

I'll be back with oil temperature update later on.

Terry in Australia · « **Reply #27 on:** May 16, 2014, 01:22:48 AM »

I've never bothered with thermostats on my coolers, although I have supplied them (Lockhart in line thermostats) for guys who were convinced that they needed them.

I've checked my oil regularly in all seasons and I've never seen any evidence of "Milky" oil caused by condensation, and when I stripped the top end of my engine last year to replace my rattly RC pistons with the 110 buck eBay specials, the engine components that I inspected were in perfect condition.

Of course, Oz winters (even here in the cooler southern states) aren't anywhere as extreme as in the US, Canada, or Europe, so they may well be necessary on your end of the pond. Cheers, Terry.

PeWe · « **Reply #28 on:** May 16, 2014, 03:42:47 AM »

Terry, thanks for your experiences.

I was rather sure that my engine does not not need any thermostat when it becomes really hot rather fast despite cool ambient temp. 105-110C when 10-15C outside driving 10-20km on a road outside the city. Good idea to check with experience here just for sure.
I checked the temp gauge in boiling water and it was correct.

My pistons are the kind of pistons you replaced in your bike. NOS RC pistons that we have discussed in another thread. Perfect for my engine with wider combustion chambers. CR back and heat as well. One more point to the famous 836 kit with nominal CR. My old pistons had lower CR due to the head. Ran very well and cooler.
Oil cooler on and I'll enjoy the more explosive reaction when twisting the throttle with higher CR

Terry in Australia · « **Reply #29 on:** May 16, 2014, 03:47:38 AM »

No worries PeWe, my bike actually feels more powerful now since I removed the Megacycle 125/75 cam and replaced it with the "unknown" cam, it might not go crazy at around 7K RPM like it did before, but it's much quicker off the line than it was before, that cam sucked! (for street riding)

PeWe · « **Reply #30 on:** May 16, 2014, 04:23:11 AM »

Unknown cam...? You have not measured the openings/closals and max lift to get an idea about the cam?
Maybe something that is still out there.... I have frame mod so a cam replacement take not that much time, blood and tears as before.
I use CX-7... like 125-75 with 3 more degrees of duration. Advanced a few degrees for better low rpm.
Nice answer when twisting throttle around 6000rpm
EDIT: I have 1 cog smaller front sprocket, 17 that help to make things happen earlier.

But I think that my old cam Action Fours SS-1 was better from the very low. 1:st gear drive slow, hit the throttle and a wheelie...

I need to test in current engine for a reliable result

I have not much experience of current cam yet due to carb jetting that was delayed by a bad new ignition coil where the wires for 2-3 had bad connection, screws left the coil.
New coils and ignition (DYNA S) I've got it to idle very smooth 1400-1500rpm.

Now running a little bit too hot, better to wait for oil cooler so I do not repeat the piston problem I had with forged RC 836 pistons 1984. 2 with hole, 3 with a bump. See photo. I hope it will be possible to weld the pistons and run again. Future will show.

voxonda · « **Reply #31 on:** May 16, 2014, 12:29:42 PM »

https://www.facebook.com/photo.php?fbid=570739846335171&set=a.302542719821553.67107.100001974813349&type=3&theater
Another way of dealing with it.

PeWe · « **Reply #32 on:** May 17, 2014, 02:11:53 AM »

Quote from: voxonda on May 16, 2014, 12:29:42 PM

https://www.facebook.com/photo.php?fbid=570739846335171&set=a.302542719821553.67107.100001974813349&type=3&theater
Another way of dealing with it.

Nice photos! Which cooler do you use? Mocal? Cooling the oil is on the top list of a racer.

I ordered 10 rows to ensure the fitment beside the horns, over the exhausts. I was thinking about 13/16 rows.
I have an old fairing made for oil cooler. Glass said to be Dunstall, fairing of local design
Something I found on a fair about 30 years ago.

I also found con rods that the seller said had been used in a compressor charged nitro fueled CB750 owned and driven by in Sweden famous Stefan Reisten resident around here. They needed new upper bushings, slightly oval. But I threw them away together with other old parts such as 2 double port Solex 45mm carbs in need of costly repair 5 years ago before my repair plans... temporarily brain damage

voxonda · « **Reply #33 on:** May 17, 2014, 07:54:23 AM »

Depends on availability, most Mocal, Setrab. Nice fairing you have there, a bit like the RCB endurance racers from the mid 70's.
Think we all had our brain damage from time to time..............................

Cheers, Rob

Terry in Australia · « **Reply #34 on:** May 17, 2014, 11:32:21 PM »

That's a fantastic looking fairing PeWe, I presume that the cooler mounted in the fairing? My cooler sits around 6-8 inches below the headlight, so I'm guessing that the cooler must mount in the fairing itself?

Going back to my "unknown" cam, I've no idea who made it, it's almost the same profile as a "K" series cam, but has around 1mm more lift than an F2 cam. It came with a stock cam sprocket so wasn't "dialled in", but like your Action Fours cam, when I gave the bike a handfull of throttle, it lifted the front wheel, something it never did with the Megacycle 125/75 cam, so I'm guessing that it's a "torque" cam, as opposed to a "full race" cam. Cheers, Terry.

PeWe · « **Reply #35 on:** May 18, 2014, 02:26:05 AM »

The fairing is one of my not done projects from the 80's. I might look for a new windscreen to make it complete.
I also bought an used modified Suzuki GS1000 fork with antidive, Tarozzi stabilisator, double brakes with discs and Campagnolo19" wheel .

My oil cooler project now will have the cooler on the frame right over the exhausts.
The fairing with oil cooler inlet might be connected to an air duct from Revotec on oil cooler and avoid long oil hoses.

Terry, about your cam. Have you checked the base circle? It might be a regrinded Honda cam if lift is the biggest difference.
My old K6 cam has 28,2mm
Action Fours SS-1 27,9mm
CX-7 26,4mm (High lift avoiding cam towers)
F2 I do not know...

johno · « **Reply #36 on:** May 18, 2014, 02:39:29 AM »

gutsy move putting in an unknown cam

you must enjoy a bit of adventure Terry, I like that.

Terry in Australia · « **Reply #37 on:** May 18, 2014, 02:42:15 AM »

Thanks PeWe, I've always liked the idea of mounting an oil cooler up under the headlight like they did on endurance racers back in the day, but like you, was worried how long the lines would last bouncing up and down, turning left and right, etc etc. Fine for a 24 hour race, but not to good for a daily rider........

My cam's definitely not a regrind, but from memory the base circle was the same as a stock K cam, with around 3mm more lift. No idea who made it, but it works very well! Cheers, Terry.

Johno, the cam was in better nick than most of the other ones in my "collection" (read "Junk Pile") so it was a no-brainer, and I really wanted to ditch that Megacycle cam, it'd be great at Phillip Island, but it's crap on High Street.............

PeWe · « **Reply #38 on:** May 18, 2014, 12:23:57 PM »

I understand the thrill to try another cam!

Next obsession with my bike might be just that, testing other cams. Now easy to change cam with the frame mod.

Terry in Australia · « **Reply #39 on:** May 19, 2014, 01:01:30 AM »

Ha ha, yeah mate, I just wish I had more time to ride my bikes. Cheers, Terry.

PeWe · « **Reply #40 on:** May 19, 2014, 01:39:23 AM »

Let's see what happen when I have sorted the oil temp problem. I'm very curious to test DP295

H2Eric · « **Reply #41 on:** June 21, 2014, 11:02:56 AM »

Oil cooler has been fitted to K9.
I used a modified CBR1000 cooler with Goodridge hose and fittings. The position of the oil cooler is not perhaps ideal, but there was little I could do about it as the horn and cables get in the way of it being any higher and thus in the full flow of the wind. Better than nothing at all I suppose with all those extra cubes.

Eric

Terry in Australia · « **Reply #42 on:** June 21, 2014, 06:39:32 PM »

That looks great Eric, how does it go with all that extra displacement? Hey I just found this seller in the UK selling what looks like a very nice oil cooler adapter, if anyone's looking for one? Cheers, Terry.

http://www.ebay.com/itm/Honda-cb750-550-500-400-350-oil-cooler-base-plate/271514555526?_trksid=p11002.c100132.m2761&_trkparms=aid%3D222006%26algo%3DSIC.FITP%26ao%3D1%26asc%3D20140212111053%26meid%3D7702570406936873494%26pid%3D100132%26prg%3D20140212111053%26rk%3D3%26rkt%3D4%26sd%3D291166639011&ssPageName=ADME:B:EOIBUAA:US:3160

H2Eric · « **Reply #43 on:** June 22, 2014, 02:25:39 AM »

Quote from: Terry in Australia on June 21, 2014, 06:39:32 PM

That looks great Eric, how does it go with all that extra displacement?

Hi Terry
As you would expect the bike has a lot more get up and go with the JMR cylinder block, big valve gas flowed head, CR31 carbs, Megacycle 125-70 cam and Dyna ignition. It ticks over nicely at around 1200rpm and pulls away cleanly from 2000rpm in top gear. It really comes alive once the tacho hits 4000rpm by which time that's an indicated 80mph in 5th gear. The riding position isn't really conducive to sustained high speeds, but it sure is fun in short bursts. Recently I noticed the beginnings of a slight weave at an indicated 110 so backed off. The clutch has a tendency to snatch when the engine is still a bit cold, but is otherwise fine. I think it's a Barnet clutch The noise from the fins on the cylinder block takes a little getting used to. It's got the standard rubbers between the fins, but maybe it could have done with a few more. Ear plugs are the answer combined with a loud exhaust

. I've done over 1300 miles on it now so I'm toying with the idea of taking the bike to the drag strip at the end of the month.

Cheers
Eric

Terry in Australia · « **Reply #44 on:** June 22, 2014, 02:42:24 AM »

Make sure you get someone to take a camera when you do mate, I'd love to see some footage of you riding it to it's limits! Cheers, Terry.

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Author Topic: Oil Cooler for CB750 (Read 21008 times)