Author Topic: Oil Cooler Suggestions for SOHC CB750 (Read 4029 times)

Finnigan · « **on:** February 08, 2021, 04:39:08 PM »

Anyone have an external oil cooler setup, specifically hoses and radiator, that mount up and look good? Cursory searches have come up with some pretty random equipment.

johno · « **Reply #1 on:** February 08, 2021, 10:31:04 PM »

Hi Finny,
Yeh there's lots out there, so what's the priority,..... style or temp reduction or combo ?
If temp reduction from sustained racing RPM obviously bigger is better but if occasional road use then a smaller cooler would be more beneficial due to quicker rise to operating temp when stopping / starting but still capable of reducing max temp at high speed touring.
Different requirements demand different sizes ( number of tubes etc) but bigger is not always best. Sounds like style is important to you Finny so the two styles, one will be a base plate under filter with two short lines up to small medium cooler , the other is bigger cooler with bigger lines running back to the oil tank line area.

So quick anecdote on my bike, dead stock K2, I used to run a small Lockhart type just to take the edge off temp on long trips across OZ, usually several thousand mile trips and in the summer with 80 to 100 deg F temps, I had one of those temp gauges in the oil tank lid with a red line at 250 deg F, riding hard ( 70 to 90mph) even in summer heat it usually hovered around 200F with the Lockhart cooler on. Only once did I ever get the temp up to the redline, mid 1970's, was stinking hot day ( 110f) two up with my girlfriend on the back on a flat straight road through the outback ( desert) and a bloke in a new 911 Porsche passed me. I hate being passed, would happily risk death than let some ponce past me so held the bike flat for over 70 miles non stop on the gas and managed to cling behind him at 110mph for about 50miles before the bike started to misfire from fuel evaporation and the ol girl dropped back to 90 to 100, I just kept it flat until we got to the next town (Hawker) where I was embarrassed to say a car beat me.

Point being when refuelling at the pump I shed the temp and it was over 250 F in the red. I changed the oil when I got home and its still running fine 40 years later. I think the cooler saved my butt that day Finny but in the winter riding around town it took about 5 minutes longer to reach operating temp on the way to work.
cheers

newday777 · « **Reply #2 on:** February 09, 2021, 09:43:43 AM »

I have 2 of the Lockhart coolers for my 75 and the 76. Both were bought in the 1970s.

Lockhart used to offer a cover for winter riding to help warm the bike up faster. It was nauga-hide with a draw string to hold it on. I've thought of making one out of leather.

754 · « **Reply #3 on:** February 09, 2021, 01:50:17 PM »

Lockhart with Hose barbs ? the 700 Lockhart comes with threaded ports , , and is bigger . Better if you want to run Real braided lines... unfortunately the ports are on top when mounted the conventional way, fine for Kawi and Suzi, not so good for Honda 4.

Sam Green Racing · « **Reply #4 on:** February 09, 2021, 04:26:35 PM »

OK Finnigan, fill us in with more details, I see you're in So Cal and it gets quite hot there, is your bike a race bike or a tourer ?
We can't help if we don't know what your problem is,

Sam.

Finnigan · « **Reply #5 on:** February 09, 2021, 04:29:09 PM »

Planning to run an 836 kit with cam and ported head. Want to run a cooler for stop and go traffic in the summer, not planning on sustained high RPM.

Alan F. · « **Reply #6 on:** February 09, 2021, 04:52:38 PM »

Quote from: 754 on February 09, 2021, 01:50:17 PM

Lockhart with Hose barbs ? the 700 Lockhart comes with threaded ports , , and is bigger . Better if you want to run Real braided lines... unfortunately the ports are on top when mounted the conventional way, fine for Kawi and Suzi, not so good for Honda 4.

I think the Lockhart sandwich plate I've got had brass 90 degree barbs on it. I took it off a K0 in a junkyard back in 04, spent 1/2 hour digging down in the dirt to even reach it. Some moron had placed a fire engine frame on top of a row of bikes and pushed them into the mud over the years. If I hadn't spotted the rusted out cooler with the Lockhart logo I'd never have known it was there.

No pics though, it'd take forever to find it.

Sam Green Racing · « **Reply #7 on:** February 09, 2021, 04:57:43 PM »

You shouldn't need a big one then as long as it is in the right place.
Place it up high on the down tubes so that it get a good blast of cool air and is not obstructed by the forks and front wheel.
See where it is in this picture.

KasperK/Denmark · « **Reply #8 on:** February 11, 2021, 01:08:42 AM »

Is the oil cooler connected to the oil tank and return hose?

Sam Green Racing · « **Reply #9 on:** February 11, 2021, 02:53:45 AM »

Quote from: KasperK/Denmark on February 11, 2021, 01:08:42 AM

Is the oil cooler connected to the oil tank and return hose?

Something like that.
Just to the rear and behind the clutch cover you can see two oil lines.
One takes oil from the tank and it is pumped around the engine where it is needed.
The second line takes the hot oil back to the tank but instead of doing it this way, you take the second line via the oil cooler before returning it to the oil tank.
Here's a picture of a bike I built, OK it's not stock but you can see the return oil line coming out of the engine, running up under the gas tank to the cooler just under the head stock.
Oil is returned along a line running under the gas tank and back to the oil tank. I hope this helps Kasper.

CB750R · « **Reply #10 on:** February 11, 2021, 10:26:29 AM »

Lockhart isn’t around anymore are they? No suggestions for new oil coolers? From what I’ve read the oil cooler fittings are close to a 10an hose size? So would a small Earl’s trans cooler or a Derale cooler with a custom fabricated mount?

Anyone doing the old oil filter adapter like Terry used to make? Hopefully this doesn’t turn into another 39 page pissing contest, let’s just assume the poster has decided he want needs an oil cooler and we don’t need a dissertation on why anyone considering this is an idiot and that Honda made a perfect machine and that it doesn’t need modifications etc... I’m too tired to hear it again.

slikwilli420 · « **Reply #11 on:** February 11, 2021, 10:50:55 AM »

Setrab oil coolers are top quality and I've had one on my race bike for 4 seasons now with no issues at all. Get their adapters based on what you need. I run -10AN on my race bike since its a perfect match to the oil fittings on the engine, but you could run -8AN with the sandwich plate setup. Mine is mounted right under the head stock isolated with rubber dampers.

CB750R · « **Reply #12 on:** February 11, 2021, 11:23:53 AM »

Quote from: slikwilli420 on February 11, 2021, 10:50:55 AM

Setrab oil coolers are top quality and I've had one on my race bike for 4 seasons now with no issues at all. Get their adapters based on what you need. I run -10AN on my race bike since its a perfect match to the oil fittings on the engine, but you could run -8AN with the sandwich plate setup. Mine is mounted right under the head stock isolated with rubber dampers.

Hey Awesome info thanks for sharing!

Looks like this is one of the top recommended ways to route the oil lines?
http://forums.sohc4.net/index.php/topic,66026.msg1255550.html#msg1255550

754 · « **Reply #13 on:** February 11, 2021, 01:33:56 PM »

There should be no shortage of used coolers out there, and adaptors.. a lot are good brands like Lockhart.
A lot of them are sold as for Harley or other makes, but coolers are the same.
The Setrab are quite wide. And can easily look akward or hit things.
UP AND over with the lines robs a bit of space under tank, and can get in the way. 180 degree fittings and going back to sandwich plate should work well . I will use - 8 fittings on mine... no point in going larger than other holes in the oiling system..

Don R · « **Reply #14 on:** February 14, 2021, 10:00:10 PM »

Yamiya has a Rockhart oil cooler listed.

Finnigan · « **Reply #15 on:** February 15, 2021, 11:31:21 AM »

I searched on Yamiya and didn't see one, can you post the link? I hope its not the 800 dollar one...

754 · « **Reply #16 on:** February 15, 2021, 02:17:43 PM »

YamYamaha 800 bux ? That seems to fit..
Serious I checked eBay last few days , Lockhart s are running mostly from 25 to 100 bux .. a few are higher.
Black, chrome , several sizes. . You will need the adaptor plate and nut if you want to run up front. .

bear · « **Reply #17 on:** February 15, 2021, 11:27:49 PM »

I will be needing a cooler for my Auto as well. Because it will have to deal with the heat generated by it's torque converter and the extra weight of the a sidecar combination I will be using a cooler designed for a 4x4 truck.
I have the room so I might as well use it.
As far as I can tell my only option will be an oil filter adapter.
Hopefully there is an adapter hidden in amongst my spares.
If not I may have to go "cap in hand" to Uncle Terry

andy750 · « **Reply #18 on:** February 16, 2021, 03:23:51 AM »

Here is one TTR400 (Kevin in SA) made for my CB750. Lines not attached.

andy750 · « **Reply #19 on:** February 16, 2021, 03:36:21 AM »

These guys in the UK also make an oil cooler kit

http://d-mengineering.co.uk/cart/index.php?rt=product/product&path=79&product_id=2789

Andy

Finnigan · « **Reply #20 on:** February 16, 2021, 09:17:33 AM »

Quote from: andy750 on February 16, 2021, 03:36:21 AM

These guys in the UK also make an oil cooler kit

http://d-mengineering.co.uk/cart/index.php?rt=product/product&path=79&product_id=2789

Andy

Exactly what I was looking for, thank you!

754 · « **Reply #21 on:** February 16, 2021, 11:53:17 AM »

It looks good , not the cheapest thing to buy, but if Lockhart was making them today price would be right up there.
Mounting looks good , I think lines could run straight down.

Here is the typical adapter you find on ebay, if you look a while .

Finnigan · « **Reply #22 on:** February 16, 2021, 05:58:27 PM »

Yep, found something jsut like that with my parts, its seen better days though and I still would need to source a radiator that fits up well

754 · « **Reply #23 on:** February 16, 2021, 06:07:28 PM »

Well if you have that part, you can run many different coolers.

newday777 · « **Reply #24 on:** February 16, 2021, 08:32:45 PM »

Quote from: Finnigan on February 16, 2021, 05:58:27 PM

Yep, found something jsut like that with my parts, its seen better days though and I still would need to source a radiator that fits up well

PM sent with a link for a cooler

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Author Topic: Oil Cooler Suggestions for SOHC CB750 (Read 4029 times)