Engine Cooling

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May 24, 2003
We've had 30+ degrees celius for the last week and the engine is stinking hot, you know when you can feel it heating your shins? :oops:

I saw a local 850 with a 6 row oil cooler/radiator which seems a good idea. How do you guys over in California keep the engine cool?

Can you recommend any specific parts or is it sufficient to take a smaller cooler off a Jap bike and plumb it in? Is there a downside to doing this mechanically/internally?

Hi Richard,
I have been thinking about putting some kind of oil cooler on my bike. I must admit during the summer months, I dont ride quite as much here in California, it's too hot for me let alone the bike.

Having said that I do still ride. I figure that if I am stuck at in traffic or at signals, the oil will still overheat, as the bike is not moving.

I change my oil every 1000 miles. How often do you? and what kind of oil are you using?

Let us know if you get an oil cooler, how it goes. I know Switzerland, and I wonder if you have to worry about it running too cool during winter.
I saw an Tony Hayward advertisment (the primary belt drive guy in the UK) in "Classic Bike" a couple of nights ago which appears to be exactly what we are discussing - a 7 row oil cooler with a thermostat which from memory operates in a range 72 to 84 degrees celcius. This would negate any problem of riding in winter as the thermostat wouldn't be activated. I believe the cooler cost £75 and the thermostat £29. Seems reasonable enough to me.

I'm going to wait a few months before deciding what to do as I'm moving down to Brazil (SP) in august with my family. I've seen a coupla Commandos for sale down there but dont want to take parts down in case when I arrive I dont like the bikes. I'm sure I'll be posting regularly once I arrive as both bikes are "very original" not having access to the classic scene and parts that we enjoy in europe and the States.

I ride 9 months of year on a daily basis, the other three months we're under snow! Personally I dont find the cold affects the performance of the bike. Same cant be said for me.

I use Castrol 20W50, change the oil every 1500 miles and the filter everyother oil change.
Jerry I'm still undecided on the cooler question but saw an interesting comment on the NOC list which rightly takes the question back to basics: 'what temperature range should the engine operate under?'

At the 60 degrees mentioned below the thermostat doesnt check in (until 70!) so whats the point of carring the extra weight if it aint gonna function?

"Oil coolers or not to oil cooler" Down under in summer it can get as hot as Crete or New York in July. I've been down the oil cooler track on the Commando and have taken it off.

After serious long rides in summer heat I'd put my finger into the oil tank
and couldn't feel a temp difference. I started measuring the temp by
sticking a thermometer into the oil tank instead of the finger as soon as I
hopped off the bike and flipped the seat. Now without oil cooler I've never
seen the temp over 60 C, thats 140 F for all you lot on the other side. I
just couldn't see the value in running the cooler and not getting the oil up
to a good running temp. As far as siezing a piston and blaming the oil,
maybe there was another reason why it siezed."

What temp should the oil be in the tank or am I missing the point, should the temperature be read elsewhere in the system? Thanks.
here in canada we wait for the motor to warm up gently desired effect of glee then drive slowly till she feels good then crack throttle for desired lip peel back.
Richard, It sounds like your Australian experience has already answered your question. It gets as hot in OZ as anywhere else and if you operated a Commando satisfactorily there then I doubt you would have any problems even in The Middle East - where they used Commandos for police bikes for many years.
Hi Richard
I have been running a Lochart oilcooler on my 74 Norton ever sence new, here in Queensland, Australia, very hot summers, its on all year round but our winter only gets down to about 6c, I ran it for 3 months before I put the oilcooler on and will never run without one now as well I also run a strait 50 grade oil, I run a oilcool on all my bikes and never have any overheating problems and the motor love me for it...

Its not even summer yet and we are already getting up to 30c

Hope this helps

I ran my 850 for a couple of years in the Pilbara region of Western Australia. Our favourite ride was a 300km round trip out to Auski Roadhouse on Great Northern Highway for a coke and a burger. This was in temperatures of up to 48 degrees C. I never had a problem with overheating or even rough running in this heat. Coming back to town the bike would idle beautifully with no pinging as the motor cooled after switching off. I wouldn't bother with an oil cooler. In fact I've removed the one from my other 850.

30 degrees C is a cool summers day here.
I remember reading an article a while back about the effect of oil coolers. Can't remember where now. Someone went to the effort of measuring oil temps with and without a Lockhart cooler and the drop in temp was only very slight. Conclusion was the same as fullauto's, probably not worth the effort.
Oil cooler is an old issue that is basically a non issue in Nortons of about any sort.
Alan Goldwaite was the one who put thermo probes in various places including the oil from exhaust side of head down push rod tunnels. The oil there got over 400'F. Jim Comstock has a probe inserted deep between the jug and finds over 500'F there. His temp probe in the front of head gets up to 400'F.

There is about only 2 conditions that can over heat, one a ridden Commando in about dry- no humidity air going up hill loaded in top gear in same direction and speed as the wind. The other would be about WOT for quite some time with engine totally covered up. This of course assumes good tune condition & timing.

I've done my own measures and heat is almost a one to one relation to how much throttle/fuel is being fed, almost regardless of air flow. I can grantee that you can not even get a Commando to 2/3'ds its hi way temps by long idle near 1000 rpm in 100'F full sun on radiating heated cement is sheltered from wind area. I left Peel idling outside my office window about 5 ft from my eyes to watch its meters for over 30 min and it would not get hotter than 250'F CHT or 900'F EGT, mostly settled to 220'F CHT and 800'sF EGT. Oil temp leaving bottom of tank only read 125-135'F. Skin of 99+% of people feel 143'F is about hottest shower they like for comparison.

Of all the places to put an oil cooler I'd have to say only the flow to head.

There has not been a completely thorough oil thread coverage on lists yet to fully cover what matters most. What matters most are the corrosive acids from reaction with moisture that come from combustion and cool down condensation.
This takes close to boiling temps 212'F to cook off water. Also the protective zinc and phosphorous metals don't become effective to bind to surfaces until at operating temps over 150'F - below that they accelerate friction wear, such as idle when there's not oil pressure to get much/any hydrodynamic pressure layer separation so metal to metal contact occurring the most but w/o the protective additives ain't sticking around to do their job. The higher Zn/P levels over 1000 ppm degrade parts life even in old flat tappet engines. So too much of a good thing is too much. Chevy Corvair experts know the score here and then some.
They know to let engine get full temp before leaving or loading it much. Best Manx owner blip throttle for 10-15 min sitting still - every now and then feeling the fins. Partly to stablize thermal parts clearances but also to get the tappet protective metal package working too.

In Ms Peel prime it took 30+ min of near red line in low gear sports bike spanking games to get the max oil tank temp to 195' F. Then when turning to go home 60 miles away in lazy relaxed 80-90 mph cruise in twisting hwy, oil temp dropped in under a min to below 165'F in summer heat over 95'F. Just running at 120 mph for half mile long opens only got oil temp to 170'F. Peel was still eager to pull another 15 mph w/o much delay ok. Max I ever got - EGT 1375'F and CHT 425'F.

Old school was to just cut vents in TS tank cover. Some like Alan G. made an space age looking finned plate cooler that was part of the cover itself for most compact attractive effective radiator. I can't remember seeing oil coolers on vintage racers of all makes, but may have over looked that somehow. i expect to have to insulate spinal oil tank but sure thinking about a head oil only cooler in boosted Peel, but not a worry to even put a meter on plain Trixie Combat after seeing what it took to even get Peel to moisture cooking temps. Inside exhaust side of head is whole another issue but at conflict with rest of the engine needs.

Main oil factor in our bikes is to let it get hot enough to cook off moisture and then change it often as can afford. Another thread is needed to cover the couple dozen oil varieties chart we and other air cooled road craft should select from.

Picture a cover with 3 inch strip of Al fins running length of the cover and sticking out proud a bit in the air flow. I've the pdf file to share private but can't covert or copy the image to display here.
Oil Coolers for the Norton Commando motorcycle
Prices: primer finish $99.95
painted, with decal $129.95
please specify black, silver, red or primer
and 750, 850 or MkIII decal
Available from:
Magic Devices
1780 Chanticleer Avenue
Santa Cruz, CA 95062
(408) 475-7505
• Replaces stock side cover, using original bolts
• Solid-state design - no hoses or fittings to leak oil
One must consider that the circulating oil is much hotter than that in the oil tank. I have measured temperatures in the tank of 220°F+ with highway riding. I spoke to an engineer from Spectro Oils. It was his recommendation I add an oil cooler, with a thermostat. Having done so, I find tank temperatures much lower. Around 180°F. Keep in mind I'm using an uncalibrated meat thermometer under differing conditions. There's a very good possibility no two Nortons will run the same temperature. Mine is a 72 Combat with a Web 12a cam, Boyer ignition and 32mm twin Amals. I suspect rider weight would account for some difference, too. I scale out 250+ lbs.
Jim, I've carried two 50# feed bags and 3 cases of beer many times, when I was living on Ms Peel and did not see oil temps like yours ever. If not calabrated meter who knows what either of us actually got, though my meters were either aircraft or standard automotive type, not kitchen crude nor lab grade fine.

I'm really concerned about the flash temps of oil in super charged Peel's head.
I want to try to increase oil flow to exht side, just don't know how much to attempt by relieving the rocker shaft, or just flipping them as in low pressure early twins. Exht. guides never see suction, as sealed on intake and open under pressure plus with Drouin even the intakes should never feel a suck into chamber. So no valve seals needed, I think.

Only other thing I can think might help lower carbonizing break down is extra cooling to oil entering head. I've a spare frame tube on either side of engine to tap into for this possibly. With thermo color change paint would be interesting to watch. Otherwise guess I'll just suffer along with both too low oil temps plus too high at same time, no good compromise beyond what's traditional. I have a lot invested like others so would like best life out of it before I go.
Oh Wow Ludwig, thank you very much for the head air flow mods. I cleaned up the over casting deep inside of barrel and head, this will be fun and functional to do, cool. I loved looking at the Norton early ads on their head design showing the air paths. I only remove some the grosser casting errors as some just looks good and smoother gets hotter. Picture really helped my simple mind.

On Ms Peel, she's got the insides thermal coated but also outside in Black Body Emission coat as Swains calls it. Weill experiment with more exht. rocker oiling down tunnels and cooling head oil feed via a frame tube or two. For a land speed, would have to spray water at fins or just not burn enough fuel to make a mark.
That drilling a hole in the fins is a neat tip.
Is this a old modification trick ?
This is the first time I have ever heard of it. Makes total sense to me.

I've got a RH10 head on my bike now that I need to remove and take over to CNW for some exhaust thread repair.
I think I'll drill it like you suggest before I put it back on.
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