Oil Cooler?

[MBellRacing]

I've heard a number of people talking about how continuous high speeds (relative to a bicycle, apparently) and oil breakdown, then in other places, words of oil coolers and how they may help.

A few questions:

First off, how fast is too fast for, say, highway riding? If I'm on California's Highway-5 where the speed limit is 70mph, would I safely be able to ride 75-80mph?

If oil breakdown is a problem, would a simple oil cooler help? If so, how would one install it, and would the standard oil pressure be able to pump through one without any other issues?

Can I install an oil temp gauge somewhere in the system where it would be relatively easy to read while riding? At what temperature would I need to worry about breakdown?

...I'm building my bike fairly custom, not to be a completely original deal, so things that help make this bike closer to a daily rider are A-Ok with me!

I found this online...



I see that it is using the oil return from the head as the inlet to an oil cooler, but is the outlet as important? Can't I plumb it back in pretty much anywhere as long as it gets back to the pan?

[teazer]

That bike built by Bob McLean IIRC is now Steve Brown's if I got the story straight.

Oil is taken just after the pump on it's way to the head and crank and is diverted through a cooler. The feed is blocked off just past that feed to the cooler. Oil returning from the head just drops down the cam tunnel to the bottom end.

Get an oil temperature gauge which replaces the oil drain plug. It won't tell you the peak temperature that oil reaches but will tell you the temperature of the bulk of the oil. Past experience suggests that it will be way less than critical.

Ours was a Daytona .

[jensen]

Hi,

70 mph isn't that high, and the revs (I suppose normal / standard secondary sprocket set) are not that high either. However, it depends on the state of the engine if a speed of 75 -80 mph can be maintained over a longer period.

I have an integral oil temp sensor build in my oil pump and it measures the temp of the oil just before going into the oil gallery. On a hot and dry (low humidity) day, and riding on highway (average speed 120 km / hr (75 mph) the oil temp in the crankcase is around 80 to 90 degree's Celsius (180 F to 195 F). With the IR scanner (at my work) I read a temperatures of 100 to 130 degree Celsius (212 to 266 F).

An oil cooler is good for lowering down these temps, but, when colder, the oil can't reach it's temperature, the engine stays to cold.

Conclusion, yes, the CB72 / 77 could use an oil cooler, and when looking into an high milage engine, you will see lot's of burned oil, meaning the oil was too hot, especially on the piston pin bearing (con-rod small end) and piston floor.

But, todays oils, synthetics and minerals are capable of withstanding higher temps than in the "good old days", just make sure changing oil in every 1000 miles.

As to cold oil is not good too (even worse), I suggest not to fit an oil cooler, or make sure you tape off the cooler when not necessary.

Jensen

[teazer]

Burned oil on the lower face of a piston crown does indicate that the oil got hot, but it's more of an indication that the piston crown was too hot. Some brown stain is normal, especially with a lot of miles.

One of the many jobs that oil does is to remove heat from pistons and valves and to allow that heat to radiate out from large surfaces like the sump. That's one of the things it is designed to do.

A cooler with thermostat is a good idea in terms of adding more oil which is available to take away surplus heat, but CB72/77 does not need an oil cooler under most circumstances. Oil can stand a steady temperature far higher than those quoted.

A badly set up bike or running up hill in high gear with heavy load will all stress the motor and the oil. Jerry probably uses one on his race bikes, but he is dealing with 2x the engine size and 3 or 4 or more times the power of a stock CB72.

[jerry]

I did run a oil cooler on both 450 and 500 capacity bikes in the 80s. The oil cooler pick ups and returns were in the pump and the coolers were under the engines. Oil used at the time was Belray monograde 50 synthetic. The current bikes run no oil coolers and oil used is Amsoil monograde 60 synthetic. Proper warm up has always been of the utmost importance with motors running at a steady 4000 to 5000 rpm. On a very cold day up to 15 minutes is required. I will only let the bikes out when the clutch cover is getting hot. There is no discoloration under the piston crowns and the conrods at the little end go a very light golden colour. I dump the oil after each race meeting. The bikes run on Methanol and if I were to run on petrol I would fit coolers again. I personally believe that frequent oil changes is a big part of long term engine survival and whwen I had my own CB72 road bike I changed the oil every 500 miles. All the best Jerry

[LOUD MOUSE]

Now that jerry has discussed the oil cooler I can tell ya that the bikes are so near a CB72 engine/bike in appearance that ya would never know how jerry has built a WINNER..
I'd say that he has ideas he applies which "keeps it simple" and WORKS!
Not merely the engine but the entire bike.
Oil Pump screen there jerry?. ...............lm

I did run a oil cooler on both 450 and 500 capacity bikes in the 80s. The oil cooler pick ups and returns were in the pump and the coolers were under the engines. Oil used at the time was Belray monograde 50 synthetic. The current bikes run no oil coolers and oil used is Amsoil monograde 60 synthetic. Proper warm up has always been of the utmost importance with motors running at a steady 4000 to 5000 rpm. On a very cold day up to 15 minutes is required. I will only let the bikes out when the clutch cover is getting hot. There is no discoloration under the piston crowns and the conrods at the little end go a very light golden colour. I dump the oil after each race meeting. The bikes run on Methanol and if I were to run on petrol I would fit coolers again. I personally believe that frequent oil changes is a big part of long term engine survival and whwen I had my own CB72 road bike I changed the oil every 500 miles. All the best Jerry

[jerry]

Oh. You mean the air seperator young LM. Jerry