TOPIC:

Never ran a thermostat on any of my bikes that had oil coolers. In cool weather on the street (35~50F) I would block off 2/3's of my oil cooler with duct tape.
If the duct tape started to show slight signs of melting I would remove the duct tape. If the duct tape looked like it was still on the roll, I left it on the oil cooler.
I picked up that trick from sports car road racers. Used that trick when I lived back in Chicagoland where it got that cold two times a year!!!

 

How necessary is an oil cooler?
What are the engine parts that can be adversely affected by excessive heat?

Dr. Gamma wrote:

Never ran a thermostat on any of my bikes that had oil coolers. In cool weather on the street (35~50F) I would block off 2/3's of my oil cooler with duct tape.
If the duct tape started to show slight signs of melting I would remove the duct tape. If the duct tape looked like it was still on the roll, I left it on the oil cooler.
I picked up that trick from sports car road racers. Used that trick when I lived back in Chicagoland where it got that cold two times a year!!!

 

Doc G I have nothing but respect for the knowledge and experience you hold but the above confuses me, surely what you are saying is that a coolers requirement is sporadic. All an $80 thermostat does is replace the duct tape exercise with something that takes care of itself and optimises oil temperature automatically so you can go about your business ?

MLMG wrote:

How necessary is an oil cooler? That depends on the temperature you are using the bike in (not sure of the climate in Uruguay) but in your case with a big bore high compression motor personally I would say you should have one (IMHO)

What are the engine parts that can be adversely affected by excessive heat? Don't forget the oil "cools" as well as "lubricates" overheating the oil will cause bearing damage, possible piston/bore damage and will effect clutch operation (short answer is everything that relies on oil to cool and lubricate !)

Wookie58 wrote:

Warren3200gt wrote:

Do you mean thermostat or do you mean temp guage? 
If you put a thermostat in the oil feed line surely the head will be starved of oil until the gearbox oil temp reaches high enough for the thermostat to open and allow flow or am I misunderstanding something.?



 

The thermostat simply takes the cooler out of the circuit until it is needed, you still get full flow to the head but a small amount is diverted through the cooler to avoid " cold shocking" the system when the thermostat opens (same as a coolant thermostat on a water cooled motor which takes the radiator out of circuit until operating temp is reached)

OK, so it has a bypass in it. 
The minimal amount an oil cooler increases oil capacity by will just take a few seconds extra to get to its optimum operating temperature. 
Oil efficiency reduces with increased temperature so unrestricted flow is beneficial not detrimental. 
Far simpler to use a climate relevant viscosity oil as kawasaki advised. 
Kawasaki didn't even fit oil coolers to these bikes let alone cooler thermostats despite selling to global temperature extremes. 
Use the correct oil for your region and an oil cooler for the one freak hot week per year but there is no benefit I can see to fitting a thermostat to the line. 

Warren3200gt wrote:

Wookie58 wrote:

Warren3200gt wrote:

Do you mean thermostat or do you mean temp guage? 
If you put a thermostat in the oil feed line surely the head will be starved of oil until the gearbox oil temp reaches high enough for the thermostat to open and allow flow or am I misunderstanding something.?




 

The thermostat simply takes the cooler out of the circuit until it is needed, you still get full flow to the head but a small amount is diverted through the cooler to avoid " cold shocking" the system when the thermostat opens (same as a coolant thermostat on a water cooled motor which takes the radiator out of circuit until operating temp is reached)

OK, so it has a bypass in it. 
The minimal amount an oil cooler increases oil capacity by will just take a few seconds extra to get to its optimum operating temperature. 
Oil efficiency reduces with increased temperature so unrestricted flow is beneficial not detrimental. 
Far simpler to use a climate relevant viscosity oil as kawasaki advised. 
Kawasaki didn't even fit oil coolers to these bikes let alone cooler thermostats despite selling to global temperature extremes. 
Use the correct oil for your region and an oil cooler for the one freak hot week per year but there is no benefit I can see to fitting a thermostat to the line. 

All of the above are very valid points, however I do wonder why KHI chose to fit factory coolers to some air cooled models (GPZ - Zephyr etc) and not others. The cooler/no cooler debate will rage on for ever I guess.
My personal opinion (and that's all it is) is that under certain circumstances a cooler can be beneficial however, something that doesn't seem to have been mentioned is the detrimental effects of "over cooling" the oil which can be increased engine wear, increased fuel consumption and degradation of the oil as it doesn't get hot enough to burn off contaminants such as condensation. Using a thermostat gives you the best of both worlds, extra cooling when you need it and not when you don't. I guess there is a reason why vehicle manufacturers fit thermostats not only to engine oil coolers but also transmission fluid coolers and in some high performance applications differential oil coolers as well.
The bottom line is "do what you feel is right for you"

Look at pages 37,38 John Brookes, KHI made at 5 june 1973 OIL COOLER KIT available for the Z1 (whitout a thermostat!!). Why the cooler? I think for the head because cracks in the head almost always starts at cyl. 2 and 3. Thats a heat problem overthere i think. In the past i used also a thermostat like in this story but i dont like it and removed it because of the limitation of  the oilflow in the thermostat caused by the diameter of the pipeholes. Now i have/ride for many years with only a cooler(like dr gamma) special made for for the Z 1 range and vever problems.  
 

I was planning on using a thermal bypass on mine but rode the bike through the winter without one. I have a gauge on the cooler and it showed the temperature was at optimal level after a few minutes of riding. By other standards the winters are mild but the summers are HOT. Glad I had it then.   Been running mine 5-6 years with no problems. 
Steve

SWest wrote:

I was planning on using a thermal bypass on mine but rode the bike through the winter without one. I have a gauge on the cooler and it showed the temperature was at optimal level after a few minutes of riding. By other standards the winters are mild but the summers are HOT. Glad I had it then. 

 Been running mine 5-6 years with no problems. 

Steve

What are the winter temperatures like in your part of the world Steve - I guess your oil temp is running around 90 - 100 degrees C

Over the decades of riding all over the USA Oil coolers have a place for all of us at one time or another on AIR cooled motorcycles.
In Michigan the need is limited  but wont hurt.  The main time needed here is due to being stranded in heavy stop and go traffic.
 I burned down my Kaw due to lack of airflow over the motor at the big car cruise known as The Woodward Dream Cruise. Pistons melted and scuffed the cylinder walls
so a rebuild was needed..This is without a oil cooler installed  but even a oil cooler may not of made the difference because of lack of air moving over the motor,,.
 While working out west   in California, Arizona , New Mexico and Colorado I installed a oil cooler on my HD ElectraGlide not for traffic jams , but 
for extreme heat, and steep mountain grades which put a heavy load on the motor. , 
 So in closing . I do believe in oil coolers to help out , but they are not a cure all, for lack of air flow over the motor. as the oil cooler needs airflow to work properly

I have never had over heating issues on a bike with a stock engine.
Once you overbore them to the point of thinning out the liners then its time for a oil cooler.

I live about parallel with Michigan and we get hot Summer weather for about 2 months when it can hit 93-97F and be very humid.
With a modified engine I am always worried about air flow over the motor, and try to avoid traffic jams or constant stop/go situations.

If you have a modified engine I think having a oil cooler is wise if you want your engine to live a happy life.
I don't think a thermostat is needed in such a simple system.

Wookie58 wrote:

SWest wrote:

I was planning on using a thermal bypass on mine but rode the bike through the winter without one. I have a gauge on the cooler and it showed the temperature was at optimal level after a few minutes of riding. By other standards the winters are mild but the summers are HOT. Glad I had it then. 

 Been running mine 5-6 years with no problems. 

Steve

What are the winter temperatures like in your part of the world Steve - I guess your oil temp is running around 90 - 100 degrees C

In the winter it can get to 30-49* F. Sometimes lower but I don't get out in it. In the summer it can get to 121* but I ride in the mornings. The oil temp can get over 300* but goes down when moving. I had the sensor on the head and it scared me so I moved it to the cooler. 
Steve