The International CBX Owners Association

The early CBX's had straight studs. I guess they blew head gaskets and Honda retrofitted stronger, thicker, spiral studs. Why didn't Honda realize the X would blow head gaskets before they went on sale world wide? I believe it's due to the insufficient oil cooling capacity of the X.

On an air cooled engine the tolerances are much loser then a water cooled one. Different metals expand and contract at different rates. The rate of expansion for aluminum is greater then steel. The pistons are aluminum. The sleeves are steel. I've gotten a CBX engine hot enough in traffic to where I killed the engine and it would not turn over. After sitting for 15 minutes, the pistons have cooled and contracted enough to where the engine turns over and starts. That's not recommended.

Synthetic oil might not keep it that much cooler but loses less lubrosity at extremely high tempreratures then mineral base oil.

We Americans are noted for abusing our toys. When we got the CBX, we rode to the Grand Canyon. Idling in traffic for hours. Rode them through Death Valley. Went to Vegas. Every time getting them hotter then the Japanese intended. Piss poor product evaluation on their part.

Every time the engine got really hot, The aluminum barrels would compress against the head gasket. Squashing it. Maybe even stretching the studs a little. Once the studs stretch, they don't return. We forget to change the oil, for a loong time. We add some occasionally. The oil gets reeal thin. Is it any surprise we blow the head gaskets?

I've had oil temp guages on 3 different X's. Every one with a stock cooler would reach temp's in excess of 300degrees fahrenheit on a 70 degree day with normal (for me) riding. While in Colorado, I was riding my 82 loaded with lots of stuff and my fat ass. Chris was on his 80. He's much smaller then me. Out of curiosity after a ride, I felt his valve cover and mine. I had to touch his fast and immnediately remove my hand so it wouldn't get burned. I could hold my hand on mine indefinitely. I have a 13 row stacked plate cooler. Your oil needs to get hot enough to evaporate any moisture in it and mine stayed at 180 to 220 for the whole trip. Including 112degree days across the desert.

I've had X's with over 100,000 miles with no engine problems. I've worn out swing arm bushings/bearings, pro link bushings, fork bushings, steering head bearings, brake rotors, etc. I've had the holes the bolts that hold the brake calipers go through elongate. I've used synthetic in my X's since 1983. Those that I've ridden hard have had big coolers also.

If you have an early X with straight studs, don't let it get hot and you shouldn't need to change them. Dr Tom broke an engine at Mid Ohio racing vintage and bought an early engine at the swap meet. It has small studs. He raced with it and did good. He has a big cooler on his bike. I gotta go drive my truck now.

Many years ago (when the buffalos were on the prairie,) I read that one of the main limitations for silly horsepower in the CBX engine was high cylinder head operating temperatures....
As George intimated, by lowering the operating temperature of the oil this could have an oil/air cooling effect..... However I feel that for all weather day to day driving, a thermostat would be advisable....

The early smooth studs were only on the first approx 4,900 motors. My 79 CBX originally had them , but when I lost the 2nd gear in 1985, we took the engine apart and replaced them.
Some other thoughts:
As the combustion takes place mainly in the cylinder head, the head has to dissipate the major part of the heat created through the process. Much more than the cylinders. Cooling the head is more critical. Most evident by the large cooling fins on the heads of most air-ccoled motors. When Porsche made the transition from air- to liquid-cooled on their flat six, only the heads were liquid cooled.
I was always suspicious that many hp hop-ups on CBXes would be fatal mistakes as the complex set-up of the inline six would doom it as the necessary heat dissipation can not be achieved.
Remember only barely 30% of the energy that you feed the gasoline engine will turn into useable power, the other 69% or so go out the exhaust or turn into heat to be dissipated by engine cooling. If you are able to bump the output of a CBX motor by 50% and want it to be reliable for more than a quarter mile run, you ned to make sure, you provide cooling and heat dissipation for an increase of the equivalent of 100 hp heat load.

George and I were talking about the cooling of CBXs out in Colorado. I suggested that with a bit of creative hoxe routing, one could stack two stock coolers. I have a CB900F cooler lieing about, with no lines.. But the lines are easily made, using the stock ends.

Winter project........

It would probably be easier to adapt a CB1100R or CBX750 oil cooler. Those things have 12 or 13 rows.

an 1100F cooler is an easy installation using the stock lines. It's about twice the size of the CBX cooler. Oil does need to get up to a temperature high enough to turn condensation in the oil to steam and in every day operation with the 13 row coolers, my X's usually run between 180-220 degrees f. I've considered a thermostat and would seriously look for one if I lived and rode in a cooler climate. I guess we're torn between oil too hot and too cool.

I don't think that the oil in an air-cooled engine is enough to transfer heat away from the head. There is just not enough oil flow in there. I agree with George, that too big of an oil cooler may represent the problem of not "cooking out" the moisture. I have seen air-cooled motors turned into partially liquid-cooled by welding a water jacket around the head..

While in Colorado, I was riding my 82 loaded with lots of stuff and my fat ass. Chris was on his 80. He's much smaller then me. Out of curiosity after a ride, I felt his valve cover and mine. I had to touch his fast and immnediately remove my hand so it wouldn't get burned. I could hold my hand on mine indefinitely-Mike, when you get back from Europe, ride your X out to California and we'll compare your head temp with my head temp.

Mike, I am running a 1100f cooler on my Turbo. How much bigger would you say a (CBX750 oil cooler) be that you said had 12 or 13 rows? I have never seen a cbx750 oil cooler. Louis

Now here is an interesting approach to the engine cooling problems! These integrated air-ducts are supposed to channel fresh air to the rar of the cylinder and the carbs. This would probably be a concept that would benefit Andreas Georgeades' 12-cyl bike's rear bank.

Mans ingenuity once again, however only effective whilst in motion....

Louis wrote:Mike, I am running a 1100f cooler on my Turbo. How much bigger would you say a (CBX750 oil cooler) be that you said had 12 or 13 rows? I have never seen a cbx750 oil cooler. Louis

If I had a turbo bike, I think I would invest in an Earl's cooler - They're larger (and nicer looking) than any factory motorcycle oil cooler

Don

Louis wrote:Mike, I am running a 1100f cooler on my Turbo. How much bigger would you say a (CBX750 oil cooler) be that you said had 12 or 13 rows? I have never seen a cbx750 oil cooler. Louis

The CB1100R oil cooler is the only one that has 13 rows. The CBX750 unit is smaller. The advantage of the Honda oil coolers over an Earl's is, that they look more integral to the original bike design and they don't need custom hose connectors. In the end, it is a matter of personal taste and preference.

I think at this time my 1100f cooler is ok for my turbo, due to the fact i have a extra quart of oil in the bike with a larger oil pan and running Amsol.

Maybe even stretching the studs a little. Once the studs stretch, they don't return.

I don't think there's any way in Hell you'll stretch those studs. That would mean you'd have to exceed the elastic limit of the material. Remember that the units of elongation are inches/inch, then consider the length of the studs. It shouldn't take much more than that