Topic: How hot should the engine cases get?

[drumstyx]

Just went for the first ride since getting everything back together for the 'final' time in this rebuild, and it's definitely my longest ride yet. Aside from some little carb hiccups (cracking it on the freeway in 5th always seems to make it hesitate -- it's fine at lower speed at the same RPM, but at highway speed for some reason it hesitates) everything feels pretty great

I went to tuck away a wire I noticed was hanging out (one of the wires from the hondaman transistorized ignition) and touched the lower oil fitting, which to my surprise was *very* hot. Too hot to touch longer than an instant, indeed. So I touched around the case and notice that yeah, it's pretty darn hot all over -- clutch cover, valve cover, under the carbs etc, all too hot to touch.

Now, I'm not stupid, engines get hot, but how hot should they be, really? I haven't tested it with this in mind, but I swear on my Concours (water cooled, to be fair) I can touch the engine side cases without too much discomfort. It's still not somewhere you want to keep your hand, but I'm almost certain it was cooler than this.

I've seen some numbers thrown around in fahrenheit for a 550, but I don't have an IR thermometer, I have my hands. So, in old-school mechanic terms, how hot is too hot on the engine cases?

[Jerry Rxman Griffin aka MuthaF'er]

oil temp maybe 200 - 230'ish.

[drumstyx]

oil temp maybe 200 - 230'ish.

Alright, so it's not unreasonable that my immediate reaction to touching it is to pull away -- that's near-oven temperature.

[seanbarney41]

#$%* will get hot, perfectly normal, don't touch

[drumstyx]

#$%* will get hot, perfectly normal, don't touch

Lol fair enough. Been a while since I had an air-cooled bike to be honest, so I guess it makes sense I'd have forgotten what's "normal"

[seanbarney41]

I like to warm my hands on the valve cover on cold days.  You can feel the heat right through thick leather gloves.

[American Locomotive]

Air cooled engines run far hotter than liquid cooled motors. Cylinder head temperatures of around 275-325°F are pretty normal.

[uksparky]

When i get home after ride i can cook bacon and eggs with skillet on top of the engine its so bloody hot lol.......... thats why you should change your oil around 2,000 miles

[PeWe]

Checked oil temp in tank? This oil dipstick with thermometer is useful. Yamiya and others on eBay sell it. Maybe there are similar for other CB's.
120C is 248F
I have opened up the exhaust and increased fuel screws after that reading.
I prefer minimum 100C, 212F to make sure condense water will vapor and leave thru the breathers.

I use full synth oil that is said to withstand higher temp better. Less quality oil must be changed more frequent if it work hot. The oil additives will break down quicker. I'm not an expert, but I believe in a good temp around 100-110C (212-230F)

[PeWe]

I do not want to change oil more frequent than 5000 km ( 3150 miles).
5000-8000km OK for me if most is crusing with OK temps.
Break-in period after total engine repair different. 100km, 1000km.

[bryanj]

Don't care what oil it is 1500 miles is about it as the gearbox hammers the hell out of it, synthetic is worse as there is no zinc in it

[Deltarider]

It all depends on how you use the bike. Many short rides and you'll have to change say every 3000 km. But on like long holiday rides I'm pretty confident to do 6000 km, which happens to be the prescribed interval for the CB650 and I fail to see what essential difference there is between the CB650 and the CB500/550. 

[PeWe]

5000km on one oil change has not happened yet in modern times. Often something to do that end up in changing oil. I'll see how the oil will feel between my fingers. There is a huge difference to get a worn out oil between fingers than a fresh.

My car need oil change at max 10.000km, oil turns very thin and loose its "oiliness". It has a turbo that is very hot, cooking oil to bitumen plus carbonized hard particles/flakes which is common in that engine when people change oil to seldom (over 15.000km). VAG 1.8T with 3.7L oil. Medium quality full synth Aral 0W-40.

My K6 has better oil, but will get half distance than my car just for sure. I'll see how the oil will feel between my fingers. It is superior the mineral and semis I have used during break-in. Castrol  and Motul that need more frequent change as I noticed.
Better oil, longer intervals is what I trust. And opposite.

[Biebs]

Get a IR temp gauge very useful can check individual exhaust pipe temps.

I also use mine to check trailer hubs temps after a good drive, air condition output house and car.  Very useful tool.

 

[Deltarider]

Get a IR temp gauge very useful can check individual exhaust pipe temps.
 

Can you explain us a bit more why it is 'very useful' to check exhaust pipe temps.

[evanphi]

Get a IR temp gauge very useful can check individual exhaust pipe temps.
 

Can you explain us a bit more why it is 'very useful' to check exhaust pipe temps.

Simple way to see if they are all the same mixture. Cooler would be richer, hotter would be leaner.


Also just a fun tool to use. I love mine. I checked all the windows in my house when I got one.

[Deltarider]

Simple way to see if they are all the same mixture. Cooler would be richer, hotter would be leaner.

Yeah, that's the theory... in practice it's not that simple. I have an infrared thermogun and IMO it's more of a gadget. The thing is, infrared measures the surface (think: nano thin) only. You can test it: grab a beercan from your fridge (5^o). Almost within a second the can measures say 16, 17^o.

[robvangulik]

Either your thermometer or your refridgerator must be bad, i just tried and i could see the temp rise veeery slowly some 10°c in 10 minutes. Never measured beertemp before
And do test your header temps, and see what happens when you turn 1 ims closed.....

[754]

Check the temp of a black helmet vs white.

[Deltarider]

And do test your header temps, and see what happens when you turn 1 ims closed.....

I may give that a try. BTW, just repeated the beer test. In the fridge the can was 3,8^o. Three seconds later after I put the can on the sink, I measured 16,6^o. Nothing wrong with the thermometer. I'd mistrust yours...

[TwoTired]

Simple way to see if they are all the same mixture. Cooler would be richer, hotter would be leaner.

Yeah, that's the theory... in practice it's not that simple. I have an infrared thermogun and IMO it's more of a gadget. The thing is, infrared measures the surface (think: nano thin) only. You can test it: grab a beercan from your fridge (5^o). Almost within a second the can measures say 16, 17^o.

That’s thermal properties at work, as one would expect. Surface measurements don’t evaluate the internal fluid or gas temps. But for readings on pipes, cases, and hubs, it’s perfectly accurate for comparison’s sake. And useful.

+ one.

Delta clearly has no thermodynamic training or education.  His measurements are almost certainly flawed because he only has his own unproven theories and fake beliefs.  He can't support anything with actual science.  His world revolves around hearsay.

Follow the lame at your own detriment.

Cheers,

[754]

Beer cans can be very thin, like 3 thou.. less than.1mm.
 But, while I can see the can exterior trying to warm, and perhaps condense, the greater mass I would expect is the beer keeping the exterior cold.
 Especially when you consider that liquid transfers heat around 200 times faster than air.
 That said I was warned not to trust the heat gun for accuracy, that it was affected by reflectivity. But to use it more as a comparison.... in my case I was machining without coolant and the material was overheating. So at a certain number if that was cool enough to resume working, then it always was.... so you could go by that.
 Also when we read a black helmet at Bonneville it was at brainfrying temps.

 Another thing happened we tried to use it to anneal aluminum. A shiny surface.. at 500 degrees it did not seem to anneal the aluminum. I reverted to my soap trick, drawing lines across the work, then heating till it turned black... that did the trick.
 So while they can be useful as a comparison tool, I would not trust the temps shown on a cheap thermogun.
 Fwiw..

[American Locomotive]

All IR temperature measuring devices - be it IR temp guns or IR cameras are dependent on the emissivity of objects. Unpainted aluminum, chrome, polished metals, etc...  may not give accurate numbers with an IR temp gun. It'd probably be fine for most uses if your engine doesn't have polished fins.

[Deltarider]

Simple way to see if they are all the same mixture. Cooler would be richer, hotter would be leaner.

Yeah, that's the theory... in practice it's not that simple. I have an infrared thermogun and IMO it's more of a gadget. The thing is, infrared measures the surface (think: nano thin) only. You can test it: grab a beercan from your fridge (5^o). Almost within a second the can measures say 16, 17^o.

That’s thermal properties at work, as one would expect. Surface measurements don’t evaluate the internal fluid or gas temps. But for readings on pipes, cases, and hubs, it’s perfectly accurate for comparison’s sake. And useful.

How useful is it to see a difference after closing the airscrew one full turn? How accurate is that? I can't remember ever having read praises here like: "WOW! What a wonderful instrument is this! It's a must." Mind you, I tested not only a beer can but also my four pipes. Disappointing results, just as my friend, a mechanic, had predicted. Listening to my mufflers tell me way more. IMO you'd better save that money for more beer.

Delta clearly has no thermodynamic training or education.

  HAHAHA, you wanna discuss 'training and proper experience' again?

His measurements are almost certainly flawed because he only has his own unproven theories and fake beliefs.

Eh... fake? Man, I just described what I've experienced? And it was a 'proper' experience, I can tell you.

He can't support anything with actual science.

Let us wait how you will support your claim that 10kΩ plug caps are benificial for spark duration. You really know how to keep us in suspense.

His world revolves around hearsay.

Oh, but when I do, I'm always open about it and tell where I've found or heard it, so anyone can check. Have you ever unveiled where you found your info? Ever?