Air cooled engine temp

[Disco Dan]

I have a air cooled 650 motorbike engine and do not have the stock temp gauge. I have a temp sensor and was wondering what the ideal running temp should be and what a very high/dangerous temp would be.

At the moment it ranges between 80c to 160c

[Disco Dan]

Upon a quick google search I found this info for a similar albeit larger bike:

Does this sound about right? Ideally I would like a 'dangerous' temp - where the oil becomes too thin to lubricate properly.


ambient temps under 50 F (10 C) - engine temp 160 F (71 C)

ambient temps 50 F - 70 F (10C - 21 C) - engine temp 180 F (82 C)

ambient temps 70 F - 90 F (21 C - 32 C) - engine temp 200 F (93 C)

ambient temps over 100 F (38 C) - engine temp 220 F (105 C)

The highest I've ever seen the engine temps for an extended period of time was an all day ride in 95-110 F temps. The gauge read right around 260 F (127 C) for several hours with no ill effects.

It appears that the thermostat is set to fully open at about 180 F (82 c), and maintain an approach temperature of about 110 - 120F (43 - 49 C). Once temps get near or exceed 100F, the cooler is on the very edge of capacity, but will do ok.

[Disco Dan]

However mine is 100% air cooled. No oil cooler.

[Max Preload]

Given NZ's average ambient temperature, I'd say don't worry about it. There's not a lot you can do about it anyway. That said, my '91 XR600 did have extended fins with braces, on the head.

[Ixion]

I seen iron heads glowing red hot. Engine kept running fine.

Don't worry about it unless you're turboed or running methanol.

[Voltaire]

I agree, don't worry about it.
I did a tour of Europe in an overloaded modified Kombi van a few years ago and I had fitted temp and pressure guages.
The engine is air cooled with an oil cooler ( for those too young to remember)
On a 40 degree day in Spain oil pressure dropped slightly below the usual 300/250 kpa but the temperature of the oil went from the normal 80 degrees to well over a 100. Oil light did not even flicker.
Of course if the guages had not been there I would have known no difference....
So there you have it, a totally unrelated answer to you question.

[Highlander]

I don't recall seeing any temperature indication on any of the air cooled bikes I've ridden. Can only assume that if temperature was of concern they would have put a gauge to keep an eye on.

[Disco Dan]

Cheers, yes not concerned it will overheat... as it probably cant...

I have a nerdy/geeky temperature thingy attached to one of the spark plugs. I pretty much have two little lights that come on at set temps of my choosing...

Sitting at lights and one comes on.. "hmm thats pretty warm" but nothing to worry about :Punk:

Cheers for replies!

[Dooly]

The oil temp gauge on my Ducati 1000SS air cooled has only ever got as high as 110, and usually runs about 99-103.

[Motu]

I used to give my VW's death....and managed to kill a few too.One day I heard the gen/cooling fan belt go....and kept the throttle down hard on the motorway.Went 3 exits past my exit,came back,thrashed it around the streets for awhile....and then gave up.They don't overheat.

Off road bikes can be thrashed all day at low speed/no air speed,and get nowhere near hot.Hottest aircooled bike I've ever seen was a Kawa quad - I put my palm on the alt cover,and it was like a hot iron - my palm went red and smooth,all finger prints gone.They continued to ride the bike for the rest of the day....non stop.