Air-cooled vs liquid-cooled.

[Ixion]

Kind of related.

Still trying to get to the bottom of my 250RS hot-starting-of-doom and `what's an idle?' situation.

What sort of temp would be normal for an air-cooled bike? I want to measure how hot it's getting and see if overheating is the problem.

That is difficult to answer, because the question would be "how hot where ?"
There will , for instnce, be a great difference in temperature between the area adjacent to the exhaust valves and that adjacent to the inlets . To affect starting , the important temperature would doubtless be that of the carurettor. Manufacturers often make inlet manifolds from some phenolic substance that does not conduct heat. Is yours such?

Perhaps you could measure your bike and another aircooled model (say, the ffwabbitt) and compare them? An even better test might be the temperature of the carburettor float bowl.

[xwhatsit]

I do get hot nuts.

Seen funny little carburettor spacers on Yahoo Japan Auctions.

Stator, coil, CDI will all be inspected over hols.

[scumdog]

Tell that to Erik Buell!

WHOOOOOSSSSSSSSSSSSHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH goes the Buell switched off at the top of a hill.

Hey that rhymes.

And some of the 'bagger' Harleys have a system that kills the ignition to the rear cylinder when idling in heavy traffic and things get hot..

[Big Dave]

And some of the 'bagger' Harleys have a system that kills the ignition to the rear cylinder when idling in heavy traffic and things get hot..

And opens the exhaust valve.
Fitted on the Police Bikes that do parade work I hears

[Ocean1]

As I have read in a print publication of late, the new thing is only the first thing to be based on that engine and chassis. I guess there will be more laid back 1125 (1125S ?) missing the scoops and a more powerful one with all the trimmings (1199YCAISE (You Can't Afford It Special Edition) ?) in a couple of years to have a stab at superbike.

"Informed speculation" suggests the 1125R is a direct replacement for the XB12R, but that the XB12S, X etc will remain in production for some time.

1125 to 1199 ain't a big jump, but still not an easy proposition for a narrow angle V twin unless you're stroking it too. That may make it less than ideal for a racing engine. I understand that Buell's design criteria for the Rotax were based 100% on the need for a market-competitive sprotbike. The fact that the capacity was apparently defined with only that in mind seems to be seen as proof they're not interested in racing them. It doesn't rule out a superbike variant, but it may well make a competitive one a big ask.

[Forest]

I'm surprised that nobody has mentioned the issue of engine noise.

In my experience, air-cooled motors produce more mechanical noise than liquid-cooled motors. They constantly rattle, clunk, and plink.

I've noticed the same thing with cars. Just listen to a VW Beetle or Kombi.

[Ixion]

Mr Jim2 made that point earlier. It is true. Devoid of a sound deadening water jacket (and with fins to add resonance), air cooled motors will always be noiser than water cooled ones. Whether that is a problem is largely in the ears of the auditor I guess.

[Ocean1]

Mr Jim2 made that point earlier.

He did.

And you've just reminded me that early Suzukis (TS250 for one) had rubber chocks wedged in the fins to shut them up a bit. Didn't seem to make any discernable difference when they were taken out though.

[imdying]

The reality is that it's not worth worrying about... as far as reliabilty is concerned, water cooling has proven sufficiently reliable that after a billion odd cars produced, they're still using it.

[McJim]

Mr Jim2 made that point earlier. It is true. Devoid of a sound deadening water jacket (and with fins to add resonance), air cooled motors will always be noiser than water cooled ones. Whether that is a problem is largely in the ears of the auditor I guess.

My little Duc doesn't make noise....it makes music.

[Big Dave]

My little Duc doesn't make noise....it makes music.

Shame it's all percussion.

[FilthyLuka]

Shame it's all percussion.

badum psch

[Forest]

Mr Jim2 made that point earlier. It is true. Devoid of a sound deadening water jacket (and with fins to add resonance), air cooled motors will always be noiser than water cooled ones. Whether that is a problem is largely in the ears of the auditor I guess.

Whoops - I missed that somebody else had mentioned it.

[lanci]

Who cares about reliability when air-cooled sounds so fucking good!

[avgas]

Actualy oil is not as good as water for heat transfer - heat an iron bar to red heat and quench it in water for 10 seconds,then grab the hot end.Now try the same quenching in oil.....you'll burn your hand for sure,it doesn't transfer the heat to the liquid as fast.But that slower heat transfer is more controllable and is used with good effect in heat treatments.

Yes but try making decent fins to work on a water cooled bike. Also water cooled bikes are only as good as the pump (in most bikes water pump = bad quality as you know), oil convection cooling only fails when the law of physics fail.
Also worst case scenario, drill a hole in a component in a water cooled engine, then do the same in a oil cooled. In the water cooled one components (usually alloy) desintergrate.
However you do raise the good point, working on a nicely polished oil cooled bike is like as dangerous as lifting pots off a stove. If its hot you soon learn how hot.