The recent hot weather is causing concerns as my MC21 (300 motor with big triple core radiator. No fan until I figure how to shoe horn one in what little space I have) is running very hot.
It has Motul coolant and the level is fine. Stripped the Coolant pump and it spins when kick start is depressed.
On regular roads I can keep it around a nice 55 Deg but on any motorway distances the temp creeps up to hi 50's and even 62 Deg due to constant throttle and little deceleration. Outside temp 28 Deg.
I don't recall this problem last year and no fan has never been an issue before (no commuting)
Does coolant have a useful life?
How about just water?
I know you racers have to use water for different reasons but if you could choose what would you use?
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if it had a tail - it would wag

Are you having a laugh? The engine should be running at 70 - 80 degrees Celcius / centigrade at all times!
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

ye man, anything shy of the red is A ok
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Deadly serious actually.
Got the 55 Deg advice from Sean Brown , a respected racer so hence my concern.
However thanks for this new advice and I'll chill (ho ho) a bit.
I'll be cringing but will let it creep up a bit more.

Thanks again.
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if it had a tail - it would wag

I dunno what Sean has been racing, but you really shouldn't be giving your engine a lot of stick unless it's running ABOVE 60 degrees.

Most four strokes run best at about 80 degrees, in fact my car runs at 95. Two strokes seem to operate better a little lower, and anything between 70 and 80 is perfect.
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Most race 2 stroke run between 62-65deg. Some do aim a little lower that I think that's more personal preference.

My 300, when running, would often go 70deg+ on motorways in summer.
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If I have to take the carbs off once more...

My 300 is a dedicated track bike and i never rev it hard until its showing over 60 degrees on the dash. Once above that it gets nothing but merciless THRASH whilst on track. The radiator seems to have no problem keeping the temp under control through the hard use.

No need to cringe mate its supposed to run at over 60 degrees.
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After years of moaning about immigrants now i am one...

Thanks everyone. and I'm grateful.

Bit of a relief really.

One day I planned on slinging it in the van and taking it to a Spanish GP, being a Sito Pons rep and all that, to cause a bit of a stir.

All that hot weather is not such a concern now.
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if it had a tail - it would wag

BIKE magazine rode mine from Santander to the Valincia GP last year for the final round, so it'll be absolutely fine.
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Manny Fagnet wrote:Deadly serious actually.
Got the 55 Deg advice from Sean Brown , a respected racer so hence my concern.

Alan Armour (he of double F400 champion on an RGV250 fame) reckons 55 deg was optimum for power.
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Please do not PM me technical questions, if you can't find it on the Forum start a thread

Blimey, I'd have thought the radiator needed for that would have been so big it slowed him down!
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball