I'm thinking it wouldnt be that hard since there is a little room in there still for a bigger cooler. Better radiators or a higher pressure radiator cap would lower the temps more I would think.

 

A little trick from the car-world: Use as little antifreeze as you can get away with. It raises the boiling point, but does a significantly worse job of cooling (lower heat transfer).

Don't run plain water (bad for the radiators), but a lot of folks run 10%-30% antifreeze instead of 50% or even more.

If it doesn't get that cold where you live, or you want to swap in a "summer mix" once in a while, try running 20% antifreeze and see if it helps.
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Pregnant tubes

 

Or fill bike's cooling system with EngineIce liquid. It does not do any "wonders" they suggest on their website (marketing b...t), but it does work a bit better than regular mix and does not affect pump and does not corrode system.

Very popular amingst motocrossers here, but almost impossible to buy in Belgium if you not motocrosser
In US available in every second bike store!
Consists of de-ionized water and some regular propylene glycol components, pre-mixed in .. some proportions - never bothered to read it all.
On my previous Honda Hornet (599 in US) did made small, but exactly needed difference.