250's are a blast on the track! You'll want to buy a bottle of 'water wetter' to mix with distilled water before adding to prevent corrosion..you can find it at any bike shop or Canadian Tire.
Side fairing panel needs to come off, and there will be rubber hoses coming from the rad that need to be drained of the coolant. Let the bike cool first so you don't burn yourself. You'll want to have gloves on and a wide catchpan underneath since the coolant usually sprays in all directions.
You'll want to run plain distilled through once or twice to get all the coolant out, so fill 'er up with distilled, making sure everything is sealed back tight and start the bike for a few minutes to let the water circulate. Drain and repeat, only this time fill with distilled + water wetter mix, adding to the fill level on the coolant reservoir (plastic container) also. Once you've finished this, rock the bike from side to side and squeeze a little on the hoses to let air bubbles escape and make sure it's topped up once again. Go for a quick ride and afterwards confirm the radiator is full and the reservoir is at the fill line before putting the fairing back on.
Good luck!
