changed the antifreeze today using Peak 50/50 pre-diluted antifreeze.

On the bottle Peak does not say its silicate free , but on there website it states it is indeed silicate free. The jug even says safe for aluminum radiators and motorcycles of all kinds. Got the jug from Advance Auto along with a $5 rebate.

Flushed the radiator with a mix of white vinegar and distilled water. Used a water measure and it took about 6 cups to fill the radiator.

The drain is located on the bottom of the water pump. I used the tools that came with the bike to remove the drain.

Also there is a screw holding the radiator cap on, and all of the radiator fluid will come out the drain with the cap removed.

Started the bike to let the block get warm to the touch before draining.

I didn't notice and rust or anything draining from the radiator.

The only dirt I found was in the overflow tank, which I removed with distilled water, with the overflows drain hose removed.

Keep in mind the white vinegar/distilled water mix is also a 1:1 or 50/50 mix, example 2 cups white vinegar 2 cups distilled water.

 

You got my curiosity up on the radiator cap being retained by a screw. Mine just unscrews until you line up the tangs on the cap and rad neck. Is there something different on other models?

Yeah, not unusual for a little debris in the overflow tank. Good for you. A lot of people neglect the cooling system.

 

Yea I kept trying to get the radiator cap off and it wouldn't turn!

There is a screw that goes through the cap and catches the "tang" on the radiator.

2012 model KLX250s.