how should i clean the one way bearing??

WD-40/ motor spray/ throttle body cleaner etc. Anything that degreases and is not corrosive. Then apply 3-in-1, ball bearing, or machine oil to the needle bearings before putting it back on the shaft to keep it working smoothly.

I don't like to use WD-40 as it tends to build up a varnish that can gum things up.

i have used brake clean
but its a little harsh comparied to regular nitro clean
so use the nitro clean