Well done. Now you are hooked.
A suggestion....when an engine has had dirty oil in it I never use a flush. They are too aggressive and can dislodge chunks of dirt which then block oil ways.
My preferred method is to change the oil more frequently. Oil contains detergents which clean the engine. The detergents are exhausted long before the oil stops lubricating. So on an engine with an unknown service history I do a few oil changes at somewhere between 1-2k, then extend the intervals until the oil is staying clean for longer.
On bikes I tend to change the oil every 3k regardless.
On one my cars I changed the oil every 5k and at 130k decided to replace the timing chains. A mate who was a workshop manager gave me a hand as we needed to use a 4 post lift to raise the engine slightly. He commented that the interior of the engine looked like a brand new engine. Everything was clean and golden, not a trace of carbon deposits anywhere.