Join Date: Nov 2009
Location: Lander, Wyoming
Here is my suggestion before resorting to professional cleaning by a radiator shop.
These aluminum motorcycle radiators are so 'thin-walled' I discourage the use of over-the-counter automotive cooling system flushing mixtures.
You've drained the system, good. You've now got some flow, after compressed air, OK. Now re-connect the hoses. And Re-fill the system with 'Distilled White VINEGAR'.
Stick a piece of cardboard completely over the radiator and go ride it till the temp gauge needle is 'flirting' with the Red Zone. Ride it for 10-20 minutes, flirting with the red zone.
Ride it back to your place and leave it running as you put your glove liners on and your Rubber Gloves ON. Place a ketch bucket under the water pump, and pull the drain bolt from the water pump, with the engine still running! When the drain starts blowing mostly air, kill the engine.
Allow the engine to cool down. Flush with clear water. Re-fill with clear water, take it for a ride. If all seems normal, drain water and re-fill with proper coolant mix.
If still not quite clean, re-fill with vinegar and re-treat the system.
Kind of like, "Lather-Rinse and Repeat if Needed"!
Modify at "YOUR OWN RISK"!
Still riding my 1987 KL650-A1. 85,000+ miles & counting