pdx650

Stray, 

     Sorry. I’m late to the party. I’m doing this flush the way you describe. I was not able to discern which one of the three bolt heads facing down (next to the oil filter) was the cylinder head drain bolt. I passed on that step. I am in the middle of the task 1/2 vinegar 1/2 distilled water on the warming up cycle and the radiator fan has already turned on. I will update after the procedure is complete.
 

Thank you for your suggestions.

j. Lawson

Portland, OR area.

I took the time to flush the radiator. I am using the Honda Type 2 (blue color) pre-mixed (50/50) coolant in my vfr. Tomorrow, I will check the mix at the filler cap with a suction bulb tester. Then I will put the fairings back on. I should change the engine oil and filter, too, while the fairings are off. I will attach photos.

From left to right: 1st gallon jug: What came out of the engine. It was below the required 50/50 mix.

2nd gallon jug: After using 50/50 distilled white vinegar (5% acidity) and distilled water. 
3rd gallon: After using 5 Tbsp of Soda crystals mixed with 0.75 gallon (3 quarts) of distilled water. 
4th gallon: Straight distilled water. The bike didn’t like this one as it reached 250*F the digital temp. gauge started flashing at the 250*F. I turned off the engine and let it cool while I washed the fairings in the tub. 
 

After all that, I drained the distilled water, flushed another gallon of distilled water down the filler cap with the drain bolt removed. I plugged the drain hole and then filled the radiator(s) with the Honda Type 2 coolant.