1985 K100RS rad flush.

After draining the old coolant (don't know what was in there) I refilled with deionized water. I ran the bike up, held it at a fast idle (2000 to 2500 RPM) and let the cooling fan cycle on and off a half dozen times or so making sure the engine was getting hot. About 10 minutes in total. I then drained the water out and it still had some green in it-to be expected of course because I don't think I can completely drain everything. I repeated the process. Still some green in it. My question is, should I be trying to get relatively clear water or just not concern myself about that necessarily?

I also decided to install a new set of Samco hoses. I spoke with one of the mechanics at my local BMW dealership regarding coolant and he said Yamaha Yamacool would be just fine for the bike, so I bought it. They did sell several other brands but the Yamacool was already premixed at 60/40.

FYI. For those who are wondering about installation of the hose that goes through the crankcase (I'm a newbie here so I don't want to be presumptuous) I lubed it up with dish soap and it slid through top to bottom quite easily. A couple of minutes in total, pushing and twisting.

Thanks,
Tom

The last couple of times I did my K75 I drained the old and filled with the new. One rinse is a good idea. Two is overkill in my opinion. It wouldn't take 1/2 ounce of the old to make the water look light greenish. Fill it. Make sure it is really full. Ride it.

As far as antifreeze goes any of the blue stuff that is designed for Japanese or European cars works fine. Doesn't have any of the additives that can affect aluminum or the cooling system.

Thanks, guys. I ended up doing it a 3rd time and it was virtually clear.

Tom

If you are happy, I am happy!