BMW R1200R R1150R/T F800 K1200R R1100R/T R1250R RnineT Message Board

It's that time to drain and change out the coolant in "Little Chubb", my F650GS Twin. It looks fairly straighforward, but I have a question of someone...possibly Cyclerob if he's listening.

I need to clamp off the radiator hose up top by the radiator cap, and the manual, of course has a BMW tool to do that with. What is a good makeshift coolant hose clamp for this purpose, other than just clamping it with some vise grips and 2 pieces of wood dowel? It's not a large hose....maybe 3/4 inch diameter.

Boxer,
I can't imagine why it would be necessary to squeeze a hose shut when changing the coolant. Can you explain it?

The manual says to clamp the hose shut then take off the coolant line on the bottom opposite side to drain. Then to open another small fitting at the top and release the clamp to finish draining the coolant. Just going on memory as I don't have the manual right here in front of me, but something to that effect. I can send you a copy of that page tonight after I get home. I'm assuming it has something to do with pressure, and a way to drain the radiator first, then the rest of the coolant from the opposite direction...but that's just an amateur's guess.

Boxer, I looked at the coolant change procedure in the CD Service Manual. They have you clamp the coolant reserve tank feed line to the radiator's top port, so it doesn't drain the tank when you disconnect the hose. When I changed my bike's coolant I left it hooked up then removed the tank for a thorough clean out. Then I was able to just lower it below the radiator top spigot fitting, unhook the hose and pour the old coolant out the cap opening.

I decided to remove the radiator and all the coolant hoses to clean-n-grease the many hose/pipe connection sealing surfaces that had become powdery and dry. Some were even a little loose from the rubber hoses' 3.5 years of aging. I also took it apart to hook up an LED power wire to the (extremely well hidden) radiator fan motor's power wire, soon to be visually telling me when the fan is running. The only hassle (for me) was removing/installing the bodywork panels.

BTW, the BMW designer's minimization of every component's weight and number of parts "shows" in everything I handled. I like that and the high priority that efficiency got in making the F800 series bikes . . . especially when I refuel it, currently at $3.749/Gallon for Texaco or Chevron Regular gas. Even in winter I am now getting 64 MPG.

I ended up just doing what you said Rob. Finished it today, so now it's freshly filled with Honda coolant. My fingers were almost frozen working on it this afternoon so tomorrow I'll get the plastic back on and she'll be ready for another season or two.

I may ride over sometime and get you to help me do that conversion to the front suspension. I need something to make the interstate bumps a little softer.

Boxer,

The GoldValve install is easy but tedious. Removing the front fork's damper rods and drilling the 6 holes in each one takes time, mostly to Dremel or hand file de-burr the new hole's hidden I.D. portions. My drill press makes it fast-n-easy to get the holes straight. It'd also be a good time to completely purge-n-replace the DOT4 fluids since the front caliper will be off.

You may need heavier fork springs for your weight (haven't seen you lately). At 160 lbs rider weight the stock springs were OK for me. We'll need to measure your bike's rider sag dimension way before anything gets taken apart so it doesn't have to come apart again for a fork spring change. Especially since you'll need to determine what length new spring preload spacer will be needed. Then riding the bike and minutely adjusting the forktube height to get it to corner neutral. Some Sat/Sun in early May when the weather gets warmer . . .

Getting back to the coolant change, some entrapped air in the cylinderhead, radiator, thermostat, pump, lines and heat exchanger will be expelled and replaced by coolant in the recovery/expansion tank. Unless you overfilled it by 3/4" at the coolant change it could be lower after running the engine and tipping it left/right. Use the sidestand the first few start-up and cool down heat cycles and all the air in the radiator will be quickly eliminated, which is desired and normal. On my F800ST a lot of bodywork screws need to come off to access the expansion tank's cap for a simple top-off.