K bike radiator fans have a high,
though not extremely so, failure rate.
If your fan has died, you can
still ride your K bike. This is because, under normal
circumstances, once you're moving at a decent speed the air
blowing by the radiator is sufficient to keep the coolant
temperature below ~104˚ C where the fan kicks in. If
you're riding in the city where you need to wait at
stoplights, then just hit the kill switch when you come to a
stop. When the light turns green, start the bike and
If your radiator cap is
blowing before the temperature warning light comes on then
this is usually an indication that the radiator cap has gone
bad and should be replaced. It is BMW part number
17111464720 and costs about $25 from a BMW dealer. (The two
rubber O-rings for the radiator cap come with that part so
you do not need to buy those separately.)
1) Buy a
new replacement fan from a BMW dealer. (Part
17401460427) However, the cost is rather high at $250+.
2) Buy a
Bosch replacement motor. The fan motor is Bosch part
0130007027 and can be had from
3) Buy an
aftermarket radiator fan. There are several options
but several people have installed a SPAL 6.5" puller fan. Product # 30100402.
Several people have built some
very nice custom brackets to mount them on a K bike:
I decided to take a much simpler
approach. A couple of 1/8" thick pieces of aluminum
sheet. Since I don't have a 3/4" drill for metal I
just cut the rubber bushing at the top in half and placed
the mounting bracket between them. This approach could be
taken with any aftermarket fan.
In order to keep it centered on
the radiator, the spacing between the holes on the top piece
is 31mm and the spacing between the holes on the bottom
piece is 35mm.
© 2013 Drake Smith - Please do
not use or reproduce this elsewhere. Feel free to link
to it though.