2013 Drake Smith - Please do not use or reproduce this elsewhere.  Feel free to link to it though.

Aftermarket Fuel Pump

Early K bikes came with a 52 mm diameter fuel pump. In 1993, BMW swtitched to a 43mm fuel pump. As of 2013, replacement fuel pumps new from BMW cost over $400!  However, years ago a K bike owner discovered that a Ford fuel pump was a good, lower cost replacement.  This style of fuel pump can now be had on eBay for about $18 shipped. (Search eBay for "2042 fuel pump") Note that the smaller terminal of the fuel pump wiring is positive.

Since this is a rather common approach, Euro MotoElectrics sells foam adapters so that the 2042 fuel pump can be retrofitted into the BMW vibration ring. Here are links for them:

52 mm foam fuel pump adapter

43 mm foam fuel pump adapter

Tip: Mount the replacement pump as low as is reasonable to maximize your range per tankfull of gas.

2013 Drake Smith - Please do not use or reproduce this elsewhere.  Feel free to link to it though.