A Beck Arnley 143-1430697 thermostat is a good replacement for the K bikes. It is a 88*C thermostat, which is close enough to the original 85*C one, for a 5th the price of the BMW one. If you do a lot of hot weather riding, you could get the 80*C thermostat, for cooler engine temps. However, these engines like to run hot, so the 88* one is probably best.
