I own a 1990 K00LT which I purchased with only 26K miles.
I live in the very bottom of the state of New Mexico and we
certainly get very hot, hot summers. Two years ago I went
to Colorado Springs and last year I tried to make it to Sedalia.
On both occasions, the K bike stalled, losing power little by
little and finally quit running as I went from 70mph to 20mph
when it finally quit altogether. I changed s/plugs, s/plug wires,
fuel filter, and disconnected the computer plug several times.
The problem persisted, but only during the hot summer months;
never during the cool weather. Then I read an article in the
"Motorcyclist" magazine about ETHANOL-and the bad effects
on high compression motorcycles.
Thereupon, I purchased STA-BIL ethanol treatment. I add two
ounces of this product to each fill up. Three trips so far this
past 2013 summer-each of 350/400 miles and the bike has
Conclusion: the small amount, 10%, of ethanol will form at the
bottom of the fuel tank and when it enters the fuel line, this is
causing the vapor lock. Hope this helps other K100 owners as
the motor was advertised as "The Million Mile" motor by BMW.