I finally broke down and installed a second relay for my '77 westy 
starter.  The problem is, the windings on the magnet get hot, and the 
resistance in the wires goes up enough that it won't fire.  The solution 
is to circumvent the long resistance path of the wires to the key and 
back using a small relay that juices the solinoid directly from the 
battery.  This bizzare fix worked for me, I can now drive long distance 
all day and she always starts.  Good luck.

gbryden@teleport.com