sync motor mod question

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "The Backs by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tcback-at-cbpu-dot-com>

I have modified a motor to run at 1800 RPM for my spark gap.  When I 
checked the RPM's on it, it came out at 1790 steady.  Did I do something 
wrong, or is this normal?  if not normal, what did I do wrong.  the motor 
is 1/6 HP, 1725  RPM and it is turning a 8" diameter x 1/2" thick phenolic 
disk with 4 electrodes.

Thanks for the help

Tom