motor windings

I believe that less turns will result in a motor that runs faster, but with less torque. Others could correct me if I'm wrong.

A few turns won't make a lot of difference, but too many and the motor will draw more current and have less torque.  Also, with too many turns difference, the imbalance between the field and armature will surely impact motor performance.

thanks guys for the replies. I just let them be and run them.

Johnbeere is correct. Reducing the field strength will result in higher speed. Under this condition the armature current is increased, so care has to be taken not to overheat the armature. It would be easy to splice on a short piece of magnet wire and replace the missing wire. The turn to turn voltage difference in the field is very small so insulating the splice could be ignored or done with a thin layer of varnish.

@David Johnston posted:

Johnbeere is correct. Reducing the field strength will result in higher speed. Under this condition the armature current is increased, so care has to be taken not to overheat the armature.

Actually, since the armature and field are in series, current is increased all the way around.

Yes, but all the voltage drop is in the armature and the field coil wire is larger than the armature coils. Field shunting and tapping  is a common practice in transit to get more speed, but it is controlled automatically to avoid overheating the armature.

Robert Hannon's book titled "O-Gauge Reference Manual 1" contains specific data on the wire size and number of turns for both the field and armature windings on most postwar locomotives. Scanning through this reference, a typical number of windings on a field is approximately 160 +/-. So, if you lost 8 turns, that is only about a 5 percent change (perhaps a little more on the outer layers due to the increased winding circumference). I doubt that would affect performance noticeably.

Very interesting info. Thanks to all replies. I think I might add wire .