Dear Pecojets:
The PIPE Here...and as I started out flying RC with a Heathkit single stick system in 1977, and STILL HAVE one or two of the KPS-14II servos that came with it, here's some TIPS I came across while using them with non-Kraft receivers...
Firstly, "ALbert.S" has the torque figures
right ON THE NOSE 
for the Kraft 14II and 15II servos...good job remembering those figures!
The KPS-15II WAS being used in the earliest Giant Scale planes in the VERY early 1980s for aerodynamic control purposes...especially the ones that were using the earliest BIG glow engines, like the old OS .80 RC two stroke engine and the Fox .78 two strokers...and even saw widespread usage in the first Quadra Q35 and Kioritz 2.4 cu. in. gasoline burning two stroke powered models. I just do NOT know how those 15II servos, with an output torque that's even LESS than the mini sized Hitec HS-225, managed to move Giant Scale control surfaces as well as they did...but they sure DID work for the Giant Scale flyers of that time!
Also, where I first switched to Ace RC receivers in 1979 from the "flaky" Heath receivers, I ALSO found out that the Kraft servos had a VERY ANNOYING TENDENCY to "travel hard over" if you turned on the receiver first BEFORE turning on the transmitter...and COULD even do so while in "normal operation"
!!! Ace RC DID have the answer to this problem...
simply place an connect up a 2.2µF value capacitor in the SIGNAL line-usually an orange wire-of the Kraft servo cable, with the "positive" end (since these were usually polarized electrolytic capacitors at that time, with marked "positive" and "negative" ends) aimed towards the receiver...and the problem went away like magic!
As far as running the Kraft servos on 6.0 volts...I'm NOT too sure that would be recommended, as Kraft DID have their OWN special servo IC in their servos (NOT the "usual" Signetics NE544 chip that many other radio makers used in the early 1980s, including Ace RC)...and where the Kraft servo ICs are most likely no longer available ANYWHERE, you'd very likely blow out the chip and POSSIBLY turn the servo into junk with an application of 6 volts to power it.
Sorry to "discourage" you about the six volt usage attempt you MIGHT be wanting to do with your vintage Kraft servos....but if you'd like to run them on the "regular" 4.8 volts, and on a non-Kraft receiver, that capacitor I mentioned in the signal line will VERY NICELY make those servos behave themselves with your more modern receiver...and you should be fine!
(For your Cub, using TWO KPS-15IIs, one for each aileron, might be your best bet, if you DO plan on using them in a Giant Scale plane, just as the fans of Giant Scale did in the "big plane era's" dawning around 1980!)
Hope these tips helped!
Yours Sincerely,
The PIPE!
