I got this question today:
Built a Dolomite fat bike for my friend Ron. Needed to "squeeze" the 209 mm dropouts to 135 since there were no fat bike motors available at the time. Also, spaced the freewheel so the gears were all available. Functioned extremely well; ha and his family loved it and all want one now. However, his granddaughter asked him to build a "chariot" to transport her severely physically challenged sister's wheelchair. Now it's almost completed (see pictures) wit the "carrier unit" almost mounted.
Long story, but we need a stronger motor now; do you have anything that can be used with his 36V, 15 a/h battery?
Here was my long answer:
check out this fat bike kit...we just have 2 left...i just found them and put them in stock yesterday. I thought we were out of stock.
http://lunacycle.com/motors/hub-moto...rs-4-inch-rim/
But I do not think this is the right solution for you Bob...here is why.
I thiink your kind of screwed in terms of power not because of your motor but because your running a 36 volt battery... you can stay with the same motor and go with a higher amp controller.
you could try our sondors upgrade contorller here which is 25 amps.... http://lunacycle.com/sondors-upgrade...er-big-36-60v/
but i dont even think that will be high enough power for you.
If that is one of our 36 volt batteries it willl do up to 50amps....you can contact ypedal.com (he is good guy YPEDAL on ES and ask him if he knows of a 40 or 50 amp controller that will work with that motor...hopefully he will sale you something all ready to hook up.
I would run 40 or 50 amps to that motor and ride it until it pops before i would think about going through the hassle of changing it.
Next time you should get a 48 or 52 volt battery and its much easier to pump more power.