So this is one of favorite threads up here, for all the work being done and for the technical extremes of Sir Jeremy's exotic work and Hillhater keeping it simple. So I'm assuming this is the Magura Twistgrip in question. http://holmeshobbies.com/product.php?productid=280
And this is as cheap as I know a Hall Effect Throttle to come. http://holmeshobbies.com/product.php?pr ... =32&page=1
Here's where I figure I can put this to work. The motor and controller, with shipping, I think was just over $30. And just powerful enough for the 7 year old nephews' bike. Gotta build a little more powerful one for the Dad, at least a 24 v.http://www.leaderhobby.com/product.asp?ID=9394001224131
I'm thinking you have to overkill with the controller size or it'll kill you.
eBay has the cheap servo tester, $2.93 with free shipping. http://www.ebay.com/itm/3-CH-4-8-6V-Mul ... 46022f4348
(Item number: 300684362568 if the link doesn't work.)
They're in another state, they gotta find their own bikes, but I pointed them in the direction of one of these for $50 on Craiglist. Great dirtbike, eh? Maybe they can find one for the not so tall Dad.
Less than $200 to build a dirtbike with a fairly light drive. Let's see you do that with a brushed motor. (Seriously. put it up there and I'll look.)