gentlejax wrote:better to me usually means "better than the parts that were on it orginally" .....which usually means to me last longer. meaning its doesnt turn into a non working piece of junk that just sits not being used...
you can certainly spend more on a higher quality controller, such as a kelly, but to me that's not cost efficient to put a nice controller on a low budget platform such as a kids razor scooter. for these type of projects i prefer to buy cheap univeral controllers in bulk, so i have spares on hand and to make upgrading/replacing much much easier. but i wouldnt say these controllers are better, wouldnt surprise me if razor controllers were coming out of the same factory. IMHO its more a case of you get what you pay for.
gentlejax wrote:I havnt taken it apart so I dont know what version it is. Its grey. thats all I Know...
may not need to take it apart if you can locate the UPC label... it'll provide the version #:

gentlejax wrote:im not trying to make it faster ..I want it to last longer.
...
so Im looking towards the worst case scenario which would be replacing motor.
i've picked up a few neglected razors off craigslist and in almost all cases the batteries were bad. if not the batteries then some combination of controller and/or throttle defect. the motors were fine every time. what i think happens is the batteries get run down too much, or there a wiring issue with the controller or throttle. preventing any damage or overuse of the motor.
getting back to the version # - for versions 36 and up razor used a motor on the E300 that uses a 10-tooth sprocket and will accept the 9-tooth sprocket. this is a nice motor for a child or lightweight rider and given the sprocket options it will overvolt well if you choose that option down the road.
for reference, i have a thread on the E300 and x-140 scooters i picked up for my kids which might be helpful for your build. my goals are similar - not too fast, decent torque, longer runtime, limited budget:
viewtopic.php?f=13&t=3063here are the links to the parts i used for the E300 rebuild:
variable speed thumb throttle with battery meter, replacing the one speed half twist throttle with no battery meter:
http://www.ebay.com/itm/252301399173?_t ... EBIDX%3AIThttp://www.ebay.com/itm/380927044225?_t ... EBIDX%3AITi bought two different types of thumb throttles and installed the latter, but in retrospect should have installed the throttle in the first link as the on/off switch is built in and in a more convenient location than having to bend down.
here's how it looks installed:

24v 500w yiyun controller, i bought 3 of these:
http://www.ebay.com/itm/252182148246?_t ... EBIDX%3AITalso bought a couple of these since i swapped out the stock reset switch:
http://www.ebay.com/itm/151817188041?_t ... EBIDX%3AIT