Motor and controller for electric mx bike

[redline2097]

I am building my kid mx bike on a Oset 12.5 frame. I considered other frames including mx bike frames but they all are way too high for my kid. I will fit 16" osets front fork and wheels to it. So it adds only 50-70mm to seat height (total 440-460mm). Also I add rebound to front and back. Only question is the motor and the controller. I want my boy to grow it with me increasing power little by little. But our goal is to go faster than 65cc bikes. So we need tons of power and torque. I can attach motor with these dimensions, 130mm diameter, 100mm depth + axle. I prefer mid drive because of balancing the weight of bike. Motor weight should be less than 5.5kgs (12 pounds).

I have been looking this combo but I am open to other more powerfull recommendations (I don't need more wattage but more torque with 150 amps would be nice)
Motor: http://www.revolt.org.il/rv-120/rv-120pro-2/
Controller: http://kellycontroller.com/kbs72221e130a24-72v-mini-brushless-dc-controller-p-1316.html

Controller size could be maximum of 160mmx120mm. Motor price should sub $500 and controller sub $400.

Any other recommendations?

 

[motomech]

But our goal is to go faster than 65cc bikes.

Not trying to be a wise a$$, but have you ever ridden a KX65?
Back in the mid '90's, we installed a KX60 motor in a YSR to compete in the American Mini Road Racing Association in So. Calif.
It was so fast, it was competitive with the modified 80's, especially in the endurance races.
Stock, w/ the right gearing, top speed was around 75 mph.

 

[redline2097]

Yep I have ridden KX60, KX80 and CR125 when I was little kid, ages 7-12. So I know what kind of vehicles they are. But power isn't all what makes good lap times. Our bike is over half of 65ccs weight and it's easier to control for young kid. I think MX tracks we drive here we are not driving more than 45-60kmh. It's much easier to novice driver to accelerate with only one gear to that speed. With ebike simulator calculated with REVOLT 120 PRO 0-50 kmh is about 3.5 seconds, i do not think 65ccs beat that easily and driver must be very good at gear change. This is not typical situation kids under 8 years.

With current stock motor (500w continious) we are driving it 2000w and it beats all 50cc bikes in acceleration to 0-30kmh.

 

[motomech]

Well, I guess that makes sense.
Wish I could help w/ your questions, hopefully some of the genius types here will be able to contribute.

 

[Dauntless]

I think the guy around here the does the most work on your kind of bike is EvolutionGTS. He's also in threads of others doing similar, so a search for him will take you to threads involving controllers like Greentime and BHS, both hub and middrive, etc.

I think you might have seen where boisrondevens prefers 18 fets with that motor.

https://endless-sphere.com/forums/search.php?keywords=evolutiongts

 

[redline2097]

Oset 16 parts came in mail. I am just wondering is the front forks 60mm travel enough for mx use?

 

[redline2097]

Frame mod is now complete, looking good. Its now 50mm lower than Oset 16.0 racing. My 3 year old kids feets just barely reaches the ground so its nice.

Now planning for motor upgrade, something between 5-8kw 15-20nm would be good. Any other recommendations than Revolt 100 / Revolt 120-short?