There's no shortage of power from the bl motor in the JD850, when I turn on pump it's running at an idle of (I've never measured exactly) maybe 30%. One valve might bump speed to 60-70%, two valves push motor to full speed. The belt drive is 2,5:1 reduction & I think the bl motor tops at 10,000rpm. The prv is set to 34bar. With 18 & 22mm cyl bores, this JD850 needs a big fast turning pump.
The Fumotec - Premacon bl motor/pumps you're referring to is supplied by Martin Kampshoff, he uses a smaller (diameter wise) bl motor, about 700kv with I assume his design planetary reduction 4,5:1 on a Jung 4003 pump.
I started out with that 4003 pump in my Fumotec hoe, motor speed accurately metered to 4500rpm, I found the hyd flow to be way too fast for 14mm cyl bores. Last month I changed pumps to a 4002 (0,30ml/rev) & with the speed set too 5000rpm idle speed, plus radio mix - all 3 valves activated will make motor speed 5800rpm max (330-385ml/min). I didn't get half hour run time with that setup before motor locked up with blown bearings, but I was liking the slower flow for much smoother fluent motion. It's that same 4003 pump that is now in the JD850.
What I've learned from this Fumotec hoe, as well as the china hoe, running any brushless motor continually below 50% of its nominal speed, it's accuracy in maintaining speed while under load is erractic. I used a 30amp E-Flite esc in the Fumotec hoe. I think the JD850 uses a 30amp E-Flite as well.
I get great service from Frank Preisendoerfer, and lots of great insight too for other personal projects. I don't waste Frank's time dickering over pennies for cheapest price and Frank don't waste my time getting what I need! Badda Boom Badda Bing Done!!!
