Flow requirements for the hoe are determined by required piston travel speed, so cylinder stroke length, cylinder/rod diameter, x flow rate controls that. Per previous gleaned pump info
2000 rpm x 10 ml = 20l/m or ~5.28 GPM
2500 rpm x 10 ml = 25l/m or ~6.6 GPM
3000 rpm x 10 ml = 30l/m or ~7.9 GPM
1000 rpm x 10ml = 10l/m or ~2.64 GPM
The actual speed of the Jimna pump needs to be known to determine it's output if it can't be obtained from a dealer or on the web.
So say the cylinder diameters are smaller than a B26 and a shorter stroke because of a smaller hoe, then they would cycle/stroke (fully extend or retract) at the same speed as a B26 with a lower flow rate. As previously noted, it's worth measuring the cylinders and doing some calcs.
"If" the Jimna direct bolt on pump runs at 2000 rpm and produces 5.28 GPM to adequately run this hoe, then getting something close to that would be the best solution.
On another forum a user states - <L285 Kubota Service manual lists the hydraulic pump output as 18.5 lit./min (or 5 gpm) at 2400 rpm>
"If" this is correct, and the requirements of the hoe are around the 5.3 GPM, then tractor hydraulics "may" run this hoe reasonably well. We know these smaller hoes aren't the greatest compared to commercial units, but may be OK for limited use at these specs.
So if someone wants to chase up the spec of the L285 tractor pump and give a Jimna dealer a ring and see if they can supply accurate pump speed it would be worthwhile.
I had a quick glance of an online service manual but didn't notice the specs of the L285 pump, it was a quick glance, and not a full service manual. If someone has access to the service manual, please check it.
If the OP has the fittings to hook up to his tractor as is and run at WOT he can see how it performs. But chasing the cylinder info diameters, stroke length, Jinma data, tractor pump data would be a good start.
Can another pump be fitted as being investigated by shootem604?
In another thread Service Dept Vic states < The 1200 Series loader was fitted to the L175, 225 and L285. The lift capacity is 800 lbs, relief pressure is 1600 psi and the pump produces 3.7gpm to make it all work nice> (which is a long way from the 5GPM possibly noted in the manual) and he also notes
<The L235 fitted with its K90 factory loader whould lift 800 lbs with a relief setting of 1950 lbs and a pump that delivers 6.2 gpm OE>
So if an L235 pump is indeed 6.2 GPM AND it fits an L285, AND the Jimna specs are in that range, there may be a solution?
EDIT: It appears the L235 is a splined shaft, appears L285 tapered, so this won't fit if that's the case?