31 liters per hour is the rating for the DF52. They are not like a positive pressure electric pump where a regulator might be required.
Even a small Facet electric pump will flow 32 gallons per hour.
I found a aircraft parts
house that has both Mikuni vacuum and Facet electric pumps for 1/3 to 1/4 the price KTM and other motorcycle related outlets want.
The Mikuni pumps listed (single and dual) do not appear to be direct replacements for the KTM/Mikuni pump, and might require a bit of fiddling, but for $20-$30... maybe you can afford to fiddle.
In the event my pump takes a dump... I may experiment with a small Facet and an adjustable regulator. The float needle and seat on a BST40 for an Adventure is not a standard gravity flow item, but rather made for a low pressure line, (maybe why its $40) so if you could adjust pressure down to 1-2 psi, it should work. All an edjumacated guess on my part... but I tend to like Facet electric pumps and have used them extensively in the past, on bizzarro applications better not discussed here, with good success.
That really is all I have this time... really.