When I added my cooler I consider several options, one being putting the cooler in with the oil return hose under the bonnet. Easy access and simply also add a temp switch to turn the fan on. The heat would then have to dissipate through the skin of the bonnet, but aluminum does that well The down side was even cold oil would go into the cooler. Once again all the MC coolers I have seen are 3/8ID and the oil return line is 1/2ID and that is a significant step down causing back pressure especially when cold.
I did not consider a temp activated fan on the sump. That would be a real possibility as the whole outside of the sump canister has a lot of surface area. Simply install a fan and once again a temp activated switch. Would be really simple with a brass three way coupling, a couple of 1/2ID nipples and run the switch off the third opening. If there was enough room, putting the fan so it sucks through some openings in the faux grill on the bonnet would vastly help with the heat dissipation.
I haven't yet really crawled under the rear yet, but maybe a high volume mini fan blowing on the bevel box is an idea as well.

Last edited by rcmatt; 21/02/19 02:10 PM.
Rodger
2018 M3W "Dreamers on the Rise"
2004 Plus 8 (wife's)
old Goldwings and a couple of Harleys