This is for the Super Duke 1290 Y hose setup. The short hose goes on very easily, lulling you into a false sense of complacency. The Y shaped hose requires removal of the throttle bodies (there are no directions for this, but you can find it if you do a deep dive on the interweb). Succinctly, remove the 4 plugs (two in between, one in front, one in back), loosen the upper clamps on the rubber tubes that joins the throttle bodies to the cylinders (there are two silver hose clamps holding each on in place), then basically get ahold of the whole TB assembly and pull (you have to pull pretty hard, probably either have the bike vertically on a track stand or have someone there to hold it for you so you don't tump it over). Once this is off, you can disconnect the big electrical connector on the left side of the frame and tip the whole assembly back (I left the fuel line connected). Now you can see the hose more clearly. From here, you take the old one off (remove the radiator ends first so they can drain the coolant somewhere besides into the motor area), and put the new one on. This involves making sure you put the delicate thermostat covers back on correctly (they only go one way, the two screws are a bit eccentric), and you then can wiggle the hose the rest of the way up and slide the hose clamp back into place (wait, you didn't forget those did you? Dang, got to start over...). Ultimately, I got it done with much bleeding and cussing. Slick, no joint in there anymore, but more of a pain in the behind than just about anything else I have done with these LC8 motors, not sure I would recommend this for amateurs (which I most certainly am, so it can be done, but cussing probably outweighs reward). Oh, the Samco hose clamp kit required to get the Samco warranty doesn't have all the little clamps you need.
If I had to to it again, would probably leave the little Y joint in and use the stock shaped hoses, although not sure it would be that much easier.
