On”old style” 4-cyl bikes with a double cradle type frame and a T-shaped airbox (when viewed from above) it was always a major battle to refit the airbox trumpets to the back of the carbs due to the lack of wriggle space and the trumpets going stiff with age (oo-er). You can’t do anything about the lack of room, but the rubber trumpets can be softened if you take them off the airbox and soak them for a decent length of time in a bowl of really hot water. It won’t make it easy, just with them a bit more flexible they can be persuaded a bit more readily to re-engage with the carbs. Judicious use of flat-bladed screwdrivers and some lubricant (steady...) like WD40 will no doubt be needed. Never a job that I enjoyed....
