plenty room in the frame and swing arm spindle to bottom frame rail geometry looks close to allow honda motor to fit..
I can see a couple of problems with the Can-Am frame, the first being a possible exhaust clearance issue with the twin downtubes fouling the off centre exhaust. The second
might be a clearance problem with the tall Honda engine fouling the diagonal downtubes going from the top frame rail to the swingarm pivot area.
Even if the engine slips inside of those braces, it'd be a nightmare getting it in and out. If those braces were removed or relocated, frame strength might be compromised.
The difficulty with the Honda's motor is to get the wet sump as low in the chassis as possible to help align the sprocket with the swingarm pivot to achieve the best chain travel. There's a
lot of engine below the crank/sprocket centreline on an XL Honda engine which usually means removing any lower rail cross braces or at worse, lowering the whole bottom cradle. The Montesa and CZ both seemed to be easy swaps with the motor slotting in pretty well but in both cases the engine sat too high because of that big lump of sump. Both frames weren't wide enough for the sump to fit between the bottom frame rails so the bottom rails had to be lowered. Besides those two frames I also measured up DT250A Yamaha, Honda CR250 Elsinore, Bultaco Pursang MK5, Bultaco M11 and Rickman Montesa frames and each failed for either exhaust and/or sump clearance problems that would require major work to cure.
Maico and Husky frames feature large engine cradles and wide lower frame rail spacing making them much easier propositions. There are others that may fit the bill...possibly the little Rickman Zundapp which seems to be able to accept everything from DT1 through to 500 Triumph engines. I also think the Sprite/American Eagle might fit the criteria except that it's probably heavier than the Honda frame, which isn't all that heavy in itself once the gizmo brackets are removed.
