I now have the ATC250R engine solidly bolted into the Benelli 2C frame.
I had to do a bit of additional grinding on the frame, but there is just enough room for the engine.
I cut 1/8″ thick x 1″ wide flat steel bar to length to create simple, point-to-point mounting brackets between the mounting points on the crankcases and existing mounts on the frame. There are a pair underneath the center of the engine, at the lower rear (under the swingarm, attached to the original centerstand tabs), and at the top rear. This type of attachment is theoretically less than ideal, however, because the individual brackets have no inherent triangulation. The whole arrangement could potentially behave like a multi-bar linkage, allowing the engine to shift longitudinally by rotating on the transverse axis. Fortunately, the various lengths and positions of these particular mounting brackets work against each other to “jam the mechanism.” Once I add new front engine mounts, which will be welded to the front downtubes, the engine will be fixed within the frame pretty solidly.
I had previously calculated that the crankcases needed to be offset 1/2 an inch to the left, so I made one of the brackets from doubled-up 1/4″ thick alloy.
I checked the alignment of the front and rear sprockets with a laser, and a half-inch turned out to be correct—or at least within tolerance.
The downside to utilizing the existing Benelli 2C engine mounts wherever feasible is the need for a bunch of different length spacers — nine at last count.
Proper fastening hardware will need to be procured later.
I also used a couple of 1/2″ solid steel bars to nudge the right passenger peg mount out, away from the the swingarm. I’m not sure I’ve shifted it quite as far out as the left side, but it’s close, and there’s plenty of clearance there, which is all that matters at this point.
