I've held off here hoping someone would come up with a cleaver solution to your problem.
My suggestion is a Allan set-screw with a washer. Washer should be drilled to accommodate the Allan wrench but smaller than the set screw O.D. Insert set-screw fully into the threaded
portion of the stem. Insert the washer into the stem gap, then un-thread the set-screw using
the Allan wrench against the washer. This should spread the gap sufficiently to remove your handlebars.
I've held off here hoping someone would come up with a cleaver solution to your problem.
My suggestion is a Allan set-screw with a washer. Washer should be drilled to accommodate the Allan wrench but smaller than the set screw O.D. Insert set-screw fully into the threaded
portion of the stem. Insert the washer into the stem gap, then un-thread the set-screw using
the Allan wrench against the washer. This should spread the gap sufficiently to remove your handlebars.