I have serious doubts about the ability of a wheelchair lift to pick up a large motorcycle. Most large cruisers have a dry weight that can be upwards of 600lbs all by themselves. Add an additional 40lbs of fuel, plus upwards of 300lb for a person and their gear, and you're getting close to 1000lbs. Now, yes, I've added the maximum weights for each estimated figure, but I know there are some big people riding big bikes out there and used those numbers for a safety margin.
Personally, if I don't go with a trailer or large folding door ramp, I'll end up using a loading lift like those seen on the back of office supply trucks. Not only are they wide enough to fit a large cruiser (my Nomad is 8' 6" with the cargo box on the back), but they are rated for very heavy loads. I've seen the delivery guys at work load a pallet of copy paper (12 cases @ 50lb/case) onto one of those things and it not make any sign of strain. So that's 600lbs of paper, plus two guys at roughly 175lb to 200lb (say 375 total), plus the pallet and industrial dollies (another 50lbs), for a total of 1025lbs.
I'll have to find out the rating for sure before installation, but they just seem more robust than a wheelchair lift.