The October 1964 issue of Popular Science contained a fascinating article about the Homelite motor plus the saw, drill, pump, and generator accessories that could be attached to it. Check it out – it contains a cool cut-away diagram of the circular saw.
Gas-powered circular saws are rare, but not so rare that there aren't a bunch of folks who collect, and sometimes – use them. The videos below show the XL-100 in action. Note how the motor exhaust blows dust off to the side; this was a design feature intended to keep dust away from the operator. One of the first things you'll notice from watching these videos is that these saws have variable speed and you can rev the motors. Don't ask me why, but I find that very appealing.