I have a 5 hp. "20" honda single stage and I asked about that one and I was told they don't have the mounting holes machined into the pull start models so I wouldn't work to put electric start on it. That was just my model though, yours may be different. I can't believe honda does two different castings for the same motor but maybe they do.
Coldfingers
I wonder which bolt holes they are referring to? I called and asked them if I could replace my motor with any off the shelf GC160 engine and they said "no, the factory models were different with an unique metric shaft" and they used a "different voltage." I knew after they told me the "voltage" thing that they just wanted me to spend the $300+ on their engine. That or the person i got on the phone lacked experience. I tossed on a cheap clone with a 3/4 inch shaft. The shaft was a perfect fit.
This message was modified Jan 29, 2009 by Underdog