6 or 8 years ago, I tried to hook up my Yaesu FT-50 on a bracket on the handlebar, with a home made headset and a PTT under the left side controls. Everything worked great until I started the engine. It had terrible ignition noise. I could never get rid of it. At first, I thought it might be the headset, but it was still there with it disconnected. I might be tempted to try it again with my newer FT-60, but I'd see if it was noisy before I built another headset.
My "Elmer" tells a great story about using his 2 meter handheld with phone interconnect back in the 60s. He was being ignored in a busy restaurant in Arizona. He used his radio, through the club repeater telephone interconnect and dialed the restaurant, and asked for a waiter to come to his table. The guy who answered the phone flipped out. "How are you callin' me?".