In Michigan there is no verbiage in the CPL law that specifically say's "Motorcycle" BUT there was a ruling by the attorney general, that a motorcycle or car makes no difference, as the permit to carry is issued to the holder and where ever it's legal to carry you are not in violation of the carry laws. I'm trying to find the ruling, I'll post it when I find it.
Q: I am a current CPL holder. I bought a new motorcycle and wondered if it's legal to carry my revolver concealed on me while riding the bike. I also wondered if I can store or conceal the revolver in a locked compartment on the bike.
A: So long as you have a valid, Michigan CPL (Concealed Pistol License), you may carry concealed pistols anywhere in the State of Michigan except for those places listed on the "Pistol Free Areas" list in the statute, or private property where the party in control prohibits weapons in general or asks you specifically not to carry there. Note that the intent of the law is that you should lock your gun in your vehicle when you find yourself about to enter a "Pistol Free Area." (NOTE: I use the quotation marks to indicate that the statute uses the term "Pistol Free Area," but only law-abiding citizens are deterred by the rule.) The question of storage is a question of reasonableness. If you have a compartment on your motorcycle that is secure, you should be fine storing your pistol there. However, if the gun falls into the wrong hands, you could potentially face criminal and civil liability. So, be sure that your method and location of storage pass the "sniff test".