Oh I'm sure the do make them for motorcycles John. I have a neighbor that got tired of lead/acid batteries in his Honda 4 wheeler so he did some digging on the 'net and found a Lithium replacement for his application and bought it. He paid out the yang for it and was amazed at how small it was. But he installed it and hasn't been happier. Fantastic starting capability. I suppose if they're good enough for a Toyota Prius then it ought to work for a 4 wheeler.