I'm certainly no expert, but it looks like no one else has jumped on board here. I was talked into doing a girls-on-motorcycles-in-a-club shoot last year. The club was very large and all the walls and ceilings were black. It was a serious light sink. I rented a Comet 2400WS power pack, some heads, stands, two 4'x3' soft boxes, and umbrellas for relatively cheap, all things considered. I wound up using two soft boxes for virtually everything. In a brighter, smaller location I think I could have used much less power and still shot at the ISO and f/stop I wanted, but under the circumstances, I was glad I had the power. I was absolutely stunned at how much light that place soaked up. So, from my one time experience in this area, for motorcycles I would suggest about 300WS per head for main and fill in soft boxes and less for kickers if you use them. I like the rectangular reflection of soft boxes much better than round or umbrella-shaped reflections when it comes to machinery. The 4x3 soft boxes worked out about right. I thought I would want larger ones, but I was pleasantly surprised. I used them with the long axis in the horizontal plane, but I can't remember exactly why I did that. I just remember that I liked the looks of it better than with them turned the "normal" way. Depending on the bike, it will take a bit of futzing and chimping to get the reflections the way you want them – darned chrome. That's all I know about shooting motorcycles indoors.
I've shot thousands and thousands of pictures of cars, but not inside. I have a notion of what I would like if I had to do it, but since I've never done it, I think it would be wise to keep my mouth shut and not mislead you.
