I thought it might be helpful to someone to post the info I found on chains and belts. It turns out that the Ninja came stock with a 530 chain. That means it is 5/8" pitch with a 3/8" wide roller which it turns out is the same a 50 series industrial chain as far as I can tell so I am planning to run a stock (new) 46Tooth rear sprocket and then buy an industrial chain and front sprocket that is 7/8" bore with 3/16 key. This will drop onto the Motenergy motors I am looking at. It also gives me tons of options for gearing changes to tweak acceleration / speed.
I did look at a possible toothed belt drive, but the cost of pulleys is ridiculous and every time you do a gear change, it is likely that you will have to change belts as well. Another big neg is the massive size of the rear wheel pulley. Oh yeah, one more neg, unless you have a removable section in your rear suspension, you can't get a belt onto the frame. The E-Bomb does have a removable section so it is a possibility, but not worth the cost.