I had seen people using 1 turnigy motor on a cycle and getting pretty good speeds.

With 3 such motors, this thing is an overkill.

I love Turnigy! (now where did that kissing smiley go  )

Actually the more interesting aspect is how the shafts seem to be connected together, and how it would affect the ESC timing of the motors

the shafts anyways extends on both sides on the stock motor, they may have welded it.

Regarding ESC timing, I think all the ESCs are connected to the common throttle port on the RX and
its the ESC that syncs with the motor pulses right?

I believe that should solve the problem, with all ESC receiving the pulses at the same frequency from the motor and all the ESCs receiving the same signal from the RX.

I betcha the motor is:
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=5142&Product_Name=Turnigy_80-100-B_130Kv_Brushless_Outrunner_(eq:_70-55)

Sadly they could not get all of one color! The best part was the Lipo 'Farm' - its like tiny mice powering the Kart. Wonder they did not use Lead Acid battery ! Current / Weight ?