Need Electronics Help For ATV Build - Motorcycle Driveline

Hello All. I've been working away on a vehicle I designed for myself. Its an off road quad with a powertrain out of an old Zero motorcycle. I am a quariplegic so it has hand controls. See pics below. Here is a link to my google doc with the electronics info on it:

https://docs.google.com/document/d/17wvSZpfWqqRYJHhiKyu9IuPxzoJwgg7mLUIBQYmZ3-8/edit?usp=sharing

And a link to the wiring diagram I'm making:

https://docs.google.com/drawings/d/1BqVcjgjz1uTmR5OSpQhm0mYrSwt60CFIeO03JfxnxeQ/edit?usp=sharing

At this point the batteries are only reading 60v (supposed to be 84) the motor has not been spun. I need to know what to do in terms of what components I need. (main contactor? Main fuse?) I could also really use help wiring this thing up physically if anyone is local and can help - I can pay. I have welding and bike mechanic friends and they will wire it up but it would be nice to have it one by someone who knows what they are doing. If anyone has any advice on the electronics of this thing I could use the help.

Appreciate the help!

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It's looking to be a cool ride. Sorry I can't help with the wiring, but your battery needs to be checked for health. 60V is pretty low, but you really need to check at the cell level, which if you can't get to the battery poles you should be able to measure at the BMS connector. The battery is the heart of any EV and the most expensive as well as hardest to place, so the first thing to do is measure those cell voltages.