If you are just getting started, you’re probably wondering if there is a good book out there. I definitely recommend Ted Dillard’s From Fossils to Flux: A Basic Guide to Building an Electric Motorcycle (Third Edition).
You can download an electronic version of the book for only $10.
After you read From Fossils to Flux, go to: EV Album.
Search for Motorcycles by type and read all about the bikes you like best. Many of the owners provide links to websites or blogs which include great details. Read them.
Then join the ElMoto forum. Again, read about what interests you, and generally just read, read, read.
You will learn a lot by going to this site and reading regularly. Many of the forum members also have great websites with helpful advice.
Download and read the operator’s manual or spec sheet for your components before you buy them. You won’t understand it all, but you will learn more as you go. If you encounter tough questions, ask them on ElMoto. There are a lot of experienced members who love to help inexperienced folks answer intelligent questions.
There are many more out there. Ben Nelson’s detailed motorcycle build description is well worth reading: KZ440 Conversion
Noah Podolefsky’s GSX-E website has detailed advice on wiring and tools, in addition to a great build description.
This is only a sampling. Have fun finding more great motorcycle projects out there!