New Project: 1961 CB77 Superhawk

Hi Everyone!
Im new to the EV build world, but I have some experience with motorcycles, electrical, and I can learn pretty quickly, so I'm hoping I can make this all work out.

I have a 1961 Honda Superhawk with a 305cc ICE in it right now. It hasn't run in a while, and I want to make it into my first project.




After searching forums and the web, and filling out various spreadsheets to figure out necessary motor/battery specs I've come up with a rough list of what I think might work, but I would love other's input as to whether this is something that could be done or not.

My main requirements for this is that it can reach a top speed of 55mph, and have a range of 90ish miles at an average speed of 40mph.
These are due to the fact that I work seasonally and that's the distance to the place I work and the average speed of the trip. All other trips would just be around town and whatnot.

I am thinking of an 8000w hub motor for this build, the QS 273 specifically. This should get me to around 65mph with the battery pack I'm imagining I think, and saves me the trouble of figuring out a mid mount motor with my limited fabrication skills.

For the batteries, Im thinking of using 18650s at 20s25p to get me 72v and somewhere around 80ah. The batteries are where I am most out of my element so input on better options or if this won't work etc. is welcome.

Thanks in advance for all the help!

If you use the motor simulator at http://ebikes.ca, you can get a good guesstimate of the wh/mile needed, but I would guess 100 to 150 wh/mile based on some other builds and commercial MCs.

From there you can based your pack size on needing at least the wh/mile x the max range you will ever need, minimum.

I would then also recommend adding at least 25% for unpredictable conditions (weather, detours, etc) occasionally, so you can still complete that trip, and another 25% to account for pack aging, so that after the first year or two (depending on usage and other factors) you won't have to replace the pack just because it doesn't go as far as you need it to.

I thought we already had a thread about a similar bike, that would have useful info for you, but I can't find it.


The simulator can also help you figure out the power needed to go the speed you need under the conditions found on your ride.

To use it you'll have ot input nearly everything as "custom", so you might have to get some specs on the motor, and controller, from teh manufacturers or at least the sellers (QSMotor probably has this info, perhaps even in their sale thread here on ES if not on their site).

The battery info you cna just guesstimate based on the cell specs.


Some of the math to figure things out is demonstrated in other threads in this subforum, some of it in my posts, some in others. Sorry I can't help directly with that ATM as my mind is not working as it should.

You'll need closer 120ah of battery for 90 miles range at 40-45 mph.

I've got a converted Vespa P125X with a 4kw QS205 hub motor, and a 38ah 72V battery.
30 is the safe range for it at those speeds.

I know you already have the CB77 in hand, but, a CB160 would be a lighter weight bike to start with, and
maybe a better fit for that size motor.

The CB77 have collector value. You might want to do your project in such a way that does not require cutting/welding the frame.
Make it such that you can put it back to original should you decide you want to move on to something different. You'll get more money for the CB77 in original condition, and then have your motor, controller, battery, etc for another project, or to sell as a kit.

I love conversions like this so I'll be following your build. Good luck and enjoy the journey!