New to Motorcycle conversion, need opinions and some good start info

Hi all! I have recently aquired an old 1986 Honda Nighthawk, and I would like to convert it to an electric motorcycle. I have gutted it, and am ready to start buying parts in January, however I am quite overwhelmed. It seems no one has attempted to convert a shaft drive bike, or if they have I can’t seem to find a whole lot of info about it. I do know that the final drive ratio is 3.4:1 I am worried that this will not allow me to reach a top speed of 65 MPH. The requirements for this bike to work as a daily commuter are as follows. It needs to be able to go 30 miles, maintain a speed of 65 for most of it, and climb a moderate hill once. Most of the miles are highway (55 MPH speed limit), and traffic is usually light. Weather is great 99% of the year, and I will most likely not have a place to charge my bike while at work.

Since this bike is shaft drive, it kind of makes it unique and is why I really want to use this frame. I have read a few other conversion sites out there that have a final drive of 6:1, 5.??:1, etc, and they seem to reach 50 MPH or so and unless I am mistaken that is a higher reduction of shaft RPM vs Wheel RPM than what my shaft drive has. I think this means that I will have a slower acceleration, but a higher top speed. Since I am unsure how I will mate the motor to the shaft drive (I was hoping to order a custom mating shaft), I may have to use a gear ratio and chain. This can lower the top speed to allow for more hill climbing power. Not sure what ratio I should shoot for as an overall. Any ideas would be greatly appreciated.

I am also worried about range, and I am not sure I wholly grasp the Ah rating on batteries, other than more is better :D. Again, some kindergarden level eduaction here would be helpfull. I would like very much to try to get into some Lithium Ion battery packs, but the cost is quite high and I do not have a lot of funds. This will be stretched out over quite some time in order to accomodate the pocket book.

I am also finding myself short on some parts, I do not have any instrument cluster, etc. If I want to register this bike, will I have to have the original speedo? I think I fall outside of the original bikes specifications, even though the frame will hopefully not be modified, it will be a new bike entirely. I hope I can register it as such. The california DMV can, and usually is, most perplexing with these matters.

I have been planning on an Advanced Series wound DC motor, but am not sure how to go about selecting the right motor. I would like the Advanced DC X91-4001 motor, but I do not want a double shaft. I am sure they have an option for me, but I am really worried that I will buy a motor that will be underpowered for my application. I want to stay in the 72V range, but I am considering a 96V application as well. The problem is I don’t understand that difference and trade offs involved with that kind of decision. I know enough to understand that the difference is two more batteries I have to cram onto the frame. I have a hard enough time trying to envision six batteries on the frame, though I am positive it can handle that and be pleasing to the eye. I would like to make some custom fiberglass fairings for it to make it look nice and provide some aerodynamic qualities to help it along. I will most likely use the bikini fairing for the front that it came with. Anyhow, so much to think about and worry about. I could really use eveyone’s help and expertise in this!

MattH, You definantly have put yourself into an exclusive group, going with shaft drive. You will need to get a machined adapter made, but this should not be insurmountable.
If I may, I would definantly recommend a smaller motor, this is the 8" correct? This is a motor capable of pushing a mid size car at 156, and even more volts. Advance DC makes several motors that are smaller, and more twards the 60-84 volts you will probably be running. This size motor, and volts will be more than enough to provide the speed you describe, and if you are carefull you could fit enough batteries to get the range you want as well.
Please check out some of the motorcycle conversions at AustinEV You wont find shaft driven bikes (that I’m aware of) but it will give you a better idea of what is required for motors,controllers, batteries. Hope this helps, Eric

well, the X91 is indeed a double shaft. Its also a bit larger voltage range than you should need for a motorcycle.

I found myself in the same situation as you several weeks ago.

Do this. Make a cardboard motor. This X91 is a 6.7" and about 15.34" long. Its also 62Lbs. It also has no mounting plate on it.

The K91 however, is a 48-96V motor, with a good torque curve. Its ~56lbs. Its 6.7" but its 11.34" long. Its got a mounting plate on it, and can be found for about $650 on EVamerica.

In talking with Jim Husted (HiTorque), he’s said that alot of motorcycles use a 5 or 6 to 1 final gear ratio.

You never stated what CC this originally was (weight). What about a custom jackshaft to reduce the drive more?

What controller do you have in mind? This might limit your current capacity.

What batteries do you have in mind? The more lead, the more current and the more range.