<$1k DIY Neighborhood Electric Motorcycle

[captainslug]

It's finally above freezing for the first time in a month. A toasty 54F. It's so "warm" I was able to work the ice out of the garden hose.
Parts everywhere. The parts on the far right won't be needed (fuel tank, exhaust, muffler, engine brackets).

Frame is pretty filthy.

I can only get is so clean with dish soap, water, and a brush.
I'll have to clean it further by sand-blasting it. But for now it's clean enough to start cutting and welding.

Originally Posted by Ryland

Does your state require titles for mopeds?

Nope.

Originally Posted by almightybmw

1. How much empty does it weigh?
2. I'm assuming it won't have knobbies on it, something in the 16-18" rim size would be good.

1. I'm not sure at the moment. 80lbs without the wheels is my best guess. It's pretty light considering that the triple tree is the only part made from aluminum.

2. I am going to stick with dirt track tires because part of my route to work has a tendency to be muddy. There's also a creek I would like to be able to cross behind my neighbor's house that would significantly shorten another route I can take.
Being able to ride safely on mud and wet roads is the primary reason I started this project. I have to make one from scratch because there's nothing available in this configuration that's under $5,000.


I'm currently debating whether to switch to BMX rims to reduce weight, but I'm not sure if they can handle the weight of the frame (100lb), batteries (100lb), and me (130lb). I'm trying to aim for a final weight of no more than 250lb.

Tentative to-do list for this week
+ Grinding off excess tabs
+ Cut in frame well for upper most battery
+ Machine battery-rack/motor-mount parts
+ Weld in battery-rack/motor-mount parts
+ Make or buy new handlebars
+ Plan wiring schematic

[captainslug]

After measuring the frame some more and shopping around for materials I decided to start the CAD work all over again. The first two designs were too cramped or involved fairly expensive materials.
This latest design will be easily made with less than $60 worth of steel (L-channel and 1" square tube) and some sheets of polycarbonate (which I buy as scrap). All while allowing for a wider range of sprocket sizes.

And it will only require me to cut out and replace the small downtube that held the engine and skid plate, rather than having to alter the main fork of the frame.

[captainslug]

After researching tire sizing, I've found a set of Dual Sport tires to replace the current knobby tires.

Front Rim: 1.4x19
Rear Rim: 1.6x16

Stock Front Tire: 70/100-19
Stock Rear Tire: 90/100-16

Replacement Front Tire: 2.75-19
Replacement Rear Tire: 3.00-16

Rim to Tire size chart

It looks like my final gear ratio setup is determined. I will have to double check the diameter of the replacement tire before I order any sprockets though.

Max Motor Speed @ 60V: 3750 RPM
Motor to Trans: 1.7:1 (10t to 17t)
Trans to Wheel: 4:1 (12t to 48t)
Max speed: 35.5mph

I also ordered a ton of parts from TNC Scooters, and major components from eBay.

Money spent so far: $507

Wiring plan

[captainslug]

Parts! My front tire came in the mail, but the rear tire hasn't shown up yet.

Haven't done much except measure the motor, then research/shop for sprockets and chain.

As I remembered correctly, permanent magnet motors are definitely not free-spinning when unpowered, so I had to do some thinking about how to add an overrunning clutch cheaply. I'm going to be buying a bike hub that I can cut apart to build my own.

[MetroMPG]

What are the motor specs?

[captainslug]

My Boss is talking to one of his contacts about seeing if he has any nylon-lead lattice batteries in the size range I need. Don't know how that will turn out but it would be really interesting to get to play with prototype experimental batteries.

Originally Posted by MetroMPG

What are the motor specs?

Unite Motor MY1020
Permanent Magnet DC Motor
48V
1000W
3000rpm (likely to reach 3700rpm @ 60V)
Length: 6"
Diameter: 4.25"

Presumably 1.5HP

Here's an electric trial bike using the 750w geared version of this motor.
http://www.evalbum.com/1447

It's also used in electric pocket bikes.

I don't want to go beyond 1kw or my range will suffer.


Rough design concept

[captainslug]

Started work on the battery rack.

[captainslug]

Cutting and grinding the downtube, engine tabs, and wire tabs off of the frame.

[captainslug]

Some progress with welding the battery rack.


And I lathed some aluminum collimators for the high power headlight LEDs. The wide angle will be angled further downward than the narrow one.

[Daox]

Looking good!