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captainslug 12-20-2008 12:18 AM

<$1k DIY Neighborhood Electric Motorcycle
I'm quite fond of all of the commercially available electric motocross options, but not enamored with the fact that most of them start at price levels of $7,000 and above. They're mostly aimed at obtaining a near 250cc level of performance, but for my daily use I won't be needing more than 50cc. I don't need to go above 35mph and I don't intend to launch myself over 15-foot jumps.

So for the past week I've been poking around at various options and determined that I can obtain the following for under $1,000.

Top Speed: 34mph
Range: 20-25 miles
Weight: 180-220 lb
Motor: 48-60v 1kw
Battery pack: 60v 20ah

I intend to make it road-worthy, even though it will be operating within a DMV loophole that prevents it from needing a license plate or insurance. So it will include lights, turn signals, and horn, albeit custom-made ones.

bennelson 12-20-2008 07:15 PM

Sounds totally do-able, especially with what we have seen of your electric scooter/bicycle upgrade.

I assume the DMV loophole you are speaking of has to do with the definition of an electric bicycle? You are intentionally keeping max speed down or having an electric motor with a very specific power output, right?

Neighborhood Electric Motorcycle? NEM? I think you just coined a new acronym!!!!

Sounds cool

captainslug 12-20-2008 08:56 PM

Actually, I might end up naming this project NEM-0

Virginia DMV definitions

Electric Bike:

means a vehicle that travels on not more than three wheels in contact with the ground and is equipped with (i) pedals that allow propulsion by human power and (ii) an electric motor with an input of no more than 1,000 watts that reduces the pedal effort required of the rider. For the purposes of Chapter 8 of this title, an electric power-assisted bicycle shall be a vehicle when operated on a highway.
Of if you remove the pedals it becomes a Moped, and the "1,000 watts" figure disappears.

a seat that is no less than 24 inches in height, measured from the middle of the seat perpendicular to the ground and (ii) a gasoline, electric, or hybrid motor that displaces less than 50 cubic centimeters. For purposes of Chapter 8 ( 46.2-800 et seq.) of this title, a moped shall be a vehicle while operated on a highway.
50cc Electric? WUT?
But based on the definition of "Motorcycle" anything that cannot travel above 35mph is technically a Moped. I confirmed this with the Police Department, which basically just doesn't want me on the sidewalk unless I cannot match the posted speed limit.

travel on not more than three wheels in contact with the ground and is capable of traveling at speeds in excess of 35 miles per hour.
So if I aim to have a top speed of 35mph, but be unable to go beyond it then I can ride it around town like I would a normal Bicycle. I would only need pedals if I wanted to be able to pedal along on the sidewalk.

The rough plan is to take this
Cut the frame in half, weld in extensions and a simple battery rack, replace the existing motor/controller combo, and add a number of functional accessories (lights, key switch, and so on). Unlike other mountain bikes this one already has the basic shape I need.
I can either drive the rear wheel directly with the gear ratio I want, or remove the pedals and use the pedal axle to make a more precise two-stage gear ratio reduction.

The benefit of not using a hub motor is that if I later decide to register it as a motorcycle I could either install a different gear ratio, or think about making a custom derailer and sprocket cluster. Located either on the rear wheel, or the original pedal axle.

Most of the parts I intend to use are very cheap replacement parts available through sites like TNCscooters.

First step is to order the donor frame and just start measuring.

bennelson 12-20-2008 09:38 PM

Sounds like you nailed it on the legal definitions of the vehicle.

Geared sprockets are great because you CAN change your gear ratio's easily later.

On my Electric Kawasaki KZ440, I started with a 72 tooth gear on the back and a 12 tooth on the front. When the 12-tooth broke (terrible home-weld!) I replaced it with a 14.

That setup has enough power to spin the back tire, while still being able to hit 45 mph top speed. I haven't yet experimented with going to a bigger yet front sprocket as it's 25 mph speed limit in most the area I use the motorcycle.

It might be fun just to experiment with sprocket changes sometime though! :D

captainslug 12-29-2008 10:59 PM

Got a really good deal on an Xmotos 150cc rolling frame through ebay ($130 shipped!!).
Looks like this but in silver/red, sans ICE, and sans body panels.
Unlike the previous frame I was looking at this one includes hydraulic disc brakes on both wheels, and is compatible with a very wide range of wheel sizes (14" to 21").

Saved me so much money I don't have to worry about cutting/welding where needed. I can then get it powder-coated to my color of choice to protect it from rust.

captainslug 01-23-2009 01:24 AM

Frame arrived this afternoon. I'm going to spend part of Friday cleaning it.

All I did today was measure was was formerly the engine compartment in order to develop a plan for the battery rack and motor mount. And thankfully I've figure out how to fit everything in there with room to spare and only minimal cutting of the existing frame.
My preferred battery setup means I have to add a chain drive axle. This affords me more flexibility in gear ratios and the option of later changing the wheel size (in diameter and width) if I want more ground clearance.

The extra appeal to mounting everything in the original engine location is that all of the working components will be visible, and easily accessible for maintenance.

Money spent so far: $130

almightybmw 01-23-2009 06:43 AM

I love what you've got going so far. Excellent project, at a really good prtice for that frame! How much empty does it weigh? I'm assuming it won't have knobbies on it, something in the 16-18" rim size would be good. I'm loving the inverted fork, and long travel rear. Dual sport electric! Ride through backyards for shortcuts! lol

but... to nitpick the title... >$1k... that reads greater than $1000, not less than.
Been driving me nuts every time this thread pops up. Could someone fix it... please?

Keep up the good work. I think you've got the hardest part done, the platform.

MetroMPG 01-23-2009 11:51 AM

Fixed the title. Watching with interest...

Daox 01-23-2009 11:54 AM

I'm with Darin, I'll be watching this one. :) Good luck!

Ryland 01-23-2009 12:27 PM

does your state require titles for mopeds? if so then that might be your biggest hurdle, that is why I'm a fan of motorized bicycles, no title needed and in Wisconsin 30mph is the top speed if I remember correctly.

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