Introduction: Build an Electric Motorcycle on a Budget

Picture of Build an Electric Motorcycle on a Budget

The Goal of this project was to convert a classic motorcycle into a clean, quiet, electric daily driver that would reduce the amount of automobile pollution caused by my short to mid-range driving trips.

COST: $1,000
RANGE: 40 Miles
SPEED: 40mph with current sprocket setup
CURB WEIGHT: 320ish Pounds, around 50 more than original
RECHARGE COST: Less then a Penny per mile

Ahhh yes, The Electric Dream! Clean, Quiet, and best of all not a drop of Gas!

There is a lot of great information on current Electric Motorcycle Instructables, but I still ran into some snags and made some mistakes along the way. So I will do my best to cover where I went wrong to save you some time, money, and effort. When the build was over a book called Build your own Electric Motorcycle was published, Needed less to say its a resource I wish I had along the way.

Also, by no means am I an expert. In fact, the only class I failed in college was "introduction to electronics" . In saying that, I am looking forward to any comments or feedback on how to improve my project. Also follow me on Twitter or on my Electric Motorcycle Blog to  keep up with my current projects and Electric Motorcycle News.

Step 1: What You Need

Picture of What You Need

Here is a list of what you will need and how to find it:

A Plan: This is the best question to ask yourself before going out and buying anything.
How far, how fast, how much? To get a good idea of this, spend some time on: - its got 1000's of Electric Motorcycle conversions with pictures of the bikes and the components used to make them.

1.Donor Motorcycle or a rolling chassis - Check Ebay and Craigslist. Personally, I like to set up an RSS feed from my craigslist search, otherwise I browse for way to long when my ADD kicks in. I found my 1967 Honda Dream(ca160) on craigslist for $275, with frozen motor, but hey, I don't need that anyway.

2. Electric motor - There are lots of options out there, but I recommend a Brushed 48v Etek Briggs and Stration due to its price, power, and availability on eBay. The original is no longer in production so your options are to buy a used motor or get a clone. Also, if you have a local golf shop go talk to someone there - they are gear-heads too! These guys will like you and they will like your project. So see if they can cut you a deal on an electric motor, there will be plenty of just sitting around.

3. Batteries again, consult your plan. My plan was 30+ range, so I picked up some deep cycle batteries at walmart for $62 a piece. They are 12v 105 aH. Looking back, I wish I would have gone with some smaller and lighter batteries. I really don't need the amount of range these current deep cycle batteries provide.

4. A motor controller that delivers/regulates the energy from the battery to the motor. Think of this as a transmission. I found a Curtis 48volt 300 amp controller on eBay for $150.

5. A twist grip throttle that sends an electric signal to the controller - which determines how much energy is sent to the motor from the batteries. Most popular is the Magura Twist grip, available on ebay.

6. A battery charger to re-charge your batteries for continual (cyclic) use. I am still working on finding the best charger for my ride, but I would like to do something that could be out on board.

7. A high-current switch or Contact Buy this on eBay or at a Golf Cart shop. This part makes the loud "click" sound when your turn on a golf cart.

8. A high-current fuse to limit the amount of energy drawn from the batteries in case of a short/failure. Typically = to Control max amperage. I got a 2 300amp fuses on eBay for $19 bucks

9. A large gear ratio to reduce the amount of current required when accelerating (this can be accomplished with a large custom rear sprocket and a small front gear/pinion on the motor). My current gear ratio is 3:1, optimal would be 4:1+

Optional stuff: instrumentation, speedo, ammeter, or a way to judge batteries state of charge.

Step 2: Frame Modifications

Picture of Frame Modifications

Its time to make sure the Doner Bike is road ready. My bike also had a lot of rust and some body work that needed to be done.

Remove Rust:

Paint Bike:

With any old bike its a must to check front and rear suspension, barrings, and brakes. Check out Dan's Motorcycle repair guide to address any issues.

Time to put together some way to mount your batteries. Your best bet here is to create cardboard cutouts the sames size as your batteries, and then see what configuration will work best. Cuts done on moving around large heavy batteries. I was able to use some some 1 inch steel from lowes and come up with some pretty steady battery mounts. Remember to keep the battery weight as center and low as possible to help with handling.

Step 3: Assembly

Picture of Assembly

Mount the motor:

1) Use the same location as the gas engine using as much of the original frame and existing engine mount as possible. I was able to use 2 of the existing motor mounts, and then added a 1/4 inch 4x8in piece of steal, which is bolted and welded to the frame.

2) Mount the motor on the rear swing-arm. Check out for some ideas. Here is an example of a swing-arm mounted motor:

Controller, Main Contact, and Throttle:

Its is very important to mount a controller in a place that is going to get a lot of air flow, because these things can overheat and fry if your not careful. Curtis website has some really helpful information on how to mount and wire these controllers, this is a huge resource that most of the controller manufacturer offer so find yours and use it. I was able to mount on the side of the frame where the tool kit used to be. This provides easy access and lots of crisp cool airflow. The main contact was mounted on the inside of the frame, close to the batteries and controller. Below is a detail wiring guide, this is probably the most important part of this instructable and the part that gave me the most problems during the build. The main contact should be mounted in a place that is easy to get to. I put my inside the body of the frame, this was a mistake. Hard to get my big hands in there and I can never see whats going on when I am moving wires around.

Throttle should have 3 wire red/blue, brown, and black. You will need to use a multimeter to test which leads give you 0-5k ohms or resistance, these wil be connected to the controller. In my project these where the brown and red wires. Then the black wire need to be connected to battery negative or negative terminal on the main contact.

Batteries should be wired in series this means positive on battery 1 to negative on battery 2 and so on... look at the picture, I'm told its worth a thousand words.

Step 4: Troubleshooting and Issues

Picture of Troubleshooting and Issues

If you get it all together

Verify that battery (-) connects to the B- terminal of the controller. Connect
voltmeter (-) lead to this point.

Connect voltmeter (+) to the battery side of the main contactor. Check for
full battery voltage. If it is not there, the trouble is in the battery pack, the
cables to it, or the power fuse.

Connect the voltmeter (+) lead to the controller B+ terminal. You should
read a voltage 1 to 5 volts less than the full battery voltage. If this voltage is
zero or close to zero, the trouble is either a bad controller, a bad 250 & resistor
across the contactor, or an incorrectly connected cable between the contactor
and the controller. Trace the cable to make sure it is hooked up right.
Remove and test the 250 & resistor with an ohmmeter. If these check out,
the controller is malfunctioning. If you see full battery voltage at this point,
then the contactor has welded and must be replaced.

TEST 2 Check for main contactor operation and KSI

Turn the key on, place the forward/reverse switch in forward or reverse, and
apply the throttle until its microswitch operates. (In these procedures, we
assume the throttle is equipped with the recommended microswitch.)

This should cause the main contactor to operate with an audible click.
Connect the voltmeter across the contactor coil terminals. You should see
full battery voltage (minus the polarity diode drop).

The controller KSI terminal should also be getting full battery voltage.
Verify this by connecting the voltmeter (-) to the controllers B- terminal,
and the voltmeter (+) to the controllers KSI terminal.

If the contactor and KSI terminal are not getting voltage, thats the problem.
Use the voltmeter to nd out where it is not getting through. Connect the
voltmeter (-) to the controllers B- terminal and check the following points
with the voltmeter (+) lead to trace the ow:
Curtis PMC 1209B/1221B/1221C/1231C Manual 31
1. First, check both sides of the control wiring fuse.
2. Check both sides of the polarity protection diode to make
sure its polarity is correct.
3. Check both sides of the keyswitch.
3. Check both sides of the throttle microswitch.

If the contactor coil and KSI are getting voltage, make sure the contactor is
really working by connecting the voltmeter across its contacts (the big
terminals). There should be no measurable voltage drop. If you see a drop,
the contactor is defective. (We assume the recommended precharge resistor
is in place.)

TEST 3 Check the potbox circuitry
The following procedure applies to the standard throttle input conguration for
these controllers, which is a nominal 5k& pot connected as a two-wire rheostat (0
= full off, 5 k& = full on), and also to 5k&0 congurations. If your installation
uses a controller with a throttle input other than 05k& or 5k&0, nd out what
its range is and use a procedure comparable to the one below to make sure your
throttle is working correctly.

With the keyswitch off, pull off the connectors going to the throttle input
of the controller. Connect an ohmmeter to the two wires going to the
throttle and measure the resistance as you apply and release the throttle. The
resistance at the limits should be within these ranges:
RESISTANCE (in ohms)
05k& POT 5k&0 POT
Zero throttle: 0  50 4500  5500
Full throttle: 4500  5500 0  50

If these resistances are wrong, it is because the pot itself is faulty, the wires
to the pot are broken, or the throttle and its linkage are not moving the
potbox lever through its proper travel. Apply the throttle and verify that the
potbox lever moves from contacting the zero-throttle stop to nearly contact-
ing the full-throttle stop. If the mechanical operation looks okay, replace the

hope this all helps leave a comment if you got something to say, and for more infomation check out my website on electric motorcycles


moddy (author)2017-11-22

Well done. As a motorcycle enthusiast, when I get a chance to build one, I will be coming here to check this out again.

oojagapivy (author)2017-08-14

Just today I began thinking about converting my old 1964 Honda Sportscub 49cc bike to electric since it hasn't run in over 25 years.

Inspired by this article. Ty

JoeMurphy (author)oojagapivy2017-08-15

Cool! I'm happy to know people are still finding it useful. Good luck!

jdrach85 (author)2014-08-06

So I think I found the same batteries at Walmart, but they don't have a milli Amp-hour (mAh) rating on them. Instead, they say 625 MCA 9Marine Cranking Amps). Is this the same battery, and how do these relate to each other?


BJH3 (author)jdrach852016-08-26

No, they're not. There are two general type of these batteries, one is design to produce a lot of current for a short amount of time, like to start a car or boat engine. This is the type you describe with their capability measured in Cold Cranking Amps. The second type is a deep cycle battery and this is what you need. A deep cycle battery is designed to produce a low amount of current for a long time, like running an electric motor as we are doing here. You will want deep cycle batteries, ask for ones intended to run a trolling motor.

gluvit (author)2014-05-12

Great project

DirtMcGurt (author)2013-04-22

For anyone interested: I'm currently restoring a 64 Honda Benly 150, which I believe is the exact bike seen here. I have a spare parts bike with everything except a motor that would be perfect for this project. If anyone is interested I'm looking to sell. Let me know.

niuthon (author)2009-11-04

yeah, where are the brake handles?
ps - great job!

JoeMurphy (author)niuthon2010-06-02

 At the time of the photo I was only using a foot brake...I know scary and dangerous.

abadfart (author)JoeMurphy2012-11-18

old harleys only had a rear drum and no front brake

lloydrmc (author)niuthon2012-05-07

The front brake handle is on the left (visible in the first picture). On a motorcycle, the rear brake is actuated by a foot pedal, as the other hand control is the clutch (the brake would generally be on the right on a motorcycle, so he must have moved it).

PKM (author)niuthon2009-11-24

It's a geared bike- the front brake is on the right handlebar (step 3 image 4) and the rear brake is the right foot pedal (step 2 image 1).  The clutch is missing because it's unnecessary for a single-gear electric bike.

niuthon (author)PKM2009-11-29

I see you are pro indeed :) thx
anyway, this  is realy great bike ,pity no one is selling proper parts in this backwater country of mine ( i had only made a bicycle with electric hub motor - nothing special this days )

JoeMurphy (author)niuthon2009-11-22

stock my friend

AudioMaximus (author)2012-06-11

What would the legality of this be in NJ?

JoeMurphy (author)AudioMaximus2012-06-21

typically the fall under under 50cc scooter laws, but check with your DMV

okbye (author)2012-03-19

Wonderful. Did you know that bike is pretty valuable in one piece? With that much battery, time to go three wheels, no?

solivant (author)2009-10-04

what about a break system?

dufus1 (author)solivant2012-02-26

Not wanting to be naughty, but why do you need a system to "break" it? I'd just run it into a tree or something.
If I wanted to slow down or stop I would think about putting "brakes" on it.
LOL now have fun with that!

Shorting the moroe terminals will cause the motor to generate power, and then eat the power in reverse- meaning, it will resist any movment and convert it into heat. Using PWM, you can vary the strength of this effect, and voila! you have breaks!

Callum Snowden (author)solivant2010-12-09

Just flip the thing into reverse and just gently apply the throttle :)

llanyort (author)2009-09-04

don't they have a kilowatt meter that plugs into an outlet and then you can plug in your electrical device into that and measure the amount of electricity you will have used ? I plan on using this method and reimbursing my boss. im thinking its gonna be a few cents a day.

randomray (author)llanyort2012-01-22

Hmmmm , I could probably do something like that , They don't say anything about the guys pluging in the heaters on the private diesel trucks .

bbroughton (author)2011-08-15

I really appreciate your sharing your input with us. I have always wanted to do this and now that I am out of college and have the extra money I think I will begin pretty soon. I realize that using lithium batteries might be more expensive but do you think it would change the way you built the bike?

JoeMurphy (author)bbroughton2011-08-21

if you can afford lithium, Do it. Search austin ev for lithium builds.

bbroughton (author)2011-08-15

Great song on the video by the way!

jayeshshinai (author)2009-07-19

my friend made one wid an imported 1000watt motor...mounted it on a cutson 2' aluminium pipe frame wid d rear mono shock. i checked d motors used on, n none of them use "watts" as wt specs do i havta tell my dealer for a motor running on 36volts, with enuf torque to move a bike (and 2 riders) weighing a total of 170kg? clearly m not so gud wid electronics...any suggestions?

soulvoid (author)jayeshshinai2009-09-04

no trying to be rude but you need to learn how to type so everyone can read what your talking about. it took me 3 times to read over your comment to figure out what you were trying to ask. lol

jayeshshinai (author)soulvoid2011-04-13

i knw its pretty late for me to reply...ill try not eating up my words this time.
A friend of mine had got him shipped a 1000watt motor, he mounted it on a custom 2" aluminium bicycle frame which had a single rear shock absorber(soft tail bike).

hope it makes sense now,

JoeMurphy (author)jayeshshinai2009-07-20

If the motor is rated at 1000 watts and you will be running it on 36volts. Power equals current times voltage for DC, so for 36Volts means a max of 27 other words the coils of your motor are rated at 27 amps...

To draw a comparison the above project is rated at 150 amps at 48 volts so 7200 watts.

Here is some helpful formulas

Watts = Amps * Volts {can also be written Power= current x voltage}
Amps = Watts / Volts
Volts = Watts / Amps
Watt-Hours = Volts * Amp-Hours {or energy = voltage x current x time}

Batteries in series = add voltages
Batteries in parallel = add amp-hours

Motors in series = divide voltage by # of motors
Motors in parallel = divide amps by # of motors

Lance Mt. (author)JoeMurphy2010-04-17

How would we tell through this what momentum and acceleration could be achieved? 

For instance in he's case lets assume its 36 Volt, 1000 Watt, 3000 RPM, 35.6 amp, and 170kg. We understand that that it will have 1000w going through it,  as long as its a brushless dc. Do we need more information to complete this? I looked up something similar, and the shaft was 3/8” X1.25". Width is about 3/4 of length on this particular model.   Steel is generally .290 pound/ cubic inch.

Ok, from this we can probably work out how much weight it is spinning at 3000rpm using a 60 joules/ 60 watts per second.

9.5mm (D) x 31.75 (L)

19mm x Pi = 59.6902
                        59.6902 x 31.75 = Volume
                                                          Volume = 1895.16576mm3
 Volume x 0.78 g/mm3 = 1478.2292992568733614600199043514 g
                                          =  14.78 kg 

  The motor is using 1000w to turn 14.78 kg at  3000rpm  

     To save my head more ache. I'm going to pretend the weight is 147.8 kg. At a 1:1 ratio this would turn 300rpm. which is  5 rotations a second still, without gearing.  How do we work that out? I'll get a base to work off.

Oh.. It seems I could have skipped a fair bit of this by using the equation:

MPH = RPM * Tire Diameter / Gear Ratio * 336
MPH = 3000 x 4064mm inch (Average) / 1:1 x 336 = 4096512000mm/per sec maybe?

MPH = 3000 x 40.64cm / 1 x 336 = 40,965,120 cm/per sec
 OR 254.5 mph. This just doesn't seem right at all, remember. I'm doing this as I go along. Perhaps Inches will do it.

MPH = 3000 x 16inch / 1 x 336 = 16,128,000 mph. 

OHHHHHHHHH I see what I have done, I haven't put the answer at the front of the equation. Would that mean that I should reverse the current equation to get my answer?

Back to finding the base. Ideally I would like 1kg x 1w (1J) = x amount of metres

Some useful points through my searching 
"100 kW is roughly equivalent to 134 horsepower"  - 13.4 horsepower, however...

"One horsepower for rating electric motors is equal to 746 watts."

"In terms of mechanical energy, one watt is the rate at which work is done when an object is moved at a speed of one meter per second against a force of one newton. 1W = 1Js-1 = 1kgm2s-3 = 1Nms-1"

Lance Mt. (author)Lance Mt.2010-04-17

 That Equation is killing me. I'm only in year 9, it doesn't make sense to me. The 336 constant must have to take into consideration gravity, air resistance as it rises, even ground ie. 

But it does not take into consideration of weight, or little things like where the force is applied and so on. 

I have much to learn, but for another night.

arivera-2 (author)2011-03-15

Will this motorcycle work in the rain??

FurtherThanTesla (author)2011-02-08

Just wanted to say, how awesome this project is. Not only is it a nicey made electric bike, but i think it looks pretty cool too! I am concidering building a high-efficiency streamlined 3-wheeled solar car. But I want one that goes fast. So, i am intending to use the Etek motor, and a pair of 1kw panels. I came to this instructable because i need an electric car before i can have a solar car! and this is exactly the setup i wanted. Figured i would go look at someone whose been there before I spend $500 on the Etek.

mtm101097 (author)2010-11-20

This may be a stupid question, but why not use rotating light dimmer as your throttle control? They probably make very large ones capable of the power required. BTW nice instructable

Sorry, but no. That motor draws more than 5 killowatts. there is no light dimmer (mabye other than expensive industrial-grade ones) that is made to handle that load. Also, Dimmers are made to work on AC power. The motor on that bike is DC. and, lastly, that motor is for a lower voltage than what dimmers are made for, so it would draw more amps. a 5kw dimmer made for 5kw couldnt handle 300 amps at 48v.

zack247 (author)2011-01-25

this is very cool! i am taking a welding class next year and now i am thinking of making a frame for a more-or-less motorcycle shaped vehicle, if i can get that part done, i am going to use this instructable and make a bike of my own!

PS: in step 2, its donor, not doner :)

sn0manX (author)2011-01-02

just wonderin, do you still happen to have the gas tank?

spiceyweasel (author)2010-02-04

I am new to the whole EV concept, but something has been nagging me. Why do all these EV bikes exclude the transmission? Wouldn't your bikes benefit from having a taller gear ratio? I need to be able to cruise effortlessly at 70mph for at least three hours. Can you please enlighten me about the omission? Also, why do you have a smaller sprocket driving a bigger one on the wheel? Does the electric motor have that much zip?

1zork (author)spiceyweasel2010-03-16

Transmissions are torque multipliers. The torque of much smaller electric motors exceed that of internal combustion engines. Speed can be accomplished with gearing. The choice is yours.

3 hours at 70 mph requires some considerable battery capacity. One way to reduce the required power and battery capacity is to build a bike similar to the AAR "Gator" style bike. Approximately 1/2 as much power required, and hence 1/2 the battery capacity.

spiceyweasel (author)1zork2010-08-21

I was going to base my bike on the Fat Bike design....similar to very early Harley Davidson's only with an aluminum frame and wheels to reduce weight. Also, I am working on a proprietary front hub with a permanent magnet generator built into it to produce electricity while the bike is in motion. I don't know if it will help meet my range requirements, but it should help a bit. So, basically, I'll have an over sized bicycle with independent front and rear suspension and moderate sized tires built on the lightest, cheapest frame I can storage save for a back pack....and the bare minimum lights to get it D.O.T. approved as a street cycle so I can hit the freeways. I'll check out the AAR Gator to see if it meets my criteria. Thanks.

Krazeecain (author)spiceyweasel2010-10-07

Your custom front hub generator will only be useful for regenerative braking. Otherwise, if you let it generate power while you're riding, you'll only be wasting energy, as the generator will be slowing you down, so you'd have to apply more power to go faster. It's a vicious cycle that'd only serve to reduce your range in the end.

spiceyweasel (author)Krazeecain2010-10-07

Is that due to the added weight? I don't foresee a friction problem. Basically, I'm looking for something to continually charge a bank of capacitors to keep my power levels up and take the stress off the batteries. I'll figure something out.

Krazeecain (author)spiceyweasel2010-10-07

No it's not from the weight. Ok, put it this way. How is your motorcycle moving? From the electric power in the batteries, which is turned into momentum, pushing your bike forward. When you add a generator to the front wheel, you're turning that forward motion back into electricity again. You're slowing down the bike, and turning its momentum back into electricity. It's much more efficient to just leave the bike's momentum alone.

spiceyweasel (author)Krazeecain2010-10-08

I'm a bit confused. There is no friction created in the production of said electricity, is there? The batteries provide electricity which produce momentum....momentum pushes the bike forward, causing the front hub (which is NOT being used for propulsion) to create electricity, which feeds the batteries and capacitors, which push the bike forward. I don't see anything in that thread of logic which would slow the bike down. One thing I can't help noticing is that these designs invariably use small sprockets to drive a larger rear wheel sprocket. Perhaps a change in gear ratios might help a bit? I'll tweak it until I get it right.

Krazeecain (author)spiceyweasel2010-10-08

Isaac Newton: "energy cannot be created or destroyed, it can only change forms". It has nothing to do with friction, but with that law of physics. By suggesting that the front hub is giving you some free extra power, you are suggesting that energy can be created for free. Energy is never free, it always has to come from somewhere. Your front hub would be getting this energy from the momentum of the bike. That's how the regenerative braking works in hybrid cars, by letting the motor generate electricity, the car slows down. So, what have now is an energy loop, or cycle. The energy starts of as electricity in the batteries, which the motor turns into momentum. Now your hub is turning some of this momentum back into electricity, which is turned back into momentum, and the cycle goes on. No energy is gained or saved, it is in fact wasted, because of the numerous inefficiencies that plague all machines.

spiceyweasel (author)Krazeecain2010-10-08

So, what you are saying is, if I put a motor on the front hub, it WILL create some sort of friction....because SOMETHING has to cause the front wheel to slow down, if I am reading your words correctly. That's odd, since I don't feel any resistance against my hand when I crank a motor by hand. The shaft turns freely and produces electricity without a problem. There's that pesky physics again, trying to convince this poor bumble bee I can't fly.

Krazeecain (author)spiceyweasel2010-10-08

It's turning freely because there is no load, try attaching a dead battery to it, or a light bulb and there will be noticeable resistance.

spiceyweasel (author)Krazeecain2010-10-09

Ah.....resistance. I will see what I can do about it.

Yeah, magnetic resistance, its when there is a load on the coils, it pushes (and also pulls when they move away) against the magnets used, which in turn puts a load on the system... In a perfect setup, you'll lose about 10% energy over trying to keep speeds up and putting a load on. It would be a good idea to use it for regen, or "engine breaking" because you are obtaining the energy off the momentum when you want to slow it down.

energy is a funny thing, it bleeds out everywhere, sound, movement, light and heat..

About This Instructable




Bio: Maker of things. Small business builder. Follow my latest project on Twitter @joe_murphy
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