# I want to build an electric motorcycle from Scratch.



## Jayls5 (Apr 1, 2012)

Most people who do bikes stick with a single gear / belt drive, so it's prudent to get a motor that has some decent RPM capability (>5k). This allows you to select a lower gear for good torque multiplication while still obtaining a good top speed.

Space constraints are the big issue on bikes. LIPO LiCoO2 battery packs tend to have some of the best power to weight but lower cycle life, but if this is an infrequent race bike... it might be an option to consider. They are also volatile and dangerous by comparison to other lithium chemistries, so I would learn before you take the plunge on those.

In terms of cost, 3-phase A/C and brushless DC motors and controllers tend to be more expensive, but they have less issues with maintenance and can usually obtain more power at higher RPM's all things considered equal to brushed motor designs, as they have ways around back EMF limiting the speed. I personally like BLDC motors for good power density and RPM capability, but I settled for a brushed PMDC motor for cost/simplicity.

Parts you want/need:
High voltage cutoff switch capable of your amp draw, contactor rated for your voltage & amp draw, motor controller for your motor type you choose and power output, matching throttle that works with your particular controller, choice of motor, mounts + sprockets/pulleys/belts to get the power to the rear wheel, proper rated fuse, large power wire (usually MINIMUM of 4 awg even on short lengths used on a bike), charger, and choice of instrumentation. I hope i'm not forgetting anything, but there are countless choices and a lot of it is designed to work together... so once you commit to a certain design & voltage, it's prohibitively expensive to change it. Choose right from the start.


----------



## psych0hans (Oct 21, 2014)

Hi Jay, thanks a lot for your reply. What I'm going to do is start putting together an excel file with the components I need and the ones I decide on, just to keep things organized. Will keep updating this list as and when things get decided. One place I'm taking inspiration from is the GSX-E build. I have also gone trough the Ripperton build, but it's a bit too advanced and high tech for me to dig too deeply into immediately. Mine is going to be a low budget build, so I'll need to keep the pace slow and buy things only when it's time to actually install it. My target is of having an electric bike that can meet or exceed the performance of my RC390 or Ninja 250R.


----------



## Jayls5 (Apr 1, 2012)

psych0hans said:


> Hi Jay, thanks a lot for your reply. What I'm going to do is start putting together an excel file with the components I need and the ones I decide on, just to keep things organized. Will keep updating this list as and when things get decided. One place I'm taking inspiration from is the GSX-E build. I have also gone trough the Ripperton build, but it's a bit too advanced and high tech for me to dig too deeply into immediately. Mine is going to be a low budget build, so I'll need to keep the pace slow and buy things only when it's time to actually install it. My target is of having an electric bike that can meet or exceed the performance of my RC390 or Ninja 250R.


Something to keep in mind: Some components integrate stuff together. I know some controllers have internal contactors, negating the need for you to buy an external one with a supression diode. Some have precharge resistors integrated as well. Just take that into account since a lower price controller might require a few more components to be purchased on the side.

If you're looking to have 0-60 times in the sub 6 second range, you will need to plan wisely. You need to make some hard decisions about intended range and top speed. It all drastically changes the cost of the build. I suspect you haven't had as many replies because you haven't given us hard constraints.


----------



## psych0hans (Oct 21, 2014)

Jayls5 said:


> Something to keep in mind: Some components integrate stuff together. I know some controllers have internal contactors, negating the need for you to buy an external one with a supression diode. Some have precharge resistors integrated as well. Just take that into account since a lower price controller might require a few more components to be purchased on the side.
> 
> If you're looking to have 0-60 times in the sub 6 second range, you will need to plan wisely. You need to make some hard decisions about intended range and top speed. It all drastically changes the cost of the build. I suspect you haven't had as many replies because you haven't given us hard constraints.


Hi, thanks for the heads up! This is honestly just a fun project I'm taking up with my dad and brother, so we don't really have very hard constraints as of now. All I know is we want to keep it around 350-450lbs and keep it competitive with at least a 250-300cc ICE bike. We don't really have very lofty aims of 100miles plus of range, but a high top speed(~100mph) is definitely a priority. For the range, I think at a minimum, it should cover 5-8 laps in a single charge and on a more optimistic level maybe up to 20 laps, or a whole track day. The track length is about 3.3miles.

The reason we're choosing this to be a track only bike is, there is no way we can register it for road use in India and keeping it track only keeps us from having to worry about legalities and the extra complication of wiring lights, horn, indicators, etc...


----------



## psych0hans (Oct 21, 2014)

I think I found a motor-controller kit I think I fancy - http://www.electricmotorsport.com/ev-parts/motor-drive-kits-2/ac-induction-motor-kits/ac-20-kit.html

What I want to do is, use it at 48V initially and then increase to 96V once I have more funds to purchase additional batteries. Will I need separate controllers for doing this?

I also made the deal for the frame and swingarm for the bike and will be purchasing that shortly. Grand total of 206.5$ for both


----------



## psych0hans (Oct 21, 2014)

I've been doing a lot of research on motors and the EMRAX 207/8 seems pretty promising, but I'm really worried about the price impact of it. Another motor I really fancied was the 602 dual hub motor by EnerTrac. Again, price is the biggest issue, though the 602 might be considerably cheaper than the 208. 

Any advice on controllers if I want to use 48v initially and step up to 96v when funds allow? Also, what kind of AmpHrs would I need if I want a range of 30 miles at the track? Top Speed of 100mph and curb weight of 150kgs(targeted)


----------



## Tomdb (Jan 28, 2013)

emrax motor is definitely the best, but including a controller you would be looking at atleast 5000+ dollars. that is without adapting it to drive a chain.


----------



## psych0hans (Oct 21, 2014)

Tomdb said:


> emrax motor is definitely the best, but including a controller you would be looking at atleast 5000+ dollars. that is without adapting it to drive a chain.


Yeah, doesn't make sense for me at all, since mine is basically a hobby build, with no institutional backing. Anyone know if the dual hub motor is worth pursuing? @ripperton, your competition at the TTX GP were using them right?


----------

