A Guide to Building Your Own Electric "Streetfighter" Style Motorcycle
Are you a fan of "Streetfighter"? Or, perhaps you are looking for a "kick-ass" looking EV bike?
Either way, this amazing DIY EV bike project by James Biggar should be right up your street (so to speak). Follow this handy guide to find out how to make one for yourself.
Before we get stuck in we will need some things first.
Tools and equipment needed
- 11 gauge 1 inch (25mm) by 3 inches (75mm) tubing
- 3/8 inch (10mm) steel plate
- 2-1/2 inch (65mm) by 1/4 inch (8mm) DOM tubing
- 3/4 inch (19mm) bronze brushings
- 3/4 inch (19mm) steel rods
- Bearing race to fit DOM tubing
- 980lb (445kg) rear shock absorber
- Fiberglass cloth
- 1/2 (12.7mm) inch foam board
- 2-part epoxy
- Acrylic filler
- Old cushion seat
- 74V/4.3 kWh Li-Po Grepow Battery
- Platinum cure RTV silicone cure
- Motorbike kickstand
- Matte exterior proof vinyl sheet
- Universal motorbike brake levers and reservoirs
- CT-22 digital speedometer (or equivalent)
- GSXR750 Tokico brake calipers (or equivalent)
- QS 273 70H 12kW/24kWp brushless hub motor
- CAD plans for motorbike
- Suzuki GSKR 750 front suspension
- KLS72501-8080H DC motor controller
- 72V/400A contactor
- Taillight "Tail Tidy"
- Electric throttle and key switch
- 72V-12V converter
- 12V horn
- 12V turn indicators
- 12V/18W LED bar lights
- Sicass Racing handlebar switch (or equivalent)
- Angle grinder
- Power handsaw
- Belt sander
- Metal builder's square
- Welding gear and safety equipment
- Stepper drill bit
- Heat gun
- Staple gun
- Various nuts and bolts
- Paint spray gun and paint
With all your bits and pieces in order, it is time to get on with this epic build. Hold on tight.
Please note we have included the CAD files for the project above. Follow these to the letter, or modify to your own requirements.
Step 1: Cut and weld the bike's frame
First, grab your 11 gauge tubing is to cut out some of the main chassis pieces using a grinder. Be sure to wear suitable protective equipment when doing so.
You will need a variety of pieces of different shapes and sizes. Follow the CAD files as instructed. Make sure you mark out the design of the pieces using chalk and check and recheck before actually cutting.
Where required, bend the cut pieces of 11 gauge tubing into shape and begin to spot weld them together. As always, ensure you follow the instructions laid out in the CAD files when doing this.
File down any weld points once completed too.
Use clamps and builders squares where required to hold the frame together and ensure it is perfectly aligned.
Step 2: Cut and form the steel plate
Next, mark out, cut, and core your steel plate as required. Also, grab your DOM tubing and cut/form to shape.
Weld pieces as needed.
Use the cut pieces to modify an existing front suspension assembly as required. Weld the modified suspension to the steel frame you previously built.
Be sure to add cross-members and reinforcement pieces where needed. Once a large portion of the frame is complete, you can extend the welds to ensure they are strong.
File down once complete. Next, fashion to the connecting plate and weld that to the frame too.
Cut caping pieces and weld them into place too. Next move on to the rear portion of the frame.
Use 11 gauge steel, DOM tubing, and steel plate to build as required. Cut and add corners and capping pieces as instructed. At all times, file and smooth down welds to create a smooth finish.
Mark out, prepare, and drill bolt holes as needed. Use stepper drill bits to expand pilot holes. Tap bolt holes were needed too.
Add bolts and brushings as needed.
Step 3: Connect the front and rear frames and add driving wheel
With those stages complete, connect the front and rear assemblies using a swingarm pivot bar cut from your 3/4 inch (19 mm) rod. Hammer and secure into place.
Cut out, form, and weld into place other pieces like the rear suspension mounting. Next, grab your shock absorber and attach it to the mounting you just created.
Next, mount your brushless hub motor to the rear axle.
Cut more pieces from your DOM tubing, weld, cap, etc to connect the shock absorber to the rear bike frame. Add reinforcement connection bars too.
Step 4: Add the saddle mount and paint the frame
Cut, and shape, more pieces of DOM tubing to create the saddle mount. Weld into place on the frame as shown.
Reinforce with more tubing as needed. Cut and weld flange mountings to the saddle mount too.
With that complete, the main bike frame is effectively done. Now, partially dismantle, and spray paint the entire assembly.
Do this in a well-ventilated space, and wear respiratory protective equipment.
Once the paint has fully dried, reassemble the main chassis. Feed any wiring from the rear hub motor through to the center of the frame.
Mount your kickstand as needed.
Now, lubricate and mount your front motorbike front suspension the main bike frame. Secure and bolt.
Mount, and secure, your handlebars. You can either make these yourself or buy off-the-shelf versions. Adjust as needed.
Add the front wheel to the front suspension assembly. At this point, your motorbike should resemble something like this.
Step 5: Form the main bodywork
Now we can move on to some of the aesthetics of the bike. Glue a series of polystyrene blocks together, and place them over the center of the bike. Then begin to carve the shape you want for the final bodywork for the "fuel tank" part of the bike.
Once the overall shape is prepared, finesse the design of the bike frame using hand tools. You can mold it to any shape you want, but ensure it will fit on the bike frame once finished.
Do the same for the saddle portion of the bike. Continue to refine until you are happy with the final form.
Glue the two polystyrene molds together, and smooth them down using a belt sander.
Next, cover the polystyrene mold with fiberglass cloth, and saturate with 2-part epoxy. Work the cloth over the polystyrene, and remove any bubbles, folds, etc.
You want it to "fit like a glove."
Cut and fold the fiberglass around the bottom of the polystyrene mold as needed. Secure with epoxy. You are basically trying to fully encapsulate the polystyrene. Leave to cure.
Once dry, trim off any and all excess pieces, as needed. Sand down and buff all exposed parts of the fiberglass.
Mix up and spread polyester filler over the entire surface of the fiberglass. Do this until all the voids are filled and smooth out the surface as much as possible.
Leave to dry, and then sand down the entire exposed surface using a belt sander once again. Next, grab your spray paint gun, and paint the entire piece.
Fill any remaining gaps with acrylic filler. Leave to cure, and then sand down once again. Spray paint the entire assembly once again.
Apply a layer of petroleum jelly to the bodywork, and then heat blast with a heat gun. This will further smooth down the finish.
Next, mix up your platinum cure RTV silicone and pour it over the bodywork. You will probably need two coats. Leave to cure.
Once complete, mix up and pour liquid silicone over the entire bodywork. You want to build it up to a thickness of around 1/4 of an inch (6.35 mm).
Level and smooth out.
Next, repeat the fiberglass and epoxy stage once again over the entire bodywork. Leave to cure once again.
Once complete, prize the fiberglass sections away from the mold. Take care not to break them. Chop up the fiberglass sections as needed, and cast more polyester resin and fiberglass sections — especially for the bike's fairings.
Allow to cure, remove from molds, trim off excess, and sand down all sections once complete. Always wear personal protective equipment (PPE) whenever cutting or handling fiberglass.
Reattach the fiberglass pieces to the bike frame, and "glue" them together using pieces of fiberglass and epoxy resin. Add some plastic blocks to the inside to help with final mounting, and sand/buff the entire exposed surface of the fiberglass bodywork. Fill in places where needed too.
Once you are happy with the final form, remove it from the bike and spray paint it. With the paint dry, place the pieces back onto the bike to ensure they fit.
Step 7: Build the electrics
Now, grab your Li-Po battery pack, and contactor, and assemble as instructed. Then take the DC motor controller, mount the Li-Po battery pack.
Remove the fiberglass bodywork from the center, and lift the entire assembly into place under the main bike frame, and mount to the chassis.
Next, grab your CT-22 speedometer and handlebar switch and convertor, wire them all together. Then mount the speedometer between the handlebars.
Next, grab the LED lights and horn, and either build a mounting for them or mount using a suitable commercially available solution. Mount all to the front of the handlebar assembly.
Now, take your LED turn indicators, and mount them to the bike front suspension assembly, as required. Next, position and mount your universal brake levers to the handlebars. Now mount your switch, electric throttle, and handlebar grips to the handlebars.
Next, take and mount into place your brake calipers (front and rear). Connect the hydraulic piping together with the brake levers, as needed. Secure any loose cabling the bike's front suspension frame. Top up the reservoirs to the brake levers, and bleed the brakes as needed to remove any air bubbles.
Keep going until the brakes become stiff to pulling and no more air escapes from the calipers.
Step 8: Complete the wiring
If not already complete, wire up all the electrical components. Turn on the bike, and test for any issues. The rear-drive wheel should respond when the throttle is opened.
With everything working, you can continue with the final touches of the build. Next, fashion, or buy, a rear brake light mounting/bracket piece (e.g. a "Tail Tidy").
Drill mounting holes, and attached the bracket to the underside rear of the main bodywork.
Once in place, attach two more indicators LED lights, and your LED brake light. Next, attach the main bodywork back onto the bike frame and secure it into place.
If not already complete, you can also install and secure other pieces of bodywork in place, like the front wheel and headlight fairings.
Step 9: Make the seat pan
Next, grab your foam board. Use your heat gun and begin to bend the board into shape. Continue until you have the shape you need. Once complete, use your belt sander to round off any corners.
Take the board to your bike, and test it against the main bodywork fairing. Take note of any amendments that need to be made, and repeat the heating-molding-cooling, process until complete.
Once happy, mark out the shape of the main saddle using a pencil, and trim off any excess needed. Next, grab your old piece of cushion seat foam, and cut it to match the same shape as the seat.
Belt sand the cushion foam as required. Trim down the cushion foam as needed. Once complete, wrap the entire cushion and plastic foam in a covering of exterior-proof vinyl sheeting.
Staple into place, as needed. Periodically, use your heat gun to shrink-wrap the vinyl into place. Once complete, cut off any excess as needed.
Once done, secure the saddle seat to the main body bike fairing. With that, your DIY "Streetfighter" EV bike is basically complete.
You can now add some more aesthetics, like stylized paintwork, decals, or other details, to your heart's content. You may, for example, want to paint and blend in the battery pack boxing to the rest of the bike?
Now you can finally take your wonderfully hand-crafted EV bike for a spin! Well done you.
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