How to convert a Razor E300S Scooter to  a Mobility Scooter

This Scooter is only good for a person that weight is less than #250 and is moble and able to get on and off to assist the scooter in places it can't go!  (It doesn't do gravel roads and driveways well.)
It can go backwards if you spot weld the freewheel on the rear wheel, and wire a toggle switch near the Thumb Speed Controller.
It will go up hill better if you change the chain gear as shown below.  It will work great on level ground and go faster (Top Speed) without modification.

This Scooter has under gone many revision.   This is Version 5.0


        With all the major parts on hand start here:                                  Click on the thumb nail picture to enlarge to full picture.


1.       Put the scooter on a table, cut 3 2x4’s or 2x6’s 8” long to put under the middle of the scooter under the battery area.  This allows the rear wheel to be off the table, and be more stable while working on the scooter.


2.       Remove body cover 8 bolts (2 nuts)  


3.       Carefully separate all wire connectors inside battery area.   Don't short out battery!    They may explode!

4.       Label Batteries this side up.  Carefully remove the 2 batteries.  Disconnect the Black wire on the left battery from the connector on the C/B.   Tape all wires.  The batteries will be put back the same way when finished, I suggest you lay them on the workbench out of the way.     Don't make wires longer than necessary.    (Put batteries aside for later)  See pix, the wires must go under batteries in channel made for them.  Do not attempt to put any wires on top on the batteries when reassembling.    The Brake Cable, Throttle Cable and 5-C cable ( and 2-C cable if reverse is used)  as well as the battery wires have to go under or on the side of  the two batteries.   Cut f #10 wire one Red, one Black, one Blue 24" long.  They connect to battery, C/B, and relay contacts.

5.       Remove the Controller, 2 screws (Phillips SD), discard the Controller, keep the 2 screws.   


7.       Remove Battery Charger Port, when you cut the wires, leave as much length as possible so you don't have to splice wires on to them.  (Remove all hot glue) Nut is 19mm on the inside.     Save charger port w/nut.         Remove on/off switch, and discard.    Leave the circuit breaker in place.


8.       Remove kickstand, and discard. 

9.       Remove the black slide in left front of battery box.  This holds in the wires from the steering.    You will reuse the 30 amp circuit breaker wire per the diagram.



11.   Cut the connectors off the 2 wires from the motor leads (red & black) , and slide off all the shrink tubing.  Pull leads out of the battery box rear, so they are loose.  Loosely tie wrap the wires to the kick stand bolt hole.  Put back on 6” of shrink tubing.


12.   At this point the only thing in the Battery box is the brake cable that passes through it and the C/B and  cables from the brake and brake switch.

13.   Remove the Steering pipe.  Tilt over to work on Handlebars.

14.   Remove the throttle switch.   A   3mm Allen bolt is used to tighten it to the steering.  Turn handlebars over and cut off the throttle with a Drummel tool. Cut on bottom so the grinding will not show.


15.   Attach the Bell bicycle basket mounting bracket to the handlebars so that when you attach the new throttle and bell they will be positioned correctly.  It may be necessary to move the brake lever, use a 5mm Allen wrench to loosen.


16.   Attach the new throttle to the handlebars.  Position as needed; attach the cable to the steering post.  If you are adding a reversing switch you will need to add a 2 conductor cable and wire to switch.     This 2 conductor cable goes all the way to the control box.  Tie wrap and use the black plastic brad that came with the scooter to keep wires in place, leave slack in steering allowing it to be turned without binding, or rubbing.   Finish attaching the handlebars.   Mount Toggle Switch on a small piece of Aluminum and pop rivet it to the handlebars.  Note  picture below shows the cables going into the battery box, but this scooter has no reversing switch.  There would be one more cable with the wires from the reversing switch.


17.   Take the two relays with sockets attached.  Tape them together.  I like yellow tape so you can label the relays to keep them separate. 
You could just carefully solder the wires to the relay terminals.   Label the relays Run (R) Stop (S).

18.   Trim the relay socket leads to length as needed.     1.5" for spliced or unused wires.  Use heat srink on all connections or tape. 


19.   Wire the rest of the two sockets per the schematic.

20.   Push the cable from the throttle in the front opening and splice the 3 wires from the new throttle to the new 5-conductor cable.  (2 spare wires)


                                                                     If you are going to make the scooter reversable you must spot weld the areas indicated with the arrows.  This will prevent the free wheel from free wheeling.

......THE NEXT SECTION IS NEEDED ONLY IF YOU ARE CHANGING TO THE 80 TOOTH GEARING.  IF NOT GO TO STEP 36........................ The 80 tooth gear will make it easier to go up hills.

21.   Before re-assembly turn the scooter over (Batteries are out, weight is little) with chain up.  Remove the chain from the chain rings and pulley.  Remove and discard the chain guard.

22.   Remove the bolt that holds the brake to the scooter.  Two 8 mm wrenches needed.  


23.   Remove the Chain Tensioner bolt.  10 mm wrench in side, 8 mm outside.  The bolt head inside has only 2 sides, it mybe 11mm or 10mm.

24.   Before removing the rear wheel remove the chain ring on the freewheel on the wheel.  You will need a large Phillips SD and a 10 mm wrench.  Put 35# air in both tires.

25.   Make a new chain #25 28 ½” long ready to insert the locking pins.  Finish the chain with the locking pins.  Or buy a ready made chain.

26.   The rear wheel is a little tricky to remove.  On the Left side use a 5/8”wrench to loosen the nut & using a 5/8” wrench on the right to hold the nut tight.  Remove the nut and washers.  Replace that (factory nut) with {2} 10 mm nuts, tighten.  The second nut is used to lock the nuts in place.  Now remove the nut on the opposite side.  A 17 mm wrench is needed on the 10mm nuts, 5/8” wrench on the other nut.  Note: These are the nuts on the B/M.

27.   Attach new 80 tooth chain ring to the wheels free wheel.  Place the nuts on the outside.  Use 2-10mm wrenches to tighten.

28.   Put wheel back where it belongs, you will notice rubbing of the new chain ring on the frame in a couple of spots, they will need to be ground down for clearance.  See pictures.  Cover everything to keep grindings out of the parts.


29.   When finished grinding, paint the frame where you ground the paint away, to keep from rusting.

30.   Put new longer chain on the chain ring.

31.   Put wheel back where it goes on the scooter with the chain on both chain rings.  Before tightening, attach the bolt that holds the brake in place.  Two 8mm wrenches needed.  You may need masking tape on the nut to keep it from falling of the wrench.

32.   Re-attach the Chain Tensioner   Do not try to put the chain over this pulley until it is tightened back to normal with the spring giving tension to the arm.  Position chain over pulley.

33.   Be sure the washer and lock washer are positioned correctly on wheel and tighten nuts.  Two 5/8” wrenches needed.

34.   Re-check that the wheel turns freely with no dragging on the chain or chain ring.

35.   Turn back over.  Put Scooter back on top of the 2x6 blocks. 


36.   Take a piece of wire, put some lugs on the ends and position it so that it can hold the relays in place. Use the two screws from the controller you removed to hold in place.


37.  Connect the 3 #10 wires to the S relay N/C contact, Circuit Breaker, and Negative Battery Terminal.  Per the schematic.

38.   These 3 #10 wires must go under the batteries with all the cables.  If not the cover will not fit on the battery box.





42.   VERY Carefully put the batteries back in the battery box. 

43.   Wire the Battery output Red wire to the bottom of the C/B. 

44.   Take the new #10 Red and Blue wires trim to length 24".  Red to S red wire, Blue to R blue wire.   solder #22 Black wire from both S & R relays.   A new #10 Red gets soldered to the Yellow wire on the R relay, from the Top of the C/B.


46.   The back of the battery box where the wires and brake cable come out, tie wrap all to the bolt hole from the kick stand.  Slide the cover over the hole in the front of the battery box.   


47.   This should complete all the wiring inside the battery box.  Be sure all wires are either taped good or have shrink tubing over to protect them from becoming shorted.  Tie wrap wires to each other to keep from moving, and out of way when you put the cover on.  The wires all have to be 18" long as they leave the rear of the battery box.  Double check the Schematic

48.   Replace the battery hold down bar, with foam under the bar.   Wires must go under the battery in the channels, or the cover plate will not fit

49.   Position the  Deck Plate in place.  Mark the area where the seat post will be located.

50.   Position a block of wood 1 ½” wide behind the line for the seat post.   Place the Electronics Box against the wood.  Drill 4 holes through the box and the Deck Plate.  Drill 2-5/8” holes in the side of the box, one hole for the wires 1 hole for the charger port.   Attach the electronics box with 4-5mm bolts washers and lock nuts.


51.   Attach the Deck Plate, only the 2 rear bolts with nuts.

52.   Cut your new floor from a piece of quality ¾” Plywood.  The finished size is 24x14 ¾” .   ( It is best to put a 3/16" sheet of Aluminum under the Plywood for strength)  Make a template from a sheet of paper 26 ½” x 22 5/8”.  Use a protractor to make the sides of the triangle 240 Degrees.  (120 Degrees).  Cut off the two corners 1 ¼” from the 26 ½” long side on each end to make the bottom of the triangle 24”.  Cut the top of the triangle off to make the part 22 5/8” tall.  See the picture cut a notch out of the top where the steering post will be.

53.   Drill the holes in the plywood.  Drill a 5/8” hole 1 ¼” from the end of the material left, these are for the ½” tee nuts for the casters, and 6- 3/8” holes for the attaching bolts.  These holes will match the holes in the floor.

54.   Put the Tee Nuts on the top as shown. Drill one hole in each Tee Nut attach with screw to keep from turning.


55.   Attach 1/2” x 13 nut, lock washer, and large washer to each caster.   Put blue lock tight on threads of caster.   Tighten nut all way down.  Tighten caster till the top threads are flush with the top of the Tee Nuts.  Tighten ½” nuts on bottom. 

56.   Cut a piece of rug 1 ¾” to 2”  larger than the plywood.  Fold under and using tacks to attach the rug to the plywood.  Cut the rug flush with the plywood in the area where it contacts the Deck Plate.  (Use ½” rug tacks)   Trim as shown rug. 



57.   Use a sharp tool to poke holes in the rug to allow the 5mm and 6mm bolts to go through.  Be sure to add washers to the bolts.  Leave the bolts in place to align floor.

58.   Position floor plate over the Deck Plate.  Attach the two 5mm bolts next to the front wheel.

59.   Position the seat post in place.  Attach one 6mm bolt loosely.  Slide seat post in place and tighten the rest of the bolts.

60.   Bolt control box to the rear fender.    The lower left hole is where the control wires,  power wires, and motor wires go through.  The middle hole is for the charger port.  The top hole is for the toggle on/off switch. 





62.   The Programmable Controller printed circuit board should be raised off the bottom of the box.  I mount the  circuit board on a piece of clear plastic and attach plate to the Hammond Box.    Finish the wiring in the Electronics box, per Schematic.    

63.  I suggest you a add a fan to cool the printed circuit.  I used a 12 Volt computer fan with a 600 Ohm in series to drop the voltage to 12 volts.  See schematic.  Mount on the cover, drill a bunch of holes to allow air to be pulled out of the box.

64.   Attach the battery charger port to the box.  A 19mm nut on outside of box.  Use hot glue to keep from coming loose.  Wire it across the battery terminal wires. 



67.   The toggle reversing switch in not neeted if you only need forward.  To get the scooter to reverse you must spot weld the free wheel  See Pix in #20 of procedure.


70     Be careful not to short out the battery wires.

71    Trim the motor lead to length Red to Positive Black Negative motor lead from the R (Run) relay to length.
Make leads just long enough to go to either terminal just in case they need to be reversed.

72    The dip switches on the Programmable Controller have to be moved. 



Note the difference in picture for direction selection.







74    Final testing.  Note:  You must stop the motor by holding the Stop (Brake Switch) before turning off the power switch!            If you don't the controller wil continue to work and the motor will not turn off!               Place scooter on the blocks with rear wheel off ground.  Turn on power.    Move throttle, as you move control speed should increase.  If motor starts turning fast as soon as the on/off switch is turned on the usual case is the wires from the throttle in the 5 conductor cable are reversed.  Check is the rear wheel turning the right direction?  If not, reverse the Motor Wires at the PC Board.   




76    If needed you can make a seat like the one on my wife's scooter .  You will need a piece of 3/4" plywood 11"x16", a piece of 3" foam, fabric of your choice, and more tacks.  Take the seat off bike.  Save the bolts.  Separate the top of the seat from the bottom.     Discard the top part of the seat. 

77   Position the bottom of the seat on the plywood.  Note you will need to reverse the direction of the seat bottom on the plywood.  Place the bottom plate 2" from the front of the plywood.  Drill the 4 holes for the 4  5/16" tee nuts.  Tap or press  the 4   5/16" tee nuts into the top of the plywood.  Attach the plate with 1"   5/16" bolts and lock washers.   On the top attach the 3" piece of foam to the plywood with glue.  Place the fabric of choice over the whole top, and pull tight on bottom and tack the fabric with tacks of staples.  Place the new seat on the top of the seat post.  You will see that only one set of holes line up with the seat tipped as you will be using it.  You will need to drill the hole for the other bolt through the seat bottom in the position you will want the seat to be at when you sit on the scooter.

Thank you for building my Scooter.  I hope you will enjoy it as much as my wife and friend enjoy theirs.
Good Luck


If you have any questions you can email me at