Second Ride Conversion Kit SR24 for Simson SR50, SR80
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Requirements
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Scope of Delivery
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Required Tools
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Before You Begin the Conversion
The purpose of the conversion kit is to modify the above-mentioned Simson models in accordance with this installation manual and to use them on public roads as described in the user manual. Please understand that we developed the kit based on the original state of these Simson models. If your vehicle has been modified, damaged, or contains non-original parts (due to accident, wear, or intentional changes), we cannot guarantee that the kit will function correctly or fit at all. If you're unsure about your vehicle, feel free to contact us.
The document “Conversion Kit SR24 – SR50, SR80 – Installation and User Manual” provided by Second Ride GmbH is intended as a supplement to the original manufacturer’s manual. Both documents should be considered together, though explanations about the combustion engine can be disregarded.
Please read this document carefully and completely before beginning the conversion or taking your first ride. It contains warnings, advice, emergency procedures, and other important notes regarding your vehicle. Failure to follow the instructions may result in injury or danger to life, and it may reduce the performance of the vehicle. Please also carefully read all warnings and notices next to symbols — especially those concerning high voltage. Only by doing so can the conversion kit be installed and used safely. Ignoring these instructions may lead to personal injury or damage to the vehicle.
Note: The onboard battery, gearbox oil, and fuel-oil mix must not be disposed of in household waste, wastewater, or in nature. Please check how to dispose of these materials properly. Used batteries may contain harmful substances but also valuable raw materials like iron, zinc, manganese, or nickel — which can be recycled. Please return the seat battery to us after use. To ensure safe transport, we recommend using the original packaging. Contact us beforehand in any case.
Some fluids used in vehicles (battery acid, coolant, brake fluid, fuel, windshield washer fluid, etc.) are toxic and must not be inhaled, swallowed, or come into contact with open wounds. Always follow the instructions on the containers and legal handling regulations.
All technical data and descriptions in this manual were accurate at the time of printing. However, since continuous improvement is one of our core goals, we reserve the right to change products at any time. If you find errors or omissions in this document, please let us know in the Discord channel (see footnote).
Disassembly
Before beginning disassembly, remove the vehicle’s battery to avoid short circuits.
1. Preparation
The SR50 and SR80 unfortunately have a design flaw that prevents engine removal while the center stand is deployed. We recommend placing the scooter on a motorcycle lift. If not available, support the rear wheel between two crates so the wheel hangs freely and the stand can stay folded. Make sure the scooter is stable.
2. Disassembly: Bodywork
To make things easier, first remove the two footboards (1). Remove the rubber mats and unscrew the fasteners beneath. Then remove the seat (2) and the 4 screws (4) securing the tank (3). Unscrew the star nut and remove the plastic motor and electronics covers (5).
Before removing the tank, close the fuel valve (6) and disconnect the fuel hose. You can drain the remaining fuel into a suitable container (e.g., fuel canister). Now you can lift the tank out of the scooter.
3. Disassembly: Engine Connections
Start by disconnecting all electrical and mechanical connections from the engine. Unscrew the shift linkage (7) and the kickstarter (8). Loosen the clamp on the intake boot and remove it from the carburetor (9).
Remove the two screws on the back of the air filter box (10) and take it out. Unscrew the throttle and choke cables from the carburetor (9). Unscrew the speedometer cable from the chain cover (12). Also unplug the spark plug cap (13) and remove the ground wire from the engine block. Finally, disconnect the cables coming from the alternator.
4. Exhaust
At this point, the exhaust should be the only part still attached to the engine. It is fastened to the engine with a large nut (14), which can be removed using a pipe wrench or hook wrench.
Tip
If the exhaust nut is stuck, you can loosen it by placing an old flathead screwdriver into the notches and tapping it with a rubber or wooden hammer.
The rear part of the exhaust is secured by a pipe clamp. This can be opened by removing screw (15).
5. Chain
Before removing the engine, you need to take the chain off the drive sprocket.
Remove the alternator cover (12) from the engine. Then loosen both the right-side rear axle nut and the left-side axle pin of the driven wheel. A few turns are enough, since the rear wheel only needs to be pushed forward. Now screw the small nuts on the chain tensioners all the way back.
You should now be able to move the rear wheel forward. It’s time to lift the greasy chain off the drive sprocket — that’s why we included disposable gloves in the package.
6. Engine
After all this preparation, the engine is now ready to be removed. It is mounted with two long M8 bolts (16) in the engine cradle.
To loosen these bolts, the front support of the engine mount (17) must be detached, allowing the engine to tilt down.
Removing the engine can be a bit tricky. Assistance from a second person is helpful at this point. Loosen the nuts and try to pull the bolts out of the holes. It helps to slightly lift the engine while doing this.
Now you can remove it from the frame. Congratulations — your Simson is no longer a combustion vehicle!
7. Handlebar Components
On the handlebar, remove the starter/choke cable including the cover (18) and the clutch lever (19).
Et voilà! Your moped is now ready for the electric conversion kit!
Mounting the Conversion Kit
Only screws of sizes M4, M5, M6, and M8 are used for the installation. To ensure all parts are securely fastened, please apply the following torque values:
M4: 2.9 Nm
M5: 5.7 Nm
M6: 9.8 Nm
M8: 24 Nm
1. Mounting the Drive Module
Now stick the serial number label (37) onto the flat black side of the controller.
This is important because once installed, the serial number is no longer visible on the adapter block.
To fit the drive module into the SR50/SR80, you need to slightly adjust the module:
The adapter block (31) must be rotated by 30° along the motor axis, and the chain guard offset by 5°.
To do this, remove the 4 hex socket screws (33) and Schnorr washers (32) from the drive module using a 6 mm Allen key.
Set aside the adapter block and unscrew the two M8 grub screws (34) from the motor.
There might be some moist silicone on the threads — don’t worry, the vapors are harmless and smell like vinegar.
Now screw the grub screws into the two lower motor holes as shown below, so they sit slightly below the surface.
Take the adapter block and fasten it using the remaining holes. Tighten the screws with a torque of 15 Nm.
If you don’t have a torque wrench, tighten them firmly by hand, but not too tight to avoid damaging the threads.
The drive module is mounted to the vehicle just like the original engine. It’s best to have another person help again.
Lift the drive module into the motor mount (20).
Use the included M8x100 external hex bolt (22) for the upper hole and the M8x90 (21) for the lower hole.
Using a ratchet with extension and 13mm socket, and a 13mm wrench for counterhold, tighten both bolts with the supplied M8 nuts.
To complete the engine mount, attach the front support as shown in the illustration.
Now replace the chain hose holder located left of the motor shaft with the one included in your kit (47).
After replacement, the flat surface (48) should be facing downward.
This part keeps the chain sleeves in position along with the chain guard.
2. Tank Storage Compartment
Now that the drive module is folded down and installed, it’s time to install the tank storage compartment (23).
Take the tank storage compartment, 2x M6 screws, 4x M6 nuts, 4x M6 washers, and the two gas struts.
The tank storage compartment (23) has a cable channel through which the main cable (24) from the drive module to the seat bench and the SR50 rear light & indicator cable are routed. While positioning the tank storage compartment, guide both cables through the channel so that the connector of the main cable (25) sits in the designated space.
Once the tank storage compartment is in position, loosely attach the 2x M6 screws (26) & 4x washers (27) with the 2x M6 nuts (28) through the lower holes of the compartment to temporarily secure it.
Take the two gas struts (29) and insert the threaded bolts through the two upper mounting points, then screw on the nuts with washers. It’s important that in the extended state the black gas containers point downward and the metal shaft upward.
Now screw the motor cover hook (53) onto the tank storage compartment using the two M4 screws and nuts, so the original SR50 motor cover can still be hooked in.
You can now fold up the drive module and install the front support of the SR50 engine mount. The brake pedal screw may get in the way here. For folding up the drive module, you can temporarily remove it and reinstall afterward. It may also happen that when folding up, the drive module rests against the right side of the frame and would transmit vibrations while riding. For this, we have included a 50x50mm foam strip, which you can place between the drive module and the SR50 frame.
Attention
When folding up the drive module, make sure that the rear brake cable runs alongside the engine mount and does not get pinched between the drive module and the mount.
To fit our drive module into the SR50, it is attached with the 2x motor mount adapter plates (30) to the frame mount (41). For this, you will also need:
2x M8x70 hex screws (35), 2x M8 hex nuts (36), 2x M8x20x1.25 washers (37), 1x M8x24x2 washer (38), 2x M8x6 spacers (39), and 1x M8x12.5 spacer (40).
3. Chain & Sprocket Replacement
Remove the chain guard from the drive module by loosening the three M4 screws and set everything aside for later.
Before replacing the chain, take the 11-tooth sprocket and swap it with the 10-tooth one.
To do this, remove the snap ring holding the sprocket on the motor shaft. A flat-head screwdriver works well for prying it off. Once removed, take off the speedometer drive plate and the sprocket from the shaft. Now place the 11-tooth sprocket on the shaft, then the drive plate, and finally reinstall the snap ring. A water pump or needle-nose plier is especially suitable for this.
Your Simson now has the correct gear ratio to still reach 60 km/h.
Time for gloves again! Locate the master link on the installed chain and open it. Simply rotate the suspended rear wheel until the master link appears. The master link can be opened with needle-nose pliers or a flat-head screwdriver.
Attention!: Do not just pull the chain out of the chain tube once opened. You can use the old chain to easily install the new one. Connect the new chain with the new master link to one end of the old chain, then pull on the other end of the old chain until the master link appears again. Now open the master link again, place the chain over the drive sprocket of the drive module, and close it again. Pull the rear wheel backward and turn the chain adjuster nuts forward for a rough pre-adjustment.
Now for the fine adjustment: start with the right chain tensioner. Turn the nut forward until the chain inside the tube only has 2 cm of play up and down. You can test this by pinching the chain tube at its thinnest point between thumb and forefinger and moving it up and down.
When satisfied with the chain tension, adjust the other chain tensioner. With this, you set the so-called alignment of the vehicle. It sounds more complicated than it is—just make sure both wheels are in line. You can use a long straight board or simply crouch three steps behind the moped and sight the front wheel over the rear wheel with one eye.
Check the chain tension again and correct if necessary. Once both chain tensioners are properly adjusted, tighten the rear axle and nut. Finally, reattach the chain guard.
All work on the drive module is now complete, so you can reinstall the footrests on the SR50. Beforehand, attach the included transparent edge protection (51) to the sheet metal edge of the left footrest, which presses against the phase cables of the drive module.
4. Electrical
The onboard electrical system (lights and horn) is supplied by a voltage converter in the drive module.
Underneath the drive module, a black cable with a white 2-pin connector comes out. Route this to the top of the motor.
We have supplied you with two red-black cables. Plug the cable with white 2-pin connectors on both ends into the white 2-pin connector from the drive module. At the other end, connect the second cable, which has a matching white connector on one side and multiple flat plug terminals and a ring terminal on the other side.
For connecting the flat plug terminals, it’s easier to remove the connector strip by unscrewing the two Phillips screws.
Now connect the red cables of the Second Ride cable to the correct contacts on the wiring distributor for your vehicle model. Plugging them in can be a bit tricky due to the insulation, but it is possible with the right technique.
At the following link you will find the wiring diagram suitable for your vehicle. It shows which components can be removed. Don’t worry about making mistakes—our drive module has short-circuit protection, so the lights will simply not work until the error is fixed:
Wiring diagrams, technical documents, installation & operating instructions
The black wire can be fastened at the left screw point of the ground collection point ().
You also no longer need to use a fuse, since the power supply automatically shuts off in the event of a short circuit and only switches back on once the short is cleared.
The following model distinctions concern differences in the electronics.
On the /1 models, the brake light supply/logic changes, and these also have a parking light.
So be very sure which model you own.
All the following wiring descriptions are also shown in the wiring diagrams.
SR50-B3, SR50-B4, SR50C, SR50CE, SR80CE
The included relay is not required for these vehicles. Perhaps you will find another use for it.
To make the original SR50 ignition switch unnecessary, we have supplied you with the tachometer & parking light cable (red). To connect it, you must remove the tachometer cover.
Unscrew the 4 screws of the tachometer cover so that it can be removed. Here, connect the tachometer & parking light cable to the tachometer lighting contact, where the gray/red cable is attached. Then plug it onto the free tab of the same contact.
Route the other end of the tachometer & parking light cable to the horn and connect it to the contact where the black/yellow cable is attached. Then reattach the black/yellow cable onto the same contact at the free tab of the tachometer & parking light cable.
SR50/1-B3, SR50/1-B4, SR50/1 C, SR50/1 CE, SR80/1 CE
On the /1 models, the included relay must be connected as shown in the wiring diagram.
If the cable length is insufficient, swap the sides of the two connectors at the wiring distributor.
The relay is necessary because the brake light logic on /1 models is inverted and switches 12V instead of ground.
Screw the relay (49) to the left mounting point (50) at mid-height of the SR’s electronics section.
To make the original SR50 ignition switch unnecessary, we have supplied you with the tachometer & parking light cable (red).
To connect it, you must remove the headlight.
Unscrew the screw on the lower left side of the headlight a few turns so the lamp mask can be removed.
Unhook the spring tension at the top of the headlight and carefully pull out the headlight so you can access the socket contacts.
Here, connect the tachometer & parking light cable to the contact where the gray/red cable is attached. Then plug it onto the free tab of the same contact.
Route the other end of the tachometer & parking light cable to the horn and connect it to the contact where the black/yellow cable is attached. Then reattach the black/yellow cable onto the same contact at the free tab of the tachometer & parking light cable.
SR50/1 C, SR80/1 C, SR50/1 CE, SR80/1 CE
On these models, you must move the ground cable for the ignition coil to the terminal strip position specified in the wiring diagram so that the brake light relay is supplied with ground.
If your vehicle is still equipped with 6V electrics, you must replace all bulbs, the flasher relay, and possibly the horn with 12V components.
Now is the time to change the headlight bulb, tachometer lighting, and the other bulbs in the tachometer.
Good to know
The 12V bulbs are significantly brighter than the 6V versions, and the horn is also louder with 12V. After the conversion, you’ll be safer on the road.
Finally, you must plug in our brake contact cable. With this cable, the drive module detects whether you operate the rear brake (or also the front brake if it has a brake contact).
As long as the brake is applied, it will not be possible to accelerate.
Included in the package is an 80 cm long black cable with a white connector housing on one end and a flat plug terminal (22) on the other.
Connect the white connector to the white connector on the underside of the drive module, route the cable to the wiring distributor, and plug the flat plug terminal into the position defined for your vehicle in the wiring diagram.
We designed this function because there is no longer a clutch and thus no way to disconnect power transmission if a throttle malfunction occurs.
For example, the throttle grip could get stuck in the open position.
Such a scenario is no longer dangerous if you simply have to press the foot brake to cut off motor power.
Now switch the original ignition switch to the OFF position and remove the ignition key—you will no longer need it to ride your electric SR50.
5. Instrument Cluster
On the SR50N, the handlebar light switch on the right side must be removed, and the lights set to always-on, so the space can be used for the SR50 instrument cluster.
The instrument cluster (38) with button, charge level indicator, and ignition lock must be mounted in place of the choke and its cover.
Unscrew and remove these, then install the supplied instrument cluster in the same location.
Finally, route the cable under or through the instrument cover into the electronics section and lead it to the drive module.
There you can connect it with the matching connector and secure the cable to the frame with zip ties.
Attention
It is important that the cable from the drive module is routed directly forward and not underneath, otherwise it will be too short.
Both connectors have arrows indicating the correct orientation for connection.
Ensure that the cable connection allows enough slack for steering movement.
Now screw the speedometer cable to the newly installed chain guard. The plastic thread for this is located in the same place as on the removed combustion engine.
This way, your original speedometer continues to function.
Attention
Due to the use of the DUO speedometer drive, the indicated speed is about 9% higher than the actual speed.
At 60 km/h, the speedometer will show just under 66 km/h.
6. Battery / Seat Bench
Now you can screw the SR50 storage compartment cover (41), which holds the seat bench, onto the tank storage compartment.
For this you need 4x M6 washers (42) and 4x M6 nuts (42).
Insert the 4 bolts through the designated holes in the tank storage compartment and fasten them with the washers and nuts.
Tighten them only loosely at first, then try folding the storage cover down and check whether the lock hook latches into the lock.
If it does not, adjust the position of the storage cover in the tank storage compartment until the orientation is correct, then tighten firmly.
Finally, the shock absorbers must be screwed onto the storage cover.
Insert the threaded ends of the gas struts (44) into the mounting points of the storage cover and fasten them with 2x M6 washers (45) and 2x M6 nuts (46).
Now you can close the storage cover for the first time.
Press it firmly at the rear end into the lock mount. It should now click and engage in the lock.
If the hook does not latch into the lock, check the positioning of the storage compartment again. You can adjust it a few mm forward or backward by loosening the screws.
7. Throttle Cable
If you have an N1 carburetor, you can now screw the throttle cable including piston and carburetor cap onto the drive module.
If you had a different carburetor type on the combustion engine, the carburetor cap and piston will not fit, and you must replace them.
Good explanatory videos can be found on the YouTube channel Simson Werkstatt: YouTube Channel Simson Werkstatt
Which notch the carburetor needle is mounted in, or whether it is missing entirely, no longer matters for the function of the Bowden cable sensor.
To ensure that the rotation of the throttle grip is correctly converted into an electrical signal via the Bowden cable, it is important that you insert the carburetor piston (22) correctly into the designated cylinder (23) on the drive module.
Rotate the carburetor piston as shown in the picture so that the groove (29) points toward the rear wheel.
Inside the cylinder on the same side is a pin that you can feel with your finger. The carburetor piston must be inserted into the cylinder so that the groove slides over the pin.
After that, you can screw the carburetor cap (21) onto the cylinder. Make sure that the cap is screwed on far enough so that no gap is visible between the cap and the stop.
Now it’s time to adjust the throttle cable.
At the top of the throttle cable is an adjustment screw.
When the throttle grip is fully rotated forward (no throttle applied), there should be just no play on the throttle cable sheath. By turning the screw out, you reduce the play.
Later, when the battery is connected, you can check your adjustment:
- If you turn the ignition on and nothing happens when opening the throttle, the screw is turned out too far.
- If throttle input is possible and there is no play on the sheath, then the adjustment is correct.
You don’t need to worry that the upper stop could be wrong and reduce maximum power, because at full throttle the stop is always the cap itself, which is the same regardless of cable adjustment.
Attention
Be sure to reinstall the rubber cover (20) on the carburetor cap. Otherwise, the sensor could be damaged by rain.
Make sure that your throttle cable and grip have the least possible friction.
The throttle grip should return fully to the closed position by spring force alone from the fully open position.
If not, it helps to remove the throttle grip, clean and re-grease it, and/or replace the Bowden cable.
It may also be that the rubber of the throttle grip rubs against the clamp piece. To fix this, shift the rubber outward on the removed throttle grip tube.
A video guide for throttle grip maintenance can be found on the 2Radgeber YouTube channel: YouTube Channel 2Radgeber