How to Safely Bypass Speed Limiter on Jasion EB3 Electric Bike
The Jasion EB3’s speed limiter can be removed either through the display settings or by cutting a dedicated limiter wire. This guide walks you through both methods with safety checks so you can ride faster without damaging the bike or breaking local laws.
Before You Start: Know the Risks
Bypassing the limiter increases top speed from the factory 20 mph (Class 2) to around 28–30 mph. At those speeds:
- Braking distance grows significantly – your stock mechanical disc brakes may struggle to stop you in time. Test them at speed on private property before any road ride.
- The bike is no longer street‑legal on most public roads without a license, registration, and insurance. Many U.S. states classify any e‑bike that exceeds 20 mph on motor alone as a moped or motorcycle.
- Your warranty may void if the modification is detected. Jasion’s warranty policy explicitly excludes damage caused by tampering with the controller or wiring.
Always wear a certified e‑bike helmet. Consider the JARSH Commute Smart EBike Helmet with Lights, which meets Dutch NTA‑8776 and CPSC standards and includes integrated lights for night visibility at higher speeds. A helmet with lights is especially important after a speed mod because your reaction time and visibility needs both increase.
Method 1: Change Wheel Diameter in Display Settings
Many Jasion EB3 units allow you to access a hidden settings menu (often called “P‑settings”) to adjust the wheel size. A larger wheel size tells the controller the bike is moving slower than it actually is, effectively raising the speed limit. This is the least invasive method and can be reversed in seconds.
1. Turn on the bike and hold the UP and DOWN buttons on the display for about 5 seconds until the menu appears.
2. Use the buttons to scroll to P01 (wheel diameter setting) and press the Mode button to edit.
3. Change the value to one size larger than the actual tire diameter. For the standard 20‑inch tires, try setting it to 22 or 24 inches.
4. Press Mode to save, then exit the menu.
5. Test ride on private property – the display may show a slower speed, but your actual speed will be higher. Use a GPS app to confirm.
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Branch: If the Display Menu Won’t Open or Settings Don’t Stick
If the menu refuses to open, your display may be a newer or older firmware revision that locks out the P‑settings. Some users report that holding MODE + UP for 8 seconds works on certain batches. If no combination works, or if you can change the value but it resets after a power cycle, the controller is likely overriding the display. In that case, move directly to Method 2 – the wire cut is the only reliable bypass for early‑production EB3 units (units sold before mid‑2023 often have the hardware limiter).
Method 2: Cut the Speed Limiter Wire (Hardware Bypass)
If the display method doesn’t work, or you want a permanent solution, locate and cut the limiter wire. On most Jasion EB3s, this is a single white wire (sometimes looped back into a jumper connector) inside the controller housing.
1. Remove the battery and turn off the bike.
2. Unscrew the controller box (usually under the battery mount or near the rear wheel). Use a Phillips head screwdriver – the screws are often small and easy to strip, so go slowly.
3. Look for a white wire that is not connected to anything else – it may be tucked into a separate connector with a jumper loop. On some units the wire is actually a short white loop that connects two pins; simply pull the jumper off.
4. Cut the wire (or disconnect the jumper). If you cut, leave at least 1/2 inch on each side so you can reconnect later if needed.
5. Seal the exposed ends with electrical tape or heat-shrink tubing.
6. Reassemble the controller box, reinstall the battery, and test.
After cutting, the bike should run to its motor’s natural top speed (usually 28–30 mph on flat ground with a full battery). If it still seems limited, repeat the display method to ensure the controller isn’t applying a secondary software limit. Some EB3 units have both a hardware wire and a software cap – you need to clear both.
Stop/Escalate Threshold: When to Give Up and Contact Support
If after cutting the wire the bike does not power on, shows an error code (e.g., “E04” or flashing battery icon), or the motor stutters and stops under load, you may have cut the wrong wire or damaged the controller. Stop immediately – do not ride. Reconnect the cut wire using a twist‑on connector or solder and heat shrink. If the bike still malfunctions, contact Jasion customer support or a qualified e‑bike repair shop. This is the safe limit of DIY troubleshooting; further attempts risk permanent controller damage or fire from shorted wires.
Important: Never cut any wire that is part of the main power harness (thick red/black wires). Only cut the thin white signal wire. If you see multiple white wires, trace them back to the controller connector – the limiter wire is usually the one that runs alone to a two‑pin plug with nothing plugged into the second pin.
How to Verify the Bypass Worked
- Ride on a flat, straight stretch (no hills) with a full battery. Use a GPS speed app (e.g., your phone’s GPS or a bike computer) to compare displayed speed vs actual speed.
- If you used Method 1, the display will under‑report – focus on the GPS reading. A 4–5 mph difference is normal; a larger gap means you set the wheel diameter too high.
- If you used Method 2, the display should now match GPS within a few mph. If it still reads 20 mph when GPS says 28, the wire cut didn’t take effect – double‑check that you actually cut the correct wire.
Concrete success signal: On a full battery, the motor should pull you to at least 26 mph on level ground with no headwind. If the bike still stops accelerating at 20 mph, double‑check that you cut the correct wire (some models have a second limiter wire hidden deeper in the harness). A GPS reading below 24 mph after the mod indicates the bypass did not fully take effect – re‑examine your method.
Failure Mode to Watch For: Inaccurate Display and Legal Risk
Symptom: After Method 1, your display reads 12 mph while your GPS shows 22 mph.
Likely cause: Setting the wheel diameter too large (e.g., 26 on a 20‑inch tire) creates a huge speed calculation error. The controller still limits actual speed based on the corrected reading, so you may be riding faster than you think.
Safer next move: Reset the wheel diameter to the actual tire size (20 inches) and try a smaller increment (e.g., 21 or 22). The display under‑report is expected, but a 10 mph gap is excessive and can trick you into riding beyond the bike’s safe structural limits (e.g., braking from an actual 30 mph while thinking you’re doing 15). Keep the display discrepancy under 5 mph to maintain situational awareness. Also, remember that local police may not accept “the display said I was going 20” as a defense if a radar gun clocks you at 28.
Safety Checklist After the Mod
| Check | What to Do |
|---|---|
| Brakes | Adjust or upgrade pads; test stopping from 25 mph on dry pavement. Consider upgrading to hydraulic disc brakes if you regularly ride above 20 mph. |
| Tires | Inflate to the max sidewall pressure (usually 30–40 psi). Check for cracks or wear – stock tires may not be rated for sustained 28 mph speeds. |
| Lights | Add a bright headlight and taillight – higher speeds need more visibility. The JARSH helmet includes integrated lights, but a handlebar light is still recommended for road use. |
| Helmet | Wear a rated e‑bike helmet (see JARSH recommendation above). Standard bicycle helmets are tested at lower impact speeds; an NTA‑8776 helmet is designed for impacts up to 28 mph. |
Frequently Asked Questions
Will bypassing the speed limiter damage the motor or battery?
Running the motor continuously at peak RPM can increase heat and wear. Occasional use is generally safe, but sustained full‑throttle riding at 28 mph on steep hills may cause the controller to overheat or the battery to sag faster. Monitor motor temperature – if it’s too hot to touch after a ride, let it cool down before charging or riding again.
Can I reverse the bypass?
Yes – if you cut a wire, you can reconnect it with a twist‑on connector or solder and heat shrink. Display settings can simply be changed back to the original wheel size. Keep the original factory settings documented in case you need to return the bike to stock for warranty service.
Is it illegal to ride a bypassed Jasion EB3 on public roads?
In most U.S. states, any e‑bike that exceeds 20 mph on motor alone is classified as a moped or motorcycle, requiring registration, insurance, and a driver’s license. Some states have a “Class 3” category (28 mph) but require a speedometer, headlight, and taillight. Ride only on private property or follow local e‑bike laws. Penalties can include fines and impoundment of the bike.
Does the speed limiter bypass affect battery range?
Yes, because you’re drawing more power to maintain higher speeds. Expect a 15–25% reduction in range at 28 mph compared to 20 mph. Plan your rides accordingly and keep an eye on the battery gauge – it drops faster when you’re pushing the motor hard.
