Unlocking Speed: How to Make Your Razor Electric Dirt Bike Faster

Razor electric dirt bikes like the MX350, MX500, and MX650 offer thrilling off-road fun for riders of all ages. But if you've been riding for a while, you might find yourself wanting more speed from your bike. Whether you're curious about how fast your Razor dirt bike can go, want to compare different models, or are considering modifications to increase top speed, this comprehensive 2025 guide covers everything you need to know about Razor electric dirt bike speeds, performance, and safe ways to unlock more power.

Stock Speed Specifications for All Razor Dirt Bike Models

MX350 Dirt Rocket

Top speed: 14 mph (22 km/h) in High Speed Mode (default)

Low speed mode: 10 mph (16 km/h)

Motor specifications:

• Power: 350W chain-driven motor
• Type: High-torque, chain-driven
• Battery: 24V (two 12V) sealed lead-acid rechargeable
• Runtime: Up to 30 minutes continuous use (high speed mode), up to 60 minutes (low speed mode)
• Weight limit: 140 lbs
• Recommended age: 13+ years

The MX350 is Razor's entry-level electric dirt bike, perfect for younger or lighter riders who are just getting into off-road electric riding.

MX500 Dirt Rocket

Top speed: 15 mph (24 km/h)

Motor specifications:

• Power: 500W chain-driven motor
• RPM: 2,500 RPM
• Battery: 36V (three 12V) sealed lead-acid rechargeable
• Runtime: Up to 40 minutes continuous use
• Weight limit: 175 lbs
• Recommended age: 14+ years

The MX500 offers a step up in speed and power, designed for teenage and adult riders who want more performance than the MX350.

MX650 Dirt Rocket

Top speed: 17 mph (27 km/h)

Motor specifications:

• Power: 650W high-torque chain-driven motor
• RPM: 2,800 RPM
• Battery: 36V sealed lead-acid rechargeable battery pack
• Runtime: Up to 40 minutes continuous use
• Weight limit: 220 lbs
• Recommended age: 16+ years

The MX650 is Razor's most powerful standard dirt bike, capable of handling adults and offering the fastest stock speed in the Dirt Rocket lineup.

Razor SX500 McGrath (Electric Motocross)

Top speed: 15 mph

Motor specifications:

• Power: 500W motor
• Battery: 36V rechargeable
• Weight limit: 175 lbs
• Recommended age: 14+ years
• Special features: Authentic motocross frame and graphics, dual suspension

Razor RSF350 (Electric Street Bike)

Top speed: 14 mph

Motor specifications:

• Power: 350W motor
• Battery: 24V rechargeable
• Weight limit: 140 lbs
• Special features: Street bike styling, sport bike design

Factors That Affect Your Razor Dirt Bike's Speed

Rider Weight

The rider's weight significantly impacts top speed and acceleration:

• Lighter riders: Will experience speeds closer to the advertised maximum or even slightly higher
• Heavier riders: May see reduced top speed by 2-4 mph compared to specifications
• At weight limit: The bike will struggle to reach advertised speeds, especially on inclines

Example: A 100-lb rider on an MX350 might hit 14-15 mph, while a 140-lb rider might only reach 12-13 mph.

Terrain and Surface

• Smooth, flat pavement: Maximum speed achievable
• Packed dirt or gravel: Slight speed reduction (1-2 mph)
• Grass or loose dirt: Moderate speed reduction (3-5 mph)
• Uphill inclines: Significant speed reduction; steeper hills may slow bike to 5-10 mph
• Downhill: Can exceed advertised top speed (use caution!)

Battery Charge Level

Battery condition directly affects performance:

• Fully charged (100%): Full power and top speed
• 50% charge: Noticeable speed reduction (10-15%)
• Below 25%: Significant power loss, may only reach 50-70% of max speed
• Old batteries: Degraded batteries that no longer hold full charge will reduce overall performance

Tire Pressure

• Properly inflated: Optimal speed and handling
• Underinflated: Increased rolling resistance, reduced speed by 1-3 mph
• Overinflated: Slightly faster but harsh ride and reduced traction

Check tire pressure regularly – Razor dirt bikes typically use 35 PSI for rear tires and 30 PSI for front tires.

Chain Tension and Lubrication

• Properly tensioned and lubricated: Maximum power transfer to rear wheel
• Loose chain: Power loss and potential slipping
• Too tight: Increased resistance and motor strain
• Dry or rusty chain: Friction reduces speed by 1-2 mph

Temperature

• Optimal temperature (60-80°F): Best performance
• Cold weather (below 40°F): Reduced battery performance, 10-20% speed decrease
• Hot weather (above 90°F): Slight performance improvement but risk of overheating

Comparing Razor Dirt Bike Speeds

Model	Top Speed	Motor Power	Battery	Weight Limit	Age Range
MX350	14 mph	350W	24V	140 lbs	13+ years
MX500	15 mph	500W	36V	175 lbs	14+ years
MX650	17 mph	650W	36V	220 lbs	16+ years
SX500	15 mph	500W	36V	175 lbs	14+ years
RSF350	14 mph	350W	24V	140 lbs	13+ years

Speed Progression: Which Model for Which Rider?

• Beginners and younger teens (ages 13-14): MX350 or RSF350 – 14 mph provides ample excitement while being more controllable for new riders
• Intermediate riders (ages 14-15): MX500 or SX500 – 15 mph offers more speed for growing confidence
• Advanced riders and adults (16+): MX650 – 17 mph is the fastest stock option and can handle adult riders

Safe Ways to Increase Speed on Razor Dirt Bikes

Important Safety and Legal Disclaimer

Before considering any modifications:

• Warranty void: Any modification voids Razor's manufacturer warranty
• Safety risks: Increased speeds create higher risk of injury – always wear proper protective gear
• Legal considerations: Modified electric bikes may not be legal for use on public roads or trails in your area
• Age restrictions: Faster bikes should only be ridden by mature, experienced riders with appropriate safety equipment
• Liability: You assume all risk and responsibility for modifications

1. Optimize Existing Components (No Modifications)

Get the most speed from your stock bike without modifications:

• Keep battery fully charged: Always start rides with 100% charge
• Maintain proper tire pressure: 35 PSI rear, 30 PSI front
• Lubricate chain regularly: Clean and lube every 2-3 rides
• Tighten chain to proper tension: 1/2 inch slack when measured at mid-point
• Reduce weight: Remove any unnecessary accessories or cargo
• Replace old batteries: If batteries are 2+ years old, replacement can restore full speed
• Choose optimal terrain: Smooth, flat surfaces yield maximum speed

2. Battery Upgrades (Moderate Modification)

Lithium-ion battery conversion:

• Replace stock lead-acid batteries with lighter lithium-ion batteries
• Same voltage (24V for MX350, 36V for MX500/MX650) but reduced weight
• Benefits: 2-3 lbs lighter, faster acceleration, consistent power delivery, longer lifespan
• Speed increase: 1-2 mph from weight reduction alone
• Cost: $80-$150 for lithium conversion kit

Higher capacity lead-acid batteries:

• Upgrade from standard 12V 7Ah batteries to 12V 9Ah or 12V 12Ah
• Benefits: Longer runtime, more consistent power over full charge cycle
• Speed increase: Minimal direct speed boost, but maintains top speed longer during ride
• Cost: $30-$50 per battery

3. Sprocket and Gear Ratio Changes (Moderate Modification)

Increase top speed (reduce torque):

• Install smaller rear sprocket or larger front sprocket
• Example: Replace 65-tooth rear sprocket with 55-tooth sprocket
• Speed increase: 2-4 mph
• Trade-off: Reduced acceleration and hill-climbing ability
• Best for: Flat terrain riding where top speed matters more than torque

Increase torque (reduce top speed):

• Install larger rear sprocket or smaller front sprocket
• Benefits: Better acceleration, improved hill climbing
• Trade-off: Lower top speed
• Best for: Hilly or technical terrain

4. Speed Limiter Removal (Simple Modification)

Some Razor dirt bikes have speed limiters that can be removed or modified:

• Method: Speed controller modification or "bridge mod"
• Requirements: Basic hand tools, soldering iron (for some methods)
• Speed increase: 2-5 mph depending on model
• Time required: 30 minutes to 1 hour
• Legality: Check local laws – may be prohibited in some areas

Warning: Speed limiter removal can stress components not designed for higher speeds. Proceed with caution.

5. Motor Upgrades (Advanced Modification)

Higher wattage motor:

• MX350: Upgrade from 350W to 500W motor
• MX500: Upgrade from 500W to 750W motor
• MX650: Upgrade from 650W to 750W or 900W motor
• Speed increase: 3-7 mph
• Requires: Matching voltage (24V or 36V) and compatible controller
• Cost: $60-$120 for motor

Higher RPM motor:

• Install 2,800 RPM motor on MX500 (stock is 2,500 RPM) to match MX650 speed
• Benefits: Higher top speed without voltage increase
• Cost: $70-$100

6. Voltage Upgrades (Advanced Modification)

24V to 36V conversion (MX350):

• Add third 12V battery to create 36V system
• Requires: 36V controller and 36V charger
• Speed increase: 4-6 mph (from 14 mph to 18-20 mph)
• Cost: $100-$150 for controller, charger, and additional battery

36V to 48V conversion (MX500/MX650):

• Add fourth 12V battery or use 48V lithium battery pack
• Requires: 48V controller, 48V charger, motor rated for 48V
• Speed increase: MX500 can reach 25-32 mph, MX650 can reach 27-34 mph at 48V
• Cost: $150-$250 for complete conversion kit
• Caution: Higher voltage significantly stresses motor, chain, and brakes – requires upgraded components

72V high-performance systems:

• Complete performance overhaul with brushless motor and 72V battery
• Top speeds: 40-45+ mph
• Cost: $300-$600 for complete kit
• WARNING: At these speeds, Razor dirt bikes become extremely dangerous without significant additional safety modifications (upgraded brakes, suspension, frame reinforcement)

7. Complete Performance Kits

Several companies offer turnkey performance kits for Razor dirt bikes:

• Mid-range kits (48V): 25-35 mph top speed, ~$200-$300
• High-end kits (72V): 40-45 mph top speed, ~$400-$600
• Includes: Motor, controller, battery pack, charger, and installation instructions
• Installation difficulty: Moderate to advanced (2-4 hours)

Safety Equipment for Higher Speed Riding

As speeds increase, proper safety gear becomes critically important:

Essential Safety Gear for Stock Speeds (14-17 mph)

• DOT-approved helmet: Full-face recommended, at minimum a quality half-helmet
• Gloves: Protect hands in falls
• Closed-toe shoes: Sturdy boots or athletic shoes (no sandals)
• Long pants and long sleeves: Protect skin from abrasions
• Eye protection: Goggles or safety glasses

Additional Gear for Modified Bikes (20-30+ mph)

• Full-face motocross helmet: Non-negotiable at higher speeds
• Chest protector/roost guard: Protects torso from impacts
• Knee and elbow pads: Essential for high-speed crashes
• Motocross boots: Ankle support and protection
• Riding jersey and pants: Durable, abrasion-resistant gear
• Neck brace (optional): For extreme modifications approaching 40+ mph

Performance Testing and Speed Measurement

How to Accurately Measure Your Bike's Top Speed

1. Use GPS speed tracking: Phone apps like "GPS Speed" or "Speedometer" provide accurate readings
2. Find a flat, smooth test area: Long parking lot or closed road
3. Full battery charge: Test with 100% battery for consistent results
4. Proper rider weight: Use same rider for comparative tests
5. Multiple runs: Perform 3-5 speed runs and average the results
6. Document conditions: Note temperature, wind, and any modifications

Before and After Modification Testing

Always test your bike's stock speed before modifications to establish a baseline. After each modification, retest to measure actual performance gains. This helps you understand which modifications provide the best return on investment.

Legal and Ethical Considerations

Where Can You Ride Modified Razor Dirt Bikes?

• Private property: Your own property or with landowner permission (generally legal)
• Off-road parks and trails: Many have speed or motor wattage restrictions – check regulations
• Public streets: Most modified electric dirt bikes are NOT legal for street use
  • Lack required safety equipment (lights, turn signals, mirrors)
  • May exceed legal speed limits for motorized bicycles
  • Registration and insurance typically required for street-legal vehicles
• Parks and bike paths: Usually prohibited – check local ordinances

Age and Supervision Requirements

• Follow manufacturer recommendations: Respect age limits even after modifications
• Adult supervision: Required for all riders under 18, especially with modified bikes
• Mature riders only: Higher speeds demand better judgment and reaction times

Insurance and Liability

• Homeowners insurance may not cover injuries from modified bikes
• Consider additional liability coverage for high-performance modifications
• Some areas require insurance for motorized vehicles above certain wattage or speed

Maintenance for Higher-Speed Riding

Increased speeds create additional wear on components:

More Frequent Inspections

• Chain: Check tension and lubrication every 2-3 rides (vs. every 5 for stock bikes)
• Tires: Inspect for wear and maintain proper pressure before each ride
• Brakes: Test brake effectiveness before each ride; consider brake upgrades for speeds above 25 mph
• Frame and forks: Check for cracks, especially weld points and stress areas
• Electrical connections: Ensure all connections are tight and secure

Component Upgrades for Reliability

• Upgraded chain: Heavy-duty chain for high-torque applications
• Better brakes: Disc brake conversion for speeds above 20 mph
• Suspension upgrades: Improved forks and rear shock for better handling at speed
• Quality tires: Premium pneumatic tires with better grip

Troubleshooting Speed Issues

My bike isn't reaching its advertised speed

Possible causes:

• Undercharged or degraded battery – test battery voltage
• Chain too loose or too tight – adjust to proper tension
• Underinflated tires – check and inflate to recommended PSI
• Heavy rider near or at weight limit – expected behavior
• Riding uphill or on soft terrain – normal speed reduction
• Motor or controller issue – test with multimeter or consult professional

Speed decreased suddenly

• Battery needs replacement (typically after 300-500 charge cycles)
• Chain needs lubrication or replacement
• Motor brushes worn (chain-driven models)
• Controller failure or thermal protection activated

Frequently Asked Questions

Which Razor dirt bike is the fastest?

The MX650 Dirt Rocket is the fastest stock Razor dirt bike with a top speed of 17 mph. For absolute fastest option (heavily modified), some MX650 kits can reach 40-45 mph, but these require extensive modifications and are not recommended for inexperienced riders.

Can a Razor dirt bike go 30 mph?

Not stock. Stock MX models top out at 14-17 mph. However, with significant modifications (48V battery, upgraded motor and controller), the MX500 and MX650 can reach 25-34 mph. Kits that promise 30+ mph require major upgrades and pose serious safety risks without additional brake, suspension, and frame reinforcements.

How fast does the MX350 go in low-speed mode?

The MX350 reaches 10 mph in low-speed mode and 14 mph in high-speed mode. The low-speed mode is ideal for beginners or younger riders still developing riding skills.

Are speed modifications legal?

Legality varies by jurisdiction. In most areas, you can modify bikes for use on private property. However, street use with modifications is generally illegal without proper registration, licensing, and safety equipment. Off-road trails may have power or speed restrictions. Always check local laws before riding modified bikes in public areas.

Will speed modifications void my warranty?

Yes, any modification to the motor, controller, battery voltage, or electrical system voids Razor's manufacturer warranty. Modifications are done at your own risk, and Razor will not provide warranty service or replacement parts for modified bikes.

Conclusion

Razor electric dirt bikes offer exciting off-road fun right out of the box, with the MX350 providing 14 mph for younger riders, the MX500 delivering 15 mph for teens, and the MX650 topping out at 17 mph for adult riders. While these stock speeds provide plenty of excitement for most riders, those seeking more performance have numerous modification options ranging from simple battery upgrades to complete performance overhauls that can nearly triple top speed.

However, increased speed comes with increased responsibility. Always prioritize safety by wearing appropriate protective gear, understanding the legal implications of modifications, and ensuring your bike's brakes, tires, and frame can handle higher speeds. Start with simple optimizations like proper maintenance and tire pressure before considering major modifications. If you do modify your bike, do so incrementally and test thoroughly at each stage.

Most importantly, remember that Razor dirt bikes are designed for off-road fun, not street use. Whether you ride stock or modified, respect private property, follow local regulations, and always put safety first. With proper care, maintenance, and responsible riding, your Razor electric dirt bike can provide years of thrilling off-road adventures at whatever speed you're comfortable riding.