Gas Bike FAQs

Read about gas bike FAQs and get all you need to know about gas bikes, specifications and facts.

Find the right gas bicycle for you, 2-stroke & 4-stroke.

See all the pre-built gas bikes, assembled and ready to ride in our catalog.

BBR Deluxe Gas Bike Kit with 4-stroke Motor

Gas Bike - A Bicycle With A Gas Powered Helper Motor

(Not a legal opinion or interpretation) 

Gas Bike. A gas bike is a regular pedal bicycle equipped with a helper motor. It is a special category under Arizona law, recognizing hobbyists that modify their bicycle with a chain driven or friction driven "helper" motor. It can be either 4-stroke or 2-stroke, from an old Weed Wacker or a kit. However, to be legally operated on the road, it cannot be over 48cc, be less than 1Hp, and not travel at more than 20mph. Gas bikes are permitted to be operated on the right side of a road, like a bicycle, but not on bicycle paths or trails. No registration or license is required. You must have operational brakes, a headlight at night and reflectors. 

Moped. A gas bike is different than a moped. Usually, mopeds are equipped with safety items: mirror, lights, brake light, turn signal, horn, & speedometer. To be a moped, it must have operational pedals, less than 1.5Hp, less than 50cc, and travel at no more than 25mph. No title is issued, but you do need registration and insurance. You can operate a moped with any class of license.

Scooter. A scooter or a motor-driven vehicle, with no pedal requirement, is between 50cc and 80cc, less than 5Hp, and needs all safety equipment, title, insurance,  and registration, like a motorcycle. You must have a motorcycle endorsement and a valid license. Any bigger than this is a motorcycle. 

Always wear a helmet!

Gas bicycles - information and facts

Motorized Bicycle Regulations in Arizona - Frequently Asked Questions

Before you ride, review your town’s bicycle laws. This is not a legal opinion or comprehensive evaluation of the law. Consult a lawyer or other professional for any official interpretation.  

What is a motorized bicycle?

The precise definition of a motorized bicycle is not well defined in Arizona. As well, every county, city or town may impose or interpret regulations differently. Generally, a motorized bicycle means a bicycle or tricycle that is equipped with a helper motor that has a maximum piston displacement of forty-eight cc or less (under 750 watts or one Hp), that may also be pedaled, and that is operated at speeds of less than twenty-miles-per-hour. Over this limit would be a motorcycle, ATV, scooter or even a moped (moped laws usually revolve around a 20-28 mph limit and additional equipment requirements - lights, horn, brake light, etc., but must have pedals as an option). Local law enforcement is always free to stop anyone that is operating a vehicle unsafely. It is ultimately up to the operator to ensure he or she is in compliance with the laws and regulations and are operating the vehicle in a safe manner. As with any vehicle, motorized or not, you must obey the traffic rules and laws, observing and yielding to traffic control lights and markings - and traveling in the same direction as traffic. Never ride on pathways reserved for pedestrians or those that specifically prohibit motorized vehicles.

Every jurisdiction is different, but in general, the following may apply:

  • A driver’s license is generally not required to operate a motorized electric or gas powered bicycle or tricycle.
  • A certificate of title and registration is not usually required for a motorized electric or gas powered bicycle or tricycle, which avoids a vehicle license tax or plate.
  • A motorized electric or gas powered bicycle or tricycle, as described above, would be exempt from vehicle emissions inspections.
  • By definition, a motorized electric or gas powered bicycle or tricycle may use rights-of-way designated for the exclusive use of bicycles. In general, motors should be under 49cc to qualify and not exceed 20mph. In Arizona, this classification is poorly defined.
  • You must obey all traffic laws. Be courteous, ride in the bicycle lane or as far to the right as possible, and yield to others as appropriate. Never ride on the sidewalk. Sidewalks are for pedestrians only.  (however, purpose-built bike paths may be very much like a sidewalk).
  • Although you can register your Motorized Bicycle with the DMV, allowing you to operate your vehicle on the road like a motorcycle or moped, you will have to have insurance, registration, motorcycle endorsement, and required equipment (such as tail and headlight, brake light, mirror, etc.). This also means that you cannot, by definition, ride on any bicycle lane and must stay on the roadway.


We strongly recommend:

  • Install a speedometer, if the bike does not currently have one.
  • Always wear a Helmet - under 18 must wear a helmet.
  • Wear goggles or appropriate glasses to protect your eyes.
  • Install a mirror.
  • Install a bicycle headlight and tail light.
  • Wear appropriate, close-fitted, clothing, gloves and shoes for safety.
  • Check the bike for proper mechanical operation, especially the brakes, before every ride.
  • Be careful - these bikes can be very dangerous to operate.
  • If you are new to this, practice riding with the motor turned off, get familiar with the controls and operation, before starting the motor. Once running, practice straight line starts and stops, before trying to turn. 

Operating a motor assisted Bicycle on the street

To be as safe as possible in regards to the law, keep your speed under 20mph, stay out of motor vehicle traffic lanes, use bike lanes as appropriate, yield to pedestrians, obey all traffic laws, wear a helmet and be courteous. In Arizona, Law enforcement may interpret your riding how they see fit, considering public safety first.

2-Stroke Pre-Mix Gas Bike Oil and Break-In Process

Dumonde Tech 2-stroke break-in oil Dumonde Tech 2-stroke oil  Dumonde Tech Break-In Oil is specially designed for proper Break-In on any Two-Stroke engine. Recreational or Race, proper Break-in determines both the short-term life and long-term performance of all gas bike engines. Using Dumonde Tech Break-in Oil, and their procedure, gives an inexpensive performance gain over other brands and dramatic improvements over conventional oils. Generally, pure synthetic oils should not be used to break in an engine either, as they do not contain the special products to effectively coat the moving parts. The proven, complete break-in procedure, is printed on each bottle of Dumonde break-in oil. For gas bike engines, during break in, this 4-ounce bottle would mix up 0.6 gal (or 77 ounces of pre-mix gas). After break-in, use Dumonde synthetic 2-stroke racing oil at 32:1 or 4oz per gallon. You'll get longer engine life, better gas mileage and less smoke and residue. For best engine life and performance, run the break-in mixture for at least two gallons. 

Dumonde Tech Break-In / Storage Oil is a very complex formula that allows proper ring seat, work hardening and it impregnates parts with a matrix compound film to protect surfaces against lean periods and corrosion. Through research it has been found that a high percentage of these processes are not achieved with conventional oils. By not achieving these effects, performance and durability can be greatly effected.

Benefits: Measurable increased performance gains - Less engine failure - Greater cooling - Increased protection of parts against corrosion

Note: never use anything but 2-stroke oil. Using an oil that is not meant to be burned pollutes and leaves behind nasty residue in your engine. Worse, it does not lubricate the engine parts very well.

Mixing Your Gas and Oil

If you want to mix the oil right into your tank at the gas pump (not recommended), use the chart below. This will help you decide how much oil to add directly to the tank. For example, if you pump in 0.4 gallons of gas, you would add about 1 1/2 ounces of synthetic oil or 2 1/2 ounces of regular 2-stroke oil. Mix it as best you can by tilting the bike a few times. The chart is rounded up to help you measure right from the site gauge on the bottle. It's hard to measure small quantities precisely, so error on the side of extra oil versus too little. Don't over do it though. Too much will cause excess smoke and residue buildup and could foul your spark plug. Most users run their engine at 20:1 during break-in (using synthetic oil) for at least 2-gallons, then go with 32:1 (synthetic only) after break-in. The engine will last longer and run cleaner with synthetic oil. If you use regular 2-stroke oil, most manufacturers recommend you mix at 16:1 at break-in and 20:1 after break-in. Use premium gas.

2-stroke oil mixing chart

4-Stroke Gas Bike Oil and Break-In Process

Dumonde 4 cycle oil 

Dumond four cycle oil  Dumonde Tech B4 Break-in Oil, and proven break in process, is developed for proper break-in on any Gas Bike/ATV/Motorcycle, Four Stroke engine. Recreational or Race, proper break in determines both the short term life and performance of all engines. 

Dumonde Tech B4 is a very complex formula that allows proper ring seat, work hardening and impregnates parts with a matrix compound film to protect surfaces against lean periods and corrosion, in part by modern fuels, which are increasingly acidic.

Through research R & D, it has been found that a high percentage of these processes are not achieved with conventional oils. By not achieving these effects, performance and durability can be greatly effected. Following a proven break-in process assures maximum life from your Gas Bike engine.

Benefits:

  • Increased performance gains
  • Less engine failure
  • Greater cooling
  • Increased protection of parts against corrosion

Operation and Maintenance of Your Motorized Bicycle

HOBBY. Gas bikes are for those who like to tinker, build and work on their own bicycle. These bikes are kits and not meant for consistent, reliable use. You have to maintain them regularly. Bolts come loose and the 2-strokes depend on un-burned oil for lubrication. That means they can be oily and messy. Approach your bike like a hobby and you will be pleased with the results. Beware, these engines come in myriad variations and levels of quality. Generally, the less you pay, the lower the quality. 

BREAK-IN PERIOD. All new gas bike motors require a break-in period. Break-in is 100-150 miles or five-ten hours. During this time, you need to run the motor with a special break-in 2-stroke oil, mixed at 20:1 (that's 6 1/2 ounces of oil per gallon), (for 4-stroke, special crankcase oil). If not break-in oil, then use 16:1 (that's 8 ounces of oil per gallon of gas). We recommend only using Dumonde oil, especially during the break-in period. We carry Dumonde Tech oils. Dumonde Tech Break-In Oil is designed for proper Break-In on any type of engine. Proper Break-In determines both the short-term life and longevity. It helps the rings seat properly and the cylinder walls to harden. Dumonde Tech Break-In Oil is a very complex formula that allows proper ring seat, work hardening, while impregnating parts with a matrix compound film to protect surfaces against lean periods and corrosion. Through research it has been found that a high percentage of these processes are not achieved with conventional oils. By not achieving these effects, performance and durability can be greatly effected. 

RUNNING. During break-in, do not run the motor for extended periods at a constant speed and do not run at full speed. Target less than 20mph and less than 30min. Always take a few minutes at an easy, unloaded, speed to warm up (3-5 min). On cold days, use about 3/4 choke to start (up is choke on and down is choke off). Learn to turn the choke off while going slowly. On warmer days, no or little choke is needed. For the first few rides, make them shorter and take time after each ride to inspect the bike, tighten all the bolts and chain and make sure everything has settled in for the long-term.

2-STROKE OIL. After break-in, continue to use synthetic oil at 32:1 (that's 4 ounces of oil per gallon). Using synthetic oil extends the life of the motor and makes less smoke. Do expect some burned oil accumulation at the tail pipe (residue). This is normal. If you use regular 2-stroke oil, run at 20:1 (6 1/2 ounces per gallon). The typical "peanut" gas tank that comes with most gas bike kits are 1.5 Liter or 0.4 gallon (51oz). (In a pinch, that's 2.6oz of regular oil or 1.6oz of synthetic.) It is not recommended to mix the gas in the bike's gas tank. It's difficult to calculate the right mixture because residual pre-mix remains in the tank and you may not get a good distribution of oil before running.

4-STROKE OIL. On your 4-stroke crankcase oil, use a good quality, 4-stroke-specific, motorcycle oil. 15-40 is fine, such as the Dumonde GP4 and the Dumonde  B4 break-in oil for the first 100-150 miles (or five-ten hours) of operation. Synthetic is always a good choice. For best longevity, change the oil every 10 hours of use. This will ensure top performance and wear at all times. It doesn't hold much oil and has no filter, so it is best to change it often. 

FUEL. It is best to select a small gas can to mix your fuel. The best choice would be a red, steel, 2-gallon storage can, Certified by FM, UL/ULC, and TUV. This will keep your fuel fresh and safe for at least six months. Use fresh premium gas on 2-strokes. Regular is fine for the 4-strokes. A plastic container, certified for gasoline storage is OK, but the gas will need to be used in less than three months. Mixing in a gas can also lets you be more precise on your oil measurement. 

2-STROKE STARTING. To start the motor, set the choke and turn on the gas. Squeeze the clutch and hold the throttle at 1/4 open. Pedal the bike up to at least 5mph. Release the clutch in a smooth continuous motion. If you slow too much before the engine starts, start over. Allow the engine to warm up at around 10mph. Running at 20mph allows the combustion chamber to stay hot and the motor to stay in the optimum power level (best gas mileage too). Avoid idling for more than a minute or two. Un-burned oil accumulates on the spark plug at an idle and could foul the plug (engine will not run). Idling puts excess strain on the clutch and the lack of air flow could overheat the engine. If you come to a stop light, use the clutch. If the wait will be a while, stop the engine. Never run the engine at speeds under 5mph (lugging). Most riders get in excess of 75 miles per gal of gas. 

2-STROKE ELECTRICAL. For proper operation, the spark plug should be clean and not fouled by oil. The gap is 0.14. Use a B5HS or B6HS model plug. The magneto provides the electrical pulse to the CDI for a spark. The magneto should measure around 300 to 400 Ohms while disconnected. Always ensure the magneto is dry and the mounting bolts secure. Check for frayed or grounded wires - especially leaving the housing. Your CDI inputs should have a low resistance, around 10 Ohms, but you may need to make measurements with the "diode" setting to ensure accurate readings with a digital VOM. Checking for spark: With the gas turned off and the carburetor bowl empty, check for spark in a dark area by removing the spark plug, grounding the side of the plug, and turning the engine over rapidly. Make sure the connections are good throughout the chain, black wire is connected to black wire, and no pinched wires. Disconnect the kill switch wires to make certain they are free of grounds (test with them on and off). You should see a sharp blue spark on every revolution.   

SMOOTH STARTS ON ALL BIKES. Do not use the clutch to start from a stop. The clutch on these motors is not suitable for standing starts. Pedal to start. In all cases, when starting from a stop, pedal to get some speed and, while pedaling, release the clutch in one smooth motion (add throttle gradually), after you reach 5mph. For 4-strokes motors with an automatic clutch, slowly twist the throttle as you gain speed.  Continue to pedal for a bit to help the motor achieve solid operating speed (about 10mph). Two-stroke motors have a power band that hits at higher RPMs. At lower RPMs (and especially at idle) the motor will tend to foul or "load-up." Once you hit the power band, the motor will "clean-out" or begin to run stronger and smoother. Lugging the engine should be avoided, as this will cause the engine to load up. These are not motorcycles. The motor is to help you sustain speed only.

2-STROKE CARBURETOR. It is absolutely essential that the carburetor be fully seated and have no air leaks. A poorly installed or loose fitting will greatly effect operation and adjustment. Worse, air leaks can cause a lean mixture and damage the engine. Periodically, check your intake and exhaust bolts for a snug fit, as these may vibrate loose over time, especially during break-in. You cannot diagnose or adjust the fuel system unless all the fittings are seated and sealed. 

Normally, all the carburetor settings do not change. The air screw on the side of the body of the carburetor adjusts how much air mixes with the idle circuit (Idle Adjuster). The standard setting is 3 1/2 turns out from fully seated. On the NT-style carburetors, the air screw is very a very simple design. Screwing the adjuster in makes the idle speed faster and richer (too far and the bike will load up and stall). The idle speed is set by adjusting the screw for optimal idle - just fast enough to not stall out. The cap Cable Tension Adjuster nut adjuster and throttle handle adjuster are used to take up the slack in the throttle cable and can be used to hold the idle. Because the throttle cable comes manufactured at a fixed length, all the pieces from the throttle tube down to the cap nut and slide must be correct or you will be too short or long to make adjustments. If any of these pieces become worn or damaged, they must be replaced to accurately adjust the idle. Use the Primer on cold days. If you are an advanced mechanic, look at your spark plug to gauge the running mixture. Move the clip on the jet needle up to lean out the mixture or down to make it richer. Check your spark plug after running at 20mph, at full operating temperature, for at least 1/2 a mile. It should be chocolate brown. If it is dark and oily, you may need the B6HS (hotter) plug or a leaner mixture. If it is white or very clean looking, you may need to make the mixture richer (lower the clip on the needle). Warning: Running a lean mixture may damage your engine.

PARTS AND UPGRADES FOR 2-STROKES. The most effective way to improve throttle response, low-end power, torque and horsepower, is to add a few hop up parts to the fuel and exhaust system. An upgraded carburetor with better machined internals is a good starting point. Adding a reed valve will dramatically improve low-end and throttle response. Replacing the stock muffler with an expansion chamber will improve horsepower and torque. After you do those changes, you may want to change the standard 42T/44T rear sprocket to a 32T/36T. When parts break, many are available, but sometimes it is cheaper just to throw the engine out and replace the whole thing. After all, a complete kit is under $300 and you can get engine-only kits for even less. 

SPARK PLUG & AIR CLEANER MAINTENANCE. On all bikes, replace your spark plug every 500 miles or 25 hours of use. Gap to .14". You may go longer, but do risk poor combustion or a fouled plug. Clean the air filter every 100 miles or five hours. Clean it with solvent (paint thinner or kerosene) and do not oil it. Replace the filter whenever it becomes torn or ragged.

CHAIN. Most commonly, 4-stroke motors use a 420 chain and 2-stroke motors use a 415 chain. The rear sprocket is never perfectly centered, so adjust the tension based on the tightest place on the rotation. The spring tensioner can help maintain tension when you want the chain tension uniform across all of the rotation. Be careful not to over-tighten the chain because it will cause excessive wear on the drive bearing. Make certain you position the master link so the clip faces in the direction of travel that would push it into place while rotating. Keep your chain oiled, but clean - don't goop on oil, as it will attract too much dirt. The most common problem with the chain is maintaining a good chain line. If the chain line if off, the chain will climb the side of the gear on the wheel, derailing and falling off, often jamming into the wheel or breaking the chain. Adjust the tensioner so it guides the chain onto the wheel gear accurately - check the chain line before every ride.

BEFORE YOU RIDE. Before every ride, check bolts on both the bike and motor for proper tightness. These engines vibrate a lot and do wiggle loose. Do not over-tighten bolts as they do strip easily. If you have spoke wheels, check every spoke for tightness, especially on your rear wheel. (Note: starting off smoothly vastly improves wear on rear spokes.) Oil your chains with Dumond Tech chain oil as needed (usually every 100 miles). Wipe them clean after oiling. Check and adjust the chain tension. Riding any bike carries with it some risk of injury. Remember, you are responsible for the safe operation of of your bike. Take time before every ride to ensure it is safe to ride. Wear a helmet.

CLEANING. To clean the bike, spray with a good degreaser, scrub and wash with warm soapy water. Sprinkle the soapy water off, never spray. Keep water out of the exhaust port and carburetor. It is best to bag the carburetor prior to washing. If you operate the bike in the weather, rinse it off after you get home. Water gets into the bearings, so keep it clean and dry after use.

TUNE UP THE BIKE. Every year, or sooner if you ride a lot or in the weather, give the bike a good cleaning. This would include servicing all the bearings (wheels, headset, crank, chains, tensioner, brakes, etc.). Usually, the engine only needs the air cleaner and spark plug checked. Keep water out of the engine area or be very careful not to spray water into the engine area.   

STORAGE. Store your bike in a covered, well ventilated area, suitable for a gas-operated vehicle. Never bring it indoors or into a living space. Always shut off the gas tank petcock (item #4 in the exploded view). For extended periods of storage, carefully drain the carburetor bowl and dispose of the fuel properly. Premixed gas may be stored up to six months if it is in a steel can with little or no air space. 

WEAR. Over time, your engine will degrade and lose power. These engines, if operated properly as described above, will last 200 or more hours. When they do wear out, it is usually far cheaper to just replace the engine. Engine-only kits are less than $200. However, parts are available for typical wear items, like the clutch, spark plug, electric connections and carburetor, which need regular maintenance.

MY BIKE WON'T RUN. Fuel that is over three months old may be a problem. Check for a fouled spark plug. Replace it if it is crudded up. Pull the plug and rotate the engine by hand while grounding the plug on the head. The spark should be bright blue. Make sure the magneto is clean and well grounded. Check the resistance of the CDI (400 Ohms) and the magneto (10 Ohms). Check the carburetor for small bits of rust that can clog the idle jet, main jet and float bowl. Carburetor contamination is a very common problem. Tighten the head bolts to spec. Lastly, check for compression. If low, replace the cylinder, piston and rings or, engine-only kits are cheap, just replace the engine.

N-type 2-stroke carb 2-stroke carb connections

A Note of Caution From the Manufacturer and Archer's Bikes

Disclaimer: Operating a motorized bicycle and/or bicycle engine kit carries a risk of serious bodily injury. All gas bikes may be dangerous to operate. They are effectively a toy or hobby kit. Archer's Bikes does not manufacture or assemble any of these gas bike parts. All warranties are from the manufacturer only. The rider accepts responsibility for any and all vehicle operation that may lead to personal injury, economic loss, social distress, other losses, costs and damages. Archer's Bikes is not responsible for injuries and/or damages resulting from operating this motorized bicycle or bicycle engine kit. In other words: you are on your own when operating a gas bike, be careful and always wear a helmet.

Disclosure of accurate engine size: While we have chosen to use the long standing factory branding engine size of "80cc," the true displacement of the bicycle engine is 66cc. Down through the years China bicycle engine manufactures have advertised their biggest engine as 80cc, therefore we have listed them in the same way on our website. However, the bore and stroke of an 80cc being 47x38mm equals 66cc. Therefore the true displacement of the 80cc bike motor is 66cc. In the west, the volume of a cylinder is calculated by using the formula Volume = Pi x Radius Squared x Stroke. However, in the east the displacement of an engine includes the area of the cylinder head's combustion chamber as well as the volume of the cylinder. Therein lies a discrepancy between measuring standards by the manufactures in China with those in the United States. However, all "80cc" engine kits on the market today are actually 66cc in displacement size if measuring by US standards.

Important Gas Bike information

  • All gas bikes shown are assembled from kits
  • All guarantees are solely from manufacturer
  • All gas bikes are sold as-is
  • These kits are not approved for use on public highways
  • Gas Bikes are not titled and are unregistered and are not motor vehicles
  • Gas bike kits and conversions are essentially toys (your hobby)
  • Customer accepts all risks of use
  • Operating a bike, motorized bicycle or bike with a bicycle engine installed involves some risk of serious bodily injury. Buyer accepts responsibility for any and all vehicle operation that may lead to personal injury, economic loss, social distress, other losses, costs and damages.
  • Seller is not responsible for injuries and/or damages resulting from operating this motorized bicycle or bicycle engine
  • Seller is not responsible for misuse of this or any warranty
  • Not all motorized bicycles are allowed for on road use
  • We make no guarantee as to the road legality of these bike motors
  • See our terms and conditions

NOTE: Our gasoline operated products are NOT compliant with Environmental Protection Agency ( E.P.A. ) or California Air Resources Board (C.A.R.B) for the use on/off Public roads. Upon purchase, the buyer agrees to use products for racing (closed-course competition) only and NOT for on/off public roads.

Electric Bicycle Information

Dollar-for-dollar, Gas bikes generally cost less and are more powerful than an electric bike. Gasoline contains 125,000 BTUs of energy per gallon (36,650 watt-hours). That's a lot of energy and, at $2.50 per gallon, very cheap energy. Unfortunately, gas engines are very inefficient. Energy is lost in un-burned fuel, heat and friction. Electric bicycles come with an electrically-driven motor. Like gas motors, the electric motor is used to provide extra pedaling power to the bicycle. Electric bikes do cost more than gas bikes, but are clean and friendly to the environment (a typical electric bike holds 500 watt-hours of energy). E-bikes convert the stored energy far more efficiently than a gas bike. On an e-bike, the rider may use the motor to assist in pedaling or use the optional throttle, reducing the effort used to move the bicycle. All electric bikes have the option of turning off the motor and even leaving the battery at home, making the bike a traditional pedal bike. For more on this topic, go to the Electric Bike FACs page.

Electric Bike FAQs

Gas Bike Guarantees

Read our Terms and Conditions of Sale for more information on your responsibilities when operating a gas bike. All gas bike kits, assembled or not, are sold as-is, and have no warranty, other than from the manufacturer. 

Subscribe