"I got it the day after you shipped it. I love it. Thank you for building this for me! I got it together in about 45 minutes, and it runs great. Way better than my last bike."
– Zachary Bloom, the stars and pipes bike
What is a moped or motorized bicycle?
- There are two types of motorized bicycles, defined in the California Vehicle Code (VC) Sections 406(a) and 406(b).
- Section 406(a) VC refers to a moped or motorized bicycle as any two or three wheeled device having fully operative pedals for propulsion by human power, or having no pedals if powered solely by electrical energy, has an automatic transmission, and a motor which produces less than 2 gross brake horespower and is capable of propelling the device at a maximum speed of not more than 30 miles per hour on level ground.
Motorized Bicycle (Section 406(b) VC)
- Driver's License not required but rider must be at least 16 years of age.
Simply put, it's because the two-stroke exhaust system, commonly referred to as an 'expansion chamber' uses pressure waves emanating from the combustion chamber to effectively supercharge your cylinder.
In reality, expansion chambers are built to harness sound waves (created in the combustion process) to first suck the cylinder clean of spent gasses--and in the process, drawing fresh air/gas mixture (known as 'charge') into the chamber itself--and then stuff all the charge back into the cylinder, filling it to greater pressures than could be achieved by simply venting the exhaust port into the open atmosphere. This phenomenon was first discovered in the 1950s by Walter Kaaden, who was working at the East German company MZ. Kaaden understood that there was power in the sound waves coming from the exhaust system, and opened up a whole new field in two-stroke theory and tuning.
An engine's exhaust port can be thought of as a sound generator.
Each time the piston uncovers the exhaust port (which is cut into the side of the cylinder in two-strokes), the pulse of exhaust gases rushing out the port creates a positive pressure wave which radiates from the exhaust port. The sound will be be the same frequency as the engine is turning, that is, an engine turning at 8000 rpms generates an exhaust sound at 8000 rpms or 133 cycles a second--hence, an expansion chamber's total length is decided by the rpm the engine will reach, not displacement. Indeed, the only advantage to this crude pipe system was that it was easy to tune: You simply started with a long pipe and started cutting it off until the motor ran best at the engine speed you wanted. Of course those waves don't radiate in all directions since there's a pipe attached to the port. Early two strokes had straight pipes, a simple length of tube attached to the exhaust port. This created a single "negative" wave that helped suck spent exhaust gases out of the cylinder. And since sound waves that start at the end of the pipe travel to the other end at the speed of sound, there was only a small rpm range where the negative wave's return would reach the exhaust port at a useful time: At too low of an rpm, the wave would return too soon, bouncing back out the port. And at too high of an rpm, the piston would have traveled up the cylinder far enough to close the exhaust port, again doing no good.
Indeed, the only advantage to this crude pipe system was that it was easy to tune: You simply started with a long pipe and started cutting it off until the motor ran best at the engine speed you wanted.
So after analyzing this cut-off straight-pipe exhaust system, tuners realized two things: First, that pressure waves could be created to help pull spent gasses out of the cylinder, and second, that the speed of these waves is more or less constant, though it's affected slightly by the temperature of the air. Higher temperatures mean that the air molecules have more energy and move faster, so sound waves move faster when the air is warmer.
A complicating factor here is that changes in the shape of the tube cause reflections, or changes, in the sound waves: Where the section of the tube grows in diameter, there will be sound waves reflected back towards the start of the tube. These waves will be the opposite of the original waves that they reflected from, so they will also be negative pressure waves.
Aha! The next important discovery was made--by gradually increasing the diameter of the tube, a gradual, more useful negative wave could be generated to help scavenge, or pull spent gasses out of, the cylinder.
Adding Divergent Tubes, which used to be called "Megaphones," to Two-Stroke Pipes Helped Make Useful Power
Putting a divergent cone on the end of a straight pipe lengthens the returning wave, broadening the power band and creating a rudimentary expansion chamber.
So, to sum up, when the negative wave reaches the exhaust port at the correct time, it will pull some of the exhaust gases out the cylinder, helping the engine to scavenge its spent exhaust gas. And putting a divergent cone at the end of the straight (parallel) "head" pipe broadens the returning wave. The returning negative wave isn't as strong, but it is longer, so it is more likely to find the exhaust port open and be able to pull out the exhaust gases. As with plain, straight pipes, the total length of the pipe with a divergent cone welded on determines the timing of the return pulses and therefore the engine speed at which they are effective. The divergent cone's critical dimensions are where it starts (the distance from the exhaust port to the start of the divergent cone is called the "head" pipe), while the length of the megaphone and the rate at which it diverges from the straight pipe determine the intensity and length of the returning wave--A short pipe which diverges at a sharp angle from the head pipe gives a stronger, more straight-pipe-like pulse. Conversely, a long, gradual divergent cone creates a smaller pulse of longer duration.
In addition, the negative wave is also strong enough to help pull fresh mixture up through the transfer ports.
And while adding a divergent cone to the head pipe produced great tuning advantages, it had its limitations, too: The broader negative wave from a megaphone can still arrive too early and pull fresh mixture out of the cylinder. That's exactly the problem that Walter Kaaden had with the factory MZs. He realized that putting another cone, reversed to be convergent, on the end of the first divergent pipe would reflect positive waves back up the pipe. These positive waves would follow the negative waves back to the exhaust port, and if properly timed would stuff the fresh mixture that was pulled into the pipe back into the exhaust port right as the piston closed the port.
In addition to head pipe length, divergent and convergent cone lengths, an expansion chamber has three more crucial dimensions. The length of the straight 'belly' between the divergent and the convergent cones, the length of the tailpiece 'stinger', or muffler, and the diameter of the belly section. The stinger acts as a pressure bleed, allowing pressure to escape from the pipe. Back pressure in the pipe, caused by a smaller-diameter or longer stinger section, helps the wave action of the pipe, and can increase the engine's performance. This, presumably, happens since the greater pressure creates a more dense, uniform medium for the waves to act on--waves travel better through dense, consistent mediums. For instance, you can hear a train from a long way away by putting you ear to the steel railroad track, which is much denser and more uniform than air. But it also causes the engine to run hotter, usually a very bad characteristic in two-strokes.
Kaaden immediately realized a large power gain, and the expansion chamber was born.
A complete two-stroke pipe has properly tuned header, convergent, belly, divergent and stinger sections--a difficult process.
As the forces in a two-stroke pipe design have become more well-understood, designers have been able to create engines that take more advantage of them and in fact require an expansion chamber to run at all. For instance, a modern pipe has a gently divergent head pipe to keep gas velocity high near the port, a second cone of "medium" divergence, and a third divergent cone with a strong taper. A belly section connects to multi-angled convergent cones, which should exit in a straight line into the stinger for good power. As you can see, modern two-stroke expansion chambers create a complex scenario and are quite difficult to tune.
|1. How to Adjust Clutch if signs of slipping or squealing are encountered:|
|A) Disengage the clutch by pulling handle bar clutch cable lever inward and push the lock button in.
B) The bike should now roll easily. Release the clutch lever and bike should slide the rear wheel.
C) If the rear wheel does not slide when the lever is released this means the clutch needs adjusting.
D) Remove the clutch cover and then remove the locking screw that holds the Clutch Adjusting Nut.
E) Pull the clutch lever arm on left side of engine inward. Back off the Clutch Adjust Nut ½ turn CCW.
F) Release clutch lever arm and check for 1/16" slight clutch arm free-play.
G) Readjust *Clutch Adjust Nut as required to get the required 1/6" clutch arm free play.
H) Now Repeat the B) roll test. Rear wheel should now slide when the handlebar lever is released.
I) Be sure to re-install the small locking screw in outer edge of *Clutch Adjust Nut.
G) Good idea to place a small gob of grease at gear mesh area. Use grease sparingly! Then replace cover.
H) Squirt light grade oil down clutch cable sheathing to reduce friction and make for easy lever pull.
| Carbs now sent to the USA per
instructions from the Dept. of EPA the idle and air fuel mixture screws
must be epoxy sealed or made non adjustable at the factory to avoid
end-user tampering. NOTE: Carbs sent to all
other countries DO NOT have these air/fuel adjustment restrictions.
Depending on clean vs. dusty riding conditions, clean air filter every 5 to
20 hours of operation by removing the filter cover to access the screen
and element. Wash element with a de-greasing agent such as Simple Green™
or Purple Stuff™. Be sure element is completely dry before re-assembly. NOTE: If engine runs poorly clean tank shut off value filter.
|3. 3 pt. Spark Plug|
|Remove spark plug and inspect for excess carbon build
up. Clean, re-gap to .0.036" of an inch if necessary. Check plug after
every 20 hours of operation. New spark plugs are available from your dealer. Be careful using aftermarket spark plugs as heat range
and threads differ greatly. the stock plugs are around an 8 heat range. 7 hotter, 9 cooler. A 6 seems to be a good performance upgrade. An extra plug is included: When
replacing the spark plug in an Angle Fire head it's best to use a 3
point electrode spark plug P/N Z4JC to ensure total combustion. ( Ask your selling dealer for it by part number. ) Electrical components such as magnetos and spark plugs are not warranteed.
|4. Exhaust system|
|After 50 hours of operation check exhaust pipe for excessive oil and carbon build-up. If muffler is clogged
your dealer has replecements.Make sure attaching nuts are tight and no exhaust leaks are occurring. Be sure
to use supplied support strap to secure exhaust muffler to a solid anchor point on bike frame or engine.
A) To remove inside catalytic exhaust insert loosen the retaining screw on end cap and remove.
B) Pull cap and baffle out of pipe. Note: Some catalytic inserts are welded in and cannot be removed. If you need a replacement muffler contact your dealer. 2010 models have an air shield welded on the outside of muffler again per EPA rulings. This insures hot run so catalysis can clean the exhaust.
C) Clean with degreaser, rinse and dry. Re-assemble: File muffler attach flange to have smooth flat surface.
D) Always use a new exhasut gasket and good idea to use double nuts on muffler attach studs;
*NOTE: Excessive periods of low speed operation, idling or leaving fuel petcock in the “on” position during shut down periods may cause the Spark plug to foul with excessive fuel/oil mix, muffler to become clogged with unburned fuel as well. inspect the plug if the engine begins to run rough, has a hard time starting, or runs rough at max cruise speed.
|5. Standard Bike 1/2x1/8” Chain is included in kit. HD 415 is available as an option.|
|Every time the bike is ridden check the tension of the drive chain by:
A) Rolling to bicycle forward to remove slack from the bottom of the chain.
B) Find the center and push downward on the top of chain while measuring the deflection.
C) Tighten chain by loosening rear axle nuts, and pulling wheel backwards, simultaneously tightening nuts withou letting the chains slack. if deflection is more than ½ inch call for assistance.
|6. Head Bolts|
|Tighten all fasteners after each five hours of operation. Most important to check
Cylinder head bolts : Tighten in a X pattern to 15 ft/lb using a torque wrench. A two piece cylinder and
head design engine requires head bolts be kept tight. Important: Check head bolts before each and every
long ride, vibration can cause them to loosen and blow a head gasket. Caution: Do not over torque or head
bolts may break off. ( Twisted or broken head bolts due to over tightening is not covered by warranty. )
|7. Right side gears:|
|Remove cover plate and keep small amount of heavy grease on gear train. Do not over grease
as leaks will occur and also may adversely affect clutch operation.
Regular greasing if required will help reduce gear wear and keep gear
|8. Left side drive:|
|Routinely pack grease on the clutch 47mm long push rod located at the 10T sprocket and also in cover hole around the lever cam. This will make easy clutch lever operation.|
|Items, tools and extra service parts in tool kit; Typical Engine ID plates.
Obey all traffic regulations. Always wear a helmet while riding. Remember that you are riding a motorized bicycle and other traffic may not be able to see you. Never operate your motorized bicycle on a pedestrian through way or sidewalk while the engine is operating. Never operate your motorized bicycle in an unsafe manner. Check local and state laws before riding on streets & wear a helmet.
|ENGINE STARTING & OPERATION PROCEDURE|
|IMPORTANT: PLEASE READ THIS: Gas and OilMixture for Fuel ratio|
|The engine is a 2 cycle design, therefore, a gasoline/oil mixture is necessary to keep it from seizing. During the break-in period (1st gallon of fuel), the ratio is 16:1. 16parts gasoline to 1 part 2 cycle oil. After the break-in period, the ratio is increased to 24:1. 24 parts gasoline to 1 part oil. The engine crankshaft bearings are lubricated from the oil in the gas mix. A rich break in mixture ensures bearings will not cease. !WARNING! Remember safety first: Wipe up any spilled fuel. NEVER fuel a hot engine or light a cigarette while fueling. Especially don't try to light a cigarette from the hot engine. This could result in sudden fire, personal injury, loss of eyebrows. Always move your motorized bike at least 10 feet from any fueling area before attempting to start it. do not try and cook an egg on the engine or exhaust pipe. this will make the engine sticky, and may damage the painted finish. Also, Never leave the tank fuel cap off after fueling as rain water will contaminate the fuel and cause engine failure.|
|Step #1. After filling tank with the correct oil/gas mix open the tank fuel valve. Fuel line is in the open
position when the small lever is pointed down. Move choke lever to the on (up) position. This is the small lever on the right side of carburetor. All the way Up the choke is on. All the way Down the choke is off. Move
progressively downward to off position during engine warm up period.
|Engine Starting procedure for Lever Clutch Models:|
1. Pull the handlebar clutch lever inward, to disengage the engine from the rear wheel.