When and why to check the circuit
Manufacturers recommend checking every 1,000 kilometers. Under intense loads, if you have to travel hundreds of kilometers per day, inspection is required much more often. But by installing a high-quality chain, the motorcyclist will be able to reduce the number of checks.
Just by looking at the moped from the outside, it is not difficult for a specialist to determine if the chain is not tensioned correctly. Such an error when servicing a moped can lead to a break in the chain during a trip. Over-tightening occurs quite often and, despite the presence of lubrication, leads to accelerated wear of the chain. As a result, the suspension begins to work incorrectly. Over time, the hub may fail.
A poorly tensioned chain also often causes breakdowns. When moving, it will fluctuate greatly, and as a result, difficulties will arise with switching speeds. The shock load on the gearbox gears and rear hub will increase. The chain can lock the wheel axle by wrapping around it. Such a breakdown can lead to a serious accident.
The transmission of torque from the motor to the rear wheel in Alpha mopeds is carried out through a chain drive. This mechanism uses two stars connected by a chain. The first sprocket is connected to the gearbox, the second to the rear wheel.
The degree of tension changes as the pendulum moves along an arcuate path by the length of the suspension stroke. When stretching, it is important to remember that there should be a margin of 2-3 centimeters in length. Maximum tension is achieved when the following elements are lined up:
- pendulum axis;
- secondary shaft;
- wheel axle.
Video on this topic
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#41 How to determine the alpha chain stretch of a magnifying glass?
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Alpha 110 (Change timing chain)
They brought in a moped (Alpha 110) with a complaint about a foreign knocking noise in the engine, as it turned out that it was loose timing chain. Foam.
Replacing the camshaft tensioner and Delta timing belt
Repair of a Chinese moped. There was a strong blow to the engine.
Alpha 110 (Replacement of magnet chain)
Foam filter for Alfa moped https://goo.gl/MF6F3b Digital thermometer.
Preparatory work
It is imperative to clean the chain, otherwise tensioning will not work. There is grease on metal surfaces, and dust accumulates on top over time. These contaminants cannot be washed off in ordinary water; you need to use auto chemicals. It is better to choose a product in the form of an aerosol that will not corrode the seals - chain O-rings
If the mechanism is heavily dirty, it is advisable to remove the cover from the drive sprocket. It is important to ensure that the retaining nut is well tightened. The cleaning itself is carried out as follows:
- First, rotate the moped wheel while spraying the cleaning composition.
- The mechanism is left for several minutes so that the product is well absorbed into all the recesses.
- Using a stiff brush, remove dirt from the sprockets and chain.
- Use a clean cloth to wipe all parts of the mechanism.
Cleaning a moped chain
Now you need to determine the degree of wear of the elements. The chain links should not jam, ideally they move easily. It is also necessary to check the presence and condition of the seals. The sprocket teeth must not be bent, pointed or damaged. Wear on the tooth surfaces may be associated with improper installation of the rear wheel.
To determine the condition of the chain, you need to check whether there are areas where the tension is too high or, conversely, weak. To do this, you need to manually turn the wheel. If such areas are present, it means that the bushings and pins have worn unevenly. In this case, the distance between the pins increases and the chain becomes longer.
Severely worn chain
Often the cause of the appearance of sections with different tensions are problems with other components of the moped. The sprockets may be installed with an incorrectly centered hole or the wrong diameter. Uneven tension may be due to severe wear on the wheel hub or failure of the sprocket hub bearings. But other damage may also be discovered, so it is important to carry out a thorough inspection.
It is easy to determine the degree of wear by the length of the chain. To do this you need to pull it back. It is important to try to pull the chain off the sprocket at the same time. Replacement is required when, when attempting to remove, most of the sprocket tooth becomes visible. If the chain rollers are bent and squeak when driving, it is better to change the part along with the sprockets.
After cleaning, you need to align the rear wheel. This is an easy task if the axis is marked. But the marks sometimes get confused, so additional checking is necessary. As the rear wheel rotates, you need to shine a flashlight and pay attention to the chain. If it does not move straight, it means the installation was not done correctly.
After installing the rear wheel, you need to remember where the marks are located. If they are not symmetrical, this indicates that the marks were applied incorrectly. In this case, you can draw new marks on the reverse side of the chain with a marker. When tightening the rear axle, it is important to push the wrench toward the front wheel.
To change or not to change?
Suppose you are overhauling your engine: changing oil seals, crankshaft, gaskets and other devices, but you doubt whether to replace the timing chain with a new one or not. If you have any doubts, change it for a new one at the first opportunity. And now I will explain why.
See for yourself: a chain has an average service life of approximately 18,000-20,000 km of a scooter (personal experience), approximately the same as the average service life of the engine itself. And for example, after driving 6,000 km, the crankshaft jammed or the engine leaked, or something else happened that requires complete disassembly of the engine. Naturally, you disassemble the engine, replace the crankshaft with a new one, and leave the chain, which by that time has exhausted a third of its service life.
And what happens? The chain, after 12,000 km, will exhaust its service life and become unusable, but the crankshaft and other parts will be in good order and whether you like it or not, you will have to halve the engine again, because of the chain alone. Is it necessary? The chain is a consumable. Never skimp on it!
Personally, I never check timing chains. I simply throw them in the trash, no matter how awesome they seem to me. A chain is a consumable item for me, just like a spark plug, oil or oil seal. But if you are important, or money is tight, you can use the old fashioned way.
Alpha tensioner repair
alpha
Tensioner repair 149 fmb.
We stretch the chain along its length, hold it with our fingers and try to position it in a horizontal position
- If the chain describes an arc that looks very much like a 90-degree angle, then feel free to throw it in the trash.
- If the chain bends slightly and describes a small arc, then such a chain is quite suitable for further use
Tools for replacing a chain on a moped
Open-end and box-end wrenches are used. In total, you will need four keys with a diameter of 10, 14, 17 and 24 millimeters. Depending on the moped model, instead of a diameter of 24, you may need 22 mm. If you have sockets and ratchets, you can replace some of the keys with them.
To tension the chain you will need wrenches 10, 14, 17 and 24
Just in case, it is better to stock up on a flat-head screwdriver; it will allow you to lift the bolts if they cannot be removed by hand.
Before you start adjusting the valves
Therefore, after purchasing a new Alpha RX, I checked the valve clearance. For this procedure I had to buy a set of probes. In our case, you will need a probe with a thickness of 0.05 mm.
In order to calmly begin adjusting the valves, I had to unscrew the safety bars. For this we need a key of 8.
To get to the valves, you need to unscrew the valve covers located on the top and bottom of the cylinder head. To do this we need a 17 wrench. I used a spanner.
How to tension a chain on an Alpha moped - step-by-step instructions
To simplify access to the necessary components, first remove the rear left passenger footrest. The moped must be placed on the center stand. It is also advisable to unscrew the bolt and remove the exhaust pipe. If this is not done, the ratchet heads cannot be used.
Next, take two keys - 17 and 14 mm. You need to unscrew the nut to loosen the wheel axle. The nut is unscrewed, but not completely. With the second key you need to hold the axle on the reverse side so that there is a stop. If you don't hold it on the reverse side, the axis will spin.
Now you need to loosen the nut located on the other side using a wrench with a diameter of 24 mm.
Using a wrench with a diameter of 10 mm, tighten the chain tension bolt. But the tension should not be too strong.
The rear axle is weakened. You need to make sure that the teeth of the driven sprocket do not fall on the edge of the chain. To do this you need to spin the wheel. When the teeth come in from the right, you need to tighten the bolt a little using a 10 mm wrench. If they enter from the left, it is necessary to loosen it, and if from the right, then, on the contrary, tighten it.
Now you need to tighten the wheel axle with 24 and 17 mm wrenches. The second bolt is tightened with a wrench with a diameter of 14 millimeters. The chain is tight, all that remains is to install the left step and protection.
To properly tension the chain, you will have to align the marks on the sprockets. There are risks and sticks on the suspender. These marks are applied on both sides.
You need to try to ensure that the risks on the right and left coincide. If these marks are not aligned, the wheel will not stay level. Naturally, it will also spin incorrectly. As a result, the rubber will begin to wear out intensively on one side. Therefore, it is important to tighten the nuts on both sides.
For more accurate tightening, it is important to remove the cover covering the chain. Otherwise, there is a chance that it will be pulled too tight. After tensioning, the brakes may also need to be adjusted.
Useful visual video on how to tighten the chain on an Alpha moped:
Let's start adjusting the valves
Let's start with the intake valve, which is located at the top of the cylinder head. We'll need a key for 9. Yes! Not 8, not 10, but 9! Good thing I had a set of sockets in the car. But it is better to use a spanner wrench, which conveniently unscrews the pusher fixing nut on the rocker arm.
Then we need a feeler gauge with a thickness of 0.05 mm, which must be inserted between the pusher and the valve stem. By rotating the pusher, we reduce or increase the thermal gap until the probe moves with slight tension. After tightening the fixing nut, we again check the gap with a feeler gauge, which could have gone astray.
In a similar way, we begin adjusting the exhaust valve.
Tuning Alpha: increasing speed and traction
Option #1. We set the engine to 110cc
The easiest way is to install a new engine, already tuned to 110cc, which can be found and purchased online. But it is also the most expensive.
increase the engine power yourself through improvements, because the standard volume is 72 cc, and you can accelerate it to 110 cc. And here is another option - to remake the original 72cc engine by purchasing a 110 cc piston group (cylinder + piston + pin + rings) and a 110 cc cylinder head for Alpha, Delta or Zodiac mopeds. When ordering, do not forget about the set of gaskets for the cylinder-piston group, which is also presented on our website. It will cost much less.
Professional approach
Many motorcyclists treat chain tensioning as a routine procedure, during which significant tolerances can be made and the position of the rear wheel can be adjusted “by eye”. This approach when setting the required chain tension is unacceptable - all operations must be performed as carefully and accurately as possible, using special tools. If you want to extend the life of the chain and avoid severe wear on the transmission when using the motorcycle in extreme conditions, you should purchase a special laser gauge to set the optimal wheel position. In the most difficult cases, if you cannot understand the structure of the adjusting mechanism or cannot loosen it, you should contact the specialists of a motorcycle service station. They will carry out all the necessary work, providing you with a guarantee of the quality of the result and the reliability of the motorcycle.
A distinctive feature of a moped from a scooter is that the former has a chain instead of a belt, so sooner or later quite typical breakdowns occur with Alpha mopeds. The chain tends to stretch over time, after which movement becomes quite problematic. You can tension the chain yourself; no special skills are required. But know that you don’t need to tighten the chain on the Alpha moped too much; the free play should be from 2 to 3 cm, otherwise you will face much bigger problems.
So, if you don’t know how to tighten the chain on an alpha moped, follow the instructions below.
First of all, remove the passenger footrest so that it does not interfere with tensioning. Then place it on the center stand. But some experts recommend tensioning under a certain load on the moped, because on the center stand your vehicle will be supported by weight; after tensioning the chain, you will notice that it has become even more tense, like a string. This oversight leads to serious damage; many say that an overtightened chain after 1 thousand km leads to a breakdown of the entire clutch mechanism.
How to tension a chain on an Alpha moped
Next, you will have to unscrew the nuts of the central axle of the wheel, this will help loosen the wheel axle. To do this, a 14mm wrench is suitable, after that you will have to unscrew the nut located on the same axis, but then, in the case of the Alpha moped, a 24mm wrench will do. After this, we proceed to adjust the chain; on the same axis there is a chain tensioner with a nut, just enough tighten it, this will require a 10mm wrench.
You will have to tighten the nut until you feel that the chain is tensioned. In this case, the teeth should not fall on the edge of the chain, check this, and only then can you begin the final procedure - tightening the axle nuts back. Tighten these nuts well, but do not overtighten them. That's all, as you can see, tensioning the chain on an alpha moped is quite simple.
>> Repair of four-stroke scooter motor.
Repair of four-stroke scooter motor
As an example, we consider a four-stroke air-cooled scooter engine licensed by Honda, widely used on scooters from Chinese companies (for example, Lifan). The engine displacement can be 50, 125 and even 150 cm3. For other models, the design of the main components may be slightly different, but the basic repair techniques and the tools used differ slightly. Before disassembling the engine itself, it is necessary to remove the plastic casings of the forced air cooling system.
Adjusting valve clearances
When the need for adjustment arises, what tool should be used and in what sequence all work should be performed is described in detail in the section devoted to repairing the Mokika engine. The differences in the design of the scooter's engine are minor. To access the valve mechanism, you need to remove the cylinder head cover. By turning the crankshaft using a kickstarter or a socket head by the generator rotor (for which there is a hole in its cover), we achieve such a position of the timing chain drive sprocket in which two marks on the sprocket (in the form of dots) are parallel to the plane of the head connector, and one the large hole is perpendicular to them (1). In this position, using a feeler gauge, we measure (as described in the previous section) the gaps in the valve mechanism (2).
On a cold engine, the clearance should be 0.05 mm for the intake and exhaust valves. If necessary, adjust the gap as described in section (3).
Removing and installing the cylinder head
We carry out the work on the engine removed from the scooter, with the carburetor removed and the cylinder head cover removed. The cylinder head is tightened with four nuts onto anchor pins, which are screwed into the engine crankcase and pass through the cylinder head. In addition, on the left side of the engine there are two bolts that also attract the cylinder head to the crankcase. We unscrew the four nuts (4) and separate the base of the rocker arms along with the rocker arms and their axles. To relieve the timing chain tension, the chain tensioner must be removed. For the engine in question, the timing chain is tensioned automatically during operation. The tensioner housing is located in the upper left part of the engine near the carburetor and is covered with a plastic casing. We unscrew the self-tapping screw securing the casing, and then using a “10” wrench, unscrew the two bolts securing the tensioner housing and remove the entire mechanism (see Fig. 9 for the location of the mechanism). Remove the top cover of the camshaft support bearings located in the cylinder head (5). We remove the camshaft assembly with bearing and drive sprocket (6) from the support bearing beds.
Using a 10mm wrench, unscrew the two bolts securing the head to the cylinder. We tap the head and move it up along the studs as if along guides (7). The joint between the head and the cylinder is sealed with a gasket, which is important not to damage.
When reassembling the cylinder head, the greatest difficulty is the correct installation of the timing chain sprocket. We drag the chain with a wire through the cavity in the head. We put the chain on the sprocket mounted on the camshaft and place the shaft bearings on their beds in the cylinder head. We install the base of the rocker arms in place along with the rocker arms and their axles. We tighten the nuts crosswise in several steps, controlling the tightening torques using a torque wrench. Be sure to check that the valve timing is set correctly: it is necessary to align the marks on the camshaft sprocket and on the head, as well as on the generator rotor and engine crankcase. If you turn the engine crankshaft with mismatched marks, the piston may hit the valves and cause them to fail. To see the marks on the generator rotor, you need to remove its casing on the right side of the engine. Turning the crankshaft by the generator rotor, we set the “T” mark opposite the characteristic tide in the form of a horizontal shelf on the crankcase body. In this position, the timing marks in the cylinder head should coincide. If they do not match, the sprocket must be moved one or more links relative to the chain.
The work of replacing oil seals, grinding in or replacing valves does not differ from those described in the section on repairing the Mokika engine.
Removing and installing the cylinder, piston and piston rings
The cylinder is held to the crankcase by four studs and two bolts that pass through the cylinder head and through the cylinder itself. If the head has already been removed, the cylinder simply slides up along the mounting studs (8).
Determining the optimal speed during break-in.
Any technique has technical differences, and mopeds with different cubic capacity also have different maximum speeds. To determine this speed, you need to carefully study the technical data of a four-stroke moped and take 75% of the maximum speed from the data specified by the manufacturer.
For example, a 110cc moped with a 15-teeth drive sprocket has a maximum speed of 85 km/h. This means the maximum break-in speed in fourth gear will be 63 km/h.
It is also worth remembering that the throttle should not be turned more than 2/3 of the maximum value. Many novice owners of mopeds and scooters think that they need to dilute gasoline with oil, but with four-stroke engines, this is not necessary. Once in the combustion chamber, the oil does not burn and is deposited on its walls.
Video: New Alpha moped 2022 110cm³ | Alpha ZS-50C | Replacing a 14-tooth drive sprocket with a 16-tooth one | Vlog 03/2020
Tuning features
The topic related to Alpha tuning is quite common, since there are many ways to improve the quality of this moped. At the same time, the cost of modernization will be an order of magnitude lower than in the case of a similar Chinese scooter. After all, Alpha is made quite simply, so access to the power unit and external elements is as convenient as possible.
The model can be improved in various directions, so before starting work you need to decide on the qualities that you want to change. Another important nuance is that you should understand the difference between styling and tuning. The first involves solely changing the appearance, while the second option also affects the functional parameters of the vehicle.
