Motorcycle engine and mechanical noises: what can you find out?

A knocking sound when the engine is hot is almost always a symptom of a serious problem. When the engine is warm, not only hydraulic compensators, unadjusted valves or a timing chain can knock, but also connecting rods, main bearings, or a cracked piston pin, and even a piston that has cracks on its skirt. In any case, it is better to carry out diagnostics not in a garage, but by turning to a car service center for help, since most likely you will need to disassemble the engine.

Engine operating modeCauses of knocking
Knock at idle
  • low oil level;
  • detonation;
  • hydraulic compensators.
Knocking noise when under load and increasing rpm
  • crankshaft bearings;
  • incorrectly adjusted valves;
  • phase shifters;
  • pistons, cylinder walls, pins or piston rings;
  • crankshaft bearing;

general information

Consumer qualities

Buyers, first of all, are attracted not only by the fairly affordable price of mopeds of this brand, but also by:

Appearance plays an important role in the popularity of Delta mopeds

Technical features

For convenience, technical information about the most popular moped from China is grouped into a table:

ParameterMeaningParameterMeaning
NameDELTA YH 50 QTManufacturerChongqing Wonjan motorcycle China
Power unitSingle-cylinder, 4-stroke, gasoline, air-cooled, 40 cc. cm and 110 cc. cm Supply systemCarburetor
Delta moped wiringSingle-wire, 12-volt with “-” to groundIgnition systemNon-contact – capacitor discharge (CDI)
BatteryLead or helium 12 volt 9 A/hourStarting systemElectric and kickstarter
TransmissionChain, rear wheel, 4 gearsFuel consumption2.0 l per 100 km in mixed mode
BrakesMechanical, drumGas tank capacity4.8 l

For reference: the wiring of the Delta moped is designed for capacitor ignition. The photo below shows its schematic diagram.

The attached instructions for the moped also contain a CDI diagram

Electrical equipment maintenance

What can overshadow the operation of a moped is its unpredictable breakdown. And although the manufacturer uses a fairly proven operating diagram for the main components and assemblies, nevertheless, failures in the operation of one or another electronic equipment are possible. (see also the article Features of wiring an Alpha moped)

Wiring to Delta requires attention to connectors and terminals

To avoid this, the owner is required to carry out scheduled technical inspections according to the manufacturer’s recommended periods (based on mileage):

Delta battery

Such close attention to electrical equipment is due to the fact that when driving a moped, the low beam headlights must be turned on at all times. This causes increased wear and tear on all elements of the electrical system. The wiring on the Delta moped also requires attention - the quality of its connectors and connections leaves much to be desired.

The battery deserves special attention for the simple reason that if the charging relay fails, the electrolyte will begin to boil away. (see also the article IZH Planet 2 wiring diagram: installation features)

Mopeds use 2 types of batteries:

Note! Gel batteries are afraid of being completely discharged. Therefore, prolonged movement with a full load on the electrical system is unacceptable.

What to consider when buying a battery?

It’s worth noting right away that it is not necessary to buy a “native” battery for the bike. If the standard battery does not show the best results, it is worth looking for alternative options. But when choosing a battery for an Alpha 110,125 or 50 moped, you should consider the following parameters:

● Terminal type. Now there are several types of batteries on the market with different terminals. Of course, it would be better to buy a component with a suitable connection type. But if you find a really reliable battery, but the type of terminals does not match, you can always do a “twisting”.

● Case dimensions. The dimensions of the new battery should be the same as the parameters of the old one. Only in this case will you be able to install and fix the component in its original place. But if the battery is smaller, make sure it won't tip over or shake too much.

● Capacity. You need to choose a battery based on engine size. If the capacity is not enough, the starting current will simply not be enough to start the engine. Therefore, for Alpha and Delta mopeds, it is recommended to choose batteries with a capacity of 5 A/h.

● Starting current. How easy it will be to start the engine depends on this indicator. For Alpha motorcycles, it is recommended to take a battery with a starting current of 12 volts. And for 50cc Alpha bikes you can buy a 6 volt battery.

You also need to take into account the brand of the moped battery. The durability of the component depends on the manufacturer, so it is recommended to give preference only to well-known brands. If you don’t know which battery is best to choose, contact the specialists of the dvako.com.ua store.

Bicycle fork overhaul and repair

In our bicycle workshop we overhaul and repair bicycle forks of all models (fox, rockshox, marzocchi, manitou, magura, cannondale, suntour, rst, formula) using different technologies depending on mileage and model, here are some prices and descriptions for work with forks bike:

Maintenance of new forks without traces of use price 900 RUR

Scheduled economy maintenance (includes changing the oil in the pants, cleaning from dirt, checking the pressure in the air chamber) - Price from 1100 rub

Full maintenance of the RockShox fork (changing the oil in the pants and damper, cleaning from dirt, lubricating the air chamber - Price from 1500 RUR

Maintenance or repair of the fork with replacement of bushing seals and other parts, including acceleration of the fork to the desired stroke - Price from 1100 rubles to 2000 rubles , depending on the complexity and time costs.

for models older than 2006, the price can vary from 900 to 2500 rubles depending on the design

Maintenance of new forks without traces of use. Price 900 rub.

Scheduled economy maintenance of a fork with a damper separated from the fork legs. Price from 1200 rub.

Fork maintenance including oil change and clean seals - Price from 1500 RUR

Maintenance or repair of Fox forks associated with replacing oil seals, bushings, cartridge overhaul, etc. (including rebuilding the cartridge of “X” forks with theralodgic and restoring the functionality of the cartridge) - Price 1200-3000 RUR

Fork maintenance including oil change and cleaning of dirt - Price from 1400 to 2300 rubles. During operation, only original oil is used.

Fork maintenance including oil change and cleaning of dirt - Price from 1600 RUR

Scheduled economy maintenance (includes changing the oil in the pants, cleaning from dirt, checking the pressure in the air chamber) - Price from 1100 rub.

Full maintenance of the Manitou fork (changing oil in the trousers and damper, cleaning from dirt, lubricating the air chamber - Price from 1800 RUR

Economy maintenance of forks with separated damping systems.
Price 1100 rubles
Fork maintenance with oil change and cleaning of dirt - Price 1800-2500 rubles

When working with Marzocchi , the price, work time, etc. can be determined in half the cases only in the workshop, since due to the sale of the Italian company in 2004 to suntour and the subsequent bifurcation of production and technology, a huge number of models were produced, each of which has its own nuances . From year to year, fillings, leg coverings, etc. were changed in dozens of models. Under different conditions of use in real conditions, Marzocchi forks behave differently and present more and more new surprises.

Correct bearing migration - Price 1400 RUR

Complete overhaul with replacement of corrugations, filter, cleaning of bearing cartridges - Price 3300 rub. (not including corrugation and filter)

We also carry out work on replacing bearings, changing the oil in the cartridge, changing repair kits for the fork air chamber (a fairly common problem when the Lefty air chamber deflates due to the upper position of the piston)

Materials and oils used for rebuilding and repairing bicycle forks:

Replacing bicycle fork seals

We replace seals in bicycle forks; we always have seals for the entire line of RockShox, FOX, Magura, Marzocchi, Manitou forks; we also have consumables and bearings for forks from Cannondale.

When replacing oil seals in forks, we use only original materials (attention, installing non-original oil seals quickly damages the guides and fork legs)

When working with forks, we are the only place in Moscow where all types of oils are used!! Motorex, Motul, FOX, Fox fluid, motorex supergliss, RockShox, Magura oils are always available. When rebuilding forks with us, you can use both original oils and their cheaper substitutes. Moreover, we have Motul and Motorex oil substitutes in all viscosities from 2.5 to 20.

The cost of an oil change is not included in the cost of service. All oils, with the exception of Magura and DT, cost 300 rubles, regardless of quantity. Magura and DT - 500 rubles. If you bring your own oil, we will fill it for free.

The uniqueness of our bicycle service lies in the fact that we have been working with forks for more than 10 years and have accumulated vast experience. Moreover, various shock-absorbing systems were rebuilt in our service using various technologies, and all our tests and experiments were tested and verified, not directly on bicycle tracks, because we are the only bicycle service that has assembled one of the strongest cycling teams in the cross-country discipline.

Cannondale FATTY - review and instructions from the Veloline service

Knock in the engine on an alpha moped.


One of the problems motorists face on mopeds is a knocking sound in the engine. There are different types of knocking, but a knocking sound in the engine means that it definitely needs to be repaired.

Causes of engine knocking on a moped:

  1. The most harmless thing is that your valves are knocking. To check this, you will need (in the simplest version) a screwdriver; it is best to use a medical stroboscope or, well, or a professional one, if you have one. Next, take a screwdriver and apply the handle to your ear, and lean the other end against the engine. And so lean it against each part of the engine and you will be able to approximately position where you are knocking. Valve knocking differs from other knocking sounds in that it is more metallic. It feels like light pieces of metal are hitting each other. If the valves are knocking, the knocking will be louder on a cold engine than on a warm one. Typically, valve clearance decreases as it warms up, so the valves knock louder when cold.
  2. The timing chain may also be knocking. In lower engine engines, the timing chain cannot knock, because it is not there, there are pushers. They will also knock, but in this engine this is not a breakdown. The timing chain may be knocking because the timing chain tensioner is broken; if it is broken or worn out, the timing chain will start knocking. This is only checked when you disassemble the engine and check the chain. The timing chain can also stretch and the tensioner can no longer tension and the chain begins to knock. There is only one way to check this. Remove the tensioner, then you need to press on it, and if you understand that the chain does not tension when fully pressed, when the tensioner is fully recessed, then the chain definitely needs to be changed.
  3. The bearings may also be knocking. Bearings can knock in the basket, they can knock in the box. If you heard an engine knock on the right side, then if you depressed the clutch, the knocking stopped, and when you released it, the knocking started again. In this case, your release bearing has died or your clutch basket has simply weakened. Further, if the knocking occurs at idle, or when engaging any gear, then the bearings may be to blame. You will definitely have to disassemble the engine and see if you have worn out bearings, if the seal is broken and if the bearing is intact. If suddenly you experience a knocking noise only when you engage a certain gear, this means that you have a broken tooth on the gear, either a tooth or a hook. This is very bad, under no circumstances should you drive such an engine, because it could jam at one moment.
  4. The most unpleasant type of knocking that occurs on engines. If suddenly there is an oil starvation or you have driven a huge number of kilometers on this engine, then the crankshaft and connecting rod may lift up. How can one understand such a knock? The knocking sound will be as if throughout the entire engine, as if someone is hammering the crankcase with a hammer. A very sharp, loud sound that does not disappear at any speed. If you hear such a sound, turn off the engine immediately and do not try to continue driving. If your valves or timing chain are knocking, then you can drive to the garage and get it fixed; if the gearbox is knocking, then you can also get there, but it’s not advisable, and if the crankshaft is knocking, then stand still and don’t move.
  5. Bendix may also knock. When it is produced, it develops a slight imbalance. If you hear a knock from here, then you need to check the bendix.
  6. What else could a knock mean when you heard such dull knocks, but a grinding sound is added to them? If you heard that grinding and knocking and when you add gas they only intensify, then it means that the crankshaft bearings in your engine have fallen apart. Because in such engines the crankshaft lies in bearings. The main bearings are immediately replaceable.

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