Why does a 4-stroke scooter smoke (photos and videos)

The starter screams, the cord comes out

- May scream if there is a lot of lube on the balls.
It is necessary to clean the balls and the places in the ratchet where they are inserted. The cultivator released several pops and began to “float”

- Most likely, the power system is not coping, or the fuel level in the tank is low, the float axis may be skewed and perhaps there is debris under the needle valve, you need to remove everything and check the air filter, jets.

The material will be updated, we will be waiting for questions, stories about the detection of a particular malfunction and ways to eliminate it. Also see Answers to questions about a particular walk-behind tractor model on its description page.

Is your engine running but emitting white or blue smoke? Learn what can cause white smoke in your engine and how to fix it.

CAREFULLY

! Always read the engine and equipment manual(s) before starting, operating, or servicing the engine or equipment to avoid personal injury or property damage. See your authorized dealer or contact Briggs & Stratton if you are unsure of any procedure or have additional questions. Find all engine hazard warnings

The Internet teaches you a lot... Even money...

So, I’ll tell you about the reasons why a car smokes. But first I’ll tell you what happened in my case, and later in general about common possible problems; the Internet is full of standard articles! My car, a Kalina 1.4 16 valve, smoked blue smoke even when it just started and you gave the gas sharply. After some time (a couple of minutes) the smoke went away. And sometimes it would smoke at a traffic light when I accelerated sharply.

The problem with blue smoke is when oil gets into the fuel and burns, causing blue smoke.

In my case, the situation was quite terrible... They made the engine head, changed the oil caps, exhaust valves, piston and rings. All this turned out to be quite expensive... Who is interested in the prices: the rings from the piston to the viburnum 1.4 are special, indestructible and seem to be German, and they are very difficult to get... I got them for 7000 rubles. Head repair 5000 rub. Well, plus some little things... It cost me this way, because... My relatives' car service. After that, my car stopped smoking completely and now flies, or almost... I haven’t done everything on it yet...

And now about the possible reasons:

Why does the car smoke blue smoke (color).

The main reason for the appearance of blue or gray smoke is oil combustion, which means oil gets into the engine cylinders. This means that if there is blue smoke, it means that your machine is eating a lot of oil! Keep an eye on his level! Oil can get through the gaps of the piston, rings, between the valve stem and guide bushings.

Causes of excessive smoke in a 4-stroke

Unnatural smoke from the exhaust pipe of a moped or scooter can be caused by a number of problems. Among them:

Fuel mixture too rich
Wear of the piston group or oil scraper wheels
Problems with valves and their seals
Engine oil
Cylinder head gasket

The 4-stroke engine of a Chinese scooter smokes

The 4-stroke engine (139qmb) of a Chinese scooter smokes heavily and a possible reason is rings or oil seals

I didn’t want to disassemble the piston on the 139qmb Super Sport Acar scooter but I had to. An attempt to fix it by adjusting the carburetor did not lead to anything, and thick blue smoke at rpm and the smell of burnt oil indicated that the whole problem was in the piston or valve stem seals.

To my great pleasure, removing the cylinder on a 139qmb scooter engine is not a long process and after half an hour I was surprised to see the internal view of the piston group and head. The piston turned out to be 47 mm in diameter, which generally pleased me. Extra personalities are never superfluous.

There were a lot of surprises. After removing the head, it turned out to be a damaged piston bottom and a coked exhaust valve cap. After removing the cylinder and piston, the picture became completely clear.

The upper compression ring is in critical condition. The gap at the joint was within 5 mm. The oil scraper did not seem to work at all, because it did not extend beyond the groove, although it cannot be called stuck either. The wear on the cylinder mirror was visible to the naked eye.

It is necessary to change the piston group assembly. But there was no store nearby with spare parts, and buying online could take a long time. I decided (for now...) to make do with my own means. At home I found new rings from the Druzhba 4M chainsaw - 48 mm in diameter (on the engine ( 139qmb ) of the scooter - 47 mm) and began to adjust them. The scooter's second compression ring was in acceptable condition. The first one was made from “Druzhbinsk”, grinding down to almost twice the thickness. We also had to reduce the ring circumference by three millimeters, ensuring that the ring in the middle part of the cylinder had a gap at the joint of about 0.15 mm. The oil scraper ring was also made from “Druzhbinsky”. The width of it exactly matched the groove of the piston. It just had to be reduced in circumference and side grooves made for excess oil. The version is experimental and requires testing in action.

On the left are the new “friendship” rings, on the right they are adjusted for the scooter. The disadvantage of such modernized rings is that they do not match the geometry of the cylinder, because they are designed for a diameter of 48 mm and require time to break in. After installation, the engine continued to smoke, but to a much lesser extent.

Adjustment procedure

Proper engine operation depends on compliance with operating rules and strict compliance with technical inspection requirements. Before you start setting up the carburetor on the Alpha moped, you need to first carry out a number of works:

Clean the carburetor body.
Replace the spark plug.
Replace the air filter.
Make sure the connections are tight.

Now you need to accurately set the gasoline level in the float chamber by bending the float tongue. By connecting a transparent hose to the drain fitting, it is possible to determine the absolute fuel level. To do this, the hose is lifted up. Typically the height is at the junction of the carburetor caps.

The next step is to adjust the idle speed system using quantity and quality screws. The whole process takes place on a warm engine. The quality screw is screwed in until it stops and then unscrewed two turns. Start the engine and, by rotating this screw in both directions, achieve maximum speed. Then use the quantity screw to reduce the speed to the minimum stable speed. It is possible that the procedure may need to be repeated several times until the desired result is achieved.

Adjustment of the middle speed range occurs by raising or lowering the needle. To do this, you need to unscrew the throttle nut, remove the needle and move the corkscrew into one of the grooves: above the middle division to lean the mixture and below to enrich it.

How to Find and Fix Engine Smoke Problems

If you want to troubleshoot a small engine yourself and repair it.

Step 1: Are you tilting the engine or running it at an angle greater than 15 degrees? Leaning the mower or equipment may cause leakage. Level the car before proceeding.
Step 2: Checking and changing the oil is an easy way to fix such problems. Check to see if the oil is overfilled or if you are using the wrong grade/type of oil.
Step 3: Check the crankcase for leaks.
Step 4: Is the cylinder head gasket blown?
Step 5: Are the rings and/or cylinder worn?

Overheat.

Plug Type: Extremely white insulator with small black flecks and premature electrode erosion.

Consequences: loss of scooter power at high speed or under load.

Probable causes: the spark plug is not screwed in enough; The scooter's engine cooling system is not working properly; ignition of the scooter too early; The thermal range is incorrectly selected - the candle is too “hot”.

Remedy: check the torque of the scooter's spark plug; operation of the scooter engine cooling system; adjust the ignition timing; select the correct spark plug heat rating.

Type of spark plug: melted and burned central and grounding electrodes (or one of the electrodes) of the scooter spark plug; bubbling insulator with metal deposits on it.

Consequences: significant loss of scooter engine power; ignition interruptions. Continued use of such spark plugs may cause serious damage to the scooter engine.

Probable causes: thermal overload; significant overheating of spark plug parts due to glow ignition - combustion begins before a proper ignition spark appears; use of low-quality fuel; burning out of the remaining air-fuel mixture in the combustion chamber due to an incorrectly adjusted fuel system of the scooter or the ignition timing of the scooter; The thermal range is incorrectly selected - the spark plug is too “hot”.

Remedy: check the scooter engine, ignition system and fuel system, as well as the quality of the working mixture and the ignition timing of the scooter. Install new spark plugs with the correct heat rating.

The engine emits blue smoke

The engine begins to smoke blue or gray smoke if an excess amount of engine oil penetrates the cylinders. This smoke may be blue, blue, or similar shades. Engine oil smoke is thicker. If you bring paper to the exhaust pipe, greasy stains will remain on it.

The first sign that will indicate the cause of smoking is a significant excess consumption of oil (from 0.5 liters of oil per 1 thousand kilometers). In some cases, it is difficult to identify the problem only by the color of the exhaust. Diagnosis is complicated by the presence of a catalyst that purifies exhaust gases.

Definition of failure

Oil penetrates into the combustion chamber both through the piston rings and through the leaks between the valve stem and its guide sleeve. In the first case, wear of the CPG occurs. The list of possible problems includes:

The wear of the CPG elements often coincides with the fact that the compression in the engine decreases. An increase in crankcase gas pressure is also possible. It should be added that in case of slight wear of parts, the engine will smoke blue smoke only when “cold”. As the engine heats up and the thermal expansion of the parts, the gaps between the parts in the cylinder can return to relative normal. As a result, the engine smokes less noticeably or the smoke disappears completely. If the wear of the CPG is significant, then as the engine warms up, it will begin to smoke more, since the heated oil dilutes and enters the combustion chamber more actively. Thermal expansion of parts with severe wear can no longer compensate for the increased gaps.

As for the timing belt, oil smoke is often associated with wear on the valve stem, guide bushings and problems with valve stem seals. The engine may also smoke blue exhaust if there are ignition problems. To check, you can unscrew the spark plug on the problem cylinder. The presence of abundant black carbon deposits will indicate a problem.

A fairly rare cause of blue exhaust smoke can be a rupture of the special regulator membrane on automatic transmissions that have a vacuum load sensor. A design feature is the connection of such a box with the intake manifold using a special pipe. In the event of a malfunction, the engine simply draws liquid transmission oil from the automatic transmission.

Silencer for walk-behind tractor - manufacturing, shoots, flames, video

When a problem-free walk-behind tractor begins to act up, the owner falls into a kind of stupor and begins to look for the cause of the problems. The appearance of such a situation is doubly annoying when there is a lot of work and there is no time for downtime.

Often, troubles arise with the muffler, which, for certain reasons, begins to make strange sounds or even behave suspiciously. The main thing is not to panic, but to deal with everything with a cool mind. Let's get acquainted with several problems that occur most often.

The walk-behind tractor shoots into the muffler: what to do?

The owner of such useful and multifunctional equipment needs to know that interruptions in the operation of the muffler can occur due to:

thin and low-quality metal;
frequent potholes;
excessive loads;
difficult work;
fastenings of an ill-conceived plan.

Often the cause of popping noises in the muffler are gaps in the process of supplying sparks and spark plugs. To get rid of the problem, you need to unscrew the spark plug, combine its body and mass, turning the crankshaft using the existing starting handle.

At the same time, you should pay attention to whether a spark appears. If even after these manipulations the situation does not change, it is advisable to thoroughly clean the spark plug.

Flame from the muffler of a walk-behind tractor and black smoke: looking for the cause and solution

Many experts believe that such problems arise due to incomplete combustion of fuel in the unit. It is possible that a misfire, the use of an overly rich mixture, a drop in power or overheating may be detected.

If, after trying to start work, not only a flame appears, but also black smoke, then we are talking about the use of low-quality oil or seriously contaminated injectors. Naturally, it is advisable to purchase a higher quality lubricant and thoroughly clean the injectors of all excess.

When a muffler, in addition to the indicated points, also produces serious noise, and a person wants to make it quiet, then it is necessary to increase the weight of the parts, because such problems often arise due to the lightness of the components.

You can get acquainted with other problems that arise with silencers Neva, Centaur, Garden Scout, etc., as well as their solutions, thanks to the video below, where a specialist presents everything in an accessible way and gives answers to the most frequently asked questions.

Why does my scooter smoke?

Any scooter owner faces various strange faults or defects and one of the most asked questions is heavy smoke coming from the exhaust pipe of your scooter.

If you notice strong and thick smoke, do not despair and do not panic - a similar problem happens with absolutely every scooter. But be vigilant and if your exhaust pipe is emitting very thick and strong smoke, be alert and learn more about this problem, which has many factors behind it.

The first reason for thick smoke is the process after which you add oil to gasoline. Usually scooter owners do this after replacing the cylinder-piston group, so don't be afraid of this process, it's quite normal. But this is not the only case when a scooter smokes without malfunctions. The second point is the fact that any two-stroke scooter smokes. The fact is that the system of such a scooter is that oil is burned along with gasoline. That is, in any case, it ends up in the piston group and, accordingly, after the oil burns, thick smoke comes out. You must have noticed this process more than once on almost all Japanese scooters.

Worn piston group

But in any case, the smoke should not be too strong, so let’s consider the main reasons that answer the question: why does a two-stroke scooter smoke ?

Scooters have different mixtures, and if it is enriched, then the wrong amount of fuel and oil will flow into the piston group, which again contributes to heavy smoke.
Broken piston. In most cases, old piston engines begin to produce strong smoke from the exhaust.
Low speed. For this reason, a similar breakdown also occurs, because if you are not a fan of speed and drive at low speeds, the required amount of oil is not processed and begins to accumulate in the exhaust pipe, and then it begins to turn into smoke.
Faulty oil pump. Many cases of smoke have occurred due to a broken oil pump, which is not capable of handling the required amount of oil. The wrong amount gets into the piston group, and then you know what happens.

Why does smoke come from the exhaust pipe on a 4-stroke scooter?

Four-stroke scooters are very different from two-stroke scooters in their design, so they have a completely different fuel and oil handling mechanism. If you regularly notice that your scooter is smoking every time, be wary and try to correct the cause of the smoke. The mechanism of a 4-stroke scooter is made in such a way that the poured oil accumulates in a special bath, which sends it in the required quantity to the piston group. In case of frequent smoke, try to remove the piston group and look at the piston. On such scooters, an oil scraper ring is installed on the piston, and it is this ring that can allow oil to pass into the exhaust. Replace the ring, its cost is quite insignificant.

Oil scraper ring

In principle, we have examined the main reasons for scooter smoke; there are, of course, a number of other reasons, but we will not go into this. If you have questions about your scooter or want to share the reason for repairing this problem, write about it in the comments.