If you want to tinker with the constant adjustment and synchronization of 2 carburetors that come standard on a Ural motorcycle, you can make one carburetor by installing an adapter, see how to do this in the video material. Carburetors K-2401 Minsk (not China), ignition MPBSZ "Sovek". They skated 3 seasons for me (and for some others, I got a used one) until major repairs, and then this started. The symptoms are visible in the video... Judging by the soot, they are poor, and one is stronger. At XX, popping noises are clearly audible when releasing the gas. In addition to all this, one of the carburetors (right) is unstable at idle. Naturally, I sinned on everything except the carbs. A working ignition was installed from another motorcycle, all possible combinations of ignition timing. The compression is uniform, 10 in each when hot. Replaced wires, spark plugs, etc. The symptoms did not go away. Then, when replacing carburetors in some places, the symptoms also changed. This prompted the idea that... That the problem apparently turned out to be really in the carburetors. Working similar carburetors were installed, but the popping noise during a sharp release of gas and the uneven operation of one of the cylinders disappeared. We'll look for a repair kit.
Unstable operation of the Ural motorcycle
Since in the future the problem of popping noises in the muffler can lead to breakdown of the engine and other important components of the motorcycle, it needs to be solved as quickly as possible. You should consistently check the performance of systems such as: intake, ignition, exhaust. All damaged parts are replaced with new ones, connections are sealed. If all else fails, the motorcycle should be inspected by a professional mechanic, who will find the cause and tell you how to eliminate it at minimal cost and without reducing the life of the power unit. Unstable operation of the Urals, carburetor k2401. But as it turned out, “the problem was not in the bobbin,” and not even in the carburetors, but, as the autopsy showed, in the discrepancy between the timing marks. Be careful when assembling the engine - it will save a lot of time.
Reason and solution
The easiest way to get rid of pops on a carburetor motorcycle is to simply move the needle valve to a different position, changing the degree of saturation of the mixture with gasoline. It is better to entrust this operation to a specialist, since not everyone can fine-tune the carburetor. If there is electronic fuel injection, it is impossible to change the gasoline supply parameters yourself - the control unit will have to be flashed at a specialized service station.
It happens that the motorcycle shoots into the muffler and carburetor - this is often found on domestic Urals and imported choppers with a large cylinder capacity. The problem is a clogged air-fuel mixture at the inlet. To eliminate it, it is worth changing the filters and sealing gaskets, and also checking how tightly the pipes fit to the inlet fittings and whether there are any large cracks in them.
Very often, popping noises appear after replacing the muffler with a non-standard one or cutting holes in it to eliminate resistance to escaping exhaust gases. Particularly unpleasant sounds appear when installing a “direct flow”. The reason is the creation of a strong vacuum, which leads to a lean air-fuel mixture. Powerful imported motorcycles often use an exhaust gas afterburning system, which reduces their toxicity - after removing the standard muffler, its operation becomes clearly audible. To eliminate shots after changing the silencer, you must:
- Reconfigure the carburetor or reflash the control unit;
- Install filters with a different capacity;
- Disable the exhaust gas afterburning system.
On sports motorcycles whose engines run at high speeds, the problem with shots may be related to the speed limiter or crankshaft speed limiter. When a certain indicator is reached, the fuel supply may remain unchanged for some time, while the number of flares is reduced. Accordingly, a huge amount of gasoline enters the muffler, which explodes with a jerky sound, forming a “machine gun burst.” It can be heard especially well when releasing the gas after active acceleration. It is impossible to eliminate such a problem without reducing the life of the engine - you have to change your driving style so as not to irritate yourself and others with unpleasant loud bangs.
It is worth paying attention to the ignition system - missed flashes may be due to its malfunction. Carefully inspect the high-voltage wires - there should be no cracks or peeling of the insulation on them. After unscrewing the spark plugs, check to see if there is a specific deposit on their surface that appears when using low-quality gasoline or when the ignition timing is set incorrectly. If the motorcycle is equipped with an electronic ignition system, the problem can often be solved by reprogramming the control unit. Some motorcycle owners decide to make drastic changes by installing a new control unit with preset sport settings - this solves the problem of shots in the muffler, and also increases engine power and improves dynamic characteristics.
Ural shoots at the carburetor: view from IKS-1
Many people mistakenly believe that a carburetor is a rather simple device. It is in it that various mixture formation processes take place. And if the metering systems or any carburetor component is faulty, it can be very difficult to determine the cause. Therefore, the performance of the carburetor is assessed by indirect signs. They evaluate the quality of the combustible mixture that is prepared in the carburetor. And at first, before adjusting the carburetors, the ignition system and the correctness of its installation are checked. The background is in the video description at the link below. Symptoms - shooting at the carburetor at XX. The diagnosis is a mismatch of timing marks.
Well, it doesn't want to start.
Good evening, comrades. I am writing in despondency, asking for your help, to indicate the reason that this unit needs to start.
I rode around in the spring and early summer, leaving behind a curtain of smoke. In July it went up for repairs. The repair lasted two months, because it was working and we had to wait a long time for spare parts by mail. I assembled everything, it was time for the first start (Saruman started it on the ignition system), it started with half a turn, but did not work for more than a minute, because... then it turned out that the optical sensor was defective ( https://cs319417.vk.me/v319417112/8ed5/ERQMD09WU0c.jpg ), okay, while I was waiting for a new optical sensor, I started it on the cams, but was not satisfied, and went to buy an DH from VAZ, you have to ride while the warranty opto-sensor is in the mail. I drove 50 km with the VAZ sensor, then again the LED on the switch did not blink, and therefore there was no spark, and besides, the generator started leaking ( https://cs304601.vk.me/v304601112/3c75/HJQncMzZEg8.jpg ), I went through everything, installed an oil seal from a Subaru, replaced the bearing with a new one, made in Slovakia, I couldn’t find better quality. But then an opto-sensor arrived by mail, but for some reason it no longer worked. I started installing the cams again to make sure that the generator was assembled and working correctly. Oops, everything started up, the generator was working, the lamp went out, charging was going on, but since I forgot to open the tap, it didn’t work for me for long either. Well, okay, I opened it, swung it, but then he declared a boycott. Further adjustment of the MH did not help. It's like he just died.
Solution to problem 1: poor engine performance, the right cylinder sneezes into the pipe Dnepr 11, MT, Ural.
If the gap does not correspond to the specified size, the union locknut is loosened. Turn to the right or left to set the required gap. After this, the fitting is re-locked with a lock nut and the carburetor of the Ural motorcycle is adjusted. By turning off the warm engine at a minimum engine speed without load, the basic settings are made. The idle system is adjusted for each of the two mechanisms separately. The Ural carburetor is adjusted with the second cylinder turned off.
I made a video response to problem number 1 related to the poor performance of the right cylinder of the Dnepr 11 (similarly in MT and in the Urals). The essence of poor cylinder performance was that at low engine speeds and a certain load, the right cylinder began to sneeze into the pipe. In addition to problem 1, I tried to demonstrate these sneezes (although I don’t know how successful I was). In this video, I tried to show how to find the cause of the breakdown of the Dnepr (MT, Ural) motorcycle, and how to fix it. I hope I was able to answer the question “what to do if the MT engine does not work well”, or “what to do if the cylinder sneezes into the pipe and does not work well”.
You need to find a smart friend who knows how to repair Soviet equipment
Every motorist should be able to tighten the brakes, check the oil, or properly kick the wheel. However, if for some reason a person acquired a broken Soviet motorcycle, he should be prepared for much more serious problems.
If you have a wild desire to drive around the area in a hellishly growling Ural, but you can’t completely go through the wiring yourself or weld a seam on a falling off fork, you’ll have to find an enthusiast friend who will do it for you.
Counting on him to do everything for free is stupid, so you’ll either have to shell out a tidy sum or try to delve into all sorts of schemes yourself. There is a third option: a friend will be carried away by the idea of driving a restored tarantass and will work for food, but in any case you will have to prepare a base-garage, preferably heated, where you will spend your evenings trying to revive the beast.
The most difficult thing in this matter is not to lean on alcohol.
Task 1: poor engine performance, the right cylinder sneezes into the pipe Dnepr 11, MT, Ural.
The size of the fuel jet used is important here. The spark plug insulator, or rather its color, will help you find out whether you have adjusted the carburetors correctly or not. When properly adjusted, its color is dark brown. So, problem number 1 is related to the poor performance of the right cylinder of the Dnepr 11 (similar to MT and Ural).
The essence of poor cylinder performance: at low speeds and a certain load on the engine, the right cylinder begins to sneeze into the pipe. The cylinder does not fire, but rather sneezes. What could it be?
shots into the silencer
Opposition brothers! Help with advice. A dragon has taken up residence in the engine. The infection spits fire from the silencers. Everything happened after I made capital improvements to the engine (MT-11). The timing belt has been rummaged through and gutted, the valve clearances have not been adjusted, and 0.07 and 0.1 and 0.05 + various combinations. Ignition BSZ - twisted, spit, set different gaps, changed spark plugs. Carburetors - adjusted for both lean and rich mixtures, adjusted the level of the float chamber (all the options I found, 13mm from the middle of the float and 26mm from the edge of the body.), set the needle in all positions. I looked through all the forums, none of the advice helped.
Does it pop at high speeds?
Mostly when I let off the gas.
BSZ is probably buggy
I checked, put the contact number, same result
Is the spark plug visible black?
Black with any carb and ignition settings.
spark plugs, breaker, coil - all this needs to be double-checked. and don’t even install contact and don’t even try; it finally doesn’t work on my contact. Why? I don’t know and I don’t even bother, I just went and bought a normal ignition and still no problems.
Look at the air. It can get very boggy due to poor cross-country ability.
the air is new and clean, has not traveled 100 km
Still, set the ignition early, and do everything else later. Shooting into the muffler while releasing gas is the way to go.
I set the early one all the way to the millimeter, and also the later one, there was no result.
shots can only be due to a rich mixture and late ignition! look at the carbs, they overfill 99%
I leaned the mixture, lowered the float level, changed the jets (set smaller diameters) - nothing.
Start it without an air filter (remove the pipes) and you will see the difference.
It seems to me that the whole issue is in the contact oil air vent.
oil-free air, no air, started it - nothing changed
there is only one way out! swap carburetors
impossible, I have a K63T from a Vega prototype, one left and the other right and connected by diffusers through the factory pipe, there is no way to rearrange it, and it doesn’t want to work with other carbs at all.
but I would take off the spit! It doesn’t have any advantages, it just makes things worse.
it is not removable, the carbs are one whole (as intended from the factory) and can only be removed together with the rods, but I can’t plug the holes in the diffusers with a plug). The pereplyuyka divides the air mixture between the carbs and makes them easier to tune (tested). There are no complaints about the way the engine starts, and it runs well (140 with 9 axles makes it easy), but the consumption is about 8 and these damn shots give no rest.
