Running rich not only drastically decreases your miles per gallon, but can cause severe backfires in the exhaust pipe. If there is too much fuel present in the cylinder when the spark plug ignites then not all of the fuel will be successfully burned during the combustion process, there will be excess fuel that is pushed out of the cylinder head through the exhaust valve.
This unburned fuel will come in contact with atmospheric air and be surrounded by the extremely hot exhaust header. In the presence of fresh air and high temperatures, the fuel combusts and creates a loud pop or bang sound.
I was once troubleshooting a 2 cylinder motorcycle and each cylinder had a separate exhaust pipe. I would put my hand by the end of each exhaust pipe in turn to see how much air was coming out.
If one side is weaker than the other then you know you have a problem on that one cylinder. As I was reaching down to feel the air coming out, there was a loud bang and fire erupted out of the tailpipe, missing my hand by about an inch. I no longer put my fingers right by the exhaust pipe of a running motorcycle!
The culprit of getting too much fuel in your cylinder is almost always the carburetor. A dirty carburetor can cause a slew of problems. When the needle inside the carburetor gets dirty it tends to sticks to the walls next to it.
When it sticks it lets in more fuel than intended and you get a rich condition. Clean carbs should solve your problem of having a motorcycle running rich. For other ways to fix a motorcycle that is running rich, check out my article here. Just for clarification, a motorcycle exhaust header is the metal pipe connected directly to the engine, and an exhaust pipe is the last foot or two of pipe that can be disconnected or unbolted.
I was once working on a BMW R80 for a friend and the threads on the backside of the cylinder head were damaged as usual. We were having a hard time getting the exhaust nut to tighten down onto the cylinder head and finally we decided to just try it how it was. We started up the motorcycle and immediately there was loud popping coming from that side of the engine. The exhaust was escaping around that loose exhaust nut. The exhaust gases leaving the engine have a lot higher pressure than the ambient air around us, so if there is even the slightest hole between the cylinder head and the exhaust header then the fumes will escape and create quite a noise.
The best way to fix this is to tighten down your exhaust headers. Some use nuts, some use bolts, and some use compression fittings. Check the exhaust header connection every few months as part of your preventative maintenance. Really short exhaust pipes have a tendency to be troublesome, and most states have laws about how long your pipes have to be due to all of the popping and banging that they can cause.
Short pipes, also known as a shorty, are usually 12 inches or less in length and are intended to give a motorcycle a cleaner look and a little louder exhaust. This is simply too short and will often cause backfiring. A baffle is a small section of the pipe that acts in a similar way a muffler on a car does.
It tries to convert the turbulent flow of the exhaust into a more laminar and quiet flow. Engineers put a specific length of exhaust pipes on motorcycles because that way it will get the best fuel efficiency. When people put shorter pipes on, the efficiency is traded for higher performance, but with that performance comes a higher risk of backfire. The case of having a backfire when not getting enough fuel may not be as common as the other problems, but I have experienced it before.
Backfiring is bad because it is a fuel ratio malfunction and will result in a loss of power. Sometimes you can really feel the cut out of power for a brief moment. Running the motorcycle too rich or too lean can also cause the internal temperatures of the combustion chamber to get too hot and fry your engine! Uh Oh! One of the easier things to check off the list would be the spark plug.
The spark plug is responsible for the ignition and it might have bad ignition timing with the compression. Sometimes the issue can be as simple as the levels of Octane in your fuel. I recommend running a higher-octane fuel through the engine to help clean out the fuel system and possible put a halt to those backfires. I recommend always using a premium high octane fuel for your bikes. This applies to engines that use a carburetor for its fuel management system instead of fuel injection.
If your motorcycle has sat for a lengthy amount of time then it is very possible the old gas has sat in the carburetor and the impurities have settled, causing a clog and your engine to run poorly or maybe not run at all. Your carburetor has 4 components inside that make all the magic happen when you get a hand full of that whiskey throttle. If you think that you need to clean the carburetor then you need to go buy a can or 2 of carburetor cleaner, it will come in a spray can with a straw attachment.
If you have done all of this and are still experiencing backfiring problems then you more than likely have an air flow issue. On many older carburetors there are idle and mixture screws that could also need adjusting. If you have an aftermarket exhaust I would try swapping the stock exhaust back on the bike and see if the backfiring persists. There are a few different methods you could go about checking for an exhaust leak.
If you fulfill this condition, you can possibly prevent your motorcycle from backfiring due to wrong exhaust upgrades. If you love racing you must take good care of your motorbike. As such, you should start by checking the carburetor from time to time. This should be the first assignment to carry out every time your motorbike backfires.
You need to understand that fuel cannot flow smoothly through a faulty or dirty carburetor. And if it does, this will lead to a lean-running engine. Consequently, your motorcycle will backfire and even fail to accelerate.
But you can find a working solution to this problem by simply cleaning the carburetor to make the fuel flow through it properly. You may use a high-grade carburetor cleaner to eliminate all debris, leaving a clean passageway for the fuel.
The carburetor consists of four major components that make your riding possible every time you turn the throttle. But these can get clogged with dirt, preventing them from working properly.
To unclog the jets, you need to use a carburetor cleaner which comes fully equipped with a spray can and straw attachment. Using this type of cleaner, wash every component in the carburetor to open the jets for easy flow of fuel. Different motorcycles come with different types of timing. The two most important timings include the electronic timing and condenser or a points setup.
Of the two timings, the electronic one is the most effective when it comes to efficiency and time-saving. With the introduction of electronic timings a few decades ago, troubleshooting a backfiring problem has become effortless.
This is because there are very few parts to check for any fault. Electronic timing uses a simple working principle. It sends a voltage signal to the ignition coil whenever the cylinder is actually in a compression stroke.
This is also the time the same cylinder is about to fire. The entire process is a little bit complex but what matters the most is the timing.
If the timing is wrong, everything else with the engine will go wrong. So if there is a timing issue with your electronically controlled motorbike, it is likely that there will be a mechanical timing problem.
As a result, your motorbike will start backfiring when you are about to start your ride or while on the ride. The same case is true if your motorcycle uses both the points and condenser in its timings. However, you can easily take care of this problem by setting a point manually using written instructions from the motorcycle manufacturer.
You can also correct the wrong timing by using the repair manual. But this process will depend on the model of your motorbike because these two-wheelers are different in design and mode of operation. For the combustion inside the cylinder to take place as required, there is a need for a substantial amount of fuel. Anything less or more than what is necessary can cause a lot of problems in the engine.
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