Motorcycles and fuel go hand and hand but did you know something as simple as turning off the fuel off when not in use can save the engine from damage?
Do you know if your motorcycle has a reserve tank and what impact it has on the engine?
How about the fuel filter? Do you know where it is or how to tell if it is functioning properly?
Read on to discover how you can help prevent serious damage to your motorcycle.
Table of Contents
Should I turn off the fuel on my motorcycle?
If your motorcycle has a carburetor and it does not have a vacuum-style fuel shutoff valve, then most definitely yes you should turn off the fuel on your motorcycle when not in use.
On motorcycles equipped with a vacuum-style shutoff valve probably won’t have a shutoff valve as it is not necessary because fuel will not flow without the vacuum of the engine.
Fuel-injected models do not need to have a fuel shutoff valve because fuel will not flow without the fuel pump operating and the fuel injector won’t open either if the motorcycle is not running.
It is highly recommended to turn your fuel off with any motorcycle where possible when not in use to prevent damage to the engine.
What happens if I forget to shut my fuel off on my motorcycle?
For carbureted motorcycles with a standard fuel shutoff valve, if the fuel is left on when not in use, fuel from the tank can leak past the carburetor needle and seat filling your cylinder or worse the whole crankcase with gasoline.
Starting a motorcycle engine with too much fluid in it (even a gas oil mix from leaving the fuel on) will cause a spike in pressure leading to the excess fluid being forced into the airbox.
While the fuel-oil mix in the crankcase may not cause too much of an issue if caught before starting the engine you will still have to deal with “cylinder wash down”.
What is cylinder wash down on a motorcycle?
Cylinder wash down on a motorcycle is when the inside of the cylinder is rinsed off “washed down” with gasoline.
This removes the oil layer that is inside the grooves of the inner liner of a motorcycle cylinder that is needed for the proper operation of the engine.
Removal of this layer can lead to serious damage to this liner essentially destroying the top-end of a motorcycle engine.
What is a carburetor needle and seat on a motorcycle?
A carburetor needle and seat on a motorcycle is a plunger-style valve system the delivers fuel to the “float bowl” of a carburetor.
The seat is a cylinder-shaped piece that is connected to the fuel tank and carburetor float bowl.
The needle is a needle-shaped plunger that seals up against the seat when the fuel reaches a level set by the “float” to which the plunger attaches to.
This system allows the correct amount of fuel is in the float bowl for proper operation.
What is a float bowl on a motorcycle carburetor?
A float bowl on a motorcycle carburetor is a small reservoir used to hold fuel that is needed for carburetor operation.
This is usually housed on the bottom of a motorcycle carburetor and uses a needle and seat valve attached to a float to control the volume of fuel in the float bowl.
A float on a motorcycle carburetor is a mechanism that floats on top of the fuel in the float bowl and closes the needle and seat valve when the fuel reaches a certain level set by the adjustment of the float.
How does a motorcycle fuel reserve work?
A motorcycle fuel reserve works by switching from one outlet of a gas tank to another, one that has a long metal tube protruding inside the tank, to an outlet with a smaller one.
Yes, that means there is no real reserve tank on a motorcycle. It is simply a switch between two tubes of different lengths inside the gas tank.
Why is there a reserve setting on a motorcycle then?
From what I can find it seems to stem from a time when fuel gauges were a not so common thing.
Having a separate reserve setting allowed you to have a certain amount of fuel left in your tank allowing you to get a fuel station.
Predicting fuel mileage on a motorcycle can be tricky at best, even worse without a fuel gauge but having that reserve amount left gave you at least some sort of assurance you wouldn’t be stranded on the side of the road.
How long will a motorcycle reserve last?
Although it varies between motorcycles, you have about a gallon of gasoline in your reserve setting.
That translates to approximately 15 to 30 miles depending on the motorcycle and if you are driving in the city or on the highway.
Can I always run a motorcycle on reserve?
Yes, you can always run a motorcycle on reserve. It will not affect the running condition of the motorcycle.
Now if you have no fuel gauge I wouldn’t recommend it solely because of the forgetful nature of the average person.
What is a fuel filter on a motorcycle?
A fuel filter on a motorcycle is a strainer between the fuel tank and the rest of the fuel system.
Its job is to stop large particles from entering the fuel system of the motorcycle that may have found their way into the gas tank.
Whether this is dirt, rust, or yes, even foreign objects like seeds and sticks, any of these could spell disaster for your fuel system.
There are several types but they all rely on some material to sieve or strain out these particles.
Do I need a fuel filter on my motorcycle?
All motorcycles need fuel filters. Something must stop particles that are small enough that they can fit into the fuel line but are large enough to cause serious damage to internal engine components.
Without a fuel filter, your motorcycles days are numbered. The real trick here is finding what one you have!
If you have a fuel-injected motorcycle yours is part of your fuel pump. Most of the time these are built-in and cannot be replaced by themselves.
If you have a carbureted motorcycle yours is most likely near the fuel shutoff valve on the side of the motorcycle. If you cannot find it there is also a small chance that it is inside the tank.
Before fuel filters became commonplace, screens were put over the top of the inlets of the fuel shutoff valves. Some of these were even replaceable though it is rather inconvenient.
Should motorcycle fuel filter be full?
If you are lucky enough to be able to see your motorcycle’s fuel filter do not be shocked if it has a big bubble or even looks half full. A motorcycle fuel filter does not have to be full to do its job.
As long as you can see fuel moving through the filter, you should be ok. That being said if you see very little fuel inside or the fuel movement is slow or stopped you may need to investigate further.
Can I use a car fuel filter on a motorcycle?
As long as the fuel filter from the car is a simple strainer type of filter and the motorcycle is carbureted you should have no problem using it. The only real issue would be the size.
I would not recommend putting a large fuel filter on a small motorcycle and on the other end I would not recommend putting a small filter on a large motorcycle.
Can a bad fuel filter cause smoke?
I have no idea how this one got started maybe old motorcycles were clogging fuel filters with some really funky fuel or the fact that most old motorcycles burnt a lot of oil causing smoke.
No, a bad fuel filter will not cause smoke.
Final thoughts
A motorcycle’s fuel system can be complex and downright frustrating sometimes.
Knowing when to turn your fuel off, when to use the reserve tank, and how to tell if the fuel filter is functioning properly can help avoid these common mistakes that lead to engine damage.