Are you one of those people trying to figure out how to start a dirt bike before they get one just to make sure this is not as hard as it looks? If that’s the case, we couldn’t agree more. While it may look easy to some and a tad complicated to most, turning on a dirt bike is really not that hard as long as you know what to do, obviously.
Defining “Hard to Start”
Out of context, this question might seem like a simple one but it’s really not. Considering all the variables, there’s really a lot of information that you need to have or know before you can classify a bike as being hard to start or not. Questions like “Is the bike hot or cold?” or “Has the bike been sitting for several weeks” are just off the top of our heads when it comes to this.
The level of difficulty when it comes to starting your newly-acquired bike can even be influenced by something as random as draining your float bowl. As a result, we feel the fairest answer to this would be to say that each scenario has a slightly different solution and ending and it will pretty much always vary from rider to rider.
Combining this subjectivity with every person’s different starting routine as well as the ease of each bike model in terms of firing up makes for a standard answer: Every rider will experience it differently and will have to try more or less in order to get the job done.
If you’d still like a rule of thumb that you can pattern yourself after, you should watch and see if your baby takes more than five kicks to start roaring. If this continues to happen consistently as time progresses, it’s probably erring on the side of caution if you begin investigating possible starting issues at that point.
Things That Affect Starting Time but Don’t Mean You Have to Tear the Engine Down
As relative as we’ve told you this is, most bikes will usually have the same two or three things that can have a negative impact when it comes to how well they start. When it comes to carbureted bikes, the pilot jet circuit is responsible for controlling the flow from idle all the way to about ¼ throttle. This jet has a very small orifice that can easily clog and become a problem.
Once this happens, the pilot jet will become effectively useless in terms of delivering the necessary fuel so that the engine can start and the obvious consequence here is an extreme difficulty when you as the owner try to start your bike and go for a ride.
The make and model of the product is another element that will matter a lot in the long run. Depending on them, the bike may or may not come with a decompression system that is usually adjustable and should, therefore, solve your problem. On certain models, for instance, the driver has to consistently keep everything in order down there to make sure it’ll work.
This “keeping everything in order” means that a certain amount of clearance must be kept at all times between the decompression adjusting screw and the rocker arm. In just the same way as valve clearances will be frequently checked and adjusted to perfection, so may this system need a little tuning from time to time.
If you just don’t care and let it get out of spec, more and more air will start escaping each time the decompressor opens the exhaust valve and the obvious result of this will be a lowering of the engine’s compression.
Another thing worth taking into account might be your old spark plugs lying around. They can be another potential culprit as an old and worn plug will generate a weaker spark and more difficulty igniting the mixture. Learning to keep fresh plugs in the engine can really go a long way toward improving your bike’s starting tendencies in the long run.
We also feel that we should throw temperature and altitude in the mix here. You should never forget that if for some reason, you’ve had to move from sea level up to six thousand feet, the variation in air density will bring about different fueling requirements since this changes basically from region to region.
If you’ve skipped the physics class (not that we’d blame you or anything) let’s narrow this down: As altitude increases, the amount of oxygen in the air will naturally decrease. As a result, leaner and leaner jetting will be required to make the bike run correctly. The temperature will also have an impact here as warmer air means less density of said air.
Summertime jetting will then obviously mean a harder time for your bike if it’s wintertime and you’re trying to start it. The colder the temperature, the richer the jet that will have to be installed in order to cope with the increased air density.
How Do I Start a Four-Stroke Dirt Bike?
Now that we’ve narrowed down some basic conditions that can keep you down, let’s see what it takes to actually start such a beast and throttle away in a blaze of glory. This can have a lot of answers depending on the type of dirt bike and also, as we said, if it is hot, cold, carbureted, or fuel-injected.
If the engine is cold and you haven’t moved the bike for a while, you will want to have the fuel petcock turned on. Then turn on the choke, twist the throttle to wide-open three times, and then roll the engine over with your foot until the compression stroke is found. If you’re dealing with an engine that has a decompression system, you should typically feel it working.
Put on your karate shoes and kick the bike repeatedly until it starts to roar. Usually, you shouldn’t need more than three-to-five kicks until everything is up and running. This is only when your dirt bike is cold, though. Don’t worry, we’ll walk you through everything you need to do if it’s hot as well.
When everything’s hot and ready, the first thing that you want to do is depress the hot-start lever. Roll the engine over with your foot until you find the compression stroke and you know you’re there. Once again, remember that engines blessed with a decompression system will usually let you know they’re working. One-to-three kicks should be enough to start the bike.
Some More Frequently Asked Questions
Some people might also wonder why the throttle needs to be twisted wide open three times when you’re starting the dirt bike. If you’re unfamiliar with the internal components of a four-stroke carburetor, this is a great question and we’re proud of you for asking it! Not to worry, the answer we provide will be simple and to the point.
Okay, here goes: The wide majority of the dirt bikes that have been produced in the past 10 years have usually been equipped with a Keihin FCR carburetor. This bad boy comes equipped with an accelerator pump which is a tool that works like a fuel bulb that you can find on the small engine of a power washer, for instance.
As the bulb is squeezed, a splash of fuel will leak out and so the accelerator pump fulfills its purpose of smoothing out engine operations from low rotations-per-minute scenarios to quickly transitioning into a wide throttle. As the throttle gets sent to full-open, a plunger found within the carburetor is activated and works to force fuel out of the fuel bulb through an orifice.
As a result, the accelerator pump can be used to bring fresh fuel to the intake tract, initiating a smoother launching sequence. Have we been clear enough? We’re glad if we were, as understanding the mechanics of such a thing is quite important if you want to be a careful and successful dirt bike rider.
Why Carburetors Are Losing to Fuel Injection Systems
There are a few reasons why carburetors seem to fade in popularity among the biker community. To start things off, they pollute, and not in the way people think. The difference in terms of what they put out through the tailpipe when compared to fuel injection is rather negligible but they also have a bowl in which the fuel sits and evaporates when the bike is still.
Fuel-injection systems, on the other hand, are pretty much sealed so they do not allow unburned fuel to escape out into Mother Nature when the bike is merely parked there, doing nothing.
The other issue people seem to have is that carbs can be lovingly described as “imprecise”. This is not said in an unlovable voice but the fact is they just cannot be adjusted as quickly as their more advanced peers because they are mechanical in nature and the shifting process from cruising to speeding up is harder to engage in.