Two-stroke engines are a ton of fun: they’re fast, and provide plenty of power when running right. But like all engines, two-strokes can experience several problems, including bogging at full throttle. So, what causes bogging in 2 stroke engines, and how do you fix them?
The common causes of 2 stroke bogging at full throttle include using the wrong gas mix, dirty or clogged air filters, damaged spark plugs or barrel gaskets, and damaged intake manifold gaskets. Easy fixes include using the correct fuel, cleaning dirty parts, and replacing the damaged components.
These are just a few reasons for two-stroke bogging at full throttle. Read on for a rundown of other causes of your engine stalling when accelerating and how to fix them.
Why Your 2 Stroke Engine Is Bogging at Full Throttle
Do you have an old two-stroke engine that is suffering from bogging at full throttle? This is a widespread problem in older, poorly maintained two-stroke engines. As I mentioned, this can be due to different causes.
Here are some of the common reasons your engine may struggle when accelerating:
You’re Using the Wrong Gas Mix
If you have been using your two-stroke engine for years without an issue and suddenly notice that it is struggling to accelerate and lacks power when you need it most (such as when riding up hills), chances are you’re no longer using the correct gas mix.
Two-stroke engines require a specific mix of 50:1 or greater. That means for every one gallon (3.2 liters) of gas, you need 2.6 ounces (77 milliliters) of 2-stroke oil as fuel.
If you haven’t been sticking to this ratio, it might be why your engine keeps breaking down at higher speeds, where it needs all of its power to pull away or climb hills.
The Air Filter Is Dirty or Clogged
Another reason for your engine bogging is the air filter being dirty or clogged. When this happens, air cannot flow through the carburetor on the stroke engine.
As a result, the carb doesn’t go through its complete cycle of drawing in fuel, distributing it throughout the cylinders, and igniting it. This means that at high speeds, the engine lacks power.
The Spark Plug Is Old or Damaged
Spark plugs are essential components of any piston engine, including two-stroke engines. If your spark plug is old or damaged in some way, chances are that the electricity it generates will not be sufficient for your machine (source).
Keep in mind that if only one cylinder is having issues due to a faulty spark plug, this can also cause bogging. That’s because without complete combustion taking place across all four cylinders, there isn’t enough power to accelerate at high speeds.
The Carburetor Is Dirty or Clogged
Killer Motorsports reckons that if your two-stroke engine lacks power at high speeds but runs fine on flat ground, it may very well be due to a faulty carburetor. A dirty, clogged, or defective carburetor will not allow air to flow correctly (source).
As a result, the fuel will not get distributed accurately, and there won’t be an even flow of combustion throughout each cylinder. Ultimately, this means less power when accelerating because your engine isn’t pulling through all four cylinders at once.
The Carburetor Float Is Damaged or Faulty
As I mentioned above, the carburetor floats when using two-stroke engines to distribute fuel throughout each cylinder. This float is critical to proper engine function, especially at high speeds. If this float isn’t set correctly or is damaged in some way, there won’t be enough pressure in the carburetor to draw in all of the air for combustion.
Again, this will cause bogginess because you’re not getting an even distribution of gas and air through all four cylinders. The same problem can arise if your carburetor’s float needle moves too slowly or quickly. Either case can lead to bogging down at high speeds.
The Engine Intake Manifold Gaskets are Loose or Damaged
There are gaskets throughout your engine that help keep air from leaking out. If these gaskets become loose or damaged, you’re going to lose a significant amount of pressure and, therefore, power.
This is because the intake manifold works as a suction for your cylinder during each cycle, drawing in fuel and then forcing it into the cylinder with combustion. Without the suction provided by the manifold, there isn’t enough force behind the mixture within your two-stroke engine’s cylinders to pull through all four at once. That means no work gets done, and you’ll struggle to accelerate at high speeds.
The Throttle Linkage Is Broken
If your throttle linkage is broken or defective, your two-stroke engine won’t be able to accelerate at high speeds. The ratio of fuel and air should remain constant throughout each cylinder during combustion. But if the linkage is broken, this ratio changes because the gas mixture won’t have a reliable flow from the carburetor into each cylinder.
As you can imagine, this creates a lot of pressure that will significantly affect your engine’s ability to power through all four cylinders during high-speed acceleration. As before, that translates to bogging at high speed.
The Flywheel Magneto Is Not Getting Power
Flywheel magnetos generate electricity for gasoline engines so that they can go through their respective cycles. Without power moving through these magnets, it’s going to be extremely difficult for your two-stroke engine to move through all four cylinders during high-speed acceleration (source).
This is an essential component of your engine, so you should have this checked out at a certified shop if you notice bogging down at high speeds. Problems with the flywheel magneto can cause bogging down at lower speeds as well.
The Piston Rings Are Worn Out or Damaged
Finally, if your two-stroke engine has been around since the beginning of time and there are no signs of corrosion on its exterior, then there may be problems with the piston rings that need to be fixed right away. These rings provide a barrier between the compression chamber and combustion chamber within each cylinder.
If the rings are worn out or damaged, there is a very high chance that your engine will not perform well at high speeds. The same goes if the rings are too tight.
9 Easy Fixes for 2 Stroke Engines Bogging at Full Throttle
Let’s take a look at some of the ways you can resolve the above issues so that you’ll never have to worry about bogging down at high speeds again.
1. Use the Correct Gas Mix
First and foremost, make sure you’re using the proper mix of gas and oil. Otherwise, your engine is going to struggle at full throttle. While most two-stroke engines require a 50:1 gas to oil ratio, you’ll want to check your owner’s manual to ensure that your unit doesn’t require a slightly different mix.
2. Clean Out Your Air Filter
If you’re frequently driving at high speeds, then it might be time to clean out the air filter on your two-stroke engine. If it gets clogged or dirty, there won’t be enough air entering the carburetor.
To clean your air filter, follow these easy steps:
- Remove your air filter.
- Soak it in a solution of 10 parts water and 1 part laundry detergent for about 30 minutes.
- Rinse it with clean water until all of the suds are gone, then let it dry completely overnight (at least 12 hours).
Pro Tip: For the best results, swirl the filter in soapy water, occasionally using your hand to massage any clogged dirt and debris away.
3. Check and Replace the Spark Plug
If the spark plug is old or damaged, then you need to replace it ASAP. To check the condition of your spark plug, follow these steps:
- Unscrew the spark plug using a socket wrench.
- Use a wire brush to scrub away any corrosion outside the metal casing surrounding it.
- Insert a spark plug tester, then turn the wrench several times until you feel resistance.
- If you can’t find anything wrong with your spark plug, consider that good news and screw it back in place.
- If there is any dirt, rust, or corrosion around your spark plug, then you’ll need to replace it as soon as possible.
Check the following tutorial on how to replace your engine’s spark plugs:
4. Clean Your Carburettor
Cleaning your carburetor is another sure-fire way to get your two-stroke engine running at full throttle again. If it’s dirty, then there’s too much air entering the system.
To resolve this issue, you should remove the carburetor and clean it with a wire brush or compressed air in a few steps:
- Disconnect the spark plug before starting.
- Remove the carburetor from the engine, then remove the float bowl.
- Apply cleaner to your wire brush or compressed air, then scrub away any dirt or grease inside the carb.
- Soak it in a solution of 10 parts water and 1 part laundry detergent for about 30 minutes.
- Rinse with clean water until all suds are gone, then let it air dry overnight.
5. Check and Replace the Float
If the carburetor is running a bit too lean, then your float may be damaged or faulty一and you need to fix it right away. To check the condition of your float, follow these steps:
- Remove the carburetor from the engine, then remove the float bowl.
- Gently push down on the float to see how it responds一if any of the needles pop out, then you need to replace your float.
- If it’s working correctly, go ahead and screw your carburetor back in place.
6. Tighten or Replace Your Barrel Gasket
As I mentioned, a loose or damaged gasket between the carburetor and the engine can cause your engine to bog down at high speeds. To prevent that, you should tighten or replace this gasket as fast as possible. Otherwise, you’ll be faced with severe problems, ranging from poor engine performance to severe damage.
7. Replace the Throttle Linkage
If the throttle linkage is broken or disconnected, it won’t regulate the volume of fuel that enters your engine. To resolve this issue, you should tighten or replace the throttle linkage as soon as possible.
Here are the steps you should follow:
- Remove the carburetor from the engine, then disconnect it from its linkage–you can use a socket wrench to do this.
- Locate the throttle linkage, then tighten or replace it as necessary.
If you’re not sure exactly where your linkage is located, then take a look at this YouTube tutorial for more help:
8. Check the Flywheel Magneto
If the flywheel magneto isn’t getting power, it won’t be able to supply your engine with gas. As you might have guessed, that’ll cause it to bog down.
To resolve this issue, tighten or replace the flywheel magneto. Otherwise, you’ll continue having problems every time you try to rev up your engine at full throttle.
Here’s a great demo on how to fix a magneto:
Pro Tip: Make sure that there’s no dirt between the magnets near the flywheel before proceeding. If this solution doesn’t work for whatever reason, chances are some other component on your engine is broken and needs immediate attention.
9. Replace the Piston Rings
If the piston rings are worn out, then they won’t be able to keep your engine’s pistons moving fast enough. And since this solution will only buy you more time before the rings wear out again, you should replace them as soon as possible.
Here’s how to do that:
- Remove the engine covers and the piston rods. If you don’t know how to do that, see the owner’s manual for tips.
- Clean off any carbon or gunk from the sides of your pistons一you can use a wire brush for this task. If you don’t have one, I recommend this OriGlam Wire Brush Set (link to Amazon). It’s ideal for cleaning rust, dirt, and paint and will last a long time, thanks to its durable brass construction.
- Once it’s clean, pull out your replacement rings right away. Install them in the same order as the originals一the upper ring should go in first, followed by the second ring, and so on.
Final Thoughts
If your two-stroke engine is bogging down even at full throttle, you need to check the above components as soon as possible to avoid damaging them. By properly tightening or replacing the carburetor float bowl gasket, barrel gasket, throttle linkage, flywheel magneto, and piston rings on your own, you’ll save yourself a lot of time, money, and effort.
If none of these fixes help, consider hiring a professional to assist you. Otherwise, you might end up having to buy a new engine altogether. Good luck!
Recommended Reading:
