If your motorcycle dies while you’re riding, it can be unsettling, to say the least—it can also be dangerous.
If your motorcycle dies every time you slow down, there’s a problem with your fuel supply, throttle, or shifting capabilities.
That said, why your motorcycle stalls when decelerating can vary depending on whether your motorcycle’s injected fuel or carbureted.
We’ve listed the most common reasons motorcycles stall while slowing down to simplify the troubleshooting process.
1. Clutch Cable Tension Out of Adjustment
As you may have guessed, the clutch cable runs from your left-hand clutch lever down to your clutch system.
When you pull on your clutch lever, your clutch cable puts pressure on the clutch plates to disengage your clutch from your engine, making it a critical part of slowing down your motorcycle.
Clutch cables can come out of adjustment, whether from wear and tear, improper storage, or rapid temperature changes. Whether the cable is overtly slacked or too tight, the shift in physics impairs mechanical functioning, and your bike will die when slowing down.
- All clutch cables fall out of tension from time to time, so inspecting and adjusting your clutch cable is part of routine maintenance.
- If your cable is tighter than spec, the lack of free play can cause slippage, which wears out your clutch.
- That said, if the cable has too much free play, the slacked cords won’t tug on your clutch plates hard enough to move your clutch into disengagement.
Eventually, the clutch cable on every motorcycle wears out and needs to be replaced, or else it will fall out of adjustment as soon as you tweak it.
And finally, lubricating your clutch cable during every service inspection will prevent it from shifting its tension, and help it last longer, ensuring your motorcycle doesn’t stall while slowing.
2. Faulty Clutch Lever; Hand Control Not Fully Pulled In
Suppose your input on the motorcycle clutch cable is impeded, either because you’re not pulling the lever while downshifting or because the lever itself is broken. In that case, your motorcycle may die while slowing down.
If there is any interference with the clutch lever, the cable won’t have the force it needs to disengage the engine.
If the flywheel and clutch are still partially engaged when you try to slow down, the motorcycle will stall out while riding.
- It could be your thumb blocking the lever.
- Different motorcycle clutches have different feels—the clutch lever on a bike you’ve never ridden before may feel like it’s pulled in all the way because it’s a tighter clutch than you’re used to.
The clutch lever on most motorcycles is adjustable; if your bike stalls out while decelerating, try adjusting your clutch lever to your liking to ensure you’re pulling it in all the way while slowing down.
For more on this topic, please check this article to learn how to fix a faulty motorcycle clutch.
3. Motorcycle Idle Is Set Incorrectly
Your motorcycle’s idle needs to be set to a specific strength to interact appropriately with your clutch plates to accelerate and accelerate properly.
If your motorcycle is too weak or too strong, it harms your acceleration and deceleration capabilities, and your bike may stall while slowing down.
- Idle adjustments are technical procedures requiring specialized skills and tools.
- The idle rate on every motorcycle is different, depending on the make and year model.
If you’re unsure about your moto mechanic skillset, take it to a mechanic, as adjusting your idle improperly can cause even more problems than killing your engine while slowing down.
Please also read our article about why a motorcycle idles rough.
4. Restricted Air Intake System
Your motorcycle’s engine is likely combustion-based, and the air is as critical an ingredient in the recipe for ignition as fuel is.
Therefore, if your bike’s air supply is interfered with by a clog or an air leak, your motorcycle may die when slowing down.
- A bend in your exhaust pipes or damaged headers can restrict airflow in and out of your motorcycle.
- Likewise, a hole or leak in your intake manifolds allows air to escape instead of getting where it needs proper engine power.
- While braking is an essential part of slowing your motorcycle, so is what we call engine braking, which uses the disengaging engine power to slow the bike’s momentum.
If your airflow is restricted, your engine performance and power are affected, and your bike may stall while stopping.
What to Do if Your Bike Won’t Move When it’s in Gear Because Of Restricted Airflow:
- While some motorcycle air box filters can be cleaned and reused, others use temporary filters that need to be replaced during routine service maintenance.
- Clean or replace your damaged air filter.
- If there is wear to the exhaust, leaks in your intake manifold, or missing seals, you may need replacement parts for your intake/exhaust system.
Please also read our article about reasons motorcycle dies when accelerating.
5. Motorcycle’s Fuel Filter Is Clogged
Expired, corroded, or contaminated fuel can clog your motorcycle’s fuel filter, affecting your bike’s air-fuel ratio.
As the previous section pointed out, obstruction to either the air or fuel supply of your motorcycle will affect your engine power and performance.
Inspecting and cleaning/replacing your bike’s fuel filter is part of routine maintenance. Failing to keep your filter free can cause the fuel flow of your motorcycle to lag during deceleration, and your bike could die while slowing down.
While some motorcycles stock outer fuel filters, other models have their fuel filters inside their gas tanks.
- Outer filters are more straightforward to clean and replace.
- On the other hand, maintaining a tank’s internal filter requires removing the entire fuel tank.
- A clogged fuel filter is one of the most common causes of a motorcycle engine that dies while slowing down.
6. Throttle Bodies Need Adjustment
These days, most motorcycles are fuel injected.
Rather than a carburetor, these modern, computer-regulated ignition systems use injectors to deliver fuel for combustion consistently.
While fuel injector systems are much easier to maintain than the old-fashioned carburetors, inspecting and tuning the various components of the injector system is still part of routine maintenance.
Failing to balance your throttle bodies with a vacuum gauge or with a CPU device can throw your injectors turning off, causing an imbalance in your fuel ratio. Once its air-fuel supply is imbalanced, your motorcycle may die while slowing the throttle.
- There are CPU tools for sale that permit home mechanics to balance their throttle bodies.
- It’s possible to adjust the throttle beside the vacuum gauge, though it requires some mastery of the procedure to nail it perfectly.
- Regardless, we recommend having a pro mechanic inspect and tune your fuel injectors and throttle bodies per the service intervals outlined in your bike’s manual.
Fiddling with your injector balance without the proper instruments or proficiency skills can worsen the tuning and cause additional engine loss.
7. Clogged Carburetor Restricts Fuel Flow
If your motorcycle is carbureted and its carb bowl or fuel lines are dirty, clogged, or corroded, the fuel flow will be obstructed during throttle input, and your bike may die when slowing down.
Here’s What to Do if Your Cabureted Motorcycle Dies While Slowing Down:
- Disconnect the fuel hose from your tank and drain whatever fuel is left therein.
- Remove the float bowls from your carburetor and spray arb cleaner down the fuel hose until it pours out of the carburetor.
- Allow the carb cleaner to evaporate/air dry.
- Replace your fuel filter.
- Inspect the bottom of your fuel tank for debris and corrosion.
- Reinstall your fuel tank and carb, and fill your motorcycle with fresh fuel.
- To be thorough, change your spark plugs as well.
If your cycle has a carburetor, make sure to check our article about reasons a motorcycle dies when the choke is turned off.
8. Faulty Pilot Circuit
A motorcycle’s pilot circuit, including your pilot parts and jets, governs how much fuel enters the engine during idling and the small throttle inputs standard while slowing down.
A hot motorcycle engine, for example, needs less fuel when slowing down, as the warmed fuel vaporizes faster than cold fuel.
If any of the components in your motorcycle’s pilot circuit are faulty,
- Inspect your pilot screws and ensure your carbs are balanced.
- Flushing carb/injector cleaners may offer some relief. You are allowing your bike to stay running while you’re slowing.
- If you suspect the pilot circuit is at fault, you or a trusted mechanic should disassemble the carb, inspect the pilot system, and clean/replace any faulty components.
9. Weak Battery Charge
If your battery is dead, expired, or lacks sufficient voltage, you may find your motorcycle dies when slowing down.
Simply put, a weak battery doesn’t have the power to maintain the proper ignition sequencing needed to break the engine’s momentum.
- A battery with a weak charge may need to sit on a battery tender or trickle charger for a while to restore its total capacity.
- A battery that won’t hold a charge is likely expired and needs to be replaced.
- If your new battery quickly displays the same systems as your old battery, not holding a charge and causing your motorcycle to die while slowing down, inspect your charging system components.
- Also, inspect your battery terminals and wires for loose connections, shorts, or damages.
For more information, please check out this article about why motorcycle battery won’t charge while riding.
10. Valves Need Adjustment
Improper valve clearance can cause a motorcycle to stall out while slowing down.
Motorcycle valves are engineered to expand during operation, and the specified clearance amount outlined in your owner’s manual considers these physics.
If the valves haven’t been inspected or adjusted in a while, they may be only slightly off when you start your ride.
When you’re ready to slow down and come to a stop, your valves have expanded, and your bike will develop stalling and starting problems until it cools.
Valves that go out of adjustment often, despite regular inspection and tunings, are likely worn and need to be replaced.