Why Does My Chainsaw Cut Out When Hot? (Explained)

Operating a hot chainsaw can be frustrating when it suddenly cuts out on you. However, there are some practical reasons why your chainsaw might stop running when it overheats. Understanding the common causes and solutions will help you prevent cut outs and keep working safely and efficiently.

Common Causes of Hot Chainsaw Cutting Out

There are a few key reasons why your chainsaw might cut out from getting too hot:

Engine Overheating

The most common reason a hot chainsaw cuts out is engine overheating. Chainsaws generate a lot of heat from the engine and friction of the chain spinning at high speeds. If the engine overheats, it can expand and seize up, causing the chainsaw to cut out suddenly.

Engine overheating can happen from:

Running the chainsaw consistently at high speeds
Using a chainsaw that is too small for the cutting job
Operating in hot outdoor temperatures with insufficient cooling
Blocked air intakes or cooling fins clogged with sawdust
An underlying engine fault or worn out parts

Fuel Vapor Lock

Another common issue is fuel vapor lock. This happens when heat from the engine causes the fuel in the line or carburetor to vaporize into bubbles. The vapor blocks liquid fuel from getting to the engine, starving it of fuel and causing it to cut out.

Fuel vapor lock tends to affect smaller, less powerful chainsaws more often since they already run hotter.

Clutch Overheating

The centrifugal clutch can also overheat from constant high-speed operation or incorrect chain tension. Too much friction causes the clutch to slip, interrupting power transfer to the chain which makes the saw cut out intermittently.

Solutions For Chainsaw Cutting Out When Hot

Luckily, there are some handy troubleshooting tips you can follow to stop your hot chainsaw from cutting out:

1. Let The Chainsaw Cool Down

If the chainsaw motor cuts out from overheating, the first solution is to just let it cool down! Turn off the machine and allow the engine and components to cool to prevent damage.

Give it at least 15-30 minutes to dissipate heat buildup before restarting.

2. Check The Bar and Chain

Issues with the bar and chain can cause overheating and clutch slippage.

Inspect for:

Tight chain tension
Adequate lubrication along the bar
Nicked or worn out cutters
Correct alignment and reduced friction
Buildup of debris, sawdust and gunk

Adjust and clean as required. This helps prevent excess friction leading to overheating.

3. Clean The Air Intakes And Filters

Clogged air filters or cooling intakes prevent proper hot air dissipation. This allows heat to accumulate and makes the motor cut out quicker.

Use compressed air and a brush to dislodge debris around:

Air filter
Carburetor intake
Cylinder fins
Flywheel intake ports

4. Adjust The Carburetor

With fuel vapor lock or running lean, adjusting the carburetor helps optimize the fuel-air ratio.

Turn adjustment screws to:

Increase fuel flow
Reduce engine temperature
Prevent starving of fuel when hot

Refer to your chainsaw manual for proper carburetor tuning.

5. Use Correct Fuel Mix Ratios

Using the right gasoline to 2-stroke oil mix ratio is vital for engine cooling and lubrication:

Common fuel mix ratios include:

16:1 = 3.2oz of oil per 1 gallon of gasoline
50:1 = 2.6oz of oil per 1 gallon of gasoline

Check your chainsaw manual for the right fuel ratios. Incorrect mixtures can lead to overheating issues.

6. Upgrade To a Large Chainsaw

If you consistently operate at high cutting loads, upgrade to a higher power chainsaw with greater torque and cooling capacity.

Professional-grade Stihl, Husqvarna, Echo or Shindaiwa chainsaws have:

Bigger displacements from 50cc to 90cc
Enhanced air intake and filtration
Reduced vibrations and friction
More metal materials rather than plastic

While more expensive, pro chainsaws are necessary for frequent big jobs.

Tips To Prevent A Hot Chainsaw From Cutting Out

Here are crucial tips to stop your chainsaw overheating and cutting out in the first place:

1. Don’t Over-Rev The Engine

Avoid running the chainsaw engine at excessively high RPM or cutting speeds. This overworks the motor, generating more heat.

Use lower speeds for smaller tasks and intermittent cutting.

2. Ensure Proper Chain Tension

Check and adjust chain tension regularly as needed:

Tension too loose allows slack and friction
Too tight also binds the chain increasing drag

Set tension just right with under 0.5cm of slack for smooth running.

3. Sharpen The Cutters Regularly

Blunt cutter teeth require more effort to cut, producing extra friction and engine load.

File them every 5-8 tank refills to keep razor sharpness.

4. Use Good Quality Fuel And Lubricants

Poor quality gasoline and 2-stroke oils break down faster, reducing lubrication and cooling inside the engine.

Always use fresh 89+ octane fuel and reputable brand oils like Stihl HP Ultra.

5. Let The Saw Idle Between Cuts

Avoid prolonged high-load operation. Give the engine 4-5 minutes to idle after each large cut to dissipate heat.

6. Cut At Optimal Chain Speeds

Adjust your cutting speed based on wood type and chain sharpness:

Softer wood requires slower feed rate
Hard wood needs faster chain speed
Blunt chains work best slightly slower

This optimizes cutting efficiency so the saw doesn’t overheat as quickly.

7. Install a Chain Brake

A chain brake instantly stops the chain rotation after kickback. This prevents extra run time heating up the clutch and engine if you lose control.

Common Chainsaw Overheating FAQs

Still having issues with your hot chainsaw cutting out? Here are answers to some frequently asked questions:

Why does my chainsaw only overheat when cutting?

Friction from the chain links grinding through wood generates a lot of localized heat around the bar and clutch. Combined with engine heat and restricted airflow, this can cause overheating issues only when cutting.

Solutions:

Ensure adequate lubrication along bar
Reduce feed rate through wood
Adjust chain tension
Upgrade to a larger chainsaw

What temperature does a chainsaw engine run at?

While idle, a chainsaw engine runs around 250-350°F (120-175°C). When hot and under load, temperatures can exceed 450-600°F (230-315°C).

Most gas chainsaw engines can operate up to 600°F safely. Any hotter risks piston, bearing and gasket damage.

Why does my chainsaw cut out after a few seconds?

If a hot chainsaw runs fine at idle but cuts out after engaging the throttle for a few seconds, it usually indicates an issue with:

Air flow restriction when the throttle opens
An overly rich fuel mixture
Early stages of fuel vapor lock

Check the air filter, carburetor settings and fuel quality.

How can I test if my chainsaw is overheating?

Warning signs of an overheating chainsaw include:

Hot or discolored outer casing
Lack of lubrication and oil splatter on the bar
Intermittent loss of power
Popping and sputtering sounds
Smoke from the exhaust
An extremely hot clutch and areas near the chain

Use an infrared thermometer gun to test surface temperatures over 160°F (70°C) to confirm.

Does putting a bigger bar help a chainsaw run cooler?

Upgrading to a longer guide bar can help in some cases. The increased surface area dissipates heat better.

However, bigger bars also require more power and chain speed to prevent bogging down. So an underpowered saw may overheat faster.

Make sure to match the bar length to chainsaw engine capacity and use reduced kickback bars where possible.

Conclusion

It can be worrying when your chainsaw suddenly cuts out without warning after getting hot. But identifying the root causes like engine overheating, fuel vapor lock or clutch slippage helps narrow down solutions.

Following proper saw maintenance, carburetor tuning, chain adjustments and upgrades prevents most overheating issues during operation.

Now you can keep your chainsaw running reliably no matter the cutting conditions!