By: Author John Cunningham. Published: 2020/03/11 at 10:44 am
A chainsaw screaming at full tilt can be hard to take; it does make you wonder if it really needs to run this fast.
Should a chainsaw run a full-throttle? A chainsaw is designed to run at full throttle. A large tree, many times the thickness of the bar, will require full throttle.
On this page, you’ll learn why a chainsaw at full throttle when cutting is, in most cases, the safest.
Full Throttle or Not?
Before running a saw at full throttle, allow the engine to warm up a little and always use bar oil; running a saw without bar oil will damage the chain, bar, and saw.
Running a chainsaw at half throttle isn’t advised for two main reasons:
- Personal safety
- Engine protection
Timber should be cut on full throttle for safety reasons. The risk of kickback is far greater when a saw contacts timber at lower speeds.
What is kickback? Kickback occurs when the saw tip contacts the workpiece and violently throws the saw upwards and backways toward the operator. It isn’t always this violent, and your saw is fitted with a chain brake to help prevent injury.
You can help prevent kickback by:
- Applying full throttle before entering the work-piece
- Avoiding contacting the tip of the bar on the work-piece
- Use the bottom of the bar, close to the saw body to cut
- Support the work-piece when finishing the cut
- Reduce throttle when finishing out the cut
You’ll find most modern hobby saws are designed to reduce kickback. They have features such as low kickback chains and a low kickback bar, and all modern saws have a chain brake fitted.
But it is always better to be prepared; having the right kit is really important; hoodies with dangling strings or torn clothes can easily be grabbed by the chain. Wear tight clothing; chaps work great. Good solid work boots and a hard hat if working under falling branches.
I encourage all saw owners to enlist on a training day; your local hardware store will likely know where these types of day courses are held.
A two-stroke chainsaw engine is designed to run at full tilt; it’s at its happiest on full song. Running at half throttle for anything other than short periods isn’t advised. All engines need lubrication to help reduce friction and cool internal engine components. Without oil, an engine will stop dead and isn’t repairable.
A chainsaw, as you know, doesn’t have regular engine oil like a car. Instead, the oil is mixed with the gas; without oil in the gas mix, the little two-stroke engine will seize.
When a saw is at full throttle, its carburetor is tuned to supply the engine with a rich gas/oil mix. Meaning the engine is well protected from the risk of seizing. However, when running at half throttle, a saw runs leaner, and by leaner, I mean it’s getting less gas/oil mix and, therefore, less protected.
A saw can run at half throttle, but it’s not designed to work here for long periods; doing so risks damaging the engine.
Why Are 2 Stroke Engines Noisy?
Unlike a lawnmower engine, a two-stroke engine revs at much higher rpm. It can do this because a two-stroke engine is designed to power the piston (aka power stroke) on every second stroke of the engine.
A lawnmower and your car engine power the piston only one in every four strokes of the engine. The increased power strokes of a chainsaw allow the engine to rotate in excess of 12,000 RPM, far more than the 3,500 of a four-stroke mower, for example, and a 2-stroke can get up to speed far more quickly.
Basically, more combustions mean more noise.
You might find this page useful; it lists common “Chainsaw parts and tools.”
You may find the “Chainsaw trouble-shooting” section helpful.
Why does my chainsaw die at full throttle? A saw dies at full throttle because it is running lean. The top five causes of a lean-running chainsaw engine include:
- “H” jet needs to be adjusted
- Dirty carburetor
- Blocked gas filter
- Worn diaphragm
- Worn needle valve
- About the Author
- Latest Posts
John Cunningham is an Automotive Technician and writer at Lawnmowerfixed.com.
He’s been a mechanic for over twenty-five years and shares his know-how and hands-on experience in our DIY repair guides.
Johns’s fluff-free How-to guides help homeowners fix lawnmowers, tractor mowers, chainsaws, leaf blowers, power washers, generators, snow blowers, and more.