How Much Compression Should a Chainsaw Have?

how much compression should a chainsaw have

A gas-powered chainsaw is run based on its engine. This chainsaw may contain two types of engines, one is with a 2-stroke engine, and another one is a 4-stroke engine. This engine uses gasoline as its fuel.

However, a 2-stroke engine creates a vacuum pressure inside the engine, which further sucks the fuel, lights it, and finally converts it into energy into the engine.

So the pressure by which air vacuum is produced into the engine, the compression of it has a specific limit range. Excess of this limit or too below of this limit can make the engine unable to get proper energy from the fuel.

So what is the ideal pressure limit which should maintain into the engine to get an optimum engine output?

Let’s see the details on- how much compression should a chainsaw have?

Ideal compression measurement

So how much compression should a chainsaw have? The answer is- it varies according to the brand and model of each chainsaw. A small engine needs a small amount of compression, whereas a large engine obviously will take a large compression to run the chainsaw.

Though it depends on whether the capacity of your engine, however, the minimum pressure level for a two-stroke engine should stay within 100 to 160 psi. Some of our professional person related to chainsaw technology also suggests maintaining the range within 90 to 110 psi.

So some engines may run on using a little higher compression other may run on a lower compression. The temperature and the motor capacity of the engine can impact the running of the engine.

So, whatever, a chainsaw around a compression about 110 psi is the ideal measurement for any two-stroke engines.

The motor capacity and the temperature of the chainsaw defined the compression level of its engine. 

See below the description to know about these two parameters

The Motor Power

Each model of the chainsaw does not contain the same capacity’s motor. The motor capacity, which is expressed by cc, can be lower like 30 ccs in any engine, which again can higher like 50 ccs to 150 ccs in any high capacity’s engine.

So how is motor power associated with the compression level of the engine? Let me clear you very quickly-

A chainsaw with a 50 cc engine will have a compression level up to 140 to 150 psi.

And for an engine with more capacity like 60 ccs, it will have an ideal compression at more than 150 psi that is 160 psi.

The Temperature

The rule of thermodynamics is that a cold chainsaw will run slower rather than a hot chainsaw.

Thereby, a cold chainsaw will ask a compression of 85-100psi from the vacuum air, in where a hot engine will ask more than 160psi compression range from the vacuum air. 

Too hot or too cold engine, will not ask an appropriate compression rate from inside of the engine. Therefore ultimately, your engine will not produce the required compression inside of it.

Compression test

It is a simple test; you also can measure it using a pressure testing gauge. Use a ratchet or wrench to disassemble the spark plug from your engine.

Use an adaptor holding the chainsaw, and the gauge (as gauge may come with a variable size so to adapt it with the chainsaw, you should use an adapter in between them).

If you do not have an adapter, you can seal in-between the place of these two parts to find an accurate test result.

However, keep the gauge in a proper place, and start by pulling the starter rope repeatedly. Stop the pulling if the gauge needle stops its movement ups and downs.

Now check the number of the gauge in where it stops totally to doing any movement. 

This number you obtain is the pressure or compression number of this chainsaw you were examined just a while ago.

Now see the number and compare it with the standard compression range and see whether it is similar to around 110 psi or not.

 If this number is about 110 psi, which means your chainsaw has a standard compression rate. If not, then you may have to think further to enhance the potency of your chainsaw’s engine.

You can do a quick check on the compression level of your chainsaw also. Lift the chainsaw from the ground using the starter rope handle. 

When this rope pulls out a little bit of slower, provably, the engine of this chainsaw has low compression. A well-balanced compression holds the cable tightly with the engine.

Why needs the compression or pressure for a two-stroke engine?

A stroke engine has two strokes or two chambers, and it works by the presence of one piston. The function of this piston is to move up and down within the shaft. 

On the first stroke of the engine, compressed air is produced, which is finally sucked into the other side of this stroke.

And in the second stroke of the engine, ignition of the fuel is accomplished at its bottom portion, which exhausts in the form of power or energy at the top of this stroke. 

So what is the function of compression here? The compressed air in the first stroke produces a vacuum inside the chamber, which pulls the fuel on the other side of the stroke.

Without proper pressure or compression, your engine will unable to suck the fuel and therefore, will unable to ignite it. Finally will unable to convert the fuel into the form of power or energy.

And already we know very clearly, this energy is only one vehicle which can run your engine.

So what is the problem that can arise if your engine is outside the ideal compression range?

The engine of your chainsaw may contain a high or low pressure, so what the problem can arise due to this?

A highly pressurized engine will never give you a smooth work on each day. As it has to face high pressure regularly -so suddenly it will start to provide you a difficulty starting off your chainsaw.

Again a low pressure into your chainsaw indicates there is some leak inside the engine, which causes to leak the compressed air. In that case, you can probably fix the leak sometimes, but if the pressure falls below 70 psi, then immediately you have to replace the engine instead of fixing it or repairing it.

However, a low pressurized engine will repeatedly face a misfire; will run relatively lower than the normal. And if your motor has a shallow pressure inside the chamber, it will be therefore unable to start on.

Repairing of the compression damage

Generally, pressure damage indicates producing of leakage in the gasket, seals of the crankshaft, or other internal parts of the engine. 

So if the leakage is in a small tear size, you may be able to repair them; if these parts are already broken or cracked, you have to replace these parts.

And for this replacement, you have to take your engine in a professional person as soon as possible.

An improper repairing of inside parts of your engine will create more problems instead of solving the leakage issues. An engine contains some critical and complex structural metal parts, so if you are in any doubt whether you can fix it or not, don’t try to do it at your home.

A bad spark plug, providing excessive fuel, a low-quality fuel can cause producing of high compression into the engine. 

A high compression will lead to quicker combustion into the engine, but besides this, it will increase your engine’s mechanical need also. 

It also forms more NOx, more pollutants with unburned hydrocarbons. A high compression also causes you to lose your control over your engine combustion progress and so on, so on, so on…!!

However, to fix it, you can repair or replace some of the parts like spark plugs from the engine.

Final verdict

A higher or lower pressure can arise in a wide range of problems. This problem can vary from major to minor.

However, let’s finish my article by giving you a fantastic tip to follow up on the proper compression of your chainsaw.

To avoid the pressure-related problem into your engine, you at first need to rule your engine in your way.

So, start to rule on the start parts of the engine (i.e., Starter rope, recoil spring, flywheel etc.). These starter parts of the engine need to move accurately to generate the pressure appropriately inside of your engine. 

So what can you do at these starter parts of the engine? Simply unscrew all of them and check them thoroughly to avoid any further damage to them. 

However, let’s know a tricky thing, usually, the exact answer to this question-How much compression should a chainsaw have is still not well defined. But if you can access the core of the engine, you will probably understand the compression level on which your engine can work smoothly.

So this is all about today on-How much compression should a chainsaw have.

I hope and expect you have enjoyed this article very much.

Thank you.