After getting your brand new Stihl or Husky saw – or any other for that matter – you should not just go and use it as any old saw. For best service life, a new chainsaw should first broken in before you put it to heavy use.
For some years I was under the impression that break-in periods would no longer be needed with modern chainsaws. But checking the manufacturer instructions for the latest models convinced me otherwise.
In this article, I give you a short guide into chainsaw break-in. In summary, new chainsaws should be broken in by a period of light-to-medium duty use with engine revolutions and throttle opening clearly below the maximum. Most manufacturers specify 1 to 3 tanks as the break-in duration. The break-in period is recommended to ensure proper seating of piston rings other moving parts and reduces the likelihood of engine issues during the saw service life.
Next, we will shortly go through what you need to observe during the break-in, for how long, and why all of it is necessary.
NB. This article is about breaking in the saw engine. This assumes you have adjusted the chain tension and checked the chain oiler is working.
Chainsaw Break-in principles
1 Use more oil
Using more oil than normal in the fuel mix for the first few tanks is a part of a conventional break-in. While the standard gas-to-oil mix ratio is 50:1 with modern oils, the break-in tanks could use 25:1 or 33:1.
The purpose of the added oil is to ensure proper lubrication of the new engine during break-in. Note that the engine should be prelubricated at the factory, and manufacturers do not specifically instruct you to run the first tanks thicker. Doing so is added insurance, like most of the break-in.
2 Warm-up
When breaking in a chainsaw, it is good protocol to let the saw idle a few minutes before putting it to work. The idling helps to warm the engine up and ensures all moving parts are wet with oil before the engine is heavily loaded.
3 Light to medium duty
Put the saw to light-to-medium duty, variable work where you use low and middle parts of the engine revolution and throttle range. Cutting down small trees, pruning and light firewood cutting are perfect tasks.
Avoid tasks that require running the engine at high power level – wide open throttle, high revolutions – for an extended period of time. Such heavy-duty tasks to be avoided include felling or bucking large trees and chainsaw milling.
4 Idling doesn’t break in
Since you cannot put the chainsaw to heavy-duty work right away, it may be tempting to do the break-in the easy way and just let the saw idle for a few hours.
Idling is however not sufficient to break in the saw. For proper seating, the engine components need substantial loading – cylinder pressure and piston forces.
How long is the break-in period?
The general consensus is that the chainsaw break-in period should last for the first few tanks of gas. How many tanks exactly varies by manufacturer (and by source), but guidelines for Husqvarna and Stihl are in the table below.
| Chainsaw brand | Break-in period |
|---|---|
| Husqvarna | 10 h / 6…10 tanks |
| Stihl | 3 tanks |
What is the purpose of break-in?
The main purpose of chainsaw break-in is to improve the seating of the engine’s piston rings on the cylinder wall. Neither the rings nor the wall are perfectly smooth and the break-in should help the parts to wear against each other so as to mate better.
The break-in operation also helps to “bed in” all other moving parts against each other. These would typically include the crank pin and the wrist pin as well as the crankshaft bearings.
Breaking a chainsaw engine in lowers the probability of engine problems and increases expected service life of the saw.
Is break-in absolutely needed?
Breaking a chainsaw in is a part of good operation protocol but not absolutely needed: with modern saws, no adverse effects are likely to follow from an omitted break-in period.
However, breaking in is still recommended as it makes small manufacturing errors less likely to lead to more serious engine issues. In this sense, break-in is like insurance.
The truth is that many people have completely skipped break-in, i.e. put the saw to the hardest possible use right away, and still got a normal service life out of the saw. This has lead to claims that a break-in is not necessary for modern chainsaws.
While machining accuracy has indeed improved and a break-in period is less critical than it used to be, following the procedure still gives you extra insurance against engine trouble.
