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any chainsaw or small-engine experts out there?

-e-

-e-

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i was sitting there letting a new chainsaw start up and run, i wondered about break-in. it's obvious that the saws from the factory can be very tight -- so how should i run this in the next fews hours of use?" what is a good break-in protocol? some pretty large elms are coming down in the next few weeks and wonder how i should run the new saw.

i'd appreciate any suggestions.
e
 
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I am surprised that the owner's manual doesn't address this. You might want to contact them for a definite answer. My Stihl manual says not to run the saw wide open unloaded during its break-in period (I forget how long). I also think that it is good to not have it just run at idle, but to cycle the throttle with an occasional moderate rev-up. During break-in when everything is very tight, it may not be good to just let it idle for a long period because the higher than normal friction may produce higher-than-normal heat where higher RPM are necessary to get more cooling.

Bill
 
This is not about break-in but about oil/gas mixture. I have a Husky saw and the manual says to run 50:1 gas/oil mixture. A number of years ago I read a book about chainsaw lumber making and in it the author said to run 32:1 gas oil mixture. I have been doing that ever since and the saw seems to run well. I have been using this saw for over 20 years with lots of use (firewood and turning wood). I mix a 6 oz. bottle of oil with 1.6 gal. of gas. I figure it provides a bit more lubrication and that helps keep everything running better. That is the only new saw I have purchased - so I do not know about break-in.
Hugh
 
Hugh said:
This is not about break-in but about oil/gas mixture. I have a Husky saw and the manual says to run 50:1 gas/oil mixture. A number of years ago I read a book about chainsaw lumber making and in it the author said to run 32:1 gas oil mixture. I have been doing that ever since and the saw seems to run well.
Click to expand...

With synthetic oils you don't necessarily have to run as rich as the old additive types. They still run cool enough, and plug fouling is almost eliminated.

I run closer to 16:1 in blackfly season. Takes advantage of the fogging effect.
 
I'm not sure of the rationale for not running excessive unloaded speeds or not idling a lot during break-in periods, but I can tell you this...

The oil in the gas mixture provides the only lubrication there is in a two cycle engine. The richer the mixture (air/gas ratio) the more lubrication you have. That's why when you adjust the high speed mix, if you do it 'unloaded' you need to richen it up til the engine starts to "bog" or load up just a bit. As others have pointed out, the oil/gas ration will also determine how much lubrication as well. During break-in this lubrication is very critical as you have a lot of metal wearing away because everything is still very tight. (Which of course, generates a lot of heat - which could be one reason you don't want to race the engine much during this time. That high RPM generates that heat and wear that much faster. The pressures on the rings are much greater at higher RPM. So naturally they push against the cylinder walls harder and there will be more wear. If you want to check a car for engine wear, one of the things you can do is find a good hill and charge up it to see if you can spot the "blue smoke". You don't want to wear out your rings and cylinder prematurely by racing the engine.

In addition at a high RPM you're burning that much more fuel which.. adds more fuel to the fire... (Sorry 🙄 ) which generates more heat, which of course you'd like to avoid.

Idling on the other hand is not so good either. It tends to cause the engine to run "dirty," as in incomplete combustion, which means carbon build-up, which in turn can cause wear from an abrasive substance, and plug fouling, which makes the engine run worse which in turn causes incomplete combustion... and so the cycle continues.

In a 4 cycle engine, the idling, stop start kind of running (especially in colder weather) isn't very good for engines because if the engine doesn't heat up enough, gasoline will condense on the cylinder walls washing away the lubricant. Since in a two cycle the gasoline carries the lubricant, I'm not sure what effect this would have...

So if you don't have instructions for the break in period, see if you can get some.

I'm actually a little surprised it took that long for you to get the thing running though. One of the things a Mac chainsaw tech told me once was that if you saw a lot of broken starters it meant that the engine was hard to start... So don't be surprised if those blisters turn into a starter rope or spring...
 
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Manual

Go to the Husqvarna web site and download a manual for your saw. That's what I did when I bought a used 350/24". You'll also need to know the year of manufacture. You'll find that on the tag w/the model number.
 
thanks all for the info.

the husky manual doesn't really go into practical details on break-in. it only says don't run it hard for the first 10 run-hours. and that the carb is set rich out of the factory so it needs adjusting after the first 10 hrs.

additionally, the manual says to use only husky oil because it's 'designed' for the saw. it doesn't not address adding more oil at break-in (although i've heard this from others as well). it also addresses using high octane gas and gas not store over a month.

the husky web site has some useful information as well, but nothing more specific on break-in. just don't crank more than 5-6 pulls with the choke out ... and it has a de-flooding method which i didn't know before.

a friend just got the husky 3120xp/32", started it out of the box, set-up for milling, and spent 5 hours ripping boards. he broke through 2-3/8 chains and just modified the sprocket for a 404 -- obviously, he is using a different break-in technique than i :>)

just got an interesting note from another forum:
Run it hard, but don't beat it or baby it. And by beating it I mean no full bar cuts, no revving high if not under load, don't let it idle excessively, don't feather out the throttle excessively.

The breakin primarily consists of your motor seating the rings, and you want to run it pretty good for that to happen correctly. After 6-10 tanks are thru it, it will loosen up considerably. It is also set at the factory to run rich during this breakin period and at some point you will need to have someone reset the carb to realize the saws full potential. Basically, once broken in, you can then lean out the carb and it will run faster. If not sure, have the dealer do it for you.

seems the best advise so far---
 
I had a similar experience with my smaller Husky--the 350. After I bought it, I couldn't get the thing to start or even turn over. I took it back to the dealer, who services them, and they told me--not surprisingly--it was flooded. After they got it running and I got it back it has started and performed like a charm.

I blame their manual for not being more precise on the precise method of choking on the initial start-up.

Other than that, I've become a big Husky fan--very well-made saw.
 
I'm not sure that adding extra oil during the break in period is a good idea. As another fellow points out, this is the period in which your rings "seat". In other words there's a certain amount of wear that is expected to occur during this period, while the rings wear against, and conform to, the cylinder wall. I would think that "extra" oil would prolong this period.

I'd follow the manufacturers instructions. In other words, stay within specifications for best results.

I'm not sure Husky has the corner on the market for the best oil though... Sounds like they're interested in selling oil... 🙄
 
chain too tight?

how tight is the chain
if its too tight it will bog down and over heat
it should be kinda slack
 
I am very familiar with normally aspirated air-cooled aircraft engines and there are some similarities between them and small air-cooled engines, including the two-cycle engines. As mentioned in an earlier post, the rings must be "seated" during the break-in period or you will never be able to get good compression because of glazing of the cylinder walls. The quantity of oil is not relevant except that you definitely do NOT want to add more oil to the mixture. Modern 2-cycle oils are formulated (not all of them) such that you use the same quantity of oil-to-gasoline regardless of the stated oil-to-gas mixture ratio. This is not intuitive, but it is fact. The purpose of break-in is to scuff the rings and cylinder walls so that they wear to form a high compression seal. If the engine is idled for long periods of time or run at almost any other constant speed continuously the likelihood of glazing the cylinder walls is very great and once that happens, there will not be any further wear-in between the cylinder walls and rings. One of the primary reasons that the cylinder walls are very likely to glaze if the engine is idled for a very long period of time is that the engine does not get very much airflow for cooling the cylinder when idling -- therefore, the nitrided, chromed, or bare aluminum cylinder walls will get very hot and instead of scuffing, the metal will smear.

My guess on unloaded full throttle running is that the engine can run much faster unloaded that it does when running under full load cutting wood. With the tight fitting parts, it may possibly overstress some of the engine components.



The stoichiometric mixture for air to gasoline is about 13:1 at which point the combustion temperature is about 1625 deg. F. Increasing or decreasing the ratio causes the combustion temperature to decrease, but you can't go very far in either direction before combustion will not take place. At 14:1, the combustion temperature drops about 75 deg. F, but there is a problem. This condition is referred to as being "over-lean" and it leads to higher valve temperatures and detonation. The valve temperature increases because of the decrease in combustion gasses to cool the valves and the temperature of the valve seats may go 200 deg. F over normal. Detonation is an explosive burning of the fuel-air mixture rather than a smoothly burning flame-front that sweeps across the cylinder. Detonation can break valves by slamming them shut and also break rods from high shock loads. If the mixture is changed to a 12:1 "rich" mixture, the temperature also decreases about 75 deg. F, but in this case, there are more combustion gasses to cool the valves and the flame-front also sweeps more slowly across the cylinder, reducing stresses on the piston and connecting rod. The only down side is that combustion usually is not complete at the end of the stroke so unburned fuel is exhausted. In a two-stroke engine this is not a big deal because some of the exhaust fuel is sucked back into the cylinder for the next compression cycle.


Bill
 
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the saw is starting and running great -- ripped through some oak like butter -- fingers are cross but i think this saw's a winner!

thanks for all your suggestions and comments! Husqvarna returned my email question on breaking-in with references to their web site that has nothing to do with my question....perhaps it was 'lost in translation'.
 
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