STIHL 1120 Series Complete Engine Rebuild (009, 010, 011, 012 Chain Saws) (2 Viewers)

[D'Animal]

This is a step by step pictorial of the 1120 series STIHL Chain Saw tear down and reassembly.

I'm installing a crankcase in a 009L for a friend and a very good vendor here on MUD. (I can't remember exactly if he ran it over with his Pig while doing Trial Maintenance on the Rubicon or dropped it while juggling at Burning Man Festival. The details of the story are unclear to me.)

The 1120 series replace the 1116 Series and has been around a long time.
Here is the breakdown of the Generations and when they were on the market in the USA:

009 1980-1989
009 LE 1982-2002
009 Mini Boss 1993-2000
010 AV 1978-1982
010 AVE 1982-1985
011 AVT 1980-1982
011 AVE 1980-1990
011 AVET 1982-1996
012 AVE 1986-1994
012 AVET 1986-1989

The Orange 009 chain saws and the Orange 010 chain saws share the same 2.3ci engine. The difference is the 010 has Anti-Vibration mounted and is built in a rear handle configuration.

The White 009 chain saws and the White 011 chain saws share the same 2.5ci engine. The difference is the 011 has Anti-Vibration mounted and was built in a top handle and a rear handle configuration.

The White 012 chain saw shares the same basic design but was bumped to 2.8ci. The 012 has Anti-Vibration mounted and was built in a very unique top handle and a rear handle configuration.

 

[D'Animal]

To buy a new crankcase, front handle, rear handle and starter assy is not cost effective. I found a different 009 that someone ran straight gas through to use as a donor saw.

 

[D'Animal]

Here is the damaged saw.

Missing top front handle.

Crank Case Broke where the top handle mounts on the side of the carburetor box.

Rear Handle Cracked. This is a part that also contains the starter assy.

 

[D'Animal]

Drain all fluids in an approved container.


Remove air filter cover and air filter.

For the 009
Remove the 6 screws that hold the starter assy on. One of the six is one of two that hold the bottom handle bar on.

Remove the screw that holds black trigger interlock cover down. (It is on top of the saw and what you would wrap the palm of your right hand around when you are running the saw.)

Once the trigger interlock cover is removed, remove the throttle interlock and the throttle trigger. You will notice a rod connecting it to the carburetor. I am pointing at the rod using my little orange handled screw driver. You will not get the starter assy off without removing this piece.

 

[D'Animal]

From there, you gently pull the lower handlebar towards the oil cap and remove the starter assy.

Next remove the two screws holding the muffler on. There is a gasket there, so don't loose it.

Here is what you will be looking at with the muffler removed.

 

[D'Animal]

From here you should install a piston stop. This is a horizontal designed engine and the piston is parallel to the spark plug. You can use the "old School" piston stop in this saw. You cannot use this piston stop in any saw where the spark plug enters the cylinder at an angle. You will break the spark plug threads if you do.

 

[D'Animal]

Once the piston stop is installed, lossen the 13mm nut holding the flywheel on. Loosen it so it is even with the end of the crankshaft. Using a Bras Drift/Punch, give the nut a sharp smack with a small ball peen hammer against the punch. Unscrew the nut and pull the flywheel off.


On the clutch side, use a spanner wrench on the Orange 009, 010, and 011's. On the "White" series, use a 19mm socket and unscrew the clutch to the right, it's a backwards thread.


DO NOT USE AN IMPACT WRENCH!

You will see why in a few slides.

 

[D'Animal]

Remove the two screws holding the carburetor on and then remove the fuel line and carburetor.


Then remove the two screws that mount the black carburetor base. It contains the reed plate.

 

[D'Animal]

The 1120 series saw uses roller bearings for the lower connecting rod bearing. They are replaceable.

They also use needle bearings for the outer crankshaft bearings. This is a low RPM saw with a ton of torque, no need for ball bearings in these areas.

The top picture shows the lower rod bearing.

The middle picture is the connecting rod bearing holder. It fits down through the carburetor intake hole and securely holds the rod bearing in place while you take the cylinder and piston off.

The bottom picture shows what happens if you use and impact wrench on this series of saw or if you try to remove the cylinder and piston without the rod bearing holder in place.

 

[D'Animal]

So far, you have been using the standard bar wrench that came with the saw to do everything. Depending on the vintage of the saw, you may have to get a T-27 Torx wrench.

With the lower rod bearing holder in place, remove the 4 screws that hold the cylinder on. Remove the cylinder. On some versions you will have a black spacer under the cylinder, remove that as well. It just pulls off.

 

[D'Animal]

With the cylinder removed you can inspect the entire piston.

The Orange 009 and the 009 Mini Boss has One compression Ring. The early 010's had one ring as well but gained the second ring later in thier production life.

The 009L (Deluxe) has two piston rings.


Sorry for the poor quality picture. It is really hard to take a picture of a scored piston. The flash reflects off of each groove.

The top picture is the one ring piston

The bottom picture is the two ring piston. I put the cylinder back on and you are actually looking through the exhaust port. You can actually see the machine marks on the piston.

 

[D'Animal]

Now it is time to split the crankcase.

Each STIHL crankcase has matched halves. Once they are cast they are machined and bolted together and then powder coated. Alignment pins are installed as well as the screws that hold the halves together. They are then line bored for the crankshaft and then the cylinder area and the carburetor mounting area is decked to ensure a flat surface. Although the tolerances are so close you cannot see the differences Mixing and Matching crankcase halves is not recommended.

 

[D'Animal]

Take a small drift and tap the alignment pins 1/2 way out. On the 1120 sereis there are three alignment pins.

The top one is right under the throttle rod/cable area in the 6:00 position of the carburetor. It is located right above my screw driver/pointer.

The next two are around the crankcase pretty evenly spaced.

 

[D'Animal]

You can now remove all the screws holding the crankcase together, including the black quickstop hand guard.

 

[D'Animal]

From here, the crankcase pulls apart using your hands.


Do not beat on the crankshaft.

 

[D'Animal]

Here is the halves split apart and the crankshaft that has had the lower rod bearing knocked out.

 

[D'Animal]

Remove the old gaskets and clean the components and parts as needed.

I generally steam clean the entire saw before I start to work on them. It was below freezing so I did not get my steam cleaner out for this little project.


When you get new gaskets and seals, take your serial # with you. There are a few selection based on the age and the serial # splits.

 

[D'Animal]

Assemble in reverse order.















































Just kidding











I will be doing a step by step reassembly once I get the gaskets and seals I need.

 

[turbocruiser]

Wow, very cool thread, thanks for this!!!

 

[Mace]

Assemble in reverse order.


Just kidding


I will be doing a step by step reassembly once I get the gaskets and seals I need.

Awesome