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To clean the Husqvarna 445 chainsaw carburetor, remove the carburetor from the saw, disassemble both diaphragm covers, clean all fuel and air passages with carburetor cleaner and low-pressure compressed air, inspect or replace the diaphragms, needle, gaskets, and screen, then reassemble and reinstall it carefully.
For best results, use a carburetor repair kit matched to the carburetor model stamped on the carb body, commonly Walbro or Zama depending on production version.
This is important because the carburetor has very small metering passages. A single piece of dirt can block the idle or high-speed circuit.
Before disconnecting anything, take a photo with your phone.
The Husqvarna 445 uses a purge/primer bulb system, so there may be more than one fuel line:
Mark the hoses if necessary. If the purge lines are reversed, the saw may not prime or start correctly.
Then disconnect:
Use needle-nose pliers carefully. Do not tear hardened fuel lines; replace them if they crack or feel brittle.
The impulse passage is important. A diaphragm carburetor pumps fuel using crankcase pressure pulses. If the impulse passage or intake boot leaks, the carburetor may not pump fuel even if it is perfectly clean.
Work on a clean surface. The inlet needle spring is very small and easy to lose.
The metering side usually has a cover held by four small screws.
Remove:
Important: place your finger lightly over the lever while removing the screw so the spring does not fly away.
Typical metering-side order during assembly:
Carb body → gasket → metering diaphragm → cover
The pump side is the opposite side of the carburetor.
Remove:
Typical pump-side order during assembly:
Carb body → pump diaphragm → gasket → cover
This order matters. Reversing the diaphragm and gasket can prevent the carburetor from pumping fuel.
Many small two-stroke carburetors have a fine mesh screen inside the fuel circuit.
Do not soak diaphragms, rubber-tipped needles, fuel lines, primer bulbs, or plastic parts in harsh carburetor cleaner. Cleaner can swell or harden rubber components.
Clean only the bare metal carburetor body with strong solvent.
Using the straw on the carb cleaner can, spray through:
You should see cleaner exit from corresponding holes. If cleaner does not pass through, the passage may still be blocked.
Use low-pressure compressed air, roughly 20–30 psi, not full shop pressure.
Blow through every passage after spraying cleaner. Wear safety glasses because cleaner can spray back unexpectedly.
Do not use steel wire, drill bits, torch tip cleaners, or anything abrasive inside jets or calibrated holes. You can enlarge the orifice and permanently ruin the carburetor calibration.
For a badly varnished carburetor:
Ultrasonic cleaning is often more effective than spray cleaner for hardened ethanol fuel deposits inside small passages.
Replace parts if you see any of the following:
| Part | Replace if you see |
|---|---|
| Metering diaphragm | Stiff, wrinkled, curled, cracked, or hard |
| Pump diaphragm | Stiff, torn, stretched, or distorted |
| Gaskets | Flattened, torn, brittle, or stuck to the cover |
| Inlet needle | Worn rubber tip, groove, deformation |
| Fuel screen | Torn, corroded, clogged |
| Fuel lines | Cracked, hard, loose, or swollen |
| Primer bulb | Cracked, hard, leaking, or not returning |
On an older Husqvarna 445, cleaning the carburetor without replacing hardened diaphragms often gives only temporary or no improvement. A rebuild kit is usually the better repair.
The metering lever height is critical. As a general rule, the lever should sit approximately flush with the surrounding carburetor floor, but the exact height depends on the specific Zama or Walbro carburetor model. If you have the proper gauge, use it.
If the lever is too high, the carburetor can flood.
If it is too low, the engine may starve for fuel.
Use the correct stacking order:
Metering side:
\[ \text{Carb body} \rightarrow \text{gasket} \rightarrow \text{metering diaphragm} \rightarrow \text{cover} \]
Pump side:
\[ \text{Carb body} \rightarrow \text{pump diaphragm} \rightarrow \text{gasket} \rightarrow \text{cover} \]
Tighten screws evenly. Do not overtighten them; the carburetor body and covers can distort.
If you did not remove or disturb the L and H mixture screws, leave them alone.
If you removed them:
Many Husqvarna 445 carburetors have limiter caps or splined adjustment screws for emissions compliance. Final adjustment should ideally be done with a tachometer. Running too lean can overheat the two-stroke engine and damage the piston and cylinder.
Typical symptoms after cleaning:
| Symptom | Likely cause |
|---|---|
| Starts then dies | Fuel line reversed, blocked fuel filter, stiff diaphragm |
| Will not prime | Purge line reversed, cracked bulb, blocked carb passage |
| Idles but bogs on throttle | Lean setting, blocked main circuit, air leak |
| Floods badly | Inlet needle leaking, metering lever too high |
| Runs only on choke | Fuel restriction or air leak |
| High idle | Air leak, throttle linkage binding, lean setting |
Cleaning a Husqvarna 445 carburetor involves:
If the saw is more than a few years old or has sat with fuel in it, install a rebuild kit rather than simply spraying cleaner through the carburetor.
