Stihl HT 73 Instruction Manual
![Stihl HT 73 manual cover](/images/b6fb1312c01b687df0d2ade8/thumbs/thumb175x175.webp)
The Stihl HT 73 requires a 50:1 fuel mixture, which means 50 parts gasoline to 1 part 2-stroke engine oil. Use high-quality 2-stroke oil and unleaded gasoline with a minimum octane rating of 89.
To clean the air filter, remove the cover and gently tap the filter against a clean surface to remove loose dirt. If necessary, wash the filter in warm soapy water, rinse, and let it dry completely before reinstalling.
If the HT 73 won't start, check the fuel level and ensure the fuel mixture is correct. Inspect the spark plug for damage or wear and replace if necessary. Also, verify that the air filter is clean and that the choke is set properly.
The frequency of chain sharpening depends on usage, but it's generally recommended to sharpen the chain whenever it becomes dull or after every few hours of use. Using a proper round file, maintain the correct angle and file depth.
To tension the chain, first loosen the nuts on the sprocket cover. Adjust the tensioning screw until the chain fits snugly against the bar but can still be pulled around by hand. Tighten the sprocket cover nuts securely after adjustment.
It is recommended to use Stihl bar and chain oil for optimal performance and protection. If unavailable, use high-quality bar and chain oil with similar viscosity and additive properties.
To replace the spark plug, first disconnect the spark plug boot. Use a spark plug wrench to remove the old plug. Check the gap on the new plug, install it by hand to avoid cross-threading, and then tighten it with the wrench. Reattach the spark plug boot.
For off-season storage, clean the HT 73 thoroughly and drain the fuel tank. Run the engine until it stops to clear the carburetor. Remove the chain and bar, clean, and store them separately. Store the unit in a dry, sheltered area.
Excessive vibration may be caused by an improperly tensioned chain, worn or damaged guide bar, or unbalanced cutting attachment. Check and adjust the chain tension, inspect the guide bar for wear, and ensure all screws and bolts are tightened.
Regular maintenance includes checking and cleaning the air filter, inspecting the spark plug, adjusting the chain tension, lubricating the chain, and cleaning the cooling fins. Follow the user manual for specific intervals and procedures.