This document is a manual for Pretul chainsaws, specifically models MOT-6020P and MOT-6018P. It provides detailed instructions on their use, maintenance, and safety.
Function Description
The Pretul chainsaw is a portable, motorized saw designed for cutting wood. It is equipped with a 2-stroke, air-cooled engine and a cutting chain that rotates around a guide bar. The primary function is to fell trees, buck logs (cut felled trees into sections), and trim or prune branches. Safety features include a chain brake to stop the chain quickly in case of kickback, and a cutting chain designed for moderate kickback.
Important Technical Specifications
The manual covers two models: MOT-6020P (code 27045) and MOT-6018P (code 27044).
Both models feature a 60 cm³ (cc) motor with a rated power of 3 HP and a maximum motor speed of 12,500 RPM. The chain speed is 4,330.7 ft/min.
Key differences between the models are:
- Net Weight (without bar): MOT-6020P is 15.2 lb, MOT-6018P is 14.7 lb.
- Bar Length: MOT-6020P has a 20" bar, MOT-6018P has an 18" bar.
- Chain Pitch: Both have 0.325".
- Chain Gauge: Both have 0.05".
- Drive Sprocket Wheel: Both use 7 (0.325") sprockets.
- Fuel Tank Capacity: Both have 19.95 oz.
- Oil Tank Capacity: Both have 8.79 oz.
- Vibration: Front handle 3.5 m/s², rear handle 7.7 m/s² for both.
- Work Cycle: 40 minutes rest per each tank consumed, maximum 5 hours daily.
Usage Features
The chainsaw requires a specific fuel mix: unleaded gasoline (87 octane or higher) mixed with 2-STROKE motor oil at a 50:1 ratio (50 parts gasoline to 1 part oil). It is crucial to use fresh fuel mix (not stored longer than 15 days) and avoid automotive or outboard 2-stroke motor oil. The manual emphasizes using Truper synthetic oil for 2-stroke motors for extended engine life.
Starting the chainsaw involves several steps:
- Place the chainsaw on level ground, ensuring the bar and chain are clear of any objects.
- Hold the front handle firmly with the left hand and place the right foot on the rear handle base.
- Pull the chain brake backward to ensure it's in the functioning position.
- Set the switch to the ON position.
- Press the starter choke bulb 6 times.
- Pull the choke lever all the way out.
- Pull the jack-line until the motor attempts to start (no more than 3 times if above 50°F, or until it starts if below 50°F).
- Push the choke lever to the bottom.
- Pull the jack-line again until the engine starts.
- Let the motor run for 30 seconds, then press and release the throttle trigger to run at idle.
The manual provides detailed instructions for bar and chain mounting, including extending the chain, setting the bar, linking the chain to the cogwheel, and tensioning the chain. Proper chain tension is verified by inserting the flat nose of the spark plug key between the bar and a chain link, checking for a 0.05" looseness.
Cutting operations are described for felling and bucking. For felling, users must plan escape routes, consider wind direction, and make specific cuts: a 1/3 diameter notch (horizontal and 40° angle) followed by a third cut on the opposite side, 2" above the horizontal notch, leaving a 1/10 diameter hinge. For bucking, logs should be supported, and cuts made to prevent the chain bar from getting trapped, especially when cutting trunks under pressure. Trimming and pruning require extreme care, avoiding cutting from ladders or unstable surfaces.
Maintenance Features
The manual outlines a comprehensive maintenance schedule:
- After each use: General cleaning, air filter cleaning.
- Every 25 hours: Carburetor adjustment, spark plug inspection and adjustment.
- Every 50 hours: Fuel tank cleaning, fuel filter change, fuel hose replacement.
- Every 150 hours: Spark arrester cleaning.
- Every 250 hours: Spark plug replacement.
Specific maintenance tasks include:
- Cutting Chain Maintenance: Regular honing is required if wood shavings are small/dusty, forcing the bar is necessary, or the chain cuts sideways. Honing is done with a 5/32" round file, ensuring all sprockets are filed at the specified 30° and 60° angles and to the same length.
- Chain Depth Gauge: The depth gauge (cleaning sprockets) must be checked and filed to maintain a 0.025" difference in height with the drive sprockets.
- Chain Bar Maintenance: The bar should be cleaned after each use, and small grooves or lumps on the rails smoothed with a file. Lubrication orifices and the cutting chain slot must be cleaned. The bar should be reversed weekly to distribute wear, and the nose cogwheel lubricated with a grease syringe. The bar must be replaced if worn, widened, or bent.
- General Cleaning: Ventilation slots, motor cylinder blades, and ventilator blades should be cleaned with a brush or compressed air.
- Fuel Filter: Checked periodically and replaced by an authorized service center if contaminated or damaged.
- Carburetor Adjustment: Limited adjustment to "L" (moderate injection) and "H" (intense injection) nozzles (within a 1/2 turn range) should only be performed by authorized service center specialists after the engine is warm and air filter/ventilation slots are clean.
- Exhaust and Muffler Cleansing: Carbon deposits in the exhaust orifice and muffler should be removed by an authorized service center if power loss is noted. The spark arrest screen inside the muffler needs periodic cleaning and replacement.
- Chain Brake: Components should be inspected and cleaned. The brake band must be replaced if worn to half its original thickness (0.035") or malformed. The mechanism should be kept clean and lightly oiled.
- Spark Plug Replacement: The manual recommends replacing the Bosh L8RTF spark plug (0.025" electrode gap) every six months.
- Chainsaw Storage: For storage longer than one month, drain all fuel and oil, run the motor until it stops, clean the chainsaw thoroughly, and store it in a ventilated area away from corrosive agents and children.
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