Stihl FS 88 Manual

The Stihl FS 88 is a professional-grade, high-performance brushcutter/string trimmer designed for demanding clearing and trimming tasks. It features a powerful 2-stroke engine with electronic ignition, a robust gearbox, a straight shaft, an anti-vibration system, and a comprehensive set of safety features. Below are key sections for safety, features, operation, maintenance, troubleshooting, and specifications.

1. Features at a Glance 2. Safety Information 3. Assembly & First Use 4. Specifications 5. Controls and Operation 6. Cutting Attachments 7. Fuel & Lubrication 8. Maintenance Schedule 9. Storage 10. Warranty Information 11. Troubleshooting

Features at a Glance

Key components: Powerful 2-stroke engine, straight drive shaft, robust gearbox, anti-vibration system, ErgoStart, QuickStop inertia chain brake, throttle trigger lockout, and harness attachment points.

FeatureDescription
Engine Type2-stroke, single-cylinder, air-cooled
Ignition SystemElectronic ignition (CDI)
Drive ShaftStraight, solid metal shaft
GearboxHeavy-duty, grease-lubricated
Anti-Vibration SystemIntegrated dampeners in handle and shaft
Starter SystemErgoStart for easier pulling
Safety FeaturesQuickStop inertia chain brake, throttle trigger lockout
Fuel Tank CapacityApprox. 0.95 liters (1.0 US qt)
Cutting AttachmentAccepts trimmer heads, metal blades, and brush knives
Weight (without attachment)Approx. 6.8 kg (15.0 lbs)

Safety Information

Read and understand all instructions before operation. Always wear appropriate Personal Protective Equipment (PPE).

  1. PPE Required: Safety glasses, hearing protection, heavy-duty gloves, sturdy boots, long pants, and close-fitting clothing.
  2. Work Area Safety: Clear area of bystanders, especially children and pets. Be aware of thrown objects and hidden obstacles.
  3. Fuel Safety: Refuel in a well-ventilated area with engine stopped and cool. Use only STIHL MotoMix or equivalent 50:1 pre-mix fuel. No gasoline with more than 10% ethanol.
  4. Operation: Hold unit firmly with both hands. Do not operate above shoulder height. Be aware of kickback zone. Never fit metal blades for trimming near hard objects.
  5. Transport & Storage: Secure unit during transport. Store fuel in approved container, away from sparks/flames. Empty fuel tank for long-term storage.

WARNING! Failure to follow safety instructions can result in serious injury or death. The cutting tool continues to rotate after the throttle is released.

Assembly & First Use

Unpack all components. Assembly requires fitting the handle, cutting attachment, and harness.

  1. Handle Installation: Slide handle onto shaft at desired position. Align and tighten clamping bolts securely.
  2. Cutting Attachment: Ensure engine is off and spark plug boot is disconnected. Fit the chosen trimmer head or blade onto the drive shaft, securing with the appropriate nut and washer. Use the shaft lock to hold the shaft while tightening.
  3. Harness Attachment: Connect the harness rings to the attachment points on the unit. Adjust harness for a balanced, comfortable fit.
  4. Fueling: Add STIHL MotoMix or properly mixed fuel (50:1 with STIHL HP Ultra oil) to the tank.
  5. Starting: Place unit on clear, flat ground. Engage the throttle trigger lockout. Set master control lever to cold start position (choke on). Pull starter rope briskly until engine fires, then move lever to warm start position and pull again to start.

CAUTION! Ensure all fasteners are tight before operation. Do not operate without a properly installed cutting attachment guard.

Specifications

Controls and Operation

Master Control Lever: Controls choke (cold start), run, and stop positions.

Throttle Trigger: Controls engine speed. Must be used with the throttle trigger lockout engaged.

Throttle Trigger Lockout: Must be depressed to allow throttle trigger movement. A primary safety.

QuickStop Inertia Chain Brake: Located on the handle. In the event of a sudden kickback, the brake engages to stop the cutting attachment within seconds. Manually engage/disable by moving the handle forward/backward.

Starter Grip: Pull to start engine. The ErgoStart system reduces pulling force.

Operation: Start the engine on clear ground. Allow to warm up at idle for 30 seconds. Use a smooth, sweeping motion when cutting. Avoid pushing the tool into material; let the cutting attachment work at its own pace.

Cutting Attachments

The FS 88 is compatible with a range of STIHL cutting attachments.

  1. PolyCut Trimmer Head: For light grass and weeds. Uses monofilament line.
  2. Circular Metal Blades: For thick weeds, brush, and saplings up to approx. 10 cm (4 in) diameter. Choose blade type (e.g., 4-tooth, 8-tooth, 80-tooth) based on material.
  3. Brush Knives: For heavy brush and woody vegetation.

WARNING! Always use the correct guard for the attachment. Never use a trimmer head guard with a metal blade. Ensure the attachment is correctly installed and tightened.

Fuel & Lubrication

Fuel Mix: Use STIHL MotoMix (pre-mixed 50:1 fuel) or mix fresh unleaded gasoline (min. 89 RON, max. 10% ethanol) with STIHL HP Ultra 2-stroke oil at a 50:1 ratio. Shake well.

Gearbox Lubrication: The gearbox is filled with grease at the factory. Check periodically and re-grease using STIHL gearbox grease. Remove the grease plug, apply grease until it emerges from the vent, and replace plugs.

Air Filter: Clean regularly with compressed air or by tapping out debris. Replace if damaged or excessively dirty.

Spark Plug: Use recommended type (e.g., Bosch WSR 6 F). Check gap (0.5 mm / 0.020 in) and clean or replace as needed.

Maintenance Schedule

IntervalTask
Before each useCheck for loose fasteners, damaged parts, fuel leaks. Inspect cutting attachment and guard.
DailyClean exterior, check air filter, clean cooling fins.
Every 25 hoursClean spark plug, check electrode gap.
Every 50 hoursClean fuel filter (in tank), check gearbox grease, inspect fuel lines.
Every 100 hoursReplace spark plug, clean combustion chamber (decarbonizing).
As neededReplace air filter, fuel filter, worn cutting attachment components.

CAUTION! Perform maintenance only when engine is cool and spark plug boot is disconnected.

Storage

Short-term (less than 30 days): Store in a dry, secure location.

Long-term (more than 30 days):

  1. Run engine to consume fuel in carburetor, or add fuel stabilizer to a full tank and run for 2 minutes.
  2. Allow engine to cool. Drain fuel tank completely.
  3. Remove spark plug, add a teaspoon of 2-stroke oil into cylinder, pull starter rope slowly 2-3 times to coat interior, reinstall plug.
  4. Clean entire unit thoroughly.
  5. Store in a dry, dust-free place, covered if possible.

Warranty Information

STIHL Limited Warranty for professional use. Coverage varies by region. Proof of purchase from an authorized STIHL dealer is required. Warranty does not cover damage from misuse, improper fuel, lack of maintenance, or normal wear. For warranty service, contact the authorized STIHL dealer where the unit was purchased.

Troubleshooting

SymptomPossible CauseCorrective Action
Engine will not startNo fuel, flooded engine, spark plug faulty, master control in wrong positionCheck fuel level. Set master control to cold start (choke). If flooded, set to run position and pull starter with throttle open. Check/replace spark plug.
Engine starts but diesClogged fuel filter, dirty air filter, carburetor adjustmentClean/replace fuel filter. Clean air filter. Have carburetor adjusted by authorized dealer.
Loss of powerDirty air filter, clogged muffler/spark arrestor, old fuelClean air filter. Clean spark arrestor screen. Use fresh fuel mix.
Excessive vibrationLoose fasteners, bent drive shaft, unbalanced/damaged cutting attachmentTighten all bolts and nuts. Inspect shaft and attachment for damage. Replace if bent.
Cutting attachment does not spinSheared drive shaft pin, damaged gearboxReplace shear pin. If gearbox is damaged, seek service from authorized dealer.
Oil leak from gearboxDamaged seals, over-greasingHave gearbox seals inspected and replaced by authorized dealer.

Service: For repairs beyond basic maintenance, contact an authorized STIHL servicing dealer. Use only genuine STIHL replacement parts.

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