Description
Stihl KM 91 R KOMBISYSTEM Gas Powered Split Shaft Power Head
Step up to commercial-grade cutting torque and all-day fuel efficiency with the STIHL KM 91 R KombiEngine Gas-Powered Multi-Task Powerhead. Purpose-built for professional landscaping crews, large property managers, and demanding estate owners, this versatile power unit bridges the gap between lightweight consumer powerheads and heavy brush-clearing engines, powering all 14+ interchangeable STIHL KombiTools with a single reliable engine.
Under the hood, the KM 91 R features a commercial-grade 28.4 cc STIHL 4-MIX® hybrid engine (1.27 bhp / 0.95 kW). This advanced power plant combines the high torque, low exhaust emissions, and fuel economy of a 4-stroke engine with the lightweight agility, snappy acceleration, and low maintenance of a 2-stroke. An enlarged 24.0 oz. translucent fuel tank delivers up to 30% longer runtimes between fill-ups, while the automatic decompression system ensures smooth, low-effort pull starts. The heavy-duty tool-free split-shaft coupler lets you swap between grass trimmers, curved or straight edgers, pole pruners, and hedge clippers in seconds, while the ergonomic loop handle with barrier bar provides pinpoint control around tight garden edges, slopes, and fences.
Key Features:
- High-Torque 28.4 cc STIHL 4-MIX® Engine: Blends 4-stroke torque and low emissions with 2-stroke lightweight acceleration and responsiveness.
- One Powerhead, 14+ KombiTools: Quickly converts into a string trimmer, edger, pole pruner, hedge trimmer, bed redefiner, cultivator, or blower.
- Tool-Free Quick-Release Coupler: Heavy-duty aluminum split-shaft sleeve with thumb screw allows instant tool swaps and compact vehicle storage.
- Extended Run Time Fuel Capacity: 24.0 oz. translucent fuel tank keeps crews running longer between refueling stops.
- Automatic Decompression Mechanism: Automatically relieves cylinder compression during starting to dramatically lower starter cord pulling resistance.
- Simplified Starting Procedure: Semi-automatic choke lever and momentary one-touch stop switch automatically return to the run position to prevent flooded starts.
- Pleated Paper Air Filter: Industrial-grade filtration system extends service intervals and shields engine components from fine jobsite dust.
- Ergonomic Loop Handle (R): Features an adjustable barrier bar for superior maneuverability when trimming at varying angles or on uneven grades.
Specifications
| Specification | Details |
| Brand | STIHL |
| Series | KombiSystem / KombiEngine |
| Model / Series Code | KM 91 R |
| Engine Type | STIHL 4-MIX® Hybrid Engine |
| Displacement | 28.4 cc (1.73 cu. in.) |
| Engine Power Output | 0.95 kW / 1.27 bhp |
| Fuel Type | 50:1 Gasoline to 2-Cycle Engine Oil (STIHL HP Ultra or MotoMix) |
| Fuel Tank Capacity | 24.0 fl. oz. (710 cc) |
| Starting Mechanism | Manual Pull-Start with Automatic Mechanical Decompression |
| Shaft Style | Heavy-Duty Split-Shaft with Tool-Free Clamping Knob |
| Handle Configuration | Ergonomic Loop Handle (R) with Barrier Bar |
| Powerhead Weight | 9.7 lbs (4.4 kg) without fuel/attachment |
| Emissions Compliance | Meets EPA Phase 3 and CARB Tier 3 standards |
Frequently Asked Questions
What is the difference between the KM 91 R and the KM 131 R?
Both models use commercial STIHL 4-MIX® engine technology and share the same heavy-duty 24 oz. fuel tank and split-shaft coupling. The KM 91 R features a 28.4 cc engine (1.27 bhp) optimized for trimming, edging, and pruning with lower fuel consumption and less weight fatigue. The KM 131 R features a larger 36.3 cc engine (1.9 bhp) tailored for high-drag attachments like bed redefiners and power sweepers.
Does the 4-MIX® engine require separate oil changes?
No. Even though it uses overhead valves like a 4-stroke engine, the STIHL 4-MIX® engine is lubricated directly through the fuel. It runs on a standard 50:1 fuel-to-oil mix (such as premium unleaded gasoline with STIHL HP Ultra 2-cycle oil or STIHL MotoMix), eliminating oil pans, dipsticks, and separate oil changes.
What attachments are compatible with the KM 91 R powerhead?
The KM 91 R is compatible with all STIHL KombiTools, including the FS-KM line trimmer, FCS-KM straight edger, FCB-KM curved edger, HL-KM adjustable hedge trimmer, HT-KM pole pruner, BF-KM mini-cultivator, and BG-KM blower.
How does the automatic decompression system assist with starting?
The automatic decompression system momentarily opens the exhaust valve when the starter rope is pulled. This releases built-up compression in the combustion chamber, reducing the physical effort needed to pull the cord and preventing hard kickbacks.
Is an attachment included in the box with this powerhead?
No. The KM 91 R is sold as a standalone powerhead unit consisting of the engine, throttle control, and upper shaft assembly. Attachments are purchased separately so you can build the exact multi-tool system you need.
Product Specifications
selling_points: |
✔ 28.4cc 4-MIX Engine: Delivers high torque and heavy-duty power with standard gas-oil mix ✔ 30% Larger Fuel Tank: Extended runtime lets you work longer between fill-ups for maximum jobsite efficiency |
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High-performance 28.4 cc STIHL 4-MIX engine delivers exceptional torque and fast acceleration without separate oil maintenance Larger fuel tank capacity provides up to 30% longer run times between fill-ups for uninterrupted productivity |
