Products Description
MS250 Chainsaw Adjusting Screws – Idle & Carburetor Tuning
Precision Tuning Screws for STIHL 021, 023, 025, MS210, MS230, MS250
This precision adjustment screw set is designed specifically for the Zama and Walbro carburetors used on STIHL 021, 023, 025, MS210, MS230, and MS250 chainsaws. The set includes three critical tuning screws: the high-speed screw (H) for maximum power under load, the low-speed screw (L) for smooth idling and clean acceleration, and the idle speed screw (LA) for setting the base engine RPM. These screws are precision-engineered to OEM specifications, ensuring exact fitment and reliable performance. Whether you are performing a full carburetor rebuild, correcting a running issue, or simply fine-tuning for altitude changes, having the correct adjustment screws is essential for maintaining the MS250's optimal performance. The standard factory settings of H = 3/4 turn and L = 1 turn from the seated position provide a reliable baseline for most operating conditions.
Technical Profiles & Materials
Precision Carburetor Tuning – The low speed screw (L) controls the fuel-air mixture at idle and low RPM, while the high speed screw (H) governs maximum power output and engine speed under load . The idle speed screw (LA) sets the engine's base RPM when the throttle is released.
OEM Specification – Replaces genuine STIHL parts including the idle speed screw 1123 122 6200, low speed screw 1129 122 6802, and high speed screw 1123 122 6702 / 1123 122 6701 .
Factory Standard Settings – Most MS250 carburetors use a standard setting of H = 3/4 turn and L = 1 turn out from the seated position . Some earlier models use H = 1 turn and L = 1 turn .
Versatile Carburetor Compatibility – Fits Zama C1Q-S76 (most common), C1Q-S242 (newer models), and Walbro WT-215 carburetors used on MS250 and earlier 021/023/025 models .
Technical Specifications
| # | Parameter | Specification |
|---|---|---|
| 1 | High Speed Screw (H) OEM | 1123 122 6702 / 1123 122 6701 |
| 2 | Low Speed Screw (L) OEM | 1129 122 6802 |
| 3 | Idle Speed Screw (LA) OEM | 1123 122 6200 |
| 4 | Carburetor Compatibility | Zama C1Q-S76, C1Q-S242, Walbro WT-215 |
| 5 | Standard Setting (H) | 3/4 turn from seated (max) |
| 6 | Standard Setting (L) | 1 turn from seated |
| 7 | Max Engine Speed | 14,000 RPM (MS250) |
| 8 | Idle Speed | Approx. 2,800 RPM |
| 9 | Parts Kit OEM | 1123 007 1060 |
Products Application
Idle Speed Tuning
The idle speed screw (LA) sets the engine's base RPM. If the engine stops while idling, turn LA clockwise until the chain begins to run, then back it off 1/4 turn. If the chain runs at idle, turn LA counterclockwise until the chain stops, then continue another 1/4 turn .
Air-Fuel Mixture Adjustment
Start with standard settings (H = 3/4 turn, L = 1 turn from seated). For erratic idling or poor acceleration, the idle setting may be too lean-turn the L screw counterclockwise until the engine runs and accelerates smoothly .
High Altitude Operation
At high altitude, a slight correction may be necessary. Turn the H screw slightly clockwise (leaner) to compensate for thinner air. Reset to standard setting when returning to lower altitudes .
Quality and Craftsmanship Details
Products Package
About Us
As a premier garden machinery parts supplier, Jiaxing Norsun Trading Co., Ltd. bridges global distributors with over 100 vetted China manufacturers. We streamline your B2B supply chain through strict quality control, flexible production, and factory-direct wholesale pricing. Partner with us for reliable, high-volume sourcing of precision-engineered outdoor power equipment components.
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FAQ
Q: What are the standard carburetor settings for the MS250?
A: Most MS250 carburetors use H = 3/4 turn and L = 1 turn from the seated position . Some earlier models use H = 1 turn and L = 1 turn . Always verify your specific carburetor model.
Q: What carburetor models use these adjusting screws?
A: The MS250 uses Zama C1Q-S76 (most common), C1Q-S242 (newer models), and Walbro WT-215 carburetors . The adjustment screws are compatible across these models.
Q: Are these OEM genuine parts?
A: These are high-quality aftermarket replacements meeting OEM specifications. Genuine STIHL parts are also available upon request.
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