Products Description
MS250 Chainsaw Screw – Replacement Fasteners for STIHL MS250
Precision Fasteners for STIHL 025 & MS250 Chainsaws
The MS250 chainsaw uses various specialized screws for critical components, including the cylinder, muffler, and ignition system. A range of replacement fasteners is available for STIHL 025 and MS250 models, each designed for specific applications and requiring specific Torx (TX) drive sizes and installation torque . Using the correct screw type is essential to maintain proper clamping force, prevent thread damage, and ensure safe chainsaw operation. Replacement parts include cylinder screws with T27 heads and self-tapping designs, muffler mounting screws, and cylinder relief plug screws, available in singles, pairs, or comprehensive sets.
Technical Profiles & Materials
Component-Specific Fasteners – The MS250 uses specialized screws for different assemblies, including cylinder base screws with T27 (Torx) drive, muffler mounting screws, and self-tapping cylinder screws that are designed to cut their own threads in the cylinder block .
Precision M5 Thread Specifications – Cylinder screws are typically M5 size with 40mm length (M5 x 40) for standard cylinders, with self-tapping versions available in 5.3mm x 41mm for securing the cylinder to the crankcase, using T27 Torx drive heads .
Direct OEM Replacement Fitment – Replaces OEM part numbers including 9075 478 4195, 9075 478 4155, and 9075 478 3015, with aftermarket parts offering quality alternatives at competitive prices .
Technical Specifications
| # | Parameter | Specification |
|---|---|---|
| 1 | Cylinder Base Screw | TX screw T27, M5 x 40 mm |
| 2 | Self-Tapping Cylinder Screw | 5.3mm x 41mm |
| 3 | Ignition System Screws | Pan head self-tapping IS-D5x24 and IS-D4x15 |
| 4 | Torx Drive Size | T27 (for cylinder screws) |
| 5 | Recommended Torque | 12–14 Nm (cylinder screws, typical) |
| 6 | Muffler Screws | Standard fitment for 025/MS250 models |
| 7 | OEM Part Numbers | 9075 478 4195, 9075 478 4155, 9075 478 3015, 9075 478 4195 |
| 8 | Cylinder Relief Plug Screw | OEM reference 1122 025 2200 (plastic decompression plug) |
Products Application
Cylinder Reassembly & Rebuild
When rebuilding the MS250 engine, cylinder mounting screws are essential for securing the cylinder to the crankcase. These self-tapping screws (5.3mm x 41mm) cut threads directly into the cylinder block, providing a secure fit without the need for pre-tapped holes . Torque to 12–14 Nm to ensure proper clamping without stripping threads.
Muffler & Exhaust System Repair
Muffler screws secure the exhaust system to the cylinder, preventing exhaust leaks and maintaining proper engine performance. Replacement is recommended when the original screws are stripped, rusted, or lost during maintenance .
Ignition System Maintenance
The ignition module and flywheel use specific pan head self-tapping screws (IS-D5x24 and IS-D4x15) that require replacement if damaged . These screws ensure the ignition coil maintains the correct air gap for consistent spark delivery.
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: How do I confirm which screw I need for my MS250?
A:Check the location where the screw is used and measure the length and thread type of your existing screw. Cylinder screws are M5 x 40mm with T27 Torx head. Self-tapping cylinder screws are 5.3mm x 41mm. Ignition screws are pan head self-tapping IS-D5x24 or IS-D4x15. Refer to your chainsaw's parts diagram or OEM part numbers for exact identification.
Q: What is the correct torque for MS250 cylinder screws?
A: The recommended torque for MS250 cylinder screws is 12–14 Nm. Overtightening can strip the threads in the cylinder block, while undertightening can cause the cylinder to shift during operation, leading to loss of compression and potential engine damage. Always use a torque wrench for accurate tightening.
Q: What is the difference between a self-tapping screw and a standard screw on the MS250?
A: A self-tapping screw is designed to cut its own threads as it is driven into the cylinder block, forming a secure connection without the need for pre-tapped holes . A standard screw relies on existing threads. On the MS250, the 5.3mm x 41mm self-tapping screws are used specifically for attaching the cylinder to the crankcase.
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