DAYUAN Petrol Engine Compression Tester Kit — Blue Case with 3" Dual-Scale Gauge & Adapters

DAYUAN Professional Petrol Engine Compression Tester Kit is a complete compression-checking set with a 3" dual-scale gauge (0–300 psi / 0–20 bar), multiple threaded fittings and rubber cone adapters packed in a durable blue case.

Whether you service cars, motorcycles, lawn equipment or small petrol engines, accurate compression readings are essential to diagnosing worn rings, leaky valves, or head gasket issues. This kit organizes the most common spark-plug-thread sizes and provides quick-check cone adapters so you can test engines without time-consuming disassembly. The compact, foam-cut blue case keeps components secure and ready for mobile or garage use.

How do I use the DAYUAN kit to test a petrol engine's compression?

Testing is straightforward: remove the spark plug, screw the correct threaded adapter into the plug hole or fit a rubber cone for quick checks, crank the engine with the throttle wide open, and read the gauge peak. Repeat for each cylinder and compare readings to the manufacturer's spec and to each other to identify weak cylinders.

• Select the matching adapter (M10, M12, M14, M18 or included 14mm/18mm spark plug adapters).
• Attach the gauge securely to avoid leaks; use a cone adapter for non-threaded checks.
• Crank 4–6 compression strokes while watching the gauge to record peak pressure.
• Note pressure differences between cylinders; a drop >10–15% indicates a potential fault.

Which fittings and adapters are included and why do they matter?

The set includes male-threaded fittings in M10, M12, M14 and M18 sizes (each with an O-ring), plus dedicated 14mm and 18mm spark plug adapters and two rubber cone ends. These cover most petrol engine spark plug thread types and allow testing on varied equipment without modifying parts.

• M10, M12, M14, M18 male fittings with O-rings for a gas-tight seal.
• 14mm and 18mm spark plug adapters for common automotive and motorcycle plugs.
• Two rubber cone adapters for fast checks or damaged threads.
• 3" gauge with dual color 0–300 psi / 0–20 bar scale for clear readings.

What does the 3-inch dual-scale gauge tell me and how accurate is it?

The 3" dial shows both psi (0–300) and bar (0–20) so you can read results in the unit your service manual uses. The large face and color-coded zones make it simple to spot low or healthy compression at a glance; consistent technique is essential for reliable comparisons between cylinders.

• Dual scale displays psi and bar simultaneously for easy reference.
• Color-coded segments highlight common pressure ranges at a glance.
• Large 3" face improves visibility during roadside or bench testing.
• Use identical starting conditions per cylinder for the most consistent results.

Who is this for: The DAYUAN compression tester kit suits professional mechanics, mobile technicians, motorcycle and small-engine hobbyists, and DIYers who perform routine diagnostics. If you need a portable, organized solution that covers a wide range of spark plug threads and offers both threaded and non-threaded testing options, this kit delivers reliable readings and fast setup in a rugged blue carrying case.