Rato RV170

Rato RV170 vertical shaft engineThe Rato RV170 is a 173.2 cc (10.57 cu-in) single-cylinder air-cooled 4-stroke internal combustion general-purpose gasoline engine with vertical shaft, manufactured by Chongqing RATO Holding (Group) CO., LTD. The RV170 emgine is used for lawn mowers, pressure washers and tillers.

The Rato RV170 engine has a single-cylinder with a vertical shaft; an overhead valve (OHV) design; flat suction valve carburetor; recoil starter or electric starter, Capacitance Discharge Type or Inductance Discharge Type ignition system and centrifugal mechanical governor system.

A 70.0 mm (2.76 in) cylinder bore and 45.0 mm (1.77 in) piston stroke give the Rato RV170 motor a total of 173.2 cc of displacement. Compression ratio rating is 8.5±0.3:1. It produced 6.0 HP at 3,600 rpm of horsepower and 9.0 N·m (0.92 kg·m, 6.64 ft·lb) at 2,500 rpm of torque.

General information

Engine Specifications
Type4-stroke, OHV, single cylinder
Displacement173.2 cm 3 (10.57 cu-in)
Max. horsepower6.0 HP at 3,600 rpm
Max. torque (crank PTO)9.0 N·m (0.92 kg·m, 6.64 ft·lb) at 2,500 rpm
CarburetorFlat suction valve carburetor
Cooling systemForced-air
Ignition systemCapacitance Discharge Type or Inductance Discharge Type
Lubricating systemSplash
Starting systemRecoil / electric starter
Stoping systemIgnition primary circuit ground
Fuel usedUnleaded gasoline (octane number 86 or higher)
PTO shaft rotationCounterclockwise (from PTO shaft side)

Cylinder Block and Head

Cylinder block
Compression ratio:8.5:1
Bore x Stroke70 X 45 mm (2.76 x 1.77 in)
Sleeve internal diameter70.00 mm (2.7559 in)
Piston skirt outer diameter69.985 mm (2.53 in)
Number of piston rings (compression / oil):2 / 1
Connecting rod small end ID18.005 mm (0.7087 in)
Connecting rod big end ID30.02 mm (1.182 in)
Crankshaft crank pin outer diameter29.980 mm (1.180 in)
Cylinder Head
Warpage (limit)0.10 mm (0.004 in)
Valve Arrangement:OHV
Stem outer diameter (standard):INTAKE5.480 mm (0.216 in)
EXHAUST5.440 mm (0.214 in)
Cam height:INTAKE27.70 mm (1.090 in)
EXHAUST27.75 mm (1.093 in)
Valve spring free length:34.0 mm (1.3386 in)
Camshaft journal diameter:13.984 mm (0.5505 in)

Service Information

Maximum speed3400 ± 100 rpm
Idle speed1900 ± 150 rpm
Cylinder compression14.0 kg/cm2 at 1400 rpm
Valve clearance
Intake valve clearance0.15±0.02 mm (0.006±0.001 in)
Exhaust valve clearance0.20±0.02 mm (0.008±0.001 in)
Oil system
Oil type4-stroke or an equivalent (SJ)
Recommended oilSAE 10W-30, 15W-40
Oil capacity0.6 L
Main jet#65
Float height13.7 mm (0.54 in)
Pilot screw opening2-5/8 turns out
Ignition system
Spark plugNGK: BPR6ES
Spark plug gap0.7-0.8 mm (0.028-0.031 in)
Primary ignition coil resistance0.8-1.0 Ω
Secondary ignition coil resistance5.9-7.2 kΩ
Ignition coil air gap0.4 ± 0.2 (0.016 ± 0.008)
Author: Sergei Wers
About: Co-founder and CEO of a multi-brand auto repair shop (engine repair, chassis repair, body repair and painting) for over 15 years. I have been developing internet sites with technical specifications for more than seven years.

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We try to use verified sources and official documentation, however, differences between sources or errors in entering information may occur. We do not provide advice on technical issues related to the engines operation or repair. We do not recommend using provided information for engines repairing engines or spare parts ordering, use only official service manuals and spare-parts catalogs.


  1. I have a Mi T M pressure washer with your 170 series motor and need a new recoil starter and am unable to get a replacement localy. HELP

    • You can get parts for the engine depending on who uses the engine. I can get parts for my engine through the local mower shop. This mower shop can not look up the parts and order. However, since the engine is used by Poulan…Husqavarna…etc I can find the part number online…..google till something comes up and get the Poulan or husky part with the same part number. Cool huh?

  2. I have a Rato RV170 lawn mower engine. I need a carborator bowl gasket. Cannot find anywhere. local mower shops are at a loss when finding a part number. This gasket broke when I removed the bowl. Would not run and needed to be cleaned. Now it runs great but leaks gass from bowl. Help me find this penny part please?????

    • I had the same problem. I used a bowl gasket for a Briggs. For $5 you can get “Bowl Float ” box BS#796611. In this box you will find 2 bowl gaskets. Use the small gasket…it does not fit( too small)but close. To fit… push the gasket down into grove with thumb. If you push hard enough the gasket will pinch into place into groove. It should stay put and be ready for your bowl. I did this and it works perfectly.

    • I need a piston push rod for a rato 7.0 rv170. I have not been able to search one out or even find a part number.

  3. I am trying to install a off/on valve for the fuel line for a 170cc engine in my DR mower/trimmer. However, the fuel line is not 1/4, as almost all the valves are sized for. What size is the fuel line? btw, it is much smaller than 1/4

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