Five engines, one manual: the RK50, RK60, RK70, RK80-1, and RK95-1 share these 125 pages (OEM #9Y011-02650). Exploded diagrams trace every major assembly from cylinder head to flywheel, with a performance curve for each variant and troubleshooting charts that sort hard starts, rough running, and exhaust smoke. Eighty-three of those pages walk through disassembly and servicing, then a full reference section lists clearances and test values for valves, pistons, crankshaft, camshaft, and the lubrication and fuel systems. Torque the cylinder head nuts to 98.1 to 117 N-m and the flywheel nut to 300 to 390 N-m, factory tolerances straight from Kubota engineering. No more chasing numbers across forum threads while the engine sits cold. Bookmarks run by section, so open the PDF, tap a chapter, and get to work.
What's Inside This Kubota RK Series Manual
| System | Pages | Key Topics |
|---|---|---|
| Specifications | 3-4 | Engine Model And Type Specifications, Output And Speed Specifications, Combustion And Lubricating System Specifications, Cooling And Fuel System Specifications |
| Performance Curves | 5-6 | RK50 RK50-N RK50H Performance Curves, RK80-1 RK80-1-N RK80H-1 Performance Curves, RK95-1 RK95-1-N RK95H-1 Performance Curves, RK60 RK60-N RK60H Performance Curves |
| Appearance and Dimensions | 7-8 | Radiator Type Dimensions, Hopper Type Dimensions, Details Of Flywheel |
| Optional Equipment | 9-10 | PTO Shaft Assembly with Bolt, Washer & Key, Pulley Flange Assembly, Flat Pulley, V-Pulley |
| Mechanism | 11-42 | Feature (Fuel Saving, Quiet/Low Vibration, Easy Operation/Starting, High Durability, New Design/Safety Engine) |
| Disassembling and Servicing | 43-125 | Engine Identification (Model Name And Engine Serial Number, Applying Grease To Oil Seal, Direction Of Installing Snap Rings) |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Flywheel Nut Torque | 300 to 390 N-m | p. 44 |
| Cylinder Head Nuts Torque (RK50-60-70-80-1-95-1) | 98.1 to 117 N-m | p. 44 |
| RK50 Bore x Stroke | 72.0 x 75.0 mm | p. 3 |
| RK50 Lubricant Capacity | 2.0 ℓ | p. 3 |
| RK50 Fuel Tank Capacity | 7.5 ℓ | p. 3 |
| Cylinder Head Surface Flatness Allowable Limit | 0.05 mm | p. 48 |
| Compression Pressure Allowable Limit | 2.40 MPa | p. 48 |
| Valve Clearance (Cold) [RK50-95-1] | 0.16 to 0.20 mm | p. 48 |
| Engine Oil Pressure (At Idle Speed) | 50 kPa or more | p. 54 |
| Oil Pump Rotor Lobe Clearance | 0.15 mm or less | p. 54 |
| RK80-1 Injection Pressure | 21.6 to 22.5 MPa | p. 55 |
| Radiator Leakage Test Pressure | 180 kPa | p. 54 |
Kubota RK Series Common Problems This Manual Covers
Kubota RK Series diesel engine cranks but won't fire, no smoke from exhaust
Confirm the tank actually has fuel (RK50/60/70 capacity: 7.5 ℓ) and that the stop lever sits in RUN with the decompression lever fully released. If the engine turns freely but still won't fire, test compression against the 2.40 MPa allowable limit on page 48, then check injection nozzle spray condition using the diagnostic values on page 55.
Manual Section: General Engine TroubleshootingEngine runs rough at idle, misfiring on one cylinder, black exhaust smoke under load
Measure valve clearances first and set them to 0.16 to 0.20 mm cold per the clearance specs on page 48. If those are in spec, move to the injection system: check injection timing and nozzle spray pattern with the diagnostic values on page 55. Clean or swap a sticking nozzle needle, and make sure the air intake path isn't restricted.
Manual Section: General Engine TroubleshootingOil pressure warning at idle, engine oil level shows correct on dipstick p. 54
Top off the oil to capacity first (2.0 ℓ for RK50/60/70). With level correct, read oil pressure at idle; the minimum is 50 kPa per page 54. Below that, pull the oil pump and measure rotor lobe clearance; the limit is 0.15 mm per page 54. Replace the pump once clearance runs past that limit.
Manual Section: Lubricating System Diagnostics and ServicingFan belt squealing and slipping at startup, coolant temperature rising past normal p. 54
Inspect fan belt tension first. Deflection should run 5.0 to 10 mm under moderate thumb pressure; adjust or replace the belt if it falls outside that range per page 54. Pressure-test the radiator cap at 180 kPa and replace it if it leaks. Add coolant to the correct level (RK80-1/95-1 capacity: 1.6 ℓ) if it reads low.
Manual Section: Cooling System Diagnostics and ServicingHard start every morning in cold weather, white smoke for first five minutes
Check valve clearances cold before cranking; the spec is 0.16 to 0.20 mm per page 48. Test each glow plug and confirm the preheat time is long enough. Verify injection nozzle opening pressure and spray pattern with the diagnostic values on page 55. If white smoke lingers after full warmup, test cylinder compression against the 2.40 MPa allowable limit.
Manual Section: General Engine TroubleshootingEngine loses power pulling heavy loads, governor hunts and surges at full throttle p. 55
Start at the fuel tank and check the level, then inspect the fuel filter for blockage; clean or replace it if dirty. Confirm injection pipe retaining nut torque at 25 to 34 N-m per the torque specs on page 44. Test injection nozzle spray condition and opening pressure with the values on page 55. Examine the delivery valve for sticking and clean or replace it as needed.
Manual Section: Fuel System Diagnostics and ServicingFrequently Asked Questions
What are the recommended service intervals?
A "MAINTENANCE CHECK LIST" lays out the service intervals. Daily checks cover "Cooling Water and Radiator" and "Fan Belt Tension". At the initial 50 hours you change the "Engine Oil" and clean the "Oil Strainer". "Valve Clearance" gets checked every 100 hours, and "Nozzle Injection Pressure and Spraying Condition" every 300 hours.
What fluids and capacities does this machine require?
Fuel is Diesel Fuel No.2-D (ASTM D975). For lubricating oil, the spec calls for S Supplement 1 or MIL-L-46152, or API service class CD (SAE 30, 20, 10W, 10W-30). Capacities depend on the model: RK50-60-70 holds 2.0 ℓ (0.53 U.S.gals) of engine oil and 7.5 ℓ (2.0 U.S.gals) of fuel. Cooling water on RK50-60-70 runs 1.3 ℓ (0.34 U.S.gals) on the -,-N Type and 8.5 ℓ (2.2 U.S.gals) on the -H Type.
How to troubleshoot engine won't start?
A no-start traces back to a few causes. Start with "No fuel" and "Air in the fuel system", both fixed by replenishing fuel and venting air (Page M-30). Next come a clogged "Fuel pipe" or "Fuel filter" (clean them, Page S-20) and "Incorrect injection timing", which needs adjustment (Page S-25,75). "Deficient compression" may mean replacing the head gasket or correcting valve issues (Page S-32, S-53).
What torque specifications are listed?
Torque values are listed for components throughout. The "Flywheel Nut" goes to 300 to 390 N·m (30 to 40 kgf·m). "Connecting Rod Screws" on RK50-60-70 (~916058) call for 30 to 34 N·m (3.0 to 3.5 kgf·m). "Cylinder Head Nuts" across the RK50-60-70-80-1-95-1 models are set at 98.1 to 117 N·m (10.0 to 12.0 kgf·m).
What are the common electrical problems?
The troubleshooting section flags "Light Does Not Light" on Normal Type models. Causes include a "Light bulb burnt" (Replace), "Wire disconnected" or "Connector disconnected" (Check and connect, Page M-31), a "Short-circuit in lead wire" (Repair), or a "Dynamo coil malfunctioning" (Replace, Page S-82).
What do I get after purchasing this Kubota RK Series manual?
Checkout delivers a 125-page searchable PDF right away. Open it on a laptop, tablet, or phone and take it straight to the shop floor.
Can I print specific sections of this Kubota RK Series Workshop Manual?
Yes. Print as many copies as you like, with no restrictions. Plenty of mechanics print just the section they need and keep it at the bench.
Document Quality
This document is a scanned PDF with an OCR layer, allowing you to search and copy text. The OCR text is crisp, though some underlying scanned text shows slight fading or minor artifacts. Diagrams and illustrations are raster images, so they may pixelate at high zoom, but their labels are readable. Pages are generally clean, with occasional minor scan speckles or slight background unevenness. There are no notable blank or filler pages.
Reviews
There are no reviews yet.