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Home›Engines›Kohler CH25

Kohler CH25 Engine

The Kohler CH25 is a 0.72 L natural engine rated at 3600 rpm. It powers generator sets from Cummins/Onan and Genmac, including the 11RMY, HSD12 and HSG12.

Also known as: Kohler CH25

0.725 L
Displacement
3600 rpm
Rated speed
On this pageSpecsGenerator setsMaintenanceFAQTorque & specsProcedures

Engine specifications

Displacement0.725 L
Aspirationnatural
Rated speed3600 rpm

Generator sets powered by this engine

3

Shared across brands: Cummins/Onan, Genmac

Cummins/Onan 11RMYGenmac HSD12Genmac HSG12

How to read your Kohler engine serial & model number →

Common problems

4
  • Speed trim value is abnormal
    Cause: 1. Speed trim shorted or miswired.
  • Gap between speed sensor and gear teeth is too great
    Cause: 1. Gap between speed sensor and gear teeth too great. 2. Improper or defective wiring to the speed sensor.
    Fix: Check gap.
  • Defective speed sensor
    Cause: 3. Defective speed sensor
  • Battery Supply Voltage (12 VDC) is not normal
    Cause: 1. DC battery power not connected. Check for blown fuse. 2. Low battery voltage. 3. Wiring error.

Compiled from service & troubleshooting documentation across every generator set that uses the Kohler CH25.

Maintenance schedule

ItemSpecCapacityPart #Interval
Air filter—500 hr
Fuel filter—300 hr
Oil filter—100 hr
Batterybattery—
Belt—
Coolantautomotive antifreeze coolant—
OilCD—100 hr
Spark plugspark plug—

Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.

Service specifications

1
TypeItemValueUnitCondition
VoltageOxygen sensor output voltage for correct fuel mixture adjustment0.5vdc (target, adjust within -0.3)90-100% rated load, normal operating temperature

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Procedures

1
Fuel Metering Valve Adjustment Procedure adjustment

⚠ Disconnect battery cables before working on generator set (negative lead first, reconnect last)

⚠ Hot engine and exhaust system can cause severe injury or death; allow to cool before servicing

Tools: digital volt meter (DVM), oxygen sensor (A-345052), load bank capable of rated kW for the fuel being used

  1. Place generator set master switch OFF
  2. Disconnect power to battery charger, if equipped
  3. Disconnect engine starting battery, negative lead first
  4. Remove oxygen sensor plug from exhaust manifold
  5. Install oxygen sensor in exhaust manifold where plug was removed
  6. Check master switch is OFF, reconnect battery negative lead last
  7. Place controller master switch to RUN to start generator set
  8. Allow generator set to run until normal operating temperature
  9. Apply 90-100% of rated load
  10. Connect DVM leads between oxygen sensor lead and ground, measure output voltage
  11. Adjust fuel metering valve to obtain 0.5 vdc -0.3 output from oxygen sensor
  12. Remove load, allow generator set to run unloaded 5-10 minutes to cool
  13. Place master switch OFF, disconnect battery negative lead first
  14. Disconnect DVM leads, allow exhaust system to cool, remove oxygen sensor
  15. Apply antiseize compound to exhaust plug, reinstall plug, reconnect battery negative last

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Aftermarket parts that fit this engine

37
1205001 Amazon $30.38 eBay KuduParts $11.00 1205001-S Amazon $30.38 eBay KuduParts $32.00 2404167-S KuduParts $9.00 MIU12491 KuduParts $9.00 24-393-02 FridayParts $29.99 24-393-04 FridayParts $29.99 24-393-16 FridayParts $29.99 24-393-16-S KuduParts $12.00 24-393-04-S KuduParts $12.00 2455912-s FridayParts $34.80 24-584-15-S FridayParts $20.49 24-584-36-S FridayParts $20.49 055-493 FridayParts $12.25 8939200 FridayParts $12.25 2509927-S FridayParts $12.25 CH1000 Amazon eBay $59.95 FridayParts $12.25 2541807-S FridayParts $65.99 2541807 FridayParts $65.99 24-755-141-S KuduParts $16.00 6-Terminal FridayParts $12.00 25-099-04-S FridayParts $12.00 25-099-37-S FridayParts $12.00 237878-S Amazon eBay $85.00 FridayParts $42.80 28-085-02-S FridayParts $45.99 41-403-09-S FridayParts $11.99 25-403-03-S FridayParts $11.99 SO131 KuduParts $32.00 KH1205001S KuduParts $32.00 FP-XP-0033122 SV720 FridayParts $18.99 SV725 FridayParts $29.99 SV591 FridayParts $11.48 SV600 FridayParts $11.48 SV601 FridayParts $11.48 SV610 FridayParts $11.48 SV620 FridayParts $11.48 FP-XP-0010006

Parts listed by aftermarket suppliers as fitting this engine — leads compiled from supplier catalogs; verify the exact part for your serial number.

Common questions

What is the displacement of the Kohler CH25?

The Kohler CH25 has a displacement of 0.725 liters.

Which generators use the Kohler CH25 engine?

The Kohler CH25 powers 3 generator set(s), including Cummins/Onan 11RMY, Genmac HSD12, Genmac HSG12.

How often should you change the oil in the Kohler CH25?

The Kohler CH25 oil change interval is every 100 hours.

What is a common problem with the Kohler CH25 engine?

A commonly reported issue on generators using the Kohler CH25 is: Speed trim value is abnormal. Cause: 1. Speed trim shorted or miswired..