Doosan / Bobcat · G-Series

Doosan G125

110 kW standby / 100 kW prime · Diesel · Liquid-cooled

100 kW prime diesel portable generator. Cummins QSB5-G11-powered with 68 dBA operation, 176.5-gallon tank, and 24.9-hour runtime.

Doosan / Bobcat Doosan G125 generator — specifications and details
Standby power
110 kW / 100 kW prime
Voltage options
120/240V, 208V, 480V
Frequency / Phase
50, 60 Hz · 1/3-phase
Engine
Cummins QSB5-G11 · 4.5L
EPA / Emissions
Tier 4 Final
Commercialrental-fleettemporary-poweremergency-standby
Configure & Quote

Overview#

The Doosan G125 delivers 100 kW of prime power (125 kVA) from a Cummins QSB5-G11 4.5-liter engine — no DPF required for Tier 4 Final compliance, which simplifies maintenance compared to DPF-equipped competitors. The 176.5-gallon integral tank provides 24.9 hours of runtime at full load.

At 68 dBA and 6,950 lbs, the G125 bridges the gap between the smaller Cummins F3.8-powered G100 and the larger QSB7-powered G190. Standard 240V single-phase twist-lock and 120V GFCI receptacles serve mixed construction loads. Also sold as the Bobcat PG125.

Cummins QSB5 — no DPF advantage#

The G125's most significant selling point versus DPF-equipped competitors is the Cummins QSB5-G11's ability to meet Tier 4 Final emissions without a diesel particulate filter. The engine uses DOC (diesel oxidation catalyst) and SCR (selective catalytic reduction) only. This eliminates the most common maintenance complaint on modern Tier 4 portable generators: DPF regeneration failures, light-load derating, and the labor cost of DPF cleaning or replacement.

For rental fleet operators, the no-DPF configuration means the G125 can run at light loads without the risk of incomplete regeneration cycles that plague DPF-equipped units. This is particularly valuable for standby and variable-load applications where the generator may idle for extended periods between demand surges.

Our service experience#

OnPoint services Cummins QSB5-powered generators across multiple brands in Northern California. The QSB5 platform is one of the most common mid-range diesel engines in the portable power industry, which means parts availability is excellent and Cummins-trained technicians are easy to find. The 500-hour oil change interval and no-DPF aftertreatment keep the G125's total cost of ownership competitive. For buyers comparing the G125 to the G150, both share the same QSB5 platform and chassis — the decision comes down to whether your load profile genuinely needs the extra 23 kW.

Engineering specifications

Physical

Length
171 in
Width
72.5 in
Height
91 in
Wet weight
6,950 lb

Acoustic

Sound @ 7m, full load
68 dBA
Enclosure
Sound-attenuated

Fuel system & runtime

Integral fuel tank
176.5 gal

Ready to order this model?

Configure your Doosan G125

Lock the enclosure, fuel system, transfer switch, and add-ons — we'll confirm pricing, availability, and lead time within one business day. Prefer a free-form quote? That option is still here.

Configure & Quote →Just request a quote

Estimate runtime for the Doosan G125

Adjust load percent and tank size to estimate runtime. Pre-filled with this model's spec where available.

Estimate runtime on this tank

Estimated runtime

29.7 hours(1.2 days)

Fuel consumption ≈ 5.94 GPH at 75% load. Estimate based on industry-typical 1800 RPM standby curves (≈0.07 GPH/kW at full load). Actual consumption varies by engine, ambient temperature, fuel quality, and tuning.

Service intervals

Manufacturer-recommended intervals for the Doosan G125 under standby duty. Field intervals may differ based on load profile, ambient conditions, and fuel quality.

Oil & filter
Every 500 hours or 12 months
Air filter
Every 500 hours
Fuel filter
Every 500 hours
Major overhaul
≈ 20,000 hours

Common failure modes

What we've seen fail on this platform. Use as a service-planning reference, not a diagnostic — actual failure modes depend heavily on duty cycle and maintenance history.

ComponentSymptomTypical hoursSeverity
Fuel filterRestricted flow, hard starting, power loss under load500+minor
BatteryFailed to start or slow cranking after extended storage4,380+minor
Coolant hosesWeeping at clamp connections, slow coolant loss5,000+minor

Frequently Asked Questions

What is the standby power rating of the Doosan G125?
The Doosan G125 delivers 110 kW standby and 100 kW prime power. It uses the Cummins QSB5-G11 4.5-liter engine with no DPF required for Tier 4 Final compliance. Also sold as the Bobcat PG125.
What engine does the Doosan G125 use?
The G125 is powered by a Cummins QSB5-G11 4.5-liter inline-4 turbocharged-aftercooled diesel engine running at 1,800 RPM. The QSB5-G11 achieves EPA Tier 4 Final through DOC and SCR aftertreatment — no diesel particulate filter required.
What are the service intervals for the Doosan G125?
Oil changes are due every 500 hours or 12 months, whichever comes first. Air filter and fuel filter replacement intervals are 500 hours. Major engine overhaul is specified at 20,000 hours. SCR aftertreatment requires monitoring of DEF supply.
Is the Doosan G125 EPA compliant?
Yes. The G125 is EPA Tier 4 Final compliant. The Cummins QSB5-G11 meets current U.S. emissions requirements through DOC and SCR aftertreatment without a DPF, eliminating regeneration cycle complications that affect DPF-equipped competitors.
How does Doosan compare to CAT at the 125 kVA class?
Both deliver comparable power in the 125 kVA class. The G125 typically prices 15-30% below CAT portable units while using the same class of Cummins engine found in many premium generators. The no-DPF configuration is a maintenance advantage for operators concerned about regeneration management.
What control panel does the Doosan G125 use?
The G125 is equipped with Doosan's digital control panel providing auto-start, fault monitoring, voltage/frequency display, and runtime tracking. The panel also monitors DEF level for the SCR aftertreatment system.
Who services Doosan generators in Northern California?
OnPoint Generators services Cummins QSB5-powered Doosan generators across the Bay Area and Northern California. The QSB5 is one of the most common mid-range diesels in the portable power industry, and parts availability is excellent through multiple Bay Area Cummins distributors.

More in the G-Series

Cummins and Doosan engines in a purpose-built portable enclosure — 22 to 500 kW at a competitive price.

View all 13models in this series →

Similar models

Doosan / Bobcat Doosan G100 88 kW liquid-cooled standby generator

Doosan / Bobcat

Doosan G100

First Cummins-powered Doosan — Stamford alternator and Cummins F3.8 engine deliver premium-grade components at 15-30% below MQ Power/Airman pricing.

88 kW standby · Diesel · Liquid-cooled

80 kW prime diesel portable generator. Cummins F3.8-powered with 67 dBA operation, Stamford alternator, and dual-frequency switching.

Tier 4 Final3-phaseconstructionrental-fleet
Doosan / Bobcat Doosan G150 135 kW liquid-cooled standby generator

Doosan / Bobcat

Doosan G150

23% more power than the G125 in the exact same chassis and footprint. Cummins QSB5 with no DPF — bridges the gap before stepping up to the larger DualBox G190.

135 kW standby · Diesel · Liquid-cooled

123 kW prime diesel portable generator. Cummins QSB5-G12-powered with 68 dBA operation and shared G125 chassis.

Tier 4 Final3-phaseconstructionrental-fleet
Echo Echo DGK125F 110 kW liquid-cooled standby generator

Echo

Echo DGK125F

Patented SimulPhase — simultaneous single and three-phase output from one unit, eliminating step-down transformers on mixed-load sites.

110 kW standby · Diesel · Liquid-cooled

125 kVA portable diesel generator with SimulPhase technology. Built in Japan.

Tier 4 Final3-phaseconstructionrental-fleet

Need service or parts for the Doosan G125?

We service every major OEM and stock genuine parts for the most common models.

Get A QuoteOr call (831) 375-1463