DUROMAX XP20HP User manual

This manual provides information regarding the
operation and maintenance of these products. We
have made every effort to ensure the accuracy of the
information in this manual. We reserve the right to
change this product at any time without prior notice.
5800 Ontario Mills Pkwy
Ontario, CA 91764 USA
www.duromaxpower.com
Call our Customer Care Team Toll Free 8-5pm PST Mon-Fri
844-DUROMAX
REV: XP20HP_rev12072022
XP20HP
USER MANUAL

CONTENTS
1. Introduction .................................................................................................................... 6
General Safety Procedures............................................................................................ 8
Unit and Purchase Information................................................................................... 12
Engine Components ..................................................................................................... 13
Package Contents ......................................................................................................... 14
Introduction
4. Maintenance Schedule................................................................................................. 26
Break-In Period ............................................................................................................. 27
Maintenance Log........................................................................................................... 27
Checking the Oil ............................................................................................................ 28
Changing the Oil............................................................................................................ 29
Changing the Air Filter.................................................................................................. 30
Spark Plug Maintenance .............................................................................................. 32
Emptying the Gas Tank ................................................................................................ 34
Storing the Engine for Same Day Use ........................................................................ 36
Storing the Engine for Use Within 30 Days................................................................ 37
Storing the Engine for Longer Than 30 Days............................................................. 38
Maintenance and Care
3. Check the Oil ................................................................................................................. 20
Check the Fuel Level ..................................................................................................... 21
Starting the Engine ....................................................................................................... 22
Starting the Engine
2.
Adding Oil ...................................................................................................................... 16
Adding Gasoline ............................................................................................................ 17
High Altitude Operation ............................................................................................... 18
Engine Setup

For more information and resources on this model scan the QR
code below to link to our website product information page.
CONTENTS
7.
8.
6.
.......................................................................................................................... 54
Warranty
......................................................................................................... 58
Customer Service
Troubleshooting
...........................................................................................................51
Specications................................................................................................................. 43
Adjustment and Torque Value Specications ........................................................... 44
Engine Diagrams........................................................................................................... 45
Wiring Diagram ............................................................................................................. 47
Specications
5.

5
...........................................................................................................51

6
THE DUROMAX WAY
The DuroMax Way is more than just a brand, it is our understanding and appreciation of just how
important power can be to someone without it…
DUROMAX FOR HOME
Electricity in our home not
only provides comfort but
safety as well. From keeping
the heat or A/C on to keeping
our food cold, power is
essential to our daily lives.
Inevitability when disaster
strikes and we are left without
power for a prolonged period
of time, our way of life is
put at risk. This is by far the
most critical time for reliable
portable power.
DUROMAX FOR WORK
On the job site, portable
power allows you the ability
to get work done in remote
locations when traditional
power sources are usually
unavailable. Equipment like
table saws, sanders, and
work lights are a necessity
and portable power can
play a critical role in getting
a job done successfully and
eciently.
DUROMAX FOR PLAY
Camping outdoors in a
remote location can get one
in touch with nature and allow
them to forget the stress of
the day to day grind. Here
portable power can provide
comfort as well as safety. With
portable power, you can keep
your cell phone charged, light
up your campsite, or even
brew a cup of coee, all while
being miles from civilization.
The DuroMax Way is a commitment to excellence. This vision is focused on the quality, reliability,
and durability of our products combined with outstanding customer service. We understand that
having dependable power whenever and wherever you need it provides comfort, safety, and peace
of mind. It is through this philosophy that DuroMax achieves our vision of...

7
INTRODUCTION
DuroMax Power Equipment is headquartered in Ontario, California and is the industry’s leader in
Dual Fuel portable generator technology. In addition to a full assortment of portable generators
ranging from digital inverters to large 15,000-watt portable standby units, their product line
includes pressure washers, engines, pumps, and accessories.
The foundation of our company is built on quality, reliability, durability, and customer service. At
DuroMax our vision is simple, we are committed to Powering Everyone... Anywhere!
Engines that are certied to comply with U.S. EPA emission regulations for SORE (Small o Road
Equipment), are certied to operate on regular unleaded gasoline and may include the following
emission control systems: (EM) Engine Modications and (TWC) Three-Way Catalyst (if so equipped).
Notice Regarding Emissions
STOP
Please do not return
to the store.
DuroMax representatives are ready to help you
with any questions, concerns, or issues about your
new product. We can guide you through assembly,
start up, and how to operate your new engine. We
want you to be able to put your new engine to use
right away!
CALL US BEFORE YOU CONSIDER
RETURNING THE PRODUCT!
1-844-DUROMAX
TOLL-FREE

88
DANGER:This engine produces poisonous carbon monoxide gas when running. This gas
is both odorless and colorless. Even if you do not see or smell gas, carbon monoxide may
still be present. Breathing this poison can lead to headaches, dizziness, drowsiness, and
eventually death.
●Use outdoors ONLY in non-conned areas.
●Keep several feet of clearance on all sides to allow proper ventilation of the engine.
WARNING: The exhaust from this product contains chemicals known to the State of
California to cause cancer, birth defects, or other reproductive harm.
WARNING: This engine produces heat when running. Temperatures near exhaust can
exceed 150°F (65°C).
●Do not touch hot surfaces. Pay attention to warning labels on the engine denoting hot
parts of the machine.
●Allow engine to cool several minutes after use before touching engine or areas which
heat during use.
GENERAL SAFETY PROCEDURES
Please familiarize yourself with the following safety symbols and words:
●DANGER: Indicates a hazard that will result in serious injury or death if instructions are not
followed.
●WARNING: Indicates a strong possibility of causing serious injury or death if instructions are not
followed.
●CAUTION: Indicates a possibility of personal injury or equipment damage if instructions are not
followed.
SAFETY ALERT SYMBOL
The safety alert symbol is used with one of the safety words (DANGER,
WARNING, or CAUTION) to alert you of hazards. Please pay attention to
these hazard notices both in this manual and on the engine.

9
WARNING: This engine may emit highly ammable and explosive gasoline vapors, which
can cause severe burns or even death. A nearby open ame can lead to an explosion
even if not directly in contact with gasoline.
●Do not operate near an open ame.
●Do not smoke near the engine.
●Always operate on a rm, level surface.
●Always turn the engine o before refueling.
●Allow engine to cool for at least 2 minutes before removing the fuel cap. Loosen cap
slowly to relieve pressure in the tank.
●Do not overll the gas tank. Gas may expand during operation. Do not ll to the top
of the tank.
●Always check for spilled gas before operating.
●Empty the gasoline tank before storing or transporting the engine.
●Before transporting, turn the fuel valve to the o position and disconnect
the spark plug.

In addition to the above safety notices, please familiarize
yourself with the safety and hazard markings on the
engine.
GENERAL SAFETY PROCEDURES (CONTINUED)
1.5”
10

11

12
Serial Number
Serial number format
STAPLE RECEIPT HERE
The serial number will be shown in two parts. The engine
model, followed by the serial number.
Engine Model: _____________________________________________
Serial Number: _____________________________________________
A purchase receipt may be necessary for warranty parts or
service in the future. If you have a paper receipt staple it
here for easy reference.
If you purchased the unit online, save the email receipt
where you can access it, and record your details here for
convenience in the future.
Purchase Date: ____________________________________________
Order Number: ____________________________________________
Retailer Name: _____________________________________________
Serial number
The serial number is located on the engine block, to the left of
the oil ll.
UNIT AND PURCHASE INFORMATION

1. Air Filter - A removable, cleanable, oiled, element that cleans the air going into the engine.
2. Carburetor - A component used to control the air fuel mixture of the engine.
3. Fuel Tank - All metal 1.79 gallon gasoline fuel tank.
4. Recoil Starter - An easy pull recoil start to start the engine without the electric start.
5. Recoil Handle - An easy grip handle used to pull the recoil starter rope.
6. Muer - A noise dampening component that helps lower the engine decibel level.
7. Engine Shaft - A 1” diameter, 3.535” long all metal shaft with a 1/4” keyway.
8. Oil Fill - An easy access location to ll the oil for the engine.
9. Oil Drain Plug - An easy to remove oil plug that is used to drain the oil.
ENGINE COMPONENTS
13
3. Fuel Tank
6. Muer
7. Engine Shaft
8. Oil Fill
4. Recoil Starter
2. Carburetor
1. Air Filter
9. Oil Drain Plug
5. Recoil Handle

PACKAGE CONTENTS
Your engine comes with the items listed below. Please check to see that all of the following items
are included with your engine.
●Note: Actual tools may dier in appearance or design from image shown.
Spark Plug Wrench Oil Funnel
Used in spark plug
maintenance, inspection, and
installation.
Used to add oil to the engine
without messy spills.
14

ENGINE SETUP
Proper setup of your engine will get you going as soon as possible while making sure you and your
equipment are safe and cared for.
15

ENGINE SETUP
Add oil
The engine requires engine oil to operate properly. The engine, when new from the package
contains no oil in the crankcase*. You must add the proper amount of oil before operating the
engine for the rst time. This amount is equal to the oil capacity of the engine crankcase:
a. Make sure the engine is on a level surface.
b. Unscrew the oil ller cap from the engine .
c. Using a funnel, add the appropriate amount of oil
into the crankcase. You can check the oil level of the
engine with the dipstick located below the oil
ller cap. Simply pull the dipstick out and the
indicated oil level is on the end of the stick.
d. Replace oil ller cap.
1.
Step 1- Adding Oil
Model Number XP20HP
Engine Oil Capacity 40.5 . oz (1.2 L)
WARNING: DO NOT overll the crankcase. This
may damage the motor and shorting overall life
of your engine.
Engine oil recommended: SAE 10W-30.
Viscosity varies with regions and temperatures. Choose your
oil viscosity using the chart to the left.
* A small amount of oil from factory testing may be present on
arrival.
* Synthetic oil may be used after the 8 hour initial break-in
period. Using synthetic oil does not increase the recommended
oil change interval. Full synthetic 5W-30 oil will aid in starting in
cold temperatures <5ºC (41ºF).
WARNING:Do not apply engine oils with additives or 2-stroke gasoline engine oils;
they don’t have enough lubrication and may shorten the engine’s service life.
16

Step 2 - Adding Gasoline
Add gasoline
a. Make sure the engine is on a level surface.
b. Unscrew gas cap and set aside (NOTE: the gas cap
may be tight and hard to unscrew).
c. Slowly add unleaded gasoline to the fuel tank. Be
careful not to overll.
d. Replace fuel cap and wipe up any spilled gasoline
with a dry cloth.
IMPORTANT:
●To ensure that the engine runs smoothly use only FRESH, UNLEADED GAS WITH AN
OCTANE RATING OF 87 OR HIGHER.
●Never use an oil/gasoline mixture. Never use old gas.
●Avoid getting dirt or water in the fuel tank.
●Gas can age in the tank and make it hard to start up the engine in the future.
●Never store engine for extended periods of time with fuel in the tank.
Model Number XP20HP
Gas Tank Capacity 1.79 US gal. (6.78 L)
DANGER
DO NOT OVERFILL
THE GAS TANK
OVERFILLING CAN RESULT
IN A FIRE, EXPLOSION,
OR DEATH.
1.5”
WARNING: Gas can expand. Do not ll the gas tank to the very top. Leave a
minimum of 1.5 in open space. Gasoline and gas fumes are highly ammable.
Do not ll the tank near an open ame. Always check for fuel spills.
WARNING: DO NOT overll the crankcase. This
may damage the motor and shorting overall life
of your engine.
17

18
High Altitude Operation
At high altitudes, the standard carburetor air/fuel mixture will be too rich. The performance will decrease,
and fuel consumption will increase. A very rich mixture will also foul the spark plug and cause hard starting.
Operation at an altitude that diers from that at which this engine was certied, for extended periods of
time, may increase emissions. High altitude performance can be improved by specic modications to
the carburetor. If you always operate your engine at altitudes above 3,000 feet (900 meters), have a dealer
perform this carburetor modication. This engine, when operated at high altitude with the carburetor
modications for high altitude use, will meet each emission standard throughout its useful life. Even with
carburetor modication, engine horsepower will decrease by about 3.5% for each 1,000-foot (300-meter)
increase in altitude. The eect of altitude on horsepower will be greater than this if no carburetor
modication is made.
When the carburetor has been modied for high altitude operation, the air/fuel mixture will be too lean for
low altitude use. Operation at altitudes below 3,000 feet (900 meters) with a modied carburetor may cause
the engine to overheat and result in serious engine damage.
Note: Jet kits available for purchase upon request, please contact us at 844-DUROMAX to set up your
parts order.
ENGINE SETUP (CONTINUED)

STARTING THE ENGINE
If this is not your rst time using the engine there are still steps you should take to prepare it for
operation each time you use it.
IMPORTANT: At this point you should be familiar with the procedures described in the rst
portion of this section entitled “ENGINE SETUP” If you have not yet read this section, go back
and read it now.
19

Step 1 - Check the Oil
Check the oil
The engine is equipped with an automatic shuto to protect
it from damage due to low oil. Nonetheless, you should check
the oil level of the engine before each use to ensure that the
engine crankcase has a sucient amount.
To check the oil level:
a. Make sure the engine is on a level surface.
b. Unscrew the oil ller/dipstick cap.
c. With a dry cloth, wipe the oil o of the stick on the
inside of the cap.
d. Insert the dipstick as if you were replacing the
cap and then remove it again. There should now be
oil on the stick. If there is no oil on the stick, or oil
only at the very end of the stick, you should add
oil until the engine crankcase is lled (see “Adding
Oil” portion of the “Maintenance” section).
e. Be sure to replace the cap when nished checking
oil.
20
BEFORE YOU START YOUR ENGINE
Model Number XP20HP
Engine Oil Capacity 40.5 . oz (1.2 L)