Baja Comet 90cc BC90 User manual

Always wear a helmet; It could save your Life!
Do not remove this operator’s manual from this vehicle.
Please obtain, review, and follow provincial / municipal government acts and
regulations pertaining to owning and operating an off-road vehicle.
OWNER’S MANUAL
Model Number: BC90
Minimum Age Requirement: 16
Rev. A (US)
012709
Baja Comet 90cc Mini Bike
Read this manual carefully. It contains important safety information.
No one under the age of 16 should operate this Mini Bike .

ii
Congratulations on your purchase of the BAJA INC. Mini Bike.
Your Mini bike is warranted to be free of manufacturing defects in
material and workmanship for a period of 90 days from the date of
purchase. During the warranty period BAJA, INC. will at its option,
repair, provide replacement parts or replace your BAJA INC. Mini Bike
at no charge. This warranty does not cover normal wear items or
damage caused by neglect or misuse of the product.
Engine Warranty – 90 days
Frame Warranty – 90 days
Warranty is void if:
Frame is bent or broken due to abuse
Wheels are bent or broken
Fender bent or broken due to abuse
Any sign of impact, accident, jumping, spin-outs or roll over.
BAJA, INC. is not liable for any damage claim or liability claim person
or otherwise resulting from the operation of this product in any way.
Should you experience a problem with your vehicle, please call Baja Inc. customer
service line toll free at 1-888-863-2252 between the hours of 7am and 5pm Monday
through Friday MST (Mountain Standard Time). MDT (Mountain Daylight Time)
during the daylight saving time. You will be instructed how to proceed.
A COPY OF THE SALES RECEIPT IS REQUIRED.

iii
This manual should be considered as a permanent
part of the vehicle and should remain with the
vehicle when resold or otherwise transferred to
a new user or operator. The manual contains
important safety information and instructions
which should be read carefully before operating
the vehicle.
WARNING
The engine exhaust from this product contains
chemicals known to the State of California to cause
cancer, birth defects or other reproductive harm.
CALIFORNIA PROPOSITION 65
WARNING
!
!

1
NOTICE TO USERS.............................................................................................2
SAFE OPERATION..............................................................................................3
SAFETY GEAR....................................................................................................4
MODIFICATION OF VEHICLE.............................................................................4
PRE-RIDE CHECKLIST.......................................................................................5
MAIN DATA..........................................................................................................6
PARTS & SUBASSEMBLIES..............................................................................7
LOCATION OF WARNING LABELS ...................................................................9
OPERATION ........................................................................................................10
FUEL FILLING .............................................................................................10
ENGINE STARTING AND STOPPING.........................................................11
LEFT HANDLEBAR SWITCH......................................................................12
GEAR SHIFTING .........................................................................................13
CHECK-UPS, ADJUSTMENT AND MAINTENANCE..........................................14
CHANGING THE OIL...................................................................................14
CHECK-UP OF SPARK PLUG ....................................................................15
VALVE CLEARANCE...................................................................................16
CHECKING & CLEANING THE AIR FILTER...............................................17
ADJUSTING THE THROTTLE CABLE .......................................................18
ADJUSTING THE CARBURETOR ..............................................................18
ADJUSTMENT OF REAR AND FRONT BRAKE ........................................19
ADJUSTMENT OF CHAIN...........................................................................20
GREASING PROCEDURES TO THE DRIVING CHAIN..............................20
VEHICLE WASHING....................................................................................21
INSTRUCTIONS FOR STORAGE ...............................................................22
RESUMPTION OF SERVICE AFTER STORAGE .......................................23
TABLE AND TORQUE OF FASTENERS ....................................................23
MAINTENANCE ROUTINE DIAGRAM........................................................24
TROUBLE SHOOTING ................................................................................25
WIRE DIAGRAM ..........................................................................................26
VIN AND SERIAL NUMBER LOCATION.....................................................27
EMISSION CONTROL SYSTEM WARRANTY............................................28
Table of Contents

2
Please read this manual and follow all instructions carefully. To emphasize the
special information, the symbol and the words WARNING or CAUTION have
some special meanings. Pay attention to the messages.
NOTE: Indicating special information which is to make maintenance easier or
instructions clearer.
WARNING and CAUTION are arranged like this:
This user’s manual contains important safety and maintenance information. Read
it carefully before riding. Failing to follow the warnings contained in this manual
could result in INJURY or DEATH.
It is important that this manual remain with the vehicle when you transfer it to
another user or owner.
All information, illustrations, photographs and specications contained in
this manual are based on the latest product information available at the time
of publication. Due to improvements or other changes, there will be some
discrepancies in this manual. We reserve the right to make product changes at
any time, without notice and without incurring any obligation to make the same or
similar changes to the vehicle previously built or sold.
WARNING-or-CAUTION
The rst part will identify a POTENTIAL HAZARD.
The second part will describe WHAT COULD HAPPEN if you ignore
the WARNING or CAUTION.
The third part will describe HOW TO AVOID THE HAZARD.
CAUTION
Indicates a potential hazard that could result in vehicle damage.
WARNING
Indicates a potential hazard that could result in death or injury.

3
SAFE OPERATION
Rules for Safe Operation
· A pre-operation check must be conducted before starting engine to insure
safety, prevent mishaps, and prevent damage to components.
· It is strongly suggested that all operators take a certied motorcycle rider’s
course prior to operating the vehicle.
· Full attention is required during driving; paying close attention to the
following points to avoid any injury to you by other motorized vehicles:
· Do not drive too close to other vehicles.
· Never operate this mini bike at night. Night is dened as the period of time 30
minutes before sunset to 30 minutes after sunrise.
· Driving at high speeds is the cause of many accidents; do not drive at a speed
that the actual situation does not permit.
· This user’s manual contains important safety and maintenance information.
Read it carefully before riding. Failing to follow the warnings contained in this
manual could result in INJURY or DEATH.
· It is important that this manual remain with the vehicle when you transfer it to
another user or owner.
· All information, illustrations, photographs and specications contained in
this manual are based on the latest product information available at the time
of publication. Due to improvements or other changes, there will be some
discrepancies in this manual. We reserve the right to make product changes
at any time, without notice and without incurring any obligation to make the
same or similar changes to the vehicle previously built or sold
· Always avoid operating this mini bike on paved surfaces, including;
sidewalks, paths, parking lots, driveways, streets, roads, and highways.
Never operated this or any Off-Road Vehicle on a public street, road or
highway where motor vehicles are in operation.

4
SAFETY GEAR
1. Never operate this mini bike without wearing a DOT approved motorcycle
helmet which ts properly. Operators should also wear eye protection
(goggles or face shield), gloves, boots, long-sleeved shirt or jacket, and long
pants.
2. Loose clothes are not suitable for motorcycle driving or riding as they may
get caught on footrest or in moving parts.
MODIFICATION OF THE VEHICLE
CAUTION
Never perform any unauthorized modications to this vehicle. Only use
original replacement part which can be obtained through BAJA INC.
888-863-2252

5
Pre-Ride Checklist
Before Starting the Engine
1. Engine oil level
a) Check for leaks
b) Tighten filler cap securely.
c) Add oil if required.
2. Fuel level
a) Add fuel as necessary.
b) Do not overfill (no fuel in the filler neck).
c) Do not mix oil with gas.
d) Replace cap tightly.
e) Do not refuel a hot engine. Allow engine to cool before adding fuel.
3. Warning decals
a) Make sure all warning decals are legible and securely attached.
b) Replace as necessary.
4. Tires
a) Ensure that both tires are in safe riding condition.
b) Both tires must be inflated to the pressure indicated on the tire sidewalls.
5. Drive chain
a) Check condition and tension.
b) Lubricate and adjust tension as necessary.
6. Throttle
a) Check for smooth operation. Make sure the throttle “snaps” back to idle.
b) Check for frayed cable or damaged cable housing. Replace
damaged cable.
c) Check for mud, debris and ice in the throttle cable/mechanism. Clean out
any contamination.

6
MAIN DATA
Description Data Description Data
Overall length 1539 mm
(60.61 in.)
Brake Type Drum
Overall width 669.8 mm
(26.37 in.)
Capacity of
gasoline tank
3L (.79 gal.) 87 octane or higher
unleaded gasoline
Overall height 959.6 mm
(37.78 in.)
Capacity of oil tank .24L (.25 qt.)
Wheelbase 1070 mm
(42.11 in.)
Displacement of
cylinder
86cc
Ground
clearance
189.7 mm
(7.47 in.)
Ignition means Magneto
Vehicle weight 67.59 kg
(149 lbs.)
Idling speed 1500 ± 100rpm.
Weight capacity 69.4 kg
(153 lbs)
Spark plug MEIYA - A7TC, NGK - C7HSA,
DENSO - U22FS-U, CHAMPION
- Z10YC
Front wheel 3.50 - 10
36psi
Spark plug gap 0.6-0.7mm
(.024”-.028”)
Rear wheel 3.50 - 10
36psi
Valve Clearance Intake 0.002 inch (0.05 mm)
Exhaust 0.003 inch (0.0762 mm)

7
PARTS & SUBASSEMBLIES
Brake lever
Throttle twist grip
Engine stop switch

8
Front Wheel
Front Shock
Absorber
Side Stand
Rear Wheel
Seat Cushion
Air Filter
Headlight
Foot pegs
Drive Chain
Vehicle Identication
Number
Brake Drum
Rear
shock
Kick start lever
Oil ll plug/dipstick
Carburetor
Spark plug
Ignition key switch
Taillight
PARTS & SUBASSEMBLIES
Fuel tank located
under seat
Shift lever
Oil drain bolt
Foot brake
Brake drum
Mufer

9
1
2
LOCATION OF WARNING LABELS
Read and follow all of the warnings labels on your Mini bike. Make sure you
understand all the labels. Keep the labels on the Mini bike. Do not remove them
for any reason. If a label comes off or becomes difcult to read, you should get a
replacement by contacting Baja Inc.
1
2
3
3
No one under the age of 16
should operate this vehicle
without adult supervision.
WARNING
● Study the owners manual carefully
● Always wear a helmet, eye protection
and protective riding gear.
● Do not drive while drinking alcohol or
while on medication.
WARNING
THIS VEHICLE IS AN OFF ROAD VEHICLE
AND IS NOT INTENDED FOR USE ON
PUBLIC ROADS OR HIGHWAYS.

10
OPERATION
Fuel lling
The capacity of the fuel tank is 3L (.79 gal) Use only 87 octane or higher unleaded
gasoline. Unscrew the gas cap by turning it counter clockwise and carefully ll
the tank with unleaded gasoline through the opening. DO NOT MIX GAS AND
OIL TOGETHER, THIS IS A 4-STROKE ENGINE. Replace the gas cap by carefully
aligning the threads on the cap and the tank and turning the cap clock wise. Wipe
any spilled fuel from the mini bike using a cloth and dispose of the cloth properly.
DO NOT SMOKE OR REFUEL THE VEHICLE NEAR OPEN FLAMES OR NEAR
HEATING UNITS. ONLY REFUEL THE VEHICLE IN OPEN AREAS TO REDUCE THE
LIKELIHOOD OF THE BUILD UP OF GASOLINE FUMES.
DO NOT OVERFILL TANK. FUEL LEVEL SHOULD BE BELOW FILLER NECK
Fuel level
Filler neck
Fuel tank cap located
under seat cushion
Unlock seat cushion
with ignition key

11
ENGINE STARTING
1. Set ignition key switch to “ ” (ON) position.
2. Place mini bike in neutral gear.
3. Ensure there is fuel in fuel tank.
To start a cold engine:
1. Place choke lever in “UP” (ON) position.
2. Start engine with kick lever
3. Once engine has started, allow engine to warm up approximately 3 - 5
minutes. . (Do not rev the engine. Revving a cold engine could cause damage).
4. Place carburetor choke lever in the “DOWN” (OFF) position when engine has
sufciently warmed up.
Procedures for stopping the engine:
1. Release throttle twist grip to slow engine RPM’s to idle.
2. Shift mini bike transmission to neutral position.
3. Set ignition switch key to “ ” (OFF) position.
CAUTION
Verify oil level prior to starting
Starting the engine with low or no oil will damage engine.
CAUTION
Unnecessarily increasing RPM’s to a high level while
Mini Bike is warming up is harmful to engine.
WARNING
Never start the engine in a closed place as the exhausted gas
from the vehicle contains toxic carbon monoxide.
Choke lever
ON
OFF

12
LEFT HANDLEBAR SWITCH
Engine stop switch
The engine stop switch is provided on the left handlebar.
When the switch is turned to “ ” (off) position, the engine will not start or will
stop engine if running.
When the switch is turned to “ ” (on) position, the engine can start and the
vehicle can be driven.
ON button
OFF button

13
GEAR SHIFTING
Reduce throttle before shifting. Never increase the throttle while shifting gears.
Depress Shift lever to place gear in 1st, 2nd, 3rd or 4th. Lift up on shift lever to
down shift or place gear in neutral.
Do not rest foot on gear-shift lever while operating mini bike. Resting foot on shift
lever could damage the transmission, or cause transmission to shift unexpectedly.
Shifting sequence
(N) Neutral
(1) 1st gear
(2) 2nd gear
(3) 3rd gear
(4) 4th gear
Points of Attention during Drive
1. Avoid unnecessary idling of engine at high speeds. Idling engine at high
speeds can damage engine.
2. Down shift to lower gears when there is insufcient power to climb hills or
continue forward.
3. As a general rule, the front brake provides approximately 70% of
stopping power. Always use both the rear brake pedal and front brake
lever simultaneously when stopping. Using both front and rear brakes
simultaneously will stop mini bike with greater stability.
4. Decrease the throttle while braking.
Shifting to higher gears
Down shifting to lower gears or neutral
N 1 2 3 4

14
CHECK-UPS, ADJUSTMENT AND MAINTENANCE
Checking the Oil
Check engine oil each time prior to operating mini bike.
The oil level should be between the upper and lower lines on oil dipstick.
1. Set Mini Bike on level ground, remove oil plug/dipstick, wipe dipstick clean,
insert dipstick into crankcase to check oil level. Note: There is no need to
screw dipstick completely in hole to check level.
2. Add lubricating oil up to edge of the ll hole
3. re-install oil dipstick.
Lubricating Oil Recommended
The lubricating oil is an important factor affecting the performance and service life
of the engine. Please refer to the chart for the correct grade of engine oil based on
the environmental conditions in your area. Do not use any other type of oil other
than what is recommended in the chart. DO NOT MIX OIL WITH THE GASOLINE.
Lubricating oils of different viscosity shall be employed in different regions and at
different temperatures.
CAUTION
Never start the engine when there is insufcient lubricating
oil. Otherwise, it will cause harm to the engine.
Oil dip stick
MACHINE
OIL
TEMP.
°C
°F
-30
-22
40
104
-20
-4
-10
14
0
32
10
50
20
68
30
86
20W-50
15W-40
10W-30

15
CHANGING THE OIL
1. Let engine warm up approximately 3 minutes to warm up oil.
2. Shut off engine, remove “Screw Plug” located at bottom of the engine and
let oil drain into an approved collection container. DO NOT PERFORM THIS
PROCEDURE WHILE THE ENGINE IS HOT. SERIOUS BURNS COULD RESULT
FROM CONTACT WITH HOT OIL.
3. Dispose of used oil properly. For proper disposal procedures, contact your
local oil recycling center.
4. Clean and re-install the “Screw Plug” . Torque to 18 ft.lb.
5. Rell engine with 0.25 qt. (0.24L) of recommended oil, recheck the amount of
oil in the engine by using the oil dip stick.
CHECK-UP OF SPARK PLUG
1. Remove the spark plug cap. Remove
spark plug by using the spark plug wrench
provided.
2. Clean spark plug all around or replace plug
if it is corroded or there is too much deposit
on it.
3. Regulate gap of spark plug to
0.6-0.7mm (.024”-.028”).
3. The spark plug of the designated type
should be used. The applicable type of
spark plug: MEIYA - A7TC, NGK - C7HSA,
DENSO - U22FS-U, CHAMPION - Z10YC
0.6-0.7mm
(.024”-.028”)
Screw plug for oil draining

16
VALVE INSPECTION
REFER TO MAINTENANCE SCHEDULE IN THIS OWNER’S MANUAL FOR VALVE
ADJUSTMENT INSPECTION INTERVALS.
Valve clearance should be:
Intake: 0.002 inch (0.05 mm)
Exhaust: 0.003 inch (0.0762 mm)
Excessive clearance will cause noise. Insufcient clearance will cause loss of
power and possibly damage the valves.
For those who are mechanically procient and have the proper tools, instructions
on adjusting the valve clearance are given in the service manual. If assistance is
needed please contact Baja Inc. to nd your local service center.

17
CHECKING & CLEANING THE AIR FILTER
TAP AIR FILTER ON A FIRM SURFACE TO DISLODGE AS MUCH DIRT AND
debris as possible. NOTE: If tapping air lter does not remove the dirt and debris,
replace air lter.
CAUTION
The air lter element must be intact or the engine will suck in dust and dirt,
resulting in a shorter service life of the engine.
Water should be prevented from entering into the lter when washing the
vehicle.
The lter element shall be cleaned gently. Replace the air lter element with
a new one if it is broken or cracked.
Clamp
Air lter