My 2012 Trailmaster XRX 300
I bought my Trailmaster XRX 300 in July of 2013. The MSO (Manufacture’s
Statement of Origin) say’s that it is a 2012 model. I wanted to take proper care of
my buggy. Do the work, maintenance, replacing, and repairing all myself. The
manual’s that came with the buggy left a lot to be desired and information was
lacking greatly. In my search for information I was finding that my model differed
greatly in some aspects from other buggies of a different model year. And in some
case’s possibly different from some in the same model year. The information I
needed was for my buggy, not any other. So the search began! This manual is an
accumulation of information from many different source’s in hopes of getting all the
information needed and in one place for easy access.
This is a work in progress. I’ll be adding to it and changing some things from time
to time as I find the information, better pictures, etc…
If you have information or pictures that you believe should be added or replaced, please send revisions to:
I’ll check the ideas against my buggy and correct accordingly.
Section 1: Standard Owner’s Manual that came with my buggy. This means that
any mistakes you see
were made in China. I merely copied and pasted. Starts page 3, ends page 32.
Section 2: Standard Part’s Manual that came with my buggy. And has also been copied and pasted. Starts
page 33, ends page 66.
Section 3: ENGINE OIL, Starts page 67, ends page 67.
Section 4: TRANSMISSION GEAR OIL, Starts page 68, ends page 68.
Section 5: CVT SYSTEM COVER, VARIATOR, RAMPS, SLIDERS, ROLLERS, CLUTCH,
SPRINGS, BELT, CLUTCH BELL Starts page 69, ends page 75.
Section 6: CARBURETER & SPARK PLUG, Starts page 76, ends page 79.
Section 7: EXHAUST, Starts page 80, ends page 80
Section 8: TIRE’S & MISALANIOUS INFORMATION, OTHER PICTURES Starts page 81, ends page
Section 9: PARTS & PICTURES THAT WORK ON MY BUGGY
Starts page 82, ends page 84
Engine Oil Type: 10w 40 with moly, Capacity: 1 ½ qt. = 1419.529419 ml
Image: MY BUGGY: Engine Oil Drain & Strainer Plug Placement.
Image: MY BUGGY: Engine Oil Check & Fill Placement
Gear Box Oil Type: 75w 90 with moly, Capacity: 750 ml, Rear Plug for Drain.
Image: MY BUGGY: Gear Oil Fill Hole
Image: MY BUGGY: Gear Oil Fill Hole
Image: MY BUGGY: Gear Oil Drain Plug
On my model buggy, it is my understanding that the forward & reverse gear box use the same oil space. As in
there is no separate fill & drain for the reverse box. Other models have a separate fill & drain for both forward
& reverse gear box.
Images: MY BUGGY: CVT system covered & CVT cover removed
NOTE: Cover Screws are all the same length with 8mm head size.
The Continuously Variable Transmission (CVT) system consists of two parts: the variator (drive pulley), and the
clutch (driven pulley). These are connected by the CVT belt. Gates #856-23
The CVT system works through the changing of the distance between the plates on the two pulleys. Basically,
when the plate width on the variator pulley decreases. the clutch pulley plate width increases, and vice versa.
This creates an infinite number of possible gear ratios, as the transmission is altering itself on the fly to adapt to
the current driving condition.
Image: CVT system with cover removed. Not XRX 300, just for reference
The variator is driven directly by the engine. Inside the variator are 8sliders/rollers that are positioned in
individual slots with ramps that they will move along outward when centrifugal force is applied. As the
sliders/rollers move outward, they press against the ramp plate which causes the pulley plates of the variator to
move toward one another, compressing the belt. This “V” shape created by the pulley plates pushes the belt
outward, which draws the belt inward on the driven (clutch) side, increasing the gear ratio.
Images: Not XRX 300, just for reference.
NOTE: Round Rollers and “Slider” Rollers are interchangeable parts and have different physical appearance,
but serve the same function.
At idle, the rollers are at their innermost position, the variator pulley plates are at their farthest apart, and the
CVT belt is low on the variator side and high on the clutch side (see Image 2). With increasing RPMs, the
rollers move outward along their ramps applying pressure to the ramp plate, which compresses the variator
pulley plates and squeezes the CVT belt outwards.
Rollers come in many different sizes and weights, depending on application.
For : My Buggy
- Lighter roller weights (7-9g) will give more climbing power at the cost of some top end speed.
- Heavier roller weights (13-15g) will allow more top speed at the serious expense of climbing ability – but are
great for flat-ground racing.
- In the middle range (10-12g) is a combination of the two.
NOTE: Roller weights that are at the lowest recommended end of the scale are often too light to fully push the
variator plate far enough out to achieve maximum speed. Similarly, the heavier weights quickly move you into a
higher gear ratio at the expense of low end power. Please keep this in mind when choosing the right weights for
your style of riding.
Rollers and sliders should be inspected annually (at minimum) for wear. Rollers are especially prone to
developing flat spots that inhibit their ability to move smoothly. If this occurs, they should be replaced. This is
one advantage of sliders, as they already have flat sides and are not affected by this wear as quickly as rollers.
Images: Not XRX 300, just for reference.
Images: Not XRX 300, just for reference.
In the CVT transmission system, the rollers are actually working against the spring tension of the main torque
spring on the clutch side.
Performance and racing variators have specially engineered “ramps” for the rollers. Many have teflon ramps
and ramp cover plates for reduced roller friction. This means smoother transition between “gears”.
Variator & Clutch Nuts: 19mm
Clutch Main Spring Nut: 46mm
Gates Belt # 856 - 23
Dr. Pulley Hit Clutch# 201205 / 45 Degree / Red Main Spring / M Pillows, KeeperNut 40 ft lbs torque.
Dr. Pulley Variator# V201202 / 9gm slider weights, 8each, Slider Size: 20 x 12, KeeperNut 40 ft lbs torque.
Drive Face Outer Diameter (A): 132mm Boss Inner Diameter (C): 19mm Boss Outer Diameter (B): 28mm
Ramp Plate Inner Diameter Valley to Valley (D): 19mm Ramp Plate Inner Diameter Peak to Peak (E): 17mm
Clutch Bell Size: 145 mm, Clutch is 3 mm smaller.
Changing Variator Slider Weights
Remove the variator assembly, being extra careful to hold the variator, ramp plate (behind it), and center
dowel pin together as one unit. The center dowel pin can be set aside. Holding the variator with the smooth
pulley side down, lift off the ramp plate to expose the rollers.
Note: During variator installation, hold the variator and top ramp plate as one piece, replace the center dowel
pin, and put it all back on the drive shaft, pushing the entire assembly all the way to the back. Keep pressure on
the variator and top plate at all times. If the top plate should open even a small amount, one or more of the
slider weights could tip over out of position and performance will be negatively impacted.
Note: You may have to pry apart the clutch pulley plates to get the belt enough slack to get onto the variator
Images: Not XRX 300, just for reference.
The lighter the sliders the longer you will stay in low range.
The lighter the sliders the more top end lost
Note Dr. Pulley name position on slider weight for proper placement.
The clutch in a CVT system engages when the centrifugal force of the spinning clutch overcomes the tension of
the clutch arm springs and allow the clutch pads to engage with the clutch bell, creating movement.
The clutch springs dictate at what speed the clutch engages.
The stiffer the main spring equals a quicker down shift
PILLOW SPRINGS: The pillow springs decide at what rpm the clutch locks up.
Image: Clutch Springs
Racing and performance clutches are made of higher quality materials, such as metal composite or kevlar clutch
pads to reduce wear and heat damage. These clutches often have much larger clutch pads for better engagement
with the clutch bell. Clutches can be altered with different rated arm springs to change their engagement RPMs.
The main clutch torque spring compresses the clutch pulley plates together, forcing the belt outward and acting
against the variator. As the rollers compress the variator side pulley plates when RPMs increase, the belt is
forced outward on the variator. Since the belt is a constant length, this causes the belt to be pulled inward on the
clutch, overcoming the tension of the torque spring.
What do the different clutch springs do?
The main torque spring makes it harder for the variator to draw the belt inward on the clutch. This keeps the
buggy in a lower gear ratio longer, and “downshifts” faster when decelerating so you have more power when
you hit the gas again. This is especially helpful when climbing or coming out of a corner. A higher tension main
torque spring downshifts you more quickly than a lower tension spring, but be aware that high spring tensions
can prevent very light roller weights from ever reaching the maximum position inside the variator, sacrificing
Example: 7g roller weights and a Red 2000 RPM main spring will give you a LOT of low end, but sacrifice top
Clutch arm springs control when the clutch arms and pads engage with the clutch bell. These springs are rated at
1000, 1500, and 2000 RPMs. This means that the clutch has to be spinning at this RPM speed before the
centrifugal force will overcome the spring tension and allow the clutch pads to engage. This is not the same as
engine RPMs, as the engine will be idling at some rate and the engagement RPM is on top of this.
Example: If the engine idles at 1000 RPMs, and the clutch arm springs are rated at 2000 RPMs, then the motor
will have to rev to at least 3000 RPMs before the clutch will engage. Using higher tension arm springs can
result in what seems like high motor RPMs at low speeds. The large main torque spring does not affect this
Belt comes off easier from variator end first. Remove the nut on the variator and take off the fan. (An impact
wrench works best)
WARNING: The clutch main spring assembly is under spring pressure. When the clutch nut is removed, the
clutch assembly will spring apart with force. Use extreme caution when removing.
Press and hold firmly with feet while removing large retaining nut. Can be reinstalled the same way,
remember to use thread locker with larger nut. My nut size is 46 mm.
Important Note: For some aftermarket springs, the spring collar may not fit into the new spring. In these
cases, it is OK to omit the spring collar during reassembly.
The CVT belt is the link between the variator and clutch drives. A good belt is necessary for peak performance,
and belts should be inspected for fraying and wear and replaced if necessary.
Belts are available in regular and Kevlar varieties. Kevlar belts are stronger than regular belts and tend to last
Slide the clutch back over the shaft, put the clutch bell back on, and put the nut on and tighten it
up. 40 ft. lbs. torque
Replace the belt by putting it on the pulley on the clutch side first. Squeeze the pulley in about ¼” so
the belt will sit inside. (ONLY A LITTLE)
DO NOT PUT THE BELT ALL THE WAY INSIDE THE PULLY. Only about a ¼” or it will get stuck.
Slide the other end of the belt over the variator shaft. Replace the fan and nut. 40 ft. lbs. torque
When I put my belt back on, I first installed the clutch completely (thread locker & torque)
Then I installed the back half of the variator with the shaft sleeve, squeezing tightly and taking care not to let
the sliders move from their install position. Then I put the belt on clutch side first, then up over the variator
shaft, tight against the back side pulley. Next I installed the outside half of the variator pulley & fan. I tightened
this main nut a little at a time, rocking the system clock and counter clock wise at each stage of tightening as not
to pinch the belt in the variator. The rocking action allows the belt to seat while torqueing main variator nut
without damaging the belt.
The clutch bell is something that you should inspect annually at minimum, and more often if you find that you
are bogging down when climbing with the engine revving high and the wheels won’t spin. This can be
indicative of a “glazed” or smoothed clutch bell and/or clutch pads.
A tremendous amount of frictional heat is created when pushing the climbing limits of your buggy, and this
eventually leads to smoothing of the inside edge of the clutch bell. The heat (and smoke) can turn the bell a
purplish color and result in a very smooth, glazed appearance. When this happens, it’s time to replace the clutch
bell and inspect your clutch pads for possible clutch replacement as well.
NOTE: Examine the inside of the clutch bell. The inside edge should be rough, not smooth like glass. A smooth
interior inhibits a good engagement of the clutch with the bell and decreases performance.
Image: Clutch Bell: My buggy is 145 mm i.d.
Spark Plug: NGK-Stock - DPR8EA-9 NAPA p/n 4929//Up Grade - DPR8EIX-9 NAPA p/n 2202
NOTE: Spark Plug Gap: 0.06 mm to 0.07 mm
Spark Plug Testing for Proper Fuel/Air Mixture
Coat plug threads with graphite grease for easy removal.
Replace your current spark plug with a fresh spark plug .
Start the buggy and drive it for 5-10 minutes. Drive at a range of speeds, but try to get wide open throttle if
Shut off the buggy and remove the spark plug . Check the color of the tip:
- If the color is very light or light brown and the engine is not running smooth you have a lean condition (too
much air, not enough fuel). Check the intake manifold again with carb cleaner as in step 14. If no leaks, you will
need a larger sized jet.
Images: Lean Plug
- If the color is very dark black, and the engine is not running smooth you have a too rich condition (too much
fuel, not enough air). You will need a smaller sized jet.
- If the color is a dark brown or slightly black ashy color and the motor runs smoothly throughout acceleration,
then you've got the proper fuel/air mix!
Image: Perfect Fuel Mix Plug
If you're not getting satisfactory results from adjusting this screw, go to the next larger or smaller jet size as
determined by the spark plug testing.
In many cases, the stock carburetor on mini-buggies is perfectly functional for most purposes, even after
upgrading other parts of the Air-Exhaust system. It is only at the highest ends of looking for performance gain
that a larger sized carburetor may become necessary.
Stock carburetors are generally in the 24mm to 28mm range. Performance carburetors are available in 30mm
and 32mm sizes and the carburetor outlet is 2 inches and takes the 2 inch Uni Filter.
On the carburetor: Driver’s side port is the fuel inlet.
Rear facing port is a drain line.
Very bottom port from float bowl is a drain line.
Carburetor 360 View: Actual XRX 300 Carburetor pictures.
Image: Shows vacuum port passengers side of intake which connects to fuel tank valve bottom port.
Also shows vacuum port in front side of intake which connects to front side of the valve shown mounted to
frame behind passengers seat, shown upper right of picture below.
Image: Is not XRX 300, just for reference.
FYI: Carburetor Inlet Diameter is 2 inch (for your other than OEM air filter needs) Also there is not a lot of
room for a performance air filter. A 2 inch diameter extension with a 5/16 inch vacuum nipple about 7 inches
long will get you thru the narrow suspension for plenty of room.
Carburetor Jets and Rejetting
Inside the carburetor, the main jet is the primary fuel delivery to the combustion chamber. The fuel is mixed
with air before the resulting air/fuel vapor travels down the intake manifold into the engine.
It is of key importance for best performance to use a proper sized main jet for an optimal air/fuel mixture!
The correct size of main jet to use depends on several factors:
- Carburetor size
- Type of air intake and exhaust
- Performance cylinder head or big bore kit installed?
- Riding environment
- Altitude and ambient temperature
This can result in widely different jet sizes depending on your unique factors. Generally speaking, with just a
UNI filter upgrade, you’ll need a jet somewhere between 120 and 130. If upgrading the air intake and exhaust,
you’ll need between 125 and 140 and possibly larger depending on your carburetor, exhaust, and riding location
(elevation above sea level).
When deciding on which jets to get for rejetting, it’s a good idea to get a range of 3-4 different sizes of jet so
you can properly narrow it down to the correct size. This is not something that you want to guess on and hope
it’s the right size. Use a fresh spark plug when testing each different jet size. Examining the spark plug will tell
you if you are running too lean (light or no color on the spark plug end) or too rich (thick black buildup on
spark plug). You’re looking for a nice caramel brown to light black color – the motor should rev smoothly
through its full ramp up and not pop as it revs down.
Since the engine is basically a mechanism for moving air through it, improving your air intake system is only
half the job. What is the point of having great air inflow if the muffler is restricting the outflow?
A performance muffler opens up the airflow further and unlocks the full power of your air-exhaust system.
Racing exhausts give a great sound and get more power out of your buggy.
Remember, every time you upgrade your air and exhaust system, you will likely have to rejet the carburetor.
Front Tire’s: Size: 20 x 7 x 8, Which means that tire is 20 inch’s tall, 7 inch’s wide, 8 inch’s diameter rim size
Lug Pattern: 4 / 110 mm, 10 mm wheel stud size. Wheel lug torque is maximum 70 ft. lbs.
Tire pressure: 7 psi to 9 psi
Rear Tire’s: Size: 22 x 10 x 10, Tire is 22 inch’s tall, 10 inch’s wide, 10 inch’s diameter rim size hole.
Lug pattern: 4 / 137 mm, 10 mm wheel stud size. Wheel lug torque maximum 70 ft. lbs.
Tire pressure: 8 psi to 9 psi
Engine Oil: 10w 40 with moly, Capacity: 1 ½ qt. = 1419.529419 ml
Gear Box: 75w 90 with moly, Capacity: 750 ml, Rear Plug for Drain.
Radiator Hose: 18mm id.
Fuel Filter: ¼”
Fuel Lines: ¼” & 3/16”
Spark Plug Gap: 0.06 mm to 0.07 mm
Light Bulbs: Several different #’s for each bulb. A little confusing.
Park/Brake: Duel Element 5watt: P21/5w: BAY 15D: 1157, 299 old# P25/2
Turn Signal: Single Element 10 watt: R10W: BA 15S: 1156, 282 old# R19/10
Headlight: Duel Element S2 12v 35/35w, BA20D, 2TP
Park light in with headlight: Push in, Single Element W5W, 280
Suggested Onboard spares:
For / Rev cable
Regulator / Rectifier
Wire ties, 3"-24"
fuel line fuel line clamps
Small ratchet straps
and the tools required to change any item carried.
Spare chain & M/link(s)
assorted nuts & bolts
Parts that work on my buggy:
Image: Dr. Pulley 201205 HiT Clutch
Image: Dr. Pulley 201202 Variator
Both Dr. Pulley part numbers are what works on my buggy…
Image: OEM Starter for XRX 300
Image: TURN SIGNAL: BULB: Single Filament, R10W, BA 15s, 1156, 282, old# R19/10
Image: PARK/BRAKE: BULB: Double Filament, P21/5w, BAY 15d, 1157, 299, old# P25/2
Image: HEAD/PARK: BULBS: Headlight: Duel Element S2 12v 35/35w, BA20D, 2TP
Park light in with headlight: Push in Single Element W5W, 280
Image: My Performance Coil
Image: Gas Tank Fuel Valve
Top connector closest to fuel tank go’s to fuel filter then to carburetor fuel inlet.
Bottom connector go’s to passengers side vacuum port on intake.