Fantom FR21 User manual

50201 SILVER STREET
VICKSBURG, MI 49097
PH. 269-649-9583
FAX [phone]
WWW.FANTOMRACING.COM

FANTOM® FR21 / FR27
Thank you for purchasing a Fantom® FR21 or FR27 Racing Engine.Your new engine has been developed to provide superior
performance and longevity for both racing and sport applications. To attain the maximum enjoyment from your new engine, even
if you have prior experience with engines, please review the following information – you won’t be sorry – knowledge is power!
Table of Contents
1. TABLE OF CONTENTS 21. ENGINE MAINTENANCE
2. TOOLS & SUPPLIES / REMOVING OLD ENGINE 22. ENGINE MAINTENANCE / CAUTION STATEMENT
3. INSTALLING FR 21/27 23. NEWS / WARRANTY
4. INSTALLING FR 21/27 24. FR 21/27 REPLACEMENT PARTS
5. INSTALLING FR 21/27 / ENGINE OPTIONS 25. FR 21/27 REPLACEMENT PARTS
6. ENGINE OPTIONS / OPERATIONAL GUIDELINES 26. FR 21/27 REPLACEMENT PARTS
7. OPERATIONAL GUIDELINES
8. OPERATIONAL GUIDELINES
9. OPERATIONAL GUIDELINES
10. OPERATIONAL GUIDELINES
11. STARTING YOUR ENGINE
12. STARTINGYOUR ENGINE / BREAK-IN (HEAT CYCLING)
13. BREAK-IN (HEAT CYCLING)
14. BREAK-IN (HEAT CYCLING)
15. BREAK-IN (HEAT CYCLING)
16. BREAK-IN (HEAT CYCLING) / NEEDLE VALVES
17. NEEDLE VALVES
18. NEEDLE VALVES
19. NEEDLE VALVES / ENGINE MAINTENANCE
20. ENGINE MAINTENANCE
1WWW.FANTOMRACING.COM

TOOLS & SUPPLIES REQUIRED FOR EASY INSTALLATION
• 3/32 Hex Wrench • 5/64 Hex Wrench • 1.5mm Hex Wrench
• 2.5mm Hex Wrench • 5/16 Nut Driver • 5.5mm Nut Driver
• Needle Nose Pliers • Piston Stop (Clutch Tool) • Phillips Screwdriver
• Flat Blade Screwdriver • Hobby Knife • Thread Lock
• New Fuel Line • Filter Oil • After-Run Oil
• Throttle Return Spring • Air Filter • Manifold
• Small Nylon Tie Straps (air filter) • Large Nylon Tie Straps (manifold) • Pipe Wire Mount
REMOVING THE OLD ENGINE (If Applicable)
1. If your new Fantom engine is replacing an existing engine, you will need to remove your old engine from the vehicle, following
your vehicle’s instruction manual. If this is a new installation, please refer to this manual for installation instructions.You
may also want to refer to your vehicle’s instruction manual for any special instructions not covered in this manual.
2. If applicable, remove your old engine from the original engine mount and set it aside to use with your new Fantom engine.
3. If applicable, disassemble the stock clutch parts from your original engine, noting the order of their removal, as you will need
to install them on your new Fantom engine in the exact reverse order that you removed them from your original engine.
Clutch removal and installation is best accomplished by using a clutch tool (piston stop tool);this can be obtained at a quality
hobby shop.This tool allows you to fully tighten or loosen the clutch nut by keeping the piston from moving up and down or
allowing the crankshaft to turn. Never wedge anything inside your engine’s exhaust or attempt to grip the shaft with pliers
as these techniques will permanently damage internal and external parts.
2
269. 649. 9583

INSTALLING THE FANTOM® FR21 OR FR27
1. Remove the glow plug and install the piston stop (clutch) tool.
2. Install your clutch parts onto your Fantom engine in the reverse order of their removal from the stock engine. If you are
installing a new clutch, follow the instructions that came with the clutch. Before installing the clutch nut, apply a small drop
of thread lock to the clean shaft threads; this will prevent the nut from coming loose. Because clutch shoes are important for
good engine performance – and are relatively inexpensive – replace them with a new stock set (if you are installing the
original clutch).
3. Remove the clutch tool and reinstall the glow plug.
4. Loosen the 5.5mm carburetor-securing nut and position (angle) the carburetor in the same position as your original
carburetor was set at, or as your vehicle’s instruction manual suggests.While pressing the carburetor firmly to the crankcase,
retighten the securing nut. Make certain that the throttle ring ball mount is properly positioned like your original carburetor,
or as instructed in your vehicle’s instruction manual; if it isn’t, loosen the small setscrew on the throttle ring and rotate the
ring to the desired location; retighten the setscrew.
5. A leaking fuel tank can cause severe problems with your engine’s performance.Therefore, inspect the tank for leaks and
replace it, if needed. Install a new fuel-line, leaving plenty of extra length; it will be cut to the proper length once the engine
is installed in the chassis.
6. Install the manifold seal to the exhaust port at the rear of the engine – making sure it’s fully seated.Follow this by fully seating
the manifold (sold separately) over the seal. Because there are so many applications for this engine, please consult your
vehicle’s manual for manifold recommendations. More than likely you will be able to use your stock manifold if this is a
replacement application.
7. Secure engine to the stock engine mount(s), using the original four bolts … add a drop of thread lock to all four bolts at this
time (clean them first).
8. Position the engine within the chassis and secure it from the underside with the four original bolts.Add a drop of thread lock
to all four bolts at this time (clean them first).Lightly tighten the bolts prior to checking the gear mesh.While holding the clutch
bell gear in place, rock the spur gear back and forth; it should measure between 0.003 and 0.005 inch of endplay. Slide the
engine back and forth in its mounted position until you achieve the proper gear mesh. DO NOT adjust the gear mesh too
tight or too loose – the gears, clutch, and engine can be severely damaged.
3WWW.FANTOMRACING.COM

Once the proper gear mesh is obtained, fully tighten the four engine mount bolts (under the chassis) and recheck the gear
mesh … one more time.
9. Snap the throttle ball cup to carburetor using needle nose pliers.
IMPORTANT: At this point, we recommend installing a throttle return spring (available at any quality hobby dealer).This is
a safety precaution, to prevent the engine from running past the idle position, in the event that you lose radio contact with
the vehicle, or have any type of radio failure. This situation could cause dangerous uncontrolled wide-open operation,
resulting in injury to person(s) and/or property damage. Install the return spring in a manner in which the throttle returns to
idle position, when the radio is off.
10. Cut the fuel tubing to the proper length and attach to carburetor inlet nipple.If possible, route the fuel line away from sources
of high temperature (e.g., tuned pipe, manifold, and cylinder head). Heated fuel may vaporize in the fuel tubing causing
erratic engine operation – cool fuel runs better.
11. Should you use a stock or aftermarket tuned pipe?We recommend using a Fantom WORKS tuned pipe.OurWORKS PIPES
produce much better performance than a stock pipe. Besides, they sound “killer” – a much raspier tone – not to mention the
cool appearance.Your Fantom dealer has these in stock or they can order one for you from one of our distributors.They are
available in natural team finish (part #FAN20014 single stage or FAN20016 dual stage) or shiny nickel finish (part
#FAN20015 single stage or FAN20017 dual stage).You can find more details on our pipes by visiting our web site
www.fantomracing.com. If you decide to use the stock pipe, attach it to the manifold using the stock silicone coupler and new
tie straps. If you use an aftermarket pipe, follow the installation instructions included with the pipe. After completing the
connection between the manifold and pipe, secure the pipe to the chassis with a standard wire mount. Finish the tuned pipe
installation by connecting the fuel tank pressure line to the pipe’s pressure fitting.
12. With the radio turned on, adjust the throttle and brake trim settings (refer to your radio manual for details):
•Set the radio trims so the throttle closes and opens fully – take your time with this procedure.
•Make sure that the transmitter throttle trigger is in the fully pulled back position at the same time the carburetor opens
completely (100%); when the throttle trigger reaches its neutral position, the carb must be simultaneously closed (0%).
In other words, you don’t want the carburetor fully open when your throttle trigger is only partially back; likewise, you don’t
want the carburetor fully closed before the trigger is in the neutral position. Faulty adjustments can damage the throttle
servo and/or make the engine act like it isn’t running properly.
4
269. 649. 9583

13. Install the air filter (sold separately). Make sure to oil the air filter.Use quality air filter treatment oil such as our Fantom Filter
Fluid™ / Filter Wash™ kit (part # FAN20111). Use a small tie strap to hold the air filter housing to the carburetor; these are
available from your local dealer or hardware store.
CAUTION: Never run your engine without an air filter. Rapid and permanent damage will result – which is NOT covered by
warranty.
Check all of your work, and read the rest of this manual (twice) to ensure that you completely understand the operational
characteristics of your new FR21 or FR27 Racing Engine.
ENGINE OPTIONS
Your FR21 / FR27 can be modified to work in optional configurations, by referring to the following information and part numbers.
1. Your FR21 or FR27 was built with a standard glow plug head button, which is best suited for off-road and/or high torque
applications.For on-road and/or high RPM applications we offer an optional turbo style head button, as well as a turbo glow
plug.The following optional head buttons and glow plug are available:
•FAN10422 .21/.27 Turbo Glow Plug
•FAN10440 .21 Turbo Head Button
•FAN10442 .27 Turbo Head Button
2. To modify the FR21 or FR27 (non-pull start models) for pull start operation, the following parts are available:
•FAN10404 Standard Crank with Pull Start Stub
•FAN10406 Pull Start Assembly
•FAN10407 Pull Start One-Way Bearing
•FAN10408 Pull Start One-Way Bearing Shaft
•FAN10409 Rear Plate for Pull Start
•FAN10417 Rear Plate Screws for Pull Start
•FAN10420 Pull Start Assembly Screws
5WWW.FANTOMRACING.COM

3. To modify the FR21 or FR27 (pull start models) for non-pull start operation, the following parts are available:
•FAN10410 Rear Plate for Non-Pull Start
•FAN10414 Gasket Set
•FAN10419 Rear Plate Bolts for Non-Pull Start
ENGINE OPERATIONAL GUIDELINES
This section covers important information useful in understanding the what, how and why of your new engine.
To get a full understanding of the remainder of this manual, it is important that we cover some basic principles first.Please make
sure you fully understand this section of the manual before proceeding.
Your new Fantom engine is built using the latest ABC technology (aluminum, brass, chrome). Expansion of the piston is
controlled by the percentage of silicon in the aluminum alloy; by matching the piston expansion to the expansion of the chrome-
plated brass cylinder-sleeve… both at normal operating temperatures (220º-290º F), the best running-fit can be obtained. (This
subject will be covered in more detail, later in the manual, in the “Break-In” section.) The cooling fin area of the cylinder head
regulates the temperature.
When a carburetor mixture is set properly, the temperature of the engine should be of little concern. The flash point of certain
modern lubricants found in high quality fuels is generally a minimum of 700º F; meaning as long as you are using high quality
fuel, your engine is protected even in extreme temperature conditions… IF THE AIR-FUEL MIXTURE IS NOT SET LEAN.
Unfortunately, over the years it has become customary to set the main needle valve by engine cylinder head temperature (usually
called temperature tuning); however, this is a bad practice. Temperature tuning can lead to overly rich or overly lean needle
settings – both can damage an ABC-type engine. Depending on the operating conditions (e.g., weather conditions, altitude,
surface you are running on, fuel type, etc.), we have found that the FR21 and FR27 cylinder head temperatures (taken with a
temperature gun; aiming down inside at the glow plug area of the cylinder head) will generally range between 220º and 290º F;
however, do not “temperature tune” to these temperatures.
6
269. 649. 9583

Tune the engine following the guidelines set forth in the “Setting The Needle Valves For Optimum Performance” section of this
manual, and consider the engine temperature a secondary issue. It is OK to check your engine’s temperature, as a reference
point, but do not “temperature tune” your FR21 or FR27.
IMPORTANT: Just because the engine is designed to run up to 290º F, do not lean the primary (main) needle valve to achieve
this head temperature, unless your operating conditions dictate it! It’s OK to run the engine this temperature ONLY if the air-fuel
mixture is properly set for the operating conditions thatYOU are running in. Also, don’t allow your engine to run too cool – you’re
not protecting its longevity! Operating the engine “blubbering rich” will cool the cylinder-sleeve to the point where the piston
will begin to rub excessively in the pinch-zone, because the cylinder-sleeve is not hot enough to expand to its intended designed
operating size.The pinch-zone is that necessary area around the top of the tapered cylinder-sleeve, where the piston comes in
contact, creating the necessary seal for proper combustion chamber compression. Excessive rubbing due to under-expansion
of the cylinder-sleeve produces pinch-zone wear. Pinch-zone wear produces combustion gas blow-by when the engine is up to
normal temperature. Combustion gas blow-by produces loss of power…the number one reason that piston and cylinder-sleeve
assemblies must be replaced.
IMPORTANT: Pinch-zone wear, resulting in loss of compression, is NOT covered by warranty.
We have no control over what brand of fuel you use, and/or the way you operate your engine.Your FR21 or FR27 is built using
the latest ABC technology, and will last just as long as any other brand of ABC type engine, as long as it is used in accordance
with this instruction manual, therefore it is your responsibility to operate your engine properly, to obtain the longest usable life
possible.
The Effect of Fuel
Different fuels drastically affect the way your engine will run. One manufacturer’s 30% nitro blend isn’t necessarily the same as
another’s – there are many variables: the type of oil (synthetic or castor), the amount of oil (% in the fuel blend), the oil blend (%
synthetic, %castor), and oil quality will require a different needle valve setting for any engine. With this in mind, here are some
rules to follow when fuel-tuning your engine:
7WWW.FANTOMRACING.COM

• Lower oil content and/or lower nitro content require leaner needle settings.
• Higher oil content and/or higher nitro content require richer needle settings.
• High oil content and/or low nitro content fuels are generally better for engine longevity.
• Low oil content and/or high nitro content fuels provide better engine performance, but reduce its longevity.
• By reducing the oil content in the fuel blend many properly tuned nitro engines will operate at a slightly reduced cylinder
head temperature. Don't misinterpret reduced cylinder head temperature as protection against engine damage; to the
contrary, less oil content will not protect the engine as well as higher oil content. The less-oil/cooler engine temperature
phenomena is beyond the scope of this manual, however, the fact remains: Reduced oil content (10%, 9%, 8%, etc.) can
lead to premature engine failure … if the air/fuel mixture becomes lean.
Although not all are directly related to fuel, the following list includes the most common causes for lean mixtures:
1. The primary needle valve is set too lean.
2. Incorrect gearing - placing too much load on the engine leads to increased head temperature, producing a lean setting.
3. A leak in the fuel system can produce a lean run from an otherwise correct needle setting.
4. Hot, humid weather conditions can produce a lean mixture setting as head temperatures rise from an otherwise correct
needle setting.
In the final analysis, if you choose to use lower oil content fuel, you may gain performance advantages, but longevity will be
sacrificed. Also, in low oil content fuel, there simply isn't enough lubricant present in the fuel-blend to defend against rapid
temperature rise (due to out-of-control friction) from a lean mixture...you have sacrificed your margin for error against massive
engine damage by running less oil.
The Effect of the Weather
Weather conditions also have an effect on how well your engine performs:
•High air temperature
•High humidity
•Low barometric pressure
8
269. 649. 9583

These conditions contribute to low oxygen density within a given volume of air; low oxygen density demands that the engine’s
needle valve be set leaner to ensure the correct air/fuel mixture ratio.
•Low air temperature
•Low humidity
•High barometric pressure
These conditions produce a higher oxygen density within a given volume of air; high oxygen density requires that the engine’s
needle valve be set richer to ensure the correct air/fuel mixture ratio. Needle valves must always be properly adjusted for the
engine to realize peak performance.Too little fuel for the amount of inducted oxygen and the engine will run lean; it will also be
starved of the lubricant’s protective qualities – lubrication and cooling.Too much fuel for the amount of inducted oxygen and the
engine will run rich; with excess fuel and lubricant, the engine will lack power.
Increased oxygen density allows more fuel to be run through the engine, producing greater horsepower.Therefore, any engine
will produce more horsepower with oxygen dense air conditions; this is why you will usually notice better engine performance in
the spring and fall months.
IMPORTANT: In cold weather conditions (e.g., winter months and/or certain regions in the world) the outdoor temperature may
make your engine run too cool. Remember, your FR21 or FR27 is designed to run best between 220º and 290º F, however, DO
NOT lean the main needle to achieve these temperatures. The engine’s design is such that the engine will run at these
temperatures in typical weather conditions that R/C vehicles are operated in (e.g., 55º to 90º). In colder weather conditions, to
attain these temperatures, we recommend wrapping the cylinder head with aluminum tape (found at hardware stores), which
insulates the cylinder head, helping the engine to run within its designed temperature range, without having to lean the needles
to achieve this. REMEMBER: High temperatures produced by the engine design are good, but high temperatures produced by
a lean needle setting are bad.
IMPORTANT: In hot weather conditions (e.g., summer months and/or certain regions in the world) the outdoor temperature may
make your engine run hotter than the typical operating temperatures between 220º and 290º F.
9WWW.FANTOMRACING.COM

DO NOT overly richen the main needle to reduce you engine’s temperature in these conditions.The engine’s design is such that
the engine will run at these temperatures in typical weather conditions that R/C vehicles are operated in (e.g., 55º to 90º). In
hotter weather conditions you may see higher than typical engine temperatures, but don’t be alarmed, as long as your engine is
tuned properly. Because of the engine’s design, we are more concerned with the engine running too cool, rather than too hot
(when the engine is tuned properly), so most importantly make sure to follow the cold weather instructions (pg. 9). In testing, we
have operated our engines in excess of 350º F with no negative effects. For proper cooling you should cut a hole in the front
windshield and for extra cooling you can enlarge the cut out area of the body around the engine.Also, limiting the amount of time
running the engine wide open will help maintain lower engine temperatures. REMEMBER: High temperatures produced by the
engine design are good, but high temperatures produced by a lean needle setting are bad.
Although not related to the weather, elevation above sea level also has an effect on engine horsepower;higher altitudes produce
lower barometric pressure and reduced oxygen density. The opposite is true of low elevations. The higher you are above sea
level, the more you must lean the needle valve, and vice versa.
The Effect of Operating Conditions
Depending on your particular operating conditions, your engine and vehicle will need to be set up properly to maximize their
potential.This mainly has to do with the surface you are running on.For example, if you are running on grass, your engine, clutch,
and shift points (if applicable) will need to be tuned differently than if you were running on pavement or dirt. Different dirt
conditions require specific tuning (e.g., loamy dirt puts a greater load on the engine compared to hard packed dirt). We have
found that with high load conditions (grass and loamy dirt), the engine runs best tuned slightly leaner, and the shift point (if
applicable) set slightly later.In low load conditions (pavement or hard packed dirt), the engine runs best tuned slightly richer and
the shift points (if applicable) set slightly early. Refer to your vehicle’s instruction manual for details regarding clutch set-up,
gearing options & recommendations, and transmission shift points (if applicable).
IMPORTANT: No matter how you prefer to tune your vehicle (shift points, clutch set up, slipper, etc.), always make sure that the
needle valves are set properly, for ideal engine operation, for the conditions that you are operating in. Don’t call your buddy, who
lives across the state or country, and expect to use his settings – every operating condition is unique.
10
269. 649. 9583

STARTINGYOUR ENGINE FORTHE FIRST TIME
First, fill your fuel tank with a high quality hobby fuel, such as Fantom SC20 / SC30 Performance Blend or SC20R / SC30R
Racing Blend Fuel. Typically, most people use 30% nitro content fuel in .21-.27 size engines to gain extra horsepower for the
heavier vehicles that these size engines are commonly installed in.
IMPORTANT: Our research has shown that fuel quality plays a very important part in how long your engine will last and perform.
There are many inferior fuels on the market – and they can cause premature wear and/or engine failure. We recommend that
you use only Fantom Fuels for the best performance and longest engine life. Fantom also suggests Trinity® Monster
Horsepower™ blended fuels as the only other recommended fuel.
Before starting your engine for the first time, make sure your carburetor is set to the baseline settings outlined on page 17 of
this manual. At any time, if you experience difficulty starting your engine, please refer to the “ENGINE OPERATIONAL
GUIDELINES” section of this manual for helpful information. Once the fuel tank is filled and the radio gear is turned-on, proceed
by priming the engine by placing your finger over the exhaust outlet for a few seconds, while turning the engine over with either
a starter box or pull start depending on your engine model; this will pressurize the fuel tank, moving fuel into the carburetor and
engine. NOTE:This technique is also helpful in starting your engine any time it won’t start within the first couple of seconds that
you turn over the engine. By placing and removing your finger over the exhaust outlet, in two-second intervals, while turning over
the engine, this maintains fuel pressure to the carburetor, which aids in starting the engine. Be careful not to overdo it though,
as flooding can occur, making the engine difficult to start. With a little practice, you will learn the technique, and should find it
very useful.
NOTE TO PULL START ENGINE OWNERS – It is very important that you DO NOT pull the starter rope out to its full length, as
permanent damage could result, which is not covered by warranty. Use short, quick pulls, only pulling the rope out about 10
inches.
IMPORTANT: Make sure your glow plug igniter is fully charged. Insufficient power to the glow plug will result in poor starting or
complete failure to start. Just because your glow plug glows (while checking it) does not mean that the glow plug is OK and/or
that the glow igniter is charged enough.
11 WWW.FANTOMRACING.COM

A low charged igniter will make a glow plug glow, and a bad glow plug will still glow sometimes, but this does not guarantee that
either is operating at 100%.We have found that the most common reasons for engine starting failures are due to bad glow plugs
and/or igniter problems. A glow plug can go bad in less than one tank of fuel, so it is always wise to check this first if you are
having difficulty starting your engine.
When starting your engine, a small amount of throttle may be needed; usually “blipping” the throttle on and off in small amounts
(1/4 throttle or less) is recommended. Some of the more expensive radios are equipped with a push button feature that moves
the throttle to a pre-set opening; this is especially helpful when trying to start an engine by yourself. Once fuel reaches the
carburetor, the engine should start immediately. If it doesn’t, look at the fuel line to see if it contains fuel, check the needle valve
settings, and glow plug and/or glow plug igniter. Because of the high compression of your new engine, it is sometimes necessary
to loosen the glow plug 1/2 to 1 turn to relieve some of the engine’s compression; this will make it easier for the starter box or
pull start to crank over your engine. Only perform this procedure if you experience difficulty starting your engine during the initial
start up and first 2-3 tanks of fuel. After the first few tanks of fuel, the engine should be broken in sufficiently and will not require
this tactic again. Once the engine starts, make sure to tighten the glow plug quickly – within the first 10 seconds of running.
BREAK-IN (HEAT CYCLING)
As your engine starts for the first time – the break-in process begins. For most ABC-type engines it’s the most critical period of
their useful lives … but few operators pay much attention to the details.
In the old days, engine break-in consisted of running the iron or aluminum piston (ringed or lapped) within a steel cylinder-sleeve,
very rich with lots of lube for hours and hours.This was intended to wear-in the engine’s rough spots, reduce friction, and improve
power and longevity. Owners of modern ABC-type engines also demand peak power and longevity; fortunately, break-in is now
an abbreviated process, requiring much less time with our method. Improvements are largely the result of CNC (computer
numerical control) production machinery.These programmed robots make individual engine components that fit together almost
perfectly – every time! This results in very little if any rough spots to smooth out. Despite such accuracy, metal components
(primarily the piston and cylinder-sleeve) require heat-cycling to relieve the internal stresses due to their fabrication.
12
269. 649. 9583

Therefore, heat-cycling (break-in) can be described as the process of heating and cooling the engine from its normal operating
temperature, at WOT (wide open throttle), to ambient temperature – time after time – until it holds a peaked setting. Break-in
(heat cycling) SHOULD NOT be considered the “wearing-in” of the internal parts as many manufacturers would like you to
believe. Our heat cycling method only relieves the internal stresses of the metal parts that occur during the manufacturing
process.
Here’s how to perform the job correctly:
1. Decide on a fuel (nitro and oil content).Your Fantom engine is designed to run best with at least 20% nitro, but no more than
30% nitro content.If you like a more “drivable” engine, choose 20%;if you like a lot of horsepower choose 30%.As previously
mentioned, most people choose 30% nitro with .21-.27 size engines.Whichever type you choose, use the same fuel for
break-in and everyday operation – for the life of the engine. Don’t indulge in the “fuel of the day” game – it only hastens
the day when you will need a new piston and cylinder-sleeve set. Here’s why:
Increased nitromethane content in the fuel causes combustion chamber temperatures to rise.This is normal since nitro is
the primary power-producing ingredient in the fuel’s chemistry. As the temperature increases, so does the expansion of the
piston and cylinder-sleeve. As described previously, the chrome-plated sleeve is engineered to expand more than the
aluminum alloy piston – as controlled by the cooling ability of the cylinder head fins.With higher nitro content fuels (e.g.,
30%), the piston to cylinder-sleeve running-fit (clearance) is a bit larger than with lower nitro fuel blends, because of higher
combustion chamber temperatures produced with higher nitro content.Therefore, if you start by using 30% nitro fuel at the
beginning of your engine’s life – with its tight pinch fit when cold – It will produce the best possible WOT performance
characteristics if you continue to use the same fuel for the life of the piston and sleeve. If you change fuel – reduce the nitro
content to say 20% - the engine will run good, but a bit of the pinch will wear away from the top of the piston because lower
cylinder temperatures equate to less expansion of the cylinder-sleeve. If you then decide to switch back to the higher nitro
fuel, the elevated temperature and expansion will produce greater piston clearance (due to its previous wear using 20%); the
elevated quantities of blow-by combustion gas will cause the engine to lose power.
13 WWW.FANTOMRACING.COM

These principles also hold true for oil content. By changing oil content, you may affect the temperature that the engine will
run at, which in turn will affect the piston / cylinder-sleeve clearance, as described on previous page.The moral of the story
is: It’s best not to change fuel, once the break-in process has begun.
2. Start your engine following the starting procedures previously covered.
3. IMPORTANT: Once started, begin running your vehicle around immediately, as described in step 4 below.
IMPORTANT: In the following break-in steps you may find what we explain to be different than what you are normally used
to, but it is very important that you follow our instructions to obtain the best performance and longest engine life.This
paragraph covers information that is very important in understanding the reasons for our break-in method, so please read it
carefully. Our principles are based on common laws of physics, so our break-in process should make more sense once you
read the rest of this paragraph. In simple terms, your Fantom engine is a true ABC type engine, which means that there is
a high silicon content aluminum alloy piston running inside of a brass sleeve that is plated with hard chrome plating.All ABC
engines are designed with an interference fit, or in other words, the sleeve is actually tapered so that the piston is pinched
at TDC (top dead center), when the piston reaches the top of its stroke. Since ABC engines don’t have piston rings, this
“pinch” is required, in place of the rings, to create the necessary compression needed to burn the fuel efficiently, ultimately
producing maximum horsepower, however, this “pinch” is actually designed to be too tight when the engine is cold, but there
is a reason for this. When heat is applied to metal it expands, and different metals expand at different rates. Brass expands
more than aluminum, thus the reason for the aluminum/brass combination, the intention being for the brass to expand more
than the aluminum.The chrome plating serves as a very slippery and wear resistant surface for the piston to efficiently
operate against.With that in mind, your engine is designed so that the top of the cylinder (sleeve) expands more than the
piston itself, so that the fit between the piston and sleeve is optimal once the engine reaches the proper operating
temperature. For proper break-in and normal operation, your engine ALWAYS needs to come up to the proper temperature
as quickly as possible, in order for the sleeve to expand enough to achieve optimal fit, otherwise the piston will scrub the
sleeve too much causing premature wear, loss of compression, and ultimately the performance of your engine will diminish.
14
269. 649. 9583

The sleeve will start expanding to the proper design parameters at approximately 205 degrees F., however, this does not
mean that this is the normal operating temperature; it only means that you need to always get your engine up to at least this
temperature as quickly as possible after the engine is started. Surprisingly, many companies today still recommend the old-
fashioned way of breaking in an engine, as described earlier in this manual, but we have found that our method not only
makes more common sense, but helps your engine run much better and with more longevity. The old-fashioned method of
break-in;running the engine at low temperatures and very rich for several tanks, destroys the piston prematurely.By breaking
in your engine the old-fashioned way, the piston actually “wears in” to the cool and under expanded sleeve size. Once the
break-in process is complete and you start running the engine up to normal temperatures, the sleeve expands further, but
the piston is already “worn in”to the smaller sleeve size.Obviously this will cause lower compression, less power, and shorter
piston and sleeve life. In contrast, using our method the piston and sleeve heat up quickly and to the designed size
parameters immediately, eliminating the constant wearing of the piston against the sleeve.
4. Here’s the tricky part: to the best of your ability, immediately begin dialing-in the high speed needle valve for maximum RPM
performance during the first tank of fuel (see more detailed information on setting the needles in the “SETTING THE
NEEDLE VALVES FOR OPTIMUM PERFORMANCE” section further in this manual). During the break-in period make sure
to keep your engine temperature at least 205º as previously mentioned by making 5 second (WOT) high speed passes back
and forth, on the type surface you prefer to operate on – this will keep the piston and sleeve hot enough while the operator
tweaks the needle during quick pit stops. A helper is very handy for this critical operation! Ideally, get the needle valves set
for maximum performance and a reliable idle as quickly as possible; generally within 5 WOT passes you should try to have
it set. If performed correctly, the engine should be running near normal operating temperatures for the entire break-in
process.Depending on the operating surface, outdoor temperature, etc., your break-in temperature will range between 205º
and 260º F., but this is on average, so don’t be alarmed if the temperature is higher. For the most part, you will see that the
main difference between our break-in method and normal operation is that during break-in there is a cool down period
required between each tank of fuel. Once the break-in period is finished, you will see normal temperatures range between
220º and 290º F. Following the above procedures, run the engine for a complete tank of fuel – then shut it down. Allow the
engine to cool down COMPLETELY before re-starting.
15 WWW.FANTOMRACING.COM

5. Continue this process for 4 tanks of fuel; this heat-cycles all the metal parts inside your engine.
IMPORTANT: Do not let the engine sit and idle for its break-in.The piston and cylinder-sleeve will not get hot enough to
expand properly, and the critical pinch-fit will disappear before you know it. In fact, we are more concerned about running an
engine too cool, rather than too hot!
SETTING THE NEEDLE VALVES FOR OPTIMUM PERFORMANCE
Carburetor settings should always be made after the engine has been brought up to normal operating temperature; this is
accomplished by running the vehicle for a minute or so.
IMPORTANT: The needle valve settings will vary from day to day depending on outside weather conditions. Don’t expect your
engine to run correctly over a period of time without adjusting the needle valves.Slight changes in weather conditions will require
needle valve adjustments.
Weather conditions can change during the same day. For example, in a race situation, if you run a qualifier in the morning and
another one in the afternoon, chances are the temperature will change, which means your carburetor will need to be readjusted.
16
269. 649. 9583

There are 3 settings that can be adjusted:
1. The high-speed (main) needle valve (see: Figure A).
2. The low-speed needle valve (see: Figure B).
3. The idle adjustment screw (see: Figure C).
4. WARNING: DO NOT adjust the screw in figure D. This is not an adjustment screw.
IMPORTANT: Carburetors are very sensitive to minor adjustments.Any adjustments should be made
in increments of 1/16th to 1/8th of-a-turn, at a time. New carburetors should be set to the following
guidelines and are not considered pre-set from the factory.The following settings are good baseline
settings but are not considered optimum.Use these settings as a starting point as optimum settings
will depend on your conditions:
•High-speed needle: 3-1/4 to 3-1/2 turns counter clockwise (CCW), out from closed.
•Low-speed needle: (see illustration 1 - approximately 2-1/4 to 2-1/2 turns CCW)
•Idle adjustment (throttle stop): should be set so that the throttle is open
approximately .5mm from the “just-closed” position (see illustration 2).
Baseline settings were obtained in the following operating conditions:
•Hard packed dirt.
•80º F (air temperature).
•Low humidity (60%)
•Using Fantom SC30 Fuel (30% nitro / 12% oil)
NOTE: Your baseline settings may differ slightly from ours.
High-Speed Needle Valve
1. Start with the high-speed (main) needle valve.This needle controls the amount of fuel allowed to pass through the carburetor
at all times.Turning the screw clockwise (CW) makes the engine run leaner; CCW makes it run richer.Continue making small
adjustments to this screw until maximum RPM and power is obtained.
17 WWW.FANTOMRACING.COM

IMPORTANT: Leaning the main needle too much may result in higher obtained RPM and power, but may starve the engine
of lubrication. Be careful not to over-lean the engine, once you get close to optimal performance. A step too lean can result
in permanent piston and cylinder-sleeve damage very quickly.
2. For maximum life, it is always best to run your engine slightly on the rich side, rather than too lean.When the engine is tuned
for maximum performance, you should still be able to see light smoke coming from the pipe at full throttle.
3. Signs of overly rich mixture:
•Sputtering and/or bogging at mid to full-throttle.
•Sluggish acceleration with excessive blue smoke coming from the exhaust.
•Excessive unburned fuel exiting exhaust.
4. Signs of overly lean mixture:
•Sagging and/or erratic engine response.
•Sudden loss of power and/or engine cuts out during mid to full-throttle.
•Over-heating (not due to engine design, but rather by over-lean needle settings).
•No smoke coming from exhaust.
•Distorted, broken and/or white glow plug coil.
Both needle valve settings (too lean and too rich) can produce similar symptoms; be observant and careful when trying to
determine what the engine is actually doing. If you get lost, refer to the factory needle settings.
WARNING: Prolonged too-lean operation of the engine produces a hot, lubrication-starved condition resulting in permanent
damage, which is not covered by warranty.
18
269. 649. 9583