Top Gas


Top Gas

Updated 2/10/17

TOP GAS CLASS REQUIREMENTS                                                                             

DESIGNATION: TG, followed by rider number.


Top Gas is the quickest index class contested at Manufacturers Cup events and is considered the stepping-stone into the Pro ranks. Most bikes compete with either big displacement normal aspirated motors to nitrous or turbocharged machines. All compete with a heads-up, pro tree start. Top Gas is run on qualified 64 bike field, based on a standard of 8.20 in the quarter mile (5.10 in the eighth mile). Standard safety requirements are the only class rules. During qualifying, runs quicker than the 8.20/5.10 index will be placed at the bottom of the qualifying sheet. During eliminations, runs quicker than the standard disqualify the rider under Handicap “break-out” procedures.



click here Points System & Caculations to see how points are scored

This class will be a points class at all MANUFACTURERS CUP events.

It will be the riders responsibility to monitor his or hers points earnings after every event. All requests for points adjustments must be made in writing to within thirty days of the points posting for the event in question on all events EXCEPT the Finals. For the Finals ONLY, all requests for points adjustments, again, must be made in writing to and within TEN days of the points being posted. Please understand the Man Cup will strive to keep the points tabulations for all classes accurately and correctly and we do hope by you monitoring your own points earnings that any errors or miscalculations can be corrected in a timely fashion.



Each motorcycle, regardless of class or category, must complete and satisfactorily pass inspection by the Technical Department before being allowed to make a trial run or participate in any event conducted by Manufacturers Cup.




Catch cans are mandatory on all motorcycles that do not utilize a stock crankcase breather routing to the air box. Engines with breather hose plumbed into a vacuum pump system also require a catch can for catastrophic failure. The catch can must be securely mounted. All vents to ambient atmosphere must have an air filter to catch any oil mist. Use of suitable size hose clamps is required.

DRY SUMPS: Entrants equipped with dry sump oil systems must have catch cans. Oil holding tanks do not qualify as catch cans. Oil holding tank venting system must contain a catch can with a minimum capacity of .5 quarts. All vents to ambient atmosphere must have an air filter to catch any oil mist.


Antifreeze containing ethylene glycol is prohibited. Radiator must contain water or approved Glycol-free replacement only.


In classes where they are accepted, aftermarket cylinder heads will be permitted with prior approval and consent of AMA Technical Department. Cylinder heads must be stock-appearing with fins (on air-cooled models) and stock bolt pattern. Stock cam chain drive method must be used, (i.e., center crank drive or end crank drive).


Injected V-twin nitro engine must utilize SFI 46.1 cylinder head engine restraints.


Must be an AMA accepted stock-type engine specifically designed and manufactured for production motorcycle use. Snowmobile engines permitted in PET. Automobile, aircraft or marine engines are prohibited. Any new concept must be submitted to the Tech Department for approval prior to competition. All engines must be started by self-contained starter or detachable electric starter. Push or roller starts are prohibited.


Required in TG and SC and on nitrous or turbo bikes in any exhibition class; Factory dry sump engines without power adders are exempt from this rule. Also Top Fuel is exempt. Required on any bike using nitrous oxide, regardless of class, except for streetbikes utilizing a street-type exhaust passing under the oil pan. Engine must be equipped with a lower-engine-ballistic/restraint device; (unit must have official Manufacturers Cup approved label sewn to outside of blanket). The use of a belly pan or sealed fairing in place of blanket allowed. All sealed fairings and belly pans must hold the contents of the engine crankcase. Stock street bikes within ten years of original manufacture date may also be waived from this oil blanket requirement.

GROUND CLEARANCE: Flexible ballistic blanket are exempt from the minimum ground clearance rules. Bikes with blankets interfering with the ground clearance inspection may remove the blanket in order to pass the inspection. With the blanket removed, all other components must pass ground clearance inspection (See 2.4.9). Competitors with a blanket below the minimum ground clearance will be required to remove the blanket every time that tech requires a ground clearance inspection.

Bikes will belly pans or other solid ballistic retention devices must pass ground clearance will all components attached.




Mandatory on all bikes. Chain or belt guards are to cover the width and at least the top run to the centerline of the sprocket of any chain/belts. The clutch assembly must have at least half of the side surface covered. The guards should be steel or .125” aluminum unless otherwise stock equipped and must be firmly mounted. Rear fender and seats are not chain guards.


No stress bearing part of any aftermarket centrifugal clutch may be cast material. Clutch cover must be adequate to protect the rider in the event of mechanical failure. Motorcycles with an engine-driven lock-up clutch may not be fired in pits unless rear wheel is elevated off the ground by a secure stand and/or front wheel placed against a solid object (competitor’s trailer, bike, van, etc.).


Any clutch covers constructed in multiple pieces must have screws, bolts or welded components. No epoxy or similar material may be used bond pieces.



Defined as any constant-mesh transmission which uses override-style shifting for any or all of the gear changes. Override shifting means that, during up-shifts, the transmission is briefly engaged in two gears at once, allowing power to be continuously applied to the rear tire during gear changes. Any transmission containing components that would allow the transmission to engage two or more gears simultaneously is considered to be an automatic. These components include, but are not exclusive to, windowed shift drums, split forks, split gears, split fork slider rings, gear or fork detent springs, etc.

Any aftermarket transmission utilizing pneumatic, hydraulic, electric, or other style drumless engagement is considered to be an automatic. Any transmission utilizing planetary gears is considered to be an automatic.


Only transmissions utilizing constant-mesh design gears, with a rotating, ratcheting shift drum and forks, are considered to be OEM-style. All components must be contained within the engine cases, and must be in their original location.




Must meet OEM brake specifications. Operational front and rear brakes are mandatory and must be in safe operating condition. Brake lines must be OEM type or braided steel hose or stainless steel line. Braided steel hose is highly recommended. Brake lines are to be routed and mounted properly to insure no contact with moving parts. Carbon fiber brake pads or disks are prohibited. The spreading of pads away from the disk is prohibited. Drilled disc brakes may be used if commercially manufactured or they meet the following requirements:

  • The original diameter must be maintained as a minimum.
  • Minimum thickness: .187”
  • Maximum hole size .500” with all holes countersunk.
  • No two holes closer than 1.25” center to center.


Unless specified otherwise within specific class requirements, all entrants must meet the following front suspension requirements:

FRONT FORKS: Rigid forks prohibited. Hydraulic-dampened tube type only, with a minimum tube diameter of 34mm. All entrants must have a minimum of 1” travel in front forks, with sufficient clearance around the fender, fairing, headlight, exhaust, etc. to allow the forks, fender, and wheel/brake assembly to safely move across the full range of fork travel at any steering angle. Forks must have enough front spring force to keep forks extended at least .50” above compression bump stop with bike sitting level and rider seated in riding position. Travel is measured from the compression bump stop to the rebound bump stop. NOTE: Having 1” of exposed fork slider DOES NOT guarantee that 1” of travel exists. No more than 1.5” of upper tube (2” on inverted forks) may be exposed above top triple clamp or clip-on, whichever is higher.


STEERING STOPS: Positive fork stops are required, with a maximum turning arc of 12 degrees in either direction. Stops must be cast or machined into the frame or steering neck, or may be welded to the frame or steering neck. Stops must have a shear strength equal to a 3/8” bolt.


LOWERING STRAPS: Nylon straps designed to limit front fork travel are legal in certain classes, check individual class rules for legality. Straps must be specifically designed for the purpose of front suspension lowering. Generic tie-downs not permitted. Travel limiting straps are not allowed on any wheelie bar-equipped bike, regardless of class. Retention straps are allowed only in SC and TG (if not using a wheelie bar). Retention straps must be no more than three years from date of manufacture. Manufacturers Cup Tech Officials may disapprove lowering straps that are not sufficient and could cause a safety issue. Front fork must travel a minimum of 1” when lowering strap is in use.



FRONT SUSPENSION & WHEEL ASSEMBLY: No ballast may be mounted to any portion of the front suspension, brake system, fender system, or rotating assembly. No parts of the front suspension, brake system, fender system, or rotating assembly may be remanufactured from exotic heavy materials, including tungsten steel, HD-17, or Mallory metal. No portion of the front fork leg assemblies may be replaced with a heavier replacement component. Aftermarket or custom forks may not be heavier than industry-standard OEM sport bike forks. Legality of such forks will be considered on a case-by-case basis.


Front suspension components other than the fork leg assemblies (this includes triple clamps, clip-on’s, fender mounts, brake calipers and hangers, etc.) may be remanufactured from any legal materials, but must be constructed to dimensions reasonable for the application, with hardware reasonably-sized for the application. Whenever possible, OEM components will be used as a reference when determining what are appropriate sizes and dimensions. Lightening holes, gun-drilling, and other weight-saving techniques utilized on the OEM components may be deleted. Pre-approval of custom or aftermarket components is highly recommended. The tech staff has final decision on all front suspension component matters, and will be closely monitoring the use of these components. Abuse of these rules will result in Manufacturers Cup implementing a maximum weight for suspension components, resulting in racers being required to remove their front ends during post-race inspections. Implementation of this weight rule may occur at any time during the season.


FRONT AXLES: Front axle assemblies may be remanufactured or replaced with aftermarket components. No part of the axle or nut may protrude more than .75″ beyond the outside of the fork legs. No part of the axle, axle nut, or spacers may exceed 1.50″ in diameter. The total weight of the front axle assembly, including spacers, nuts, washers, etc. may not exceed 5 lbs total weight. The use of lead or other heavy materials is not allowed on any axle components.



All welding shall be performed using industry-standard TIG heliarc methods. Material should be 4130 chrome-moly. The minimum diameter for all sections, except braces, brackets and gussets, shall be 1.00”. If the top main tube is of a one-piece design it must be a minimum of 2.00” in diameter.

Minimum wall thickness of all tubing is .058”. Aluminum chassis are prohibited without prior approval. Minimum seat height (with rider in position and seat compressed) measured from lowest point of seating position to ground, 20-inches unless otherwise instructed per class rules.



Overall measurements will be done as follows: Measure from the center of the front axle in a straight line to the center of the rear axle at the most extendible point on the swingarm, then from the rear axle (at its most extendible point) to the center of the wheelie bar axle; then add the two together to determine overall length.



Highly recommended for safety in all legal classes with slicks. The lowest point of the wheelie bar wheels may not be more than 3-inches from the ground. May not exceed the wheelbase of bike and must be sufficiently cross-braced to prevent side whip. On all mounting bars, butt welds or inner sleeved bar designs must have visible welded reinforcement (i.e., inner sleeve with rosettes, clam shells, bolted, etc.). Wheels must be non-metallic. All side panels must be securely fastened at 24-inch intervals minimum.



Minimum ground clearance for wheelie bar bikes is 2” measured with rider sitting on bike, straight up perpendicular to ground with 4 psi (car tire), 8 psi (motorcycle tire) in rear tire. A minimum of 2 or 3” is required for non-wheelie bar bikes, depending upon particular class rules.


The minimum ground clearance value indicates the minimum height above the ground for every part and component on the bike, except for the portions of the tires and wheels which are supporting the bike. Both hard parts and flexible components such as bodywork must be above this minimum value. The only exception to this rule is for ballistic blankets.




Tires must be in good condition. The depth of tread or wear indicator in the center of a tire must be a minimum of 0.060-inches. DOT tires on any wheel wider than 6.25-inches must have bead lock. Manufacturers Cup highly recommends that all car tires utilize a bead lock or rim screws, to attach tires to wheel. Non-bead lock wheels should utilize locking screws and should be installed at 45 to 90 degree angle in addition to side-mounted screws only. It is recommended that drag slick mounting screws only are used to prevent tire bead from unseating at high speed. Follow instructions from screw manufacturer. Holes drilled in wheel must have enough clearance to allow screws to pass freely through wall. Four screws per side minimum with eight per side recommended. For safety, tire width should not exceed rim width by more than two-inches, bead seat to bead seat. All stock wheelbase entries must maintain OEM front tire sizing.


The use of “spinner” style wheels or any wheel design that incorporates movable pieces while vehicle is in motion is prohibited. The use of carbon fiber or composites as any component on a drive wheel is prohibited on any car tire entry.




Fuel lines that do not use AN-type connectors must be fastened with a metal clamp, band or fitting (no wire). Be careful not to over tighten. Carburetor-equipped entries using a gravity-feed fuel system and flexible fuel line such as Tygon or PVC may use wire ties or safety wire as clamps on these fuel lines. Any fuel line that is part of a pump-forced fuel system must use hose clamps or AN fittings at all connections.

NITROUS BIKES: The use of steel braided or reinforced fuel lines are highly recommended on all nitrous bikes. Flame-retardant covering, such as fiberglass or Silco, is required on ALL fuel lines on carbureted nitrous entries. Covering must cover the entire run of fuel lines. Carburetor feed lines must be clamped at both ends and covered. The use of safety wire or wire ties as clamps is permissible on carburetor feed lines only.

METHANOL (Alcohol)

Methanol is a clear, colorless liquid with a mild odor at ambient temperatures. Methanol is sold in two U.S. Federal Grades: A and AA. Either grade is permitted for use in Manufacturers Cup competition, and racers should ensure that the methanol they purchase meets Federal standards of purity. The purity standards for each grade are listed in the NHRA rulebook. Methanol is tested and certified at Manufacturers Cup events through the application of various chemical analyses as considered appropriate by Fuel Check personnel. To be considered legal, methanol used in Manufacturers Cup competition must meet the Federal standards of purity. Any deviation from these standards because of impurities (beyond the limits established in the Federal specification) in the fuel sample will result in disqualification.



Nitrous oxide systems must be commercially manufactured with manufacture I.D. on all parts. Nitrous bottles must be DOT rated with a pressure relief valve and secured with a bottle bottom anti-drop strap to prevent the bottle from falling off. The use of frame or swingarm in place of a bottle for nitrous oxide is prohibited. The mounting of a nitrous bottle outside the frame rail is permissible on streetbikes only with the use of a Manufacturers Cup approved nitrous bottle valve protector; otherwise, N2O bottles must be completely contained within the bike frame rail. Outside-the-frame bottles must be securely fastened with an approved bottle bracket. See Ballast (2.4.1) for requirements for bottle mount hardware.


BOTTLE HEATERS: Heating of nitrous bottle is only permissible if accomplished by use of thermostatically or pressure switch controlled heating blanket. Bottles must be mechanically fastened; hose clamps or tie wraps are prohibited. All nitrous bikes must have thumb (butterfly) body fasteners. Purge lines must face away from the rider. It is highly recommended for all nitrous bikes to utilize a “backfire strap”, required in PM. Oil blanket or oil catch pan is mandatory on all nitrous bikes. Oil blanket or oil catch pan is mandatory on all nitrous bikes not utilizing a street-type exhaust passing under the oil pan. Single stage nitrous is defined as one nozzle per cylinder.




All nitrous bikes must have thumb (butterfly) body fasteners; all body fasteners must be able to be removed by hand without the use of tools to access nitrous bottles. Leading edge of the front of the body may have regular fasteners. Note that in case of accident and/or the potential of fire, if nitrous bottle and fuel shutoff cannot be accessed, damage to body may occur. All bikes must have front fender excluding Super Eliminator. All streetbikes must utilize a seat. Seats must be covered in upholstery. Tail section or rear fender must extend past the rear axle.


Care should be taken in the attachment of full fairing and side body panels. Wind load directly effects handling and steering input. Panels that become detached may result in loss of control. Fairings should be mounted in a position similar to the street bike it represents (i.e., headlight portion must point straight forward). Sufficient clearance is required between the front fender and headlight or fairing to allow 1” of suspension travel across the entire range of fork travel and steering angles For aerodynamic and handling reasons, the lower “nose” of bottom fairing should be placed close to the back of the front tire.


Mounting points should be as follows: At least two mounting points on top half of fairing mandatory. One in the center of the headlight supported by steering neck and/or one each side placed properly to support entire side of fairing, attached back to down tubes of chassis. Two points on each side of lower fairing are mandatory and must be securely fastened; no tie wraps or wire ties. The floor pan is the foundation for mounting the fairing and should be solid mounted. All structural mounts from inside the fairing back to chassis should be angled towards the front of bike to properly carry wind load. A mounting plate, suggested minimum size 1.5” x 2” must be used on the inside of the fairing at attachment points. All fastening must be fiberglass to metal; no fiberglass to fiberglass. Braces, brackets and gussets material should be 4130 chrome-moly steel with a minimum diameter of .375”.




AIR STORAGE TANKS: Must be Manufacturers Cup accepted. All pressurized bottles (i.e., air, CO2, etc.) used for air shifters, clutches, etc., must meet, and be engraved as meeting DOT specs. Standard low pressure air shift systems under 150psi may use non-DOT aluminum tanks if purchased from an approved supplier. All high pressure regulated air shift systems must use DOT approved tanks. PVC or plastic tanks are prohibited. Tanks must be mechanically fastened with a metal clamp or band. Tie wraps and zip ties are prohibited. Use of frame or swingarm as air storage permitted.

AIR SHIFTERS: Electric over air shifters are permissible in all classes where air shifters are allowed. Shifter systems which use an electric or hydraulic force to make shifts are considered to be air shifters.


AUTO-SHIFTING: Auto-shifting, not to be confused with an automatic transmission, is any electrical or mechanical system which causes the transmission to shift gears with no input from the rider. This is typically done based on engine speed or time-delay methods, but could include many other methods. Classes not allowed the use of auto-shifters may not have components that would allow any system on the bike to function in this manner. Any bike utilizing electrical components which have an auto-shifting capability must have the auto-shifting function disabled in some satisfactory manner, and may not have the air shifter system wired in any manner that would allow the use of an undetectable auto-shift system. Due to the many available components and systems now on the market, the tech director should be consulted to discuss the acceptable methods for satisfying these requirements on a case-by-case basis.



Batteries must be securely mounted within the frame, swing arm, or bodywork.


The use of any device, electric, electronic, pneumatic, hydraulic or mechanical, etc. that displays or transmits any on-track data or track location data, or any device mounted anywhere on the bike or in or around the track facilities that utilizes any tree sensing system will be grounds for immediate disqualification from the event and loss of all Manufacturers Cup points for the season. In addition to disqualification, the rider and any team members with knowledge of the use of such equipment are subject to fines and suspension from Manufacturers Cup events for one year.


DELAY BOXES: Permitted in TG and SC. Delay box or Delay Device is defined as any device (electronic, pneumatic, hydraulic or mechanical, etc.) built for the express purpose of creating a delay between release of line loc button, or release of foot or hand brake, or release of clutch lever and the resultant action of the motorcycle. Delay device may only delay amount dialed in; analog or digital display permitted. Delay device may serve only to create a preset delay between the release of launch button and resultant release of the launch rpm rev limiter, line-loc, clutch, etc. causing initial movement of the motorcycle. Delay device may only be connected to clutch engagement systems; i.e., launch rpm rev limiter and/or trans brake and/or line loc, and/or clutch, dependent on motorcycle. Delay devices connected to data recorders or any other equipment is prohibited. Wiring of delay box/device must be fully visible and traceable by the technical inspector. Only delay boxes/devices fitting this description will be permitted.


TRANSMITTING DEVICES: Any device mounted on the bike or rider that is capable of transmitting data or information wirelessly is considered to be a transmitting device. This includes wireless transfer systems for pit communications to and from on-board data recorders, EMS’s, ignition control boxes, nitrous or boost controllers, and any other electronic devices.

Any bike competing in any index or dial-in class may not have any type of transmitting device mounted anywhere on the bike or rider during competition (see 2.9.10). Any teams in these classes that use a wireless system to transfer data files in the pits must remove the transmitter from the bike during competition.

Bikes in Pro classes and heads-up, no breakout sportsman classes may have transmitting devices on the bike or rider, but they may not be used during the run.


Data measurement is the process of using electronic sensors to measure various engine and chassis parameters. These sensors take physical properties such as pressure, temperature, speed, travel, acceleration, position, etc, and convert these properties into an electronic signal. These signals may then be used and/or recorded by various on-board electronic control systems including data recorders, boost or nitrous controllers, OEM or aftermarket engine control systems, etc. Some classes do not allow non-factory equipped data measurement devices, and some classes allow them, but with restrictions as to their function. Check individual class specifications for additional limitations.

While most types of data sensors are allowed, some types are specifically prohibited, unless they are OEM equipment. If an otherwise-banned sensor is installed by the OEM (such as a speedometer that uses front wheel speed), the sensor may remain intact and functioning, but it must function exactly as originally designed by the OEM, and may not be used by any non-original system or component on the bike.


Data recording is the process of storing data produced by data measurement sensors, with the intent and capability of reviewing the data after the completion of the run. Internal control values from ECMs and other electronic control devices may also be stored for later review and troubleshooting. Data recording is typically an internal function of an aftermarket EMS Data may also be recorded by passive recording-only devices.

Data recorders may not detect, and they may not be activated by, radio transmitters, infrared, laser or sonic devices, or any track position devices or beacons. Also, they may not wirelessly (ie radio, infrared, sonic. etc) transmit or receive information during the run to or from any source. Any communication or transmission of information between components on board the bike must be done via hardwired communications.



2-steps are devices designed to limit the engine RPM, while allowing the rider to position the twist-throttle at full-throttle or near-full-throttle launch. This is typically done by cutting of the ignition, but it may also be accomplished by retarding the ignition or, on fuel-injected entries, by cutting the fuel delivery. This may also be accomplished by using throttle stops, secondary butterflies or restrictor valves, or any other device capable of restricting engine RPM by limiting air intake.


DATA LOGGING PARAMETERS: Manufacturers Cup tech may require any or all competitors not allowed 2-steps to data-log parameters relevant to the control of 2-step rule violations. These could include ignition and/or injection timing, switch inputs, speed inputs, map-switching parameters, etc. It is the responsibility of each and every team to know and understand the data-logging capabilities of their electronic devices, and to be capable of setting them to data-log any information requested by tech. Failure to do so, either by refusal or inability, is grounds for disqualification.



Legal electronics include: Delay boxes, ignition booster, stutter boxes, two-steps, nitrous timers, electronic throttle stops, electric shifters and shift lights. Motorcycles with electronic timers turning on nitrous oxide must also have a throttle switch to turn off the system when not at full throttle. RPM or timer activated automated shifters permitted in TG and SC. Wiring harness must be loomed in a fashion that would allow easy tracing and inspection of wiring (i.e., no taped or covered wires).



Must have a positive ignition cutoff switch attached to the rider with a lanyard. No part of the kill lanyard may be constructed of solid plastic. Lanyards must be made from leather, metal cable, solid nylon, or plastic with a nylon or cable-reinforced core. Solid or hollow plastic-only lanyards are no longer allowed. Lanyard cable must pass through metal loops or attachments, and then must be crimped back to itself utilizing a steel crimp. Non-looping crimped ends, similar to that commonly used for electrical wire terminals, are not allowed. The lanyard and end crimp must form a loop capturing the end attachment. Attachment clips or attachment rings must be constructed of metal.

Switch must be in the low-voltage side of the ignition circuit. Ignition shutoff must disable all fuel pumps and nitrous systems. Many stock machines are equipped with a handlebar mounted thumb switch which can have a lanyard easily attached for the above purpose. Engine must shut off if ignition or fuel lanyard is pulled.

All bikes must be equipped with a rider-operated switch that will allow them to kill the ignition system without removing their hand from the handlebars.

While it is fully legal to use a tether fastened to the kill switch, the preferred method is to use a kill switch that disconnects from the bike and disconnects the electrical circuit. In the event of a fall, it is possible that the OEM kill switch will not be actuated properly or that it can get knocked back on after the fall.



All entries must have a functional taillight attached to motorcycle during night operation. Once sufficient darkness requires that the track turn on its lighting system, all bikes must activate their taillights during competition. Night operation lights must be powered in a manner in which they will remain operational even if the lanyard kill switch or rider thumb switch is cut off. Bikes utilizing a taillight powered through a factory key-style ignition switch must leave switch in the “ON” position until after they clear the end of the track. Failure to have taillight activated during night competition will constitute run disqualification.


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