General

Rules contained within this primer apply equally to all classes unless otherwise specified.

Data acquisition gauges must be mounted such that protrusion above the plane of the steering wheel is kept to a minimum; however specific control of this dimension per CIK Regulations is not applicable.

Scoring transponder location on back of the seat with the following requirements:

1. The bottom of the transponder body must be located no closer than 15cm from ground level.
2. The transponder may not be mounted forward of the tangent point defined by the radius transitioning to the side of the seat and the seat back.

Specific decals must be applied to the bodywork in the locations specified by the current release of the Official USRMC Logo Placement document.

Engine

In conformance with latest revision release of Technical Regulations as released by ROTAX-BRP with the following exceptions and/or clarifications:

Dual seal requirements:

All engines sealed on April 1, 2008 or later must carry a valid secondary crankcase seal and dual seal passport, with official authorized service center stamp and signature, in accordance with USRMC dual seal directive listed at www.rmaxchallenge.com.
US GRAND NATIONALS - ALL ENGINES SUBMITTED FOR DECLARATION MUST HAVE BOTH TOP & BOTTOM SEALS

Silicone or like substance may be applied to the exhaust springs for vibration dampening only.

All classes except DD2, fuel pump must be mounted on original bracket, bottom location only.

Spark plug NGK BR.EG of any heat range is acceptable for use.

Chassis

Any sit-up, sprint kart chassis constructed in conventional manner of round, tubular steel is permitted. Chassis must conform to the dimensional specifications of the current CIK Technical Regulations in all respects with the following exceptions:

Rear axle wall thickness is per CIK for all Junior, Senior, Masters and DD2.

Brake system homologation is NOT required for any class except for DD2. Functional front braking systems are prohibited in the MicroMax, MiniMax and Junior Max classes only. All braking systems must be operated simultaneously by a single foot pedal unless necessitated by physical handicap and approved by the event scrutineer.

It is recommended to use the CIK-prescribed method (ref: two bolts minimum of 6mm diameter minimum with secure fasteners) to attach ballast. It is permitted to use the national-standard single fastener method for ballast under seven pounds provided the fastener diameter is 8mm or greater and positive safety retention methods are used. Acceptable retention methods when using a single fastener are drilled bolts and threaded fasteners used in conjunction with safety wiring or cotter pins only. Neither double-nutting nor wire "wrapping" is considered acceptable in this case. Ballast weights over seven pounds must use two fasteners with appropriate security as described in the CIK Technical Regulations.

Bumpers and Nerf Bars

Senior, Masters and Junior Max classes only:

Front and rear bumpers and side nerf bars must conform to specifications for with CIK02, -08 OR -11 only. Alteration of bumper systems is limited to length trimming to permit proper fitment of bodywork.

Front nose attachment must be as specified without alteration in content or function.

Standard steel tubing rear bumpers must conform to CIK specifications with the exception that the height of top bar must be no lower than the top of the rear axle or higher than the plane passing through the tops of front and rear tires.

US GRAND NATIONALS - FULL COVERAGE REAR BUMPERS REQUIRED - CIK- SYSTEM OR OTHER MEETING CURRENT INDUSTRY STANDARDS- MUST AT ALL TIMES COVER INBOARD HALF OF REAR TIRES

CIK RULE 2.5.3 REAR WHEEL PROTECTION - IN ALL CONDITIONS, THE REAR PROTECTION MUST AT NO TIME PROTRUDE BEYOND THE EXTERNAL PLANE OF THE REAR WHEELS.

Bodywork

Senior, Masters and Junior Max classes only:

Bodywork shall be defined as a nose cone, steering fairing and two side pods or contoured panels, constructed of high-strength plastic only. All of the components are required. Bodywork must conform to the following specifications:

Bodywork and bumpers must conform to specifications for CIK02, -08 or -11 period only. Mixing sets of any combination is permissible provided that, if using CIK08 or -11 elements, the side bumpers/side pods must match and the front bumper/nose cone must match. It is not permissible to use -02 bumpers/bars with -08 or -11 bodywork elements.

Cutting or otherwise altering of bodywork components shall be for chassis or component clearance only and is permissible on CIK02, -08 and -11 bodywork. Cutting of CIK08 and -11 bodywork is limited to right side pods for radiator clearance only.

Use of tape or similar material shall be limited to damage repair only. Covering the openings of the CIK02 side pods is permissible in wet race conditions only. Any use of tape or similar materials to provide a modified air flow over the chassis is strictly prohibited with the exception of rain shields for brake discs in wet conditions.

CIK 2.7.1.4 "WET CONDITIONS" SIDE BODY WORK MAY NOT BE LOCATED OUTSIDE THE PLANE PASSING THROUGH OUTER EDGE OF REAR TIRES

Specific side pod protrusion rule outboard of the quadrilateral formed by the four wheels is applicable. (Reference: CIK Technical Regulations, section 2.7.1.4, first paragraph)

DD2 class only:

Bodywork shall be defined as a nose cone, steering fairing and two side pods or contoured panels, constructed of high-strength plastic only. All of the components are required. Bodywork must conform to the following specifications:

Bodywork and bumpers must conform to specifications for CIK08 or -11 homologation periods only. Mixing sets of any combination is permissible provided that the homologation numbers for side bumpers/side pods are matching and the front bumper/nose cone are matching.

No alteration of bodywork components is permissible.

Specific side pod protrusion rule outboard of the quadrilateral formed by the four wheels is not applicable. (Reference: CIK Technical Regulations, section 2.7.1.4, first paragraph)

CIK 2.7.1.4 "WET CONDITIONS" SIDE BODY WORK MAY NOT BE LOCATED OUTSIDE THE PLANE PASSING THROUGH OUTER EDGE OF REAR TIRES

Tires

All classes except Micro and MiniMax, dry tires are MOJO D2 (dry) 4.5x10-5 front, 7.10x11-5 rear. Wet tires, MOJO W2 FRONT 4.0X10.0-5 REAR 6.0X11.0-5

(3) bead retention screws per CIK requirements in the outer wheel rims, front and rear, are mandatory for slick tires only for all classes except MiniMax. Bead locks are not required for wet tires in any class.

Maximum mounted front tire width is 140mm.

One set of tires (slick and wet) is allowed per event, plus one front and one rear spare (slick and wet).

Fuel and Oil

98-octane (anti-knock index) maximum, commercial, unleaded gasoline in mixture between 33:1 and 50:1 with high quality synthetic two cycle oil.

For events where the fuel is not supplied as premix, the mixture ratio shall be verified by comparison with Digatron DT-15 or DT-47 to a controlled sample at 50:1. Competitors' fuel must measure within +10/-5 points to the controlled sample.

The official fuel and oil for the USRMC is VP Racing Fuels Motorsports 93 unleaded gasoline and Motul 800 2T Factory Line Off Road full synthetic two cycle oil.

Minimax Class specific regulations

All regulations previously described apply equally to the MiniMax class unless specifically excepted in this section.

MUST USE "OLD STYLE" CLUTCH - PLASTIC OR STEEL BALANCE SHAFT GEAR PERMITTED

Original and unaltered exhaust header, ROTAX P/N 273 972, is required, inside diameter 22 +/-0,2mm.

One of the following inlet restrictors is required: Unaltered USRMC inlet restrictor shown at this link http://www.rmaxchallenge.com/page.cfm?content=4&display=127 with inside diameter of 19+0/0,2mm or unaltered BRP component part number 267 535. BRP component must show blue anodized coating all over.

Noise limit - per local limits or a maximum of 90dB (a) at 25 feet, measured perpendicular to the line of travel, engine under full load between 9,000rpm and 10,000rpm.

Wheelbase - 41 inches (1041.4mm) maximum.

The highest point at the center of the seat back shall be 12.0 inch minimum from ground level.

CIK axle wall thickness requirements are not applicable in MiniMax class.

Bumpers and bodywork, meeting industry standards must be employed at all times. For bodywork, CIK homologation is not required, but construction must be similar in form and consistent with the size of the chassis. Methods used to clear the engine package on the kart must not compromise the initial safety of the original design by exposing sharp corners or dangerous protrusions. Quick fixation mounting method for nose cone is not required.

Cadet nose cone may be of the full size design with maximum protrusion outboard of the front tires of 40mm per side.

Tire sizes MOJO D2(dry) 4.5x10-5 front and rear, MOJO W2 4.5x10-5 front and rear. Maximum mounted tire width is 145mm. Maximum circumference at any temperature is 32.25 inches. Tire circumference to be measured on tire centerline with a flat tape, track pickup removed with a rag or gloved hand. All karts must comply at latest by the time the last kart is measured after scales.

Wide rear bumpers covering both rear wheels are mandatory. Bumpers must cover at minimum the inboard half of each tire, but may not protrude outboard of the edge of either tire. Bumper construction must conform to the following requirements:

1. The rear bumper must consist of at least an upper and lower bar, both of 16mm minimum outside diameter.
2. Height of the top of the upper bar shall be no lower than the top of the rear axle or higher than the plane passing through the top of the front and rear tires.
3. Height of the top of the lower bar shall be 80 +/- 20mm from ground level.
4. The entire unit must be attached to the chassis frame in a minimum of two points to the main frame tubes, flexible connection permitted.
5. The upper and lower bars must be of continuous loop profile with a minimum bar diameter of 16mm in all places except between the chassis rails. Area between the chassis rails must also be protected by a bar of 16mm minimum outside diameter but it is not required to be part of the continuous loop. A minimum of 80 percent of the opening between chassis rails must be protected if accomplished with a secondary loop extending downward from the top bar.
6. The upper and lower bars must be - in general terms - inline and parallel to one another and connected on the outboard ends by a full radius bend of sufficient dimension to prevent injury.
7. Any possible adjustability of the bumper must not incorporate or expose sharp edges, protruding fasteners or other elements that present any danger of puncture-type injury.
8. Final acceptance of any bumper's acceptability with regards to safety lies with the event scrutineer.

In an effort to encourage progressive designs in this arena, the USRMC and its designees reserve the right to evaluate for acceptance any rear bumper design presented. In this light, bumpers not meeting these exact criteria but satisfying the intent of application can be considered for acceptance with pre-event submission of design and specifications to the local scruiteneers. Competitors/suppliers desiring evaluation of a non-conforming design are urged to consult local and/or national technical departments well in advance of the event in question.

MicroMax Class specific regulations

All regulations previously described apply equally to the MicroMax class unless specifically excepted in this section.

Engine regulations per US Primer engine section and MicroMax specific rules from BRP-ROTAX at website

http://www.maxchallenge-rotax.com/download/RMC-RMCGF_Technical_Regulations_2008_10012008_Mini_Micro.pdf

Exhaust packing must be unaltered, original, single matt with no more than 20% loss of original length due to burn back along the longitudinal axis. Matting is measured at its shortest length for this requirement.

MUST USE "OLD STYLE" CLUTCH - PLASTIC OR STEEL BALANCE SHAFT GEAR PERMITTED

Carburetor jet selection limited to 112 to 132.

Chassis: Per US Primer Mini Max rules except maximum wheelbase is 950mm.

Tires:
Slicks All classes will use MoJo D2 except DD2.
DD2 class will use MoJo D3
Wet All classes will use MoJo W2 rain

Rear Bumper:
2009 As stated in rules primer
2009 US Grand Nationals
Rear tire width under rain conditions, CIK rule 2.7.1.4 will be in force starting with the 2009 year. Rear tires may not be inside of body work or rear bumper, which ever is wider.
Rear Wheel protection CIK 2.5.3 In all conditions, the rear protection must at no time protrude beyond the external plane of the rear wheels

GN Qualification
Minimum of 4 races with a minimum of 3 races from the home series. The fourth qualifying race can be from any official US Rotax Max Challenge Series.
National Points
Best 6 races in home series.

Clutch
2009 Mini Max/Micro Max old style clutch only. Plastic or steel balance shaft gears
Junior, Senior, Masters, DD2* Clutch optional new or old style
Steel clutch must use steel balance shaft gears

*DD2 balance shaft gears remain unchanged from 2008, only steel gears are to be used for DD2