[SCCA] Special Solo II Kart Rules

This is an unofficial transcription of Appendixes H and I of the 2002 SCCA National Solo Rules. (Copyright Sports Car Club of America 2002; all rights reserved;) It is believed to be correct, but any questions should be referred to the official rules as published by the SCCA.  An official Solo Rulebook is mandatory for participation in Divisional or National events, so order your own copy here.

Changes since the 2001 Rules are shown like this;
Further changes from FasTrack are shown like this.


  • I.    Approval Procedures
  • II.   Event Operation Procedures
  • III.  Kart Eligibility
  • IV.  Safety
  • V.  Formula 125 Rules, Specificationsfor National Level Solo II Competition
  • A.  Frame/Dimensions
  • B.  Wheels and Tires
  • C.  Brakes
  • D.  Engine
  • E.  Fuel
  • F.  Car Numbers


    1. Approval Procedures

      1. Regions conducting Solo II Events which will have karts competing must so indicate on the sanction application.
      2. A post event report describing the kart portion of the event should be submitted with the usual Audit Report Form.  These event reports will be helpful to the SCCA in more effectively evaluating the kart program.
    2. Event Operation Procedures

      1. Karts will not be allowed to be driven under power through the paddock; they must be pushed either on the ground or on a portable stand.
      2. A grid area must be established that is either separated from the regular car grid or grids karts with similar sized vehicles such as formula cars.  Traffic flow to and from the grid area must be controlled.
      3. If karts are allowed which require a push start, such as shifter karts, the grid area must accommodate this need adequately.
      4. All karts will be run as a group or grouped with formula cars, and not intermixed on course with full-bodied cars.  However, at the discretion of the Solo Safety Steward, the Event Chair, and the Chief Stewards, karts may be allowed on course with full-bodied cars if the course design allows for safe separation, such as the start and finish areas being remote from each other.
      5. Event procedures regarding karts will be announced at the drivers' meeting and will also be in written form for posting.
    3. Kart Eligibility

      1. Kart eligibility is limited to racing karts recognized and regulated by a national kart sanctioning organization (WKA, IKF, ISRA, NSKA, etc) with a maximum of one 125cc engine.  125cc shifter karts are the fastest karts allowed.
      2. It is the responsibility of the kart entrant to provide the rules to which their kart is eligible and prepared.
      3. Specific designation of classes is at the discretion of the hosting region as long as the above eligibility requirements are met.
    4. Safety

      1. Karts will be safety inspected as per applicable portions of section 3.3.3 of the Solo II rules.  Particular attention must be paid to brakes, throttle action, and steering components.
      2. Drivers are required to wear the following safety gear while competing:
        1. Snell approved 1990 "M" or later full face helmet with either goggles or a full visor integral with the helmet.
        2. Leather, heavy vinyl, or abrasion resistant nylon jackets and pants.  Pants material may be substituted with heavy denim.  One piece suits are highly recommended.
        3. Shoes, socks, and gloves.
        4. Collar-type neck brace designed for motorsports use.
      3. When normally positioned in the kart for competition, the entirety of the driver shall be within the perimeter of the kart and the driver must be able to reach and operate all controls.  Loose cushions or pads are not allowed that prevent the driver from being adequately supported by the sides of the seat.
    5. Formula 125 Rules, Specifications for National Level Solo II Competition

      (note: F125 is designated as a supplemental class for all National Solo events for 2002. Status beyond that will be decided 9-02 based on participation level.)
      1. Frame/Dimensions

        1. Chassis must be constructed of carbon steel alloy using traditional tubular construction.  Nerf bars are required.  Suspensions are prohibited.  Differential mechanisms that allow the rear wheels to rotate at different speeds are prohibited.
        2. Maximum width shall be 55 inches.  Maximum length shall be 84 inches.
        3. All karts shall have bodywork on the front (nose cone), steering column and sides.  Bodywork may not extend past the rear nerf bar.  No metal body parts are allowed.  Belly pans are allowed providing they are fully confined within the frame rails.  If a belly pan is used, it must be flat and parallel to the ground from a line drawn across the rear edge of the front tires to the rear axle.  No skirts or vertical aerodynamic sealing devices are allowed to extend below the mian frame rails (this does not include the front fairing).  No wings allowed.
        4. Minimum weight is 385 lbs. as raced, including driver.  Minimum weight for women is 350 lbs. as raced, including driver.  iMinimum weight is 360 lbs for 100cc karts (same for men and women).
        5. All non-structural weights added to meet minimum weight requirements must be bolted securely to the vehicle using a minimum of 5/16" bolts using either nylock nuts, or nuts which are secured by cotter pin/safety wire or double-nutted.  Weights may not be mounted to nerf bars.
      2. Wheels and Tires

        1. Wheels must be metallic.
        2. TIRES: are limited to a maximum of 12.5 inches in diameter and a minimum of 9.0 inches in diameter.  Width is limited to 5.5 inches for the front and 7.10 inches for the rear.  Tire brand and compound may be specified at later date.
      3. Brakes

        1. Must work in such a manner to brake both rear wheels equally and adequately.  Must have front brakes operating on each front wheel.  Single rear disk is allowed for 100cc karts.
        2. Must have a dual braking system operating front and rear wheels.
      4. Engine

        1. Engines shall be a mass produced, single-cylinder, motocross motorcycle derives of Japanese origin, up to 125cc displacement and a currently available production item.  The TM Motocross 125 engine is also eligible.  Engines must use OEM components unless otherwise specified.
        2. BORE/STROKE:  Bore must not exceed 1mm (0.040") greater than the stock, factory dimension.  Stroke must be within plus or minus 0.010" of the stock, factory dimension.
        3. CARBURETION:  One carburetor, single venturi, floatbowl-type, 38mm in venturi size.

        4. Intake manifold and reed assembly unrestricted.  Pumper-type carburetors and axle/electric fuel pumps are not allowed.  Must use pulse-driven fule pump.
        5. CRANKSHAFT/CONNECTING ROD:  Must be OEM components with no alterations, i.e., no boring of holes, no machining of surfaces or counter balances.  Connecting rod and/or piston pin may not be altered.  Polishing and/or shot peening is allowed, however, no lighting of reciprocating components is allowed.
        6. CYLINDER AND CYLINDER HEAD:  The cylinder and/or head, including ports, powervalves, and castings, may be modified or machined subject to the requirements of V.D.6.  Water inlets and/or outlets may be modified for aftermarket fittings and/or hoses.
        7. EXTERNAL MODIFICATIONS:  All exterior engine components must be recognizable as OEM parts.  No aftermarket cylinders, heads, case halves, etc., are allowed.  Kick starter may be removed and plugged.
        8. IGNITION:  Only OEM ignition components for specific engine(s) are allowed, except spark plug, spark plug cap, and plug wires, which are unrestricted..
        9. EXHAUST SYSTEMS:  Fixed pipes only.  Must meet event specific noiselimitations.  (Note:  a "spec" exhaust system may be specified at a later date for Nationallevel competition.)
        10. PISTON ASSEMBLY:  Open, including piston, ring, wrist-pin, and circlips.  Coatings allowed.
        11. TRANSMISSION:  OEM cases and transmission gear ratios must be stock for engine used.  It is the responsibility of the participant to produce verifiable documentation.  Shifter mechanisms must be manually operated, no air or electric assisted shifters are allowed.
        12. MISC. SPECS:  Chain guards required on all engines.  Overflow bottles for carburetor and radiator are mandatory.  Clutch must be original oil-type.  Dry clutches are prohibited.
      5. Fuel

        Fuel must consist of gas and oil only.  No oxygen and/or nitrogen bearing additives are permitted.  Methanol is permitted as a fuel in karts for which it is a normal fuel within the rules of their sanctioning body.  This currently includes the 5HP based 4-stroke karts covered herein.
      6. Car Numbers

        Car numbers must be placed on each side and a rear plate.  Numbers must be at least six inches tall with a minimum stroke width of three-quarters of an inch.


    1. Rules and Procedures Updates

      1. As this program remains in the developmental phase, rule updates or clarifications may appear periodically in the FasTrack section of SportsCar Magazine
    2. Event Operation

      1. All procedures described in Appendix G, Section II, III, and IV would apply.  The Junior Driver Program may either be run incorporated into an event, run concurrently on a separate course, run after an event, or as a stand-alone event.
      2. In addition to the above, the following procedures would apply:
        1. Appointment of at least one Youth Steward.  Two additional assistant Youth Stewards are recommended.  Duties are described below.
        2. Conduct an additional drivers' meeting for the Junior Drivers.
        3. Provide a small area for Junior Driver vehicle orientation.
        4. Develop work assignments for Junior Drivers that are appropriate to their individual ages and background.  An alternate to a traditional work assignment could be a safety training session.  Either work assignments or training sessions will be under the supervision of the Youth Stewards.  NOTE:  Waiver duty is limited to persons above the age of majority of the state in which the event is held, however, Junior Drivers may assist an adult.
      3. Youth Steward Duties
        1. In conjunction with the event chairperson and event Solo Safety Steward, establish specific event procedures relative to schedule, grid and site layout, special instructions, Junior Driver vehicle orientation, etc.
        2. Oversee the conduct of all Junior Drivers with the authority to disciplinary action including reprimand, time penalty, disqualification, expulsion from the site, and driver suspension.
        3. Conduct a Junior Drivers' meeting that emphasizes safety, responsibility and event procedures.
        4. Conduct a Junior Driver vehicle orientation session prior ro competition runs for inexperienced drivers.
        5. Lead at least two mandatory course walks for inexperienced Junior Drivers.
      4. Pilot Program for Younger Drivers
        Selected Regions will be allowed to have drivers 5 years old and older participating on Solo II courses using Cadet carts with 3HP engines, as per WKF rules.  The Solo II course used could either be the regular event course during or after the event, or a totally separate course.  Regions may only be approved for this pilot program if they have been running a Solo II Formula Junior  program for a minimum of one year, with at least four events conducted with Junior Drivers.  The National Office, Solo/Road Rally Department, will issue the approvals to the Regions for participation in this program.
    3. Junior Driver Eligibility

      1. SCCA member.  Membership may be waived for first event.
      2. The minimum age is 12 years old.  However, the minimum age may be reduced to 8 years old for any SCCA region which requests and is approved for an exception.  Approval may be granted only after the region submits the name of its Youth Steward and a written description of how the Junior Drivers will be administered.  Additionally, the Youth Steward will be required to contact the Youth Steward in an experienced pilot program Region to learn of their experiences and methods.
      3. Completed minor competitor waiver.
      4. Atendance at Junior Driver meeting and course walk.
    4. Vehicle Eligibility

    1. Kart eligibility is limited to racing karts using five horsepower based, four cycle engines of 100cc two-cycle engines with restricted mufflers and/or induction, (8/2002) recognized and regulated by a national kart sanctioning organization (WKA, IKF, etc.) for under 16 year old drivers
    2. Engine eligibility limits will be consistent with the WKA standards for engine size, type, and modification for the driver's age.
    3. Specific designation of classes is at the discretion of the hosting region as long as the above eligibility requirements are met.
    4. Mini Cup type cars utilizing a Honda 390 motor, a full roll cage, and safety harnesses are allowed for Junior Drivers.  Specific vehicle restrictions will be published as Tech Bulletins.

    ...Jerry Mouton || jerry@moutons.org || Last modified 10/27/02