SFR Supplemental Regulations

Solo2 National Kart Rules

F125 Shifter Karts

Junior 1

Junior 2

Junior 3

Junior 4

Kart events will be run according to the 2003 Solo2 Rulebook, 
Appendices G and H.  These rules are the SFR supplement to those rules.

SFR runs only five classes of Karts at our events

1. F125 Shifter Karts Age 16 and over
2. Junior 1: Age 8 to 11, Briggs & Stratton Raptor
3. Junior 2: Age 12 to 15, Briggs & Stratton Raptor 
4. Junior 3: Age 8 to 11, Yamaha KT-100
5. Junior 4: Age 12 to 15, Yamaha KT-100

SFR Supplemental Kart Rules

• Kart chassis and engine specifications will follow the WKA Technical Manual (for kart specifications only – not conduct of event rules) outlined in sections 100, 200, 250, 500, 550, 600, 700, and 750. 
• Weights in the Formula Junior 1 & 2 classes, for the different engine preparation levels/fuel type will be adjusted, as is deemed necessary, to achieve performance parity.
• Tires: For all classes: maximum tire size for rear tires is 7.1 x 11.0-5. Maximum size for front tires is 5.0  x 10.5-5.  Tire Compound is open.
• Clutches: For all classes, wet or dry clutches allowed. Jackshaft clutch drives for 2 cycle engines allowed, but must be securely fastened to the engine and/or engine mount. No frame mounted Jackshafts. Axle clutches are not allowed
• Safety Equipment:
  • Helmets: Full coverage (full face) helmets designed for competitive motorsports use complying with Solo2 Rules section 4.3.1 regarding current required Snell rating. Eye Protection is mandatory via a full visor (clear view) integral with helmet.
  • Neck Braces: Collar-type, unaltered neck braces designed for motorsports use is mandatory in all classes.
  • Driver apparel: Drivers are minimally required to wear jackets of leather, vinyl or abrasion resistant nylon or equivalent and full-length pants to prevent or minimize abrasions. Shoes, socks and gloves are mandatory. Full abrasion kart suits are recommended.

F125 Shifter Karts - Age 16 and older

• Any race prepared kart that is not in a class higher than 125 will be eligible. For instance, 80cc karts and KT-100s are eligible.
• F125 drivers must meet qualifications for Solo2: street licensed, 16 or older.
• F125 Drivers must also meet the age limits of the licensing kart sanctioning body

Formula Junior 1 - Ages 8-11

• ENGINES: Box Stock B&S Raptor, Balanced and Blueprinted Raptor.
• FUEL: Gas or Methanol
• WEIGHT: 
  • Stock Gas Raptor: 225       
  •  B&B Gas Raptor: 245
  • B&B Methanol Raptor: 250
• OTHER: No B&S controlled Stock, Modified, limited Modified or Open Motors

Formula Junior 2 - Ages 12-15

• ENGINES: Box Stock B&S Raptor, Balanced and Blueprinted Raptor.
• FUEL: Gas or Methanol
• WEIGHT: 
  • Stock Gas Raptor: 225
  • B&B Gas Raptor: 250
  • B&B Methanol Raptor: 285
• OTHER: No B&S controlled Stock, Modified, limited Modified or Open Motors

Formula Junior 3 - Ages 8-11 

(basically mirrors 2002 WKA Mfr.’s cup series class, Yamaha Junior Sportsman)

• ENGINE: Yamaha KT-100, only heads with OEM casting “Yamaha” and cylinders with Y3 or Y4 and 787 are legal.
• FUEL: Gas and Oil
• CARBURETOR: Walbro WA55b or HPV1 with WA55B manifold.
• EXHAUST: RLV SSX-V. If hole exists in pipe for EGT sensor, EGT sensor probe must be in place. See fig. 554.3 in WKA Technical Manual. (see other for alternate configuration)
• WEIGHT: 250
• OTHER: Alternate configuration may be Walbro WB3A carburetor and 0.600 restrictor plate with RLV YBX exhaust (IKF Junior 1 class).

Formula Junior 4 - Ages 12-15 

(basically mirrors 2002 WKA Mfr.’s cup series class, Formula Yamaha Junior)

• ENGINE: Yamaha KT-100, only heads with OEM casting “Yamaha” and cylinders with Y3 or Y4 and 787 are legal.
• CARBURETOR: Walbro WB3A.
• EXHAUST: RLV SSX-V See fig. 554.3 in WKA Technical Manual.
• FUEL: Gas and Oil
• WEIGHT: 295

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