NATIONAL ROAD RACING SERIES - LAYDOWN CLASSES

∆312.1 100cc CONTROLLED Final 1 & 2:
DRIVER REQ: Age 16 and older. Road Race Class 2 License.
ENGINES: Yamaha, Piston Port, 100cc Controlled, ICA Reed
EXHAUST: Any WKA approved pipe (except 100cc Controlled or ICA Reed with IR2 pipe at a minimum of 8.75" from piston to end of connector pipe. See Figure 554.6 for IR2 Specs.) All engines – 1.75" header.
FUEL: Spec Fuel.
MINIMUM WEIGHTS: Yamaha and Piston Port engines 360 lbs. Controlled or ICA engines 390 lbs. Controlled or ICA Reed engines running RLV IR1 or IR2 pipe 370 lbs.
OTHER: ICA Reed (See Section 607, 608 and Figures 608.2, 608.3a and b for approved engines and specifications). WKA approved 1 3/4" header and pipe only; head volume 9cc's and Tillotson HL360A carburetor (See Figure 554.6 for IR2 Specs. See Section 607.3 for carb specs.)  Runs Saturday and Sunday for a single championship.

 

∆312.2 UNLIMITED FINAL 1 & 2:
DRIVER REQ: Age 18 and older. Road Race Class 1 License.
ENGINES(S), Weight, Carburetor.
One 250 cc gearbox twin cylinder, 490 lbs, See Note 7.
One 250 cc gearbox single cylinder, 460 lbs, 39mm carb, See Note 4.
One 450 cc gearbox single cylinder 4-cycle, 460 lbs., 42mm carb, See Note 5.
One 125 cc gearbox single cylinder, 420 lbs.,
One 250 cc single cylinder non-gearbox, 460 lbs., any carb.
One 150 cc single cylinder 380 lbs., any carb(s).
Two 150 cc single cylinder 490 lbs., any carb(s).
Two 100 cc single cylinder 465 lbs., any carb(s).
Two 135 cc single cylinder fan cooled (West Bend 820 and Mac 101), 420 lbs., any carb(s).
FUEL: Open
Notes: (1) All engines are 2-cycle except 450 cc gearbox.
(2) Exhaust System: The exhaust system must be a WKA approved design and comply with WKA and local ordinance exhaust noise suppression requirements. Adjustable pipes are legal on all non-gearbox engines.
(3) Technical inspection: Post race technical inspection will include kart weight, engine displacement, fuel, and exhaust system. Other tech items for specific engines are specified below.
(4) 250cc 2-cycle Gearbox Engines:
Allowed single cylinder, mass produced factory motocross engines include Rotax 244, Rotax 257, Kawasaki, Yamaha, Honda, Honda TRX, and Suzuki. Maximum cylinder displacement is 253 cc's. Engine is to be stock appearing. Interchange of parts between model years is allowed. An aftermarket cylinder head with integrated girdle may be used on the Rotax 257 engines. 250cc two cylinder and GP engines are not allowed. One single-venturi float bowl or pumper style carb is allowed. Approved slide valve carbs are Keihin, Mikuni, and Dell'Orto 39 mm model carburetors. Carburetor venturi must remain stock. Dell'Orto VHSC carburetor is not allowed. Non-electronic power jets may be added to the carburetor.
OEM ignition is required. Programmable or reprogrammable ignitions are not allowed. Rotax 244 and 257 may use Motoplat, SEM, or PVL non-programmable ignition part #70xxx. Electronic devices to alter ignition timing or carburetor are not allowed. Pneumatic exhaust control power exhaust valve is allowed. Electronically controlled exhaust power valves are not allowed. Any component, bracket, or accessory (i.e., engine girdle, pipe bracket, ignition, bracket, fuel pump bracket, etc.) may be added as long as it does not directly improve engine performance. Transmission: Gearbox is not a tech item. Slipper clutch, axle clutch, or Sprag units are allowed.
(5) 450cc 4-cycle Gearbox Engines:
Allowed single cylinder 450 cc motocross engines include Honda, CRF, KTM, or Yamaha. 12.5:1 maximum compression ratio. Carburetor to be 42 mm model as supplied by engine manufacturer. Aftermarket rods made of ferrous material are allowed but must maintain OEM length. Cranks may be balanced, but the stock stroke length must be maintained. Kick starter assembly may be removed and plugged. Add-on oil coolers or dry sump systems are approved. Engines may be updated to current model year. Engines may be modified to allow for the use of external electric starter.
Ignition: OEM Only
Transmission: OEM transmission ratios only. Components may not be machined to reduce weight. Clutch discs, plates, springs, & hardware may be aftermarket. Slipper clutch, axle clutch, or Sprag units are allowed.
OTHER: Additional restrictions may be placed on these engines at any time if it is deemed necessary to maintain parity within the class.
(6) Unlimited races will run for 30 minutes.
(7) See USSK rules for detailed engine specifications for 250 cc Twin Cylinder karts.

 

312.3 B STOCK:
DRIVER REQ: Age 18 and older. Road Race Class 1 License.
ENGINES: Yamaha; Piston Port; 100cc Controlled. All engines may be stock appearing except ICA Reed (i.e. Reed Jet, PCR, etc.) which must be controlled stock specifications.
EXHAUST: Any Fixed WKA approved pipe (No adjustable pipes allowed)
FUEL: Open fuel.
MINIMUM WEIGHTS: Yamaha & Piston Port engines 395 lbs.; 100cc Controlled 465 lbs.
OTHER: Karts must be dual-engine with engines of like category.

 

∆312.5 JUNIOR ENDURO LITE & HEAVY:
DRIVER REQ: Age 12 through 15 only, Road Race Class 3 License.
ENGINE(S): Yamaha only. Only heads with OEM casting "Yamaha" and cylinders with Y3 or Y4 and 787 are legal.
EXHAUST: RLV SBX muffler and RLV 26S Header with tube protruding through flange intact, 11.0" to 12.0" of flex from piston face to end of flex. 7/8" restrictor. (See Section 554.2 and Figure 554.2)
FUEL: Spec Fuel.
MINIMUM WEIGHTS: 320 lbs. – LITE, 340 lbs. – HEAVY

 

∆312.7 100cc PIPE MEDIUM & HEAVY:
DRIVER REQ: Age 16 & older, RR Class 3 license.
ENGINE(S): ENGINE(S): Yamaha KT100 (only Yamaha heads with OEM casting "Yamaha" are legal), ARC Comer P-50, ARC Comer P-51, PRD-RK-100, Parilla PV-92, Komet K-71
per Section 605, TKM BT82, PRC PP-100, DAP T-50, HPV 100, Komet Piston Valve.
EXHAUST: Any fixed WKA approved pipe.
FUEL: Spec Fuel.
MINIMUM WEIGHTS-MEDIUM: Yamaha - 360 lbs., Piston Port - 385 lbs., and Comer P51 - 400 lbs.
∆MINIMUM WEIGHTS-HEAVY: Yamaha 380 lbs., Piston Port - 405 lbs., and Comer P51 - 420 lbs.

 

∆312.8 YAMAHA SPORTSMAN LITE, MEDIUM & HEAVY:
DRIVER REQ: Age 16 and older. Road Race Class 3 License.
ENGINE: Yamaha KT100S, Only heads with OEM casting "Yamaha" and cylinders with Y3 or Y4 and 787 are legal.
EXHAUST: (1) RLV SBX muffler and RLV 26S Header with tube protruding through flange intact, 11.0" to 12.0" of flex from piston face to end of flex. (See Section 554.2 and Figure 554.2.) RLV SSX 7502, 7540, 7541, 7542, 7543, 7544, and SSXV 7548. (2) RLV SSX muffler. When a SSX Muffler # 7540 is used, it must be run with 4 holes up and part # 7502 must be run with 4 holes down. When an SSX Muffler # 7541 is used, it must be run with 4 holes pointed in the upper left direction. When an SSX #7543 is used, it must be run with 4 holes pointed in the upper right direction. (See Section 554.3 and Figure 554.3.)
MINIMUM WEIGHTS: SBX muffler -- 360lbs. LITE, 385 lbs. MEDIUM, 410 lbs. HEAVY.
MINIMUM WEIGHTS: SSX muffler – 340lbs. LITE, 365 lbs. MEDIUM, 390 lbs. HEAVY.
FUEL: Spec Fuel.
MINIMUM WEIGHTS: 385 lbs. MEDIUM, 410 lbs. HEAVY

 

∆312.9 100cc CONTROLLED SPEC FINAL 1 & 2:
DRIVER REQ: Age 16 and older. Road Race Class 2 License.
ENGINES: Yamaha, Piston Port, 100cc Controlled, ICA Reed.
EXHAUST: 100cc Controlled and ICA Reed engines – Only RLV IR2 pipe at a minimum of 8.75" from piston to end of connector pipe (See Figure 554.6 for IR2 Specs.) Yamaha and Piston Port engines – any WKA approved fixed pipe. All engines – 1.75" header.
FUEL: Spec Fuel.
MINIMUM WEIGHTS: Yamaha and Piston Port engines 360 lbs. Controlled and ICA Reed engines 400 lbs.
OTHER: ICA Reed engines (See Section 607, 608 and Figures 608.2, 608.3a and b for approved engines and specifications). Head volume 9cc's, and Tillotson HL360A carburetor (See Section 607.3 for carb specs).  Runs Saturday and Sunday for a single championship.

 

∆312.10 FORMULA 100 FINAL 1 & 2:
DRIVER REQ: Age 16 and older. Road Race Class 2 License.
ENGINE, FUEL, WEIGHT:
100cc Open – Open fuel – 410 lbs.
100cc Stock Appearing Piston Port – Open Fuel – 310 lbs.
100cc Stock Appearing Reed or Rotary Valve – Spec Fuel – 390 lbs.
100cc Controlled Stock 2000 – Spec Fuel – 390 lbs.
100cc Controlled Stock 2000 – Spec Fuel – 370 lbs with IR2 pipe
100cc Controlled Stock prior 2000 – Spec Fuel – 340 lbs. – Any WKA approved pipe
135cc Controlled Stock – Spec Fuel – 370 lbs. – Any WKA approved pipe
EXHAUST: All engines can run a WKA approved slippy or fixed pipe. Exception: 2000 Controlled engines running at 370 lbs. must run IR1 or IR2 pipe. All headers must be 1 3/4" except Open engines.
OTHER: COMER MIK351L, CRG S10-T1, DAP T85, ITAL ML21, JAKO 2LA, PARILLA REED JET, PCR TSL95, TSL98 and ROTAX R-100 VM-E engines must use the Tillotson HL360A carburetor. 9cc minimum combustion chamber for Controlled engines. Runs Saturday and Sunday for a single championship.

 

312.11 FORMULA 125:
DRIVER REQ: Age 18 and older. Road Race Class 1 License.
ENGINES: 125 Gearbox (laydown), B Limited, or Open. (Spec 125 engines run under B-limited rules)
EXHAUST: 125 Gearbox - no adjustable pipes. B Limited and Open - any WKA approved pipe.
FUEL: Open
MINIMUM WEIGHTS: B Limited (including Spec 125) @ 380 lbs., 125 Gearbox @ 420 lbs., Open @ 375 lbs.

 

312.12 100CC YAMAHA MEDIUM & HEAVY
DRIVER REQ: Age 16 and older. Road Race Class 3 License
ENGINES: Yamaha (Only heads with OEM casting "Yamaha" are legal.)
EXHAUST: Any fixed WKA approved pipe
FUEL: Spec Fuel
MINIMUM WEIGHTS: Medium @ 385, Heavy @ 410.