3)     Bumpers- All welds must be complete: top, sides, and bottom.

a)      All cars shall be equipped with bumpers on the front and rear of the vehicle.

b)      Bumpers must be made of 16-gauge (.065”) minimum 3/4" steel, tubular or square stock, or a minimum of 1" diameter .100” wall thickness aluminum.  Channel bumpers are not permitted.

c)      Must be 3" - 5" from the ground to the bottom of the lowest rail and at least 6" from the bottom of the lowest rail to the top of the top rail. Must have a minimum of 3 connecting bars, at least one must be in the center of the bumper.

d)      The rear bumper must cover the full width of the vehicle to at least the center of the rear tires, but not to extend beyond the outer edge of tires.

e)      The front bumper shall be a minimum of 15" and a maximum of 24" wide, centered between the main frame rails where they attach to the front of the frame.

f)        All bumper ends must be radiuses or boxed to prevent hooking other cars.

Exhaust System The exhaust system on all cars must be a minimum of 3" from any tire and is not included in measurements of the overall length of car.

      b)   The exhaust must exit to the outside of car body and frame.

4)       Fire Wall  and Flooring -

A)   All cars must have a minimum of .030” thickness firewall completely sealing driver from fuel supply and engine compartment.

b)      All cars must have a minimum of .030” thickness metal floor pan with no openings between the driver and ground. The floor pan must cover the complete underside of the driver’s compartment from nose to behind seat or beginning of firewall, in order to shield driver’s body from the ground.

c)      Any large openings between floor pan and body must have ½" x ½" screening or protective covering to prevent track debris from entering driver compartment.

4)     Frames -- All welds must be complete: top, sides, and bottom.

a)      All frames (chassis) must be made of a minimum of 16-gauge (.065”) 1" diameter tubular or (.065) 1" square stock, seamless wall or welded wall, steel or better quality.

b)      Cars must have at least two bars (.065” minimum 3/4" diameter), positioned above and outside the driver’s legs, one on each side of the car parallel to main frame rails, to protect the driver’s feet and legs from a car landing on them.

c)      Stub axles and axles must be rigidly mounted (bolted or welded) to the chassis such that there is only UNSPRUNG weight.  No SPRUNG weight allowed.

·        Hydraulic or pneumatic shock absorbers affecting motion of axles or stub axles are not permitted.

·        A visual check should reveal no springs controlling rotative axle or stub axle motion.

d)      All cars must have a footrest or heel stop to prevent feet from sliding out the nose of the vehicle.

e)      Side roll cage protection must be made of a minimum of 16 gauge (.065”) ½” diameter tubular, or (.065”) ½” square stock, seamless wall or welded seamed wall, steel or better quality. Sidebars must be placed to prevent intrusion by another vehicle into the cockpit area. All cars must have minimum of 2 sidebars, placed horizontally, vertically or diagonally. Nerf bars can not substitute for side bar protection.

5)       Head Rests

All cars must have a cushioned headrest mounted directly behind the driver’s head.  The cushion shall be mounted so that it is at the approximate height of the center of the driver’s helmet.  It must be a minimum of 4" x 4” and 2 inches thick.  It must be within the main roll-cage, as viewed from rear and sides. When in driving position, the back of the driver’s helmet must rest against the headrest.

6)       Height

A car may not be higher than 42" or lower than 32", measured from the ground up (with tires on), to the highest point.

7)      Width

May not be narrower than 37", or wider than 48", measured at the widest point of the car.

8)      Length

A car may not be shorter than 78", or longer than 92", measured from bumper to bumper.

9)     Weight

a)      Minimum weight of car after race is 200 lbs.  (without driver)

b)      Weight  of car and driver must be at least the minimum shown in Class Rules.

c)       Removable ballast must be secured to the welded chassis or other part of the car with bolts and cotter keys/safety wire.

10)   Ignition Safety Kill Switch

Cars must be equipped with a safety kill switch that will shut off the ignition for the motor.  Switch must be accessible within driver’s compartment and must be conspicuously labeled ON and OFF.

11)   Mirrors and Radios

No mirrors or radios allowed in car.

12)   Nerfing Bars- All welds must be complete: top, sides, and bottom.

a)      Must be made of a minimum of 3/4", .065” tubular or square stock steel (or aluminum of equal or better strength) and have a minimum of 3/4" over-rider bar welded on top, or a minimum 3/4", .065 tubular or square stock steel or aluminum of equal or better strength under-rider bar welded on bottom.

b)      Must extend within 2" of, but not beyond, the outside edge of the tire.

c)      Must be within 4" of the rear tires.

d)      Must be a minimum of ½ the length of the wheelbase.

e)      Must be welded or bolted securely to the frame.

13)     Oil Catch Can

a)      An oil catch can must be mounted inside the body constructed such that oil blow-by cannot leak onto the track.

b)      All oil blow-by from the engine breather system must be routed to an Oil  Catch Can .

c)      The oil catch can must be vented only to outside air.  No connection to carburetor or exhaust system permitted.

d)      The total area of all vent lines from the can must be greater than the total area of all lines connecting the can to the engine breather system.

e)       Must not leak oil on track.

14)  Roll-Over Bars - All welds must be complete: top, sides, and bottom.

a)      All cars must have a roll-cage with sidebar protection.  The main roll-cage must be made of a minimum of 16-gauge (.065) 1" diameter tubular, or (.065) 1" square stock, seamless wall or welded seamed wall, steel or better quality.

b)      Roll-cage bars must have steel gussets welded in at the four top main joints.

c)      All roll-cages must be welded to the main chassis of the car, with gussets at all welded structural joints as appropriate.

d)      The roll-bar must clear the driver’s helmet by a minimum of 3", measuring from a line between the top of the roll-bar and the top front of the roll-cage.

e)      Driver’s head and body must be entirely enclosed within the roll-cage and car body.

15)   Safety Belts

a)      Cars must be equipped with double over-the-shoulder harness, 3" lap belt, and sub strap, with a single quick-release.

b)      Belts must be fastened to the frame of the vehicle at both ends of lap belt, and end(s) of shoulder harness and sub strap.

1)    Tires and Wheels

a)      Maximum wheel diameter not to exceed 6".

b)      Maximum tire diameter not to exceed 15".

c)      All wheels must be made of quality construction and material approved for racing competition.

d)      All wheel axles must be cotter-keyed or C-clipped.

e)      Live rear only.  No slipper or ratchet hubs -- both rear wheels must be fixed.  Must use all keys.

2)       Wheelbase

Wheelbase may not be shorter than 52", or longer than 67", measured between the centers of the front and rear axles.

3)    Windshields

a)      Required, made of metal screening with a maximum spacing of ½" x ½", or clear Polycarbonate, covering entire windshield area.

b)      No glass anywhere on car.

4)       Clutches

Centrifugal dry clutches only (chain only).  Quick-change sprockets allowed.

*    State Law and Track Rules set Junior Class Requirements at this time.

†      State Law and Track Rules determine minimum age of competitors.

  Engines Allowed

Briggs & Stratton 5 HP, 4-cycle, horizontal shaft only from the following list of blocks:

Raptor I, II & III, 130202, 130232, 132232, 133202, 133232, 13502, 135232, 135230, 133230, 555206, 555205 555168

Only one (1) engine allowed in car during any race.

Engine Modifications

No alterations of any kind are allowed to the engine unless specifically stated in this section. Engines must comply with WKA STOCK 5 HP BRIGGS rules.

1)       Engine Breather System

Briggs & Stratton stock breather assembly or modified versions may be used.  No modifications of any kind to stock breather hole diameter. Modified breather can be found at most Kart shops. Breather hose must be connected only to the oil catch can.

2)      Balancing

No engine balancing allowed.

3)      Block

a)      Allen screws and stud kits allowed.

b)      Engine girdles allowed.

c)      Governor system may be partially or fully removed.  Governor paddle hole must be plugged.

d)      Maximum engine overbore allowed is .030" plus .010" for wear.  Maximum absolute measurement is 2.6025".

e)      Removal of metal at base of cylinder wall to allow use of heavy-duty connecting rod is permitted.

f)        Repairs to cylinder block may be made but must be approved by Chief Tech. Inspector in writing prior to racing.

g)      Deck to piston clearance -- The piston cannot protrude more than .005" above the block.  Machining of deck is permitted.

h)      Repairs to cylinder block are allowed, but must be approved by tech inspector in writing prior to racing. The written approval must be kept and shown to a tech inspector upon request at any race.

4)       Carburator

a)      No visual tech on carburetor bore, but .695” maximum bore.

b)      Must comply with WKA Tech Rules with exception of pressed-in plug on outside end of Briggs carburetor, which may be removed.

5)       Crankshaft

Stock OEM cast crankshaft, stock stroke of 2.4370" + .010".

6)      Exhaust

Any exhaust system allowed (must pass state and track requirements). WKA RLV-91B muffler.

7)       Cam

a)      Timing marks must be aligned.

b)      No visual tech on camshaft lobes lifter surface.  Stock lifters only.

c)      If using a heavy-duty Connecting Rod, grinding between lobes of cam for clearance only is permitted.

d)      Cam Profile limits:

INTAKE                                                                                EXHAUST

Lift (inches)                      Degrees                                  Lift (inches)                      Degrees

.050                  7E BTDC  to   0E TDC                               .050              38E BBDC to 33E BBDC

.100                10E ATDC to 17E ATDC                             .100              21E BBDC to 16E BBDC

.150                29E ATDC to 36E ATDC                             .150                2E BBDC to   3E ABDC

.200                55E ATDC to 64E ATDC                            .200              21E ABDC to 31E ABDC

MAX                 MAX. Lift is .233"                                       MAX              MAX. Lift is .233"

.200                43E BBDC to 33E BBDC                             .200              76E BTDC to 65E BTDC

.150                13E BBDC to   6E BBDC                               .150              48E BTDC to 40E BTDC

.100                  6E ABDC to 13E ABDC                             .100              28E BTDC to 21E BTDC

.050                23E ABDC to 31E ABDC                             .050              10E BTDC to   4E BTDC

EZSpin:  Start --   45E to 60E ABDC        Lift --   .012" min.                  Duration --   30E min.

EXAMPLE:  If EZSpin starts at 51E ABDC, it must go to at least 81E ABDC.

NOTE:  All Cam Profile and EZSpin Readings must be taken with zero valve lash, and will be performed in accordance with the WKA Cam Profile Tech Procedure.

8)      Flywheel

a)      Stock OEM 5 HP flywheel meeting WKA Tech Rules for the specific engine model being used.

b)      Any flywheel key or no flywheel key allowed.

c)      Paintings and coatings other than minimum factory over spray are not permitted.  Machining is not permitted.

Chipped fins due to poor casting are permitted. Broken fins are not allowed.

9)     Fuel Pumps

Stock OEM for the specific engine model being used.

10) Head

a)      Stock head only.

b)      Copper head gasket minimum .020” allowed.

c)      Single flat planar milling of stock head allowed.  No alterations to valve cavity.

11)   Ignition

The above rules state what you are allowed to do to your Sportsman engine.  Any violation of these Specifications will be subject to penalties.

The above rules state what you are allowed to do to your Pure Stock engine.  Dimensions and requirements for all engine parts will be taken from the current WKA rulebook as they apply to stock engines. If necessary, comparison will be made to new Brigg’s parts for appearance and finish. Pure Stock engines are subject to a claiming fee of $350 cash for complete engine less clutch, exhaust system, and air filter. Any violation of these specifications will be subject to penalties.