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Total Concept Racing Engines George Shear Phone:
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Tech UpdatesKSUSA Briggs World Formula Rules 2010This version supersedes all previous versions! Effective October 7, 2009 717 Briggs & Stratton World Formula Engine RulesAll parts must be B&S factory production parts unless otherwise noted in these rules. No machining, polishing or alteration of any parts is permitted unless specifically noted in these rules. All parts are subject to comparison with a known stock part. 717.1: Shrouds and covers: All shrouds and covers must be run as supplied. Cylinder shield may be bent slightly or drilled around spark plug hole to allow fitting cylinder head temperature lead and clearance for Coil Ground lead. Flywheel Cover,Top Cover and Plate are non tech items. They are replaced by Part # 555699. 717.2 : Header and silencer 717.2.1: Factory header or RLV part number 5442S. Any exhaust gasket or no exhaust gasket allowed. Sealer allowed on header. Header nuts are not required to be safety wired. Bottom bracing must be bolted to head. Factory header may be cut and turned to fit car as long as the overall length and tube size remains the same as the stock factory header: OAL 20.5 OD .9375 x .065 wall (ID .807 +/-.005) Coating the pipe is allowed. 717.2.2: Exhaust gas temp sensor is optional. 717.2.4: RLV Silencer #4100 required. If inside baffles on muffler are loose and rattle or have been altered or removed, the muffler will be deemed illegal. Coating is allowed 717.2.5: Springs attaching Silencer to header must be safety wired. 717.3 : Electric starter: Starter motor must be operational and capable of starting engine. Battery must be minimum of 8 AH rating and capable of starting warm engine. Recoil starter and flywheel starter cone optional. Starter support bracket P\N 557119 is optional. 717.4: Air filter must be Green Brand 40 X 75 filter. 717.5 : Spark plug: Any commercially available, 10 mm thread, spark plug allowed. Spark plug must be stock. Indexing washers allowed. Removal of factory sealing washer is not allowed unless using head temp sensor ring. 717.6: Fuel pump must be B&S part 557033. Must be pulsed from intake manifold only. 717.7: Clutch: May be engine and\or Jackshaft mounted. May use #219 or #35 sprocket. 717.8: Rev Limiter: Rev limit is 7100 rpm +/- 50 rpm. Rev limiter may be checked at any point in the race program. Rev limit will be checked with a suitable memory capable tachometer attached to the plug lead and the motor accelerated until the rev limiter begins to function. All rev limiters must function within 100 rpm when checked with the same instrument. Each competitor is allowed one courtesy check of the rev limiter with the instrument to be used at the event. 717.9: Fuel: Fuel to be KSUSA approved gasoline with no additional additives. Fuel may be checked by any means. Each competitor is allowed one courtesy check of fuel in his tank with the method to be used at the event. Compliance with the common source will be determined by zeroing a Digitron gas meter in a sample of source gasoline and allowing each competitor deviation of + / -5 points from zero and\or by any Digitron recommended method. 717.9.1: OIL: Any crankcase oil is allowed BUT MUST PASS THE BURN TEST AND/OR THE SNIFFER TEST. (Recommend TIFF Industries Sniffer) 717.10: Carburetor: Stock Walbro PZ carburetor only. No alterations allowed; choke excluded. Carb mount boot Briggs #557130 is required. 717.10.2 : Slide must remain unaltered. Unaltered Stock needle marked CDB is required. 717.10.3: Choke assembly is optional and may be removed and shaft holes plugged with silicon. If choke is retained choke lever may be fastened open with spring, rubber band or tie wrap. 717.10.4 : Pilot Jets: 36, 38, 40 are allowed. No drilling of jets allowed. 717.10.5: Main Jets: 90, 93, 96, 98, 100, 102 are allowed. No drilling of jets allowed. 717.10.6: Venturi measurement 717.10.6.1: Vertical .9902 max 717.10.6.2: Horizontal .7382 max
717.11: Camshaft: No alteration of the camshaft by machining, polishing, or altering is allowed. Must compare to stock Briggs part. First camshaft check will be taken at the valve spring retainers. With the lash set at zero, the movement of the valve spring retainer may not exceed .3085.
Any camshaft with a measurement at the push rod of less than .306 should be removed and measured on the grind and checked for alteration. Camshaft must be as supplied with Stock Profile and compression relief. 717.11.1: Install degree wheel, using positive stop method. 717.11.2: Check ignition timing . With the right edge of the magnet (not the magnet holder) aligned with the right edge of the notch on the bottom of the right leg of the coil as in Fig. 717.11.2 . Check the PVL ignition as illustrated in 117.11.2.2. The degree wheel should indicate between 23 and 29 degrees BTDC for either ignition.
717.11.3: Tech camshaft at pushrods. Push gently down on dial indicator stem to ensure that there is no lash when pushrods are going down.Exhaust Lobe Lift Intake Lobe 75-71 BBDC .020 34-30 BTDC 57-53 BBDC .050 18-14 BTDC 39-35 BBDC .100 2BTDC-2ATDC 25-21 BBDC .150 13-17 ATDC 9-5 BBDC .200 29-33 ATDC 12-16 ABDC .250 49-53 ATDC 25-29 ABDC .275 63-67 ATDC .3085 MAX .3085 70-66 BTDC .275 31-28 BBDC 57-53 BTDC .250 18-14 BBDC 37-33 BTDC .200 2-6 ABDC 21-17 BTDC .150 18-22 ABDC 6-2 BTDC .100 33-37 ABDC 11-15 ATDC .050 49-53 ABDC 29-33 ATDC .020 66-70 ABDC 717.12: Deck/Piston Clearance: Machining of deck surface is permitted. There will be no knife edge finishes allowed, Smooth finish only . Piston pop up cannot exceed .035 above block surface in the center of the piston. When measuring piston pop up, use the backside of the Sox pushrod gauge or set flat bar stock across piston parallel to wrist pin. Use dial indicator to check pop up on center of this bar. Carbon may be removed from the top of the piston prior to measuring. Top of piston may be filed to relieve protrusions left by number stamp on top of piston. 717.13: Bore: Maximum bore 2.725. Factory oversize pistons allowed. 717.14: Stroke: Maximum stroke is 2.204. Push piston down to take up rod play. 717.15: Head gasket : Stock B&S head gasket only. .041 minimum thickness between head bolt holes. Measurements are to be made with micrometer from inside of gasket. Fire-ring Gasket P\N 555698 is production item and legal. 717.16: Head: Head may not be altered in any way from factory specifications. Heat sink P\N 555690 is allowed. 717.16.1: Rocker Arms: Must be as produced. Length must be 2.761 minimum to 2.291 maximum. 717.16.2: Rocker Ball: Must be stock. Diameter to be .590 - .610. 717.16.3: Cylinder head gasket surface may be machined. Depth from gasket surface to head surface between valves must be a minimum of .319. Measure by using a depth micrometer. There will be no knife edge finishes allowed, Smooth finish only. No angle milling of the head.
717.16.5: Ports: 717.16.5.1: Intake port: No media blasting of any type allowed on intake port in\on the head or manifold. Must be as cast. Maximum diagonal measurement is 1.101. Maximum vertical measurement is 1.044. 717.16.5.2: Exhaust port: No media blasting of any type allowed on exhaust port. Must be as cast. Maximum I.D. of shoulder in bottom of exhaust port is .854 717.16.6: Valve seats - one 45° angle only 717.16.6.1: Intake valve seat diameter is .966 - .972. 717.16.6.2: Exhaust valve seat diameter is .844 - .850. 717.16.7: Valves 717.16.7.1: Intake valve head diameter is 1.055 - 1.065. 717.16.7.2: Exhaust valve head diameter is .935 - .945. 717.16.7.3: Valve stem diameter is .232 - .238. 717.16.7.4: Valve face must have one 45° sealing surface only. 717.17.8 Valve springs 717.17.8.1: Dual valve springs as supplied by factory are required. 717.17.8.2: Inner spring wire diameter is .066 - .068. 717.17.8.3: Outer spring wire diameter is .112 - .114. 717.17.8.4 : Valve Guides: Replacement of valve guides with B&S factory part 555645, is allowed. 717.18: Ignition: Unaltered B&S stock coil #557040 w\External Limiter or #557125 with Internal RPM Limiter is mandatory. Attachment bolts or bolt holes may not be altered. 717.18.1: Spark plug connector must be stock factory type. 717.18.2: Rubber plug boot is allowed. 717.18.3: There must be resistance from plug wire to ground on coil #557040. Resistance must be between 3000 ohms, minimum, to 6000 ohms, maximum. Coil resistance may be rechecked after a minimum of 10 minutes if correct reading is not attained upon first check. No spec available on P\N #557125. 717.18.4: Coil air gap is non tech. 717.19: Flywheel: Only stock Cast Iron or Cast Aluminum Briggs #557126 flywheel is permitted. Starter ring gear and all cooling fins must be in place. No machining, glass beading, sandblasting, painting or coating of flywheel is allowed. Minimum Flywheel Weight with starter ring, cooling fins, and attachment bolts 4 pounds 3 ozs.717.19.1: Chipped fins due to poor casting are legal. Completely broken off fins are not allowed. 717.19.2: Stock flywheel key with B & S logo is required and will determine Aluminum flywheel ignition timing. The flywheel key may be aluminum or steel. NO offset keys permitted. 717.20: One or two stock crankcase gaskets are required. 717.21: Valve Lifters: Must be stock. No Polishing allowed.717.21.1: Lifter head diameter must be .969 - .972. 717.22: Connecting Rod: Stock B&S part #557005 or 557117 rod only. Rod may not be altered or polished . Rod may be clearanced providing that it is in stock configuration and finish, with no dimpling or media blasting. Rod ends must be concentric with crank journal and wrist pin with no chamfer or breaking of edges. 717.22.1: Rod length, measured from bottom of wrist pin hole to top of crank journal hole, is 2.419 minimum to 2.429 maximum. 717.22.2: Oil hole opening is .185 no-go. Crank end of oil hole is chamfered. 717.23: Wrist pin:717.23.1: Maximum I.D. is .414. 717.23.2: O.D. is .624-626. 717.23.3: Minimum length is 1.901.
717.24: Piston rings: Three rings mandatory. Top compression ring must have chamfer or O toward top of piston. Second scraper ring must be installed with inside chamfer down and O toward top of piston. Oil ring must be installed as from factory. No alteration of rings allowed except end gapping and lapping. Maximum RING GAP of Rings .050. Rings must be self supported in the cylinder bore of the engine being inspected. Rings must remain flat. Rings must be in one piece when removed from block. Aftermarket rings are allowed if they meet the Specifications listed below. 717.24.1: Minimum width of top two rings is .095. 717.24.2: Thickness of top two rings is .059 - .064. 717.24.3: Minimum width of oil ring is .065. Ring groove must be present. Expander must be installed. 717.24.4: Thickness of oil ring is .098 - .102. 717.25: Piston: Stock kidney bean piston required. No alteration, polishing or machining allowed. Only piston skirts are coated and coating can not be removed and skirts or any part of piston be polished. Factory finish only.717.25.1: Minimum from top of piston to top of wrist pin on circlip side is .658. 717.25.2: Minimum piston length is 1.768. 717.25.3: Factory oversize World Formula pistons are allowed. 717.26: Crankshaft: Stock B&S crankshaft casting #772 and #052 only allowed, all finishes to be as factory supplied , with stock timing gear installed in stock location only. No alteration or polishing in any manner allowed. Offset crankshafts not permitted. Stock bearings required. 717.26.1: Shim(s) if used, must be installed as from factory. 717.26.2: Crankshaft journal diameter is 1.094 - 1.100. 717.27: Block: Must be stock with no alterations, except blocks may be repaired from broken rod damage, providing that repair does not constitute a functional modification of original block. No welding is permitted from the cooling fins upward.
• CYB rule: Unless the rules say you can; you cant!!! • All Tolerances +\- .001 measured with dial indicators, micrometers or calipers due to calibration variance.
Cam Profile
KSUSA Briggs World Formula Rules Rev 10/07/09 For more information contact: George Shear CTO KSUSA 918-618-6800 Or Chuck Kidwell 317-507-5968 President KSUSA
KidSprint USA Rules 2010 10/15/2009 The KidSprint USA will hereafter be referred to as KSUSA
SPECIFIC RULES 1. Age. Drivers ages 6 through 12 (A driver whose 13 th birthday falls during the racing season will be allowed to finish the season in which they began accruing points before their birthday.) may compete in the KidSprint Class. 2. Roll cage. Roll cages shall be at least 1 inch .083 wall thickness mild steel, or 1 inch .065 wall thickness chromoly steel minimum. The front section of the cage shall be no further back than the steering wheel. Roll cage shall have sufficient fore and aft bracing and strength to support the weight of the car & driver in case of an upset. Cage shall have gussets at the intersecting bars to the uprights. Bends must have at least 3 inch radius. No square or pointed corners allowed. Roll cage must be a minimum of 3above the drivers helmet to the top of the cage at any point above the drivers helmet. It is mandatory to install a cross brace behind the seat to support the shoulder harness at a point not lower than 1 1/2 below or above the top of the drivers shoulders. 3. Bumpers And Nerfs. Car must have bumper extending beyond the front and rear tires. Nothing may extend beyond a tangent line from the outside edge of the tires to the bumpers. Nothing may extend beyond the outside edge or the tires or wheels, whichever is the widest. No sharp corners or design as to hook or damage. All cars must be equipped with nerfing bars. Nerfing bars must extend to inside edge of tires, but not beyond the outside of tire. 4. Safety. Seat belts must be securely attached to the car and used at all times. Metal to metal latches only. 5 point seat belts, shoulder harness and sub strap are required. Belt dates must not be over three years old. (Example: Oct 99 may be used in 2000, 2001 and 2002.) Arm restraints are mandatory and must be adequately adjusted to keep the drivers hands below the top of the roll cage. Helmets must be full head coverage competition type and one of the three latest SNELL approvals. Nomex headsocks recommended. All drivers will wear a name brand flame-retardant uniform. Neck braces and\or cage nets with a SFI 3.2-1 rating or higher or Total Head containment seats are mandatory. SFI gloves are mandatory for safety. 5. Cockpit Controls. On and off switches must be on dash, top of the cowl or on steering wheel. On/off switch must be functional. No radio communication is allowed with the car or the driver. Cockpit controls: carb adjusters, kill switch, starter button and engine monitor. No wing sliders or pan hard adjusters driver operated in cockpits. 6. Battery . All wet cell batteries mounted in the cockpit must be covered and vented outside the cockpit area. 7. Fuel. Fuel is to be KSUSA approved. Racing gas will be Sunoco Purple; VP C-10 or C-12 or Rocket Fuel 111 octane. 8. Weight. Minimum car and driver weight: 400 lbs. 9. Suspension. Aluminum or steel body shocks are legal. 10. Wheelbase; Maximum 52 inches. Minimum 50 inches, center of front axle to center of rear axle. Rear axle to be steel or splined aluminum 1 1/4" min dia. 11. Maximum Tread Width. not to exceed 55 outside of tire to outside of tire. 12. Steering; Front wheels must be connected by a solid or tubular tie rod. Rear wheel drive only. All suspension bolts except wheel nuts must be secured by some type of locking device. 13. Brakes. Brakes will be of sufficient strength so as to slide the wheels while the car is in motion at any given time. 14. Tires And Wheels. Wheels to be 8" dia steel or aluminum non-beadlock only. Right rear spec tire to be 10 x 8.50 x 8 American Racer (McCreary) or Hoosier RD 20 of comparible size. There can be no grooving, sipeing, softening or altering the tire in any way. It should be as it arrives from the manufacturer. Wheels must be held on with 4 or more standard lug nuts or knock-off hubs. 15. Bodies. All cars must have complete bodies of Sprint Car design only. Tail sections must be in place for time trials and all races. There must be a metal firewall between driver and engine, made of 24 gauge steel or .060" aluminum. Body of car must be made of aluminum, metal, fiberglass or high impact plastic. All cars must be painted an attractive color or colors. No rear view mirrors. The only part of the car allowed to be dismantled for driver to enter or exit is a quick release steering wheel hub. All mechanically operated devices must be mounted below the drivers shoulders for safety. All fuel tanks must be equipped with a one-way check valve designed to prevent the spillage of fuel from the fuel tank vent in the event of a rollover. 16. Transmission. The drive will be by engine or jackshaft mounted clutches. No axle mounted clutches allowed. No direct drive will be allowed. Chain guards will be made of .090 inch thick aluminum or equivalent and will run on top of chain from the front of the front sprocket to the center of the rear axle. Driver must not be able to touch the chain or sprockets while sitting in the cockpit. 17. Wings. Right side board, maximum 42" x 20". Left side board, 42" x 20". Minimum size is 6 sq. ft. The wing cannot be mounted outside the centerline of the tires. Side boards may not extend more than 3" beyond center section and sides must cover center section. All wings must have 1/16" radius edges or edging. No raw edges. No wood except for ribs or spars inside center section. Lower front corner of the wings sides cannot be more than 4" below top of roll cage. Nose wings cannot exceed 24"x 18", and must carry car number. Top wings are mandatory to enter a night's event. Cars may finish without a wing if no replacement is available. 18. Numbers. All cars must have legible numbers painted in contrasting colors on both sides of car and the nose. 19. License. All drivers must be members in good standing of KidSprintUSA to qualify for prizes and contingencies supplied by KSUSA 20. Ballast. Any material used for ballast must be firmly attached as a part of the car's structure. No liquid or loose ballast such as water, fuel, oil, sand bags, rocks, log chains etc. allowed. 21. Hubs. Front hubs; Go kart type with 5/8" bearings and 5/16" wheel studs minimum. Rear hubs: Douglas 5 x 130 Go kart type or equivalent. 22. Engine Rules. Briggs & Stratton World Formula engines as defined by the KSUSA engine and FIA Homologation specs. Engine may or may not be sealed but both versions must pass Tech as defined by the previously mentioned rules upon request of a Track Official. The Briggs World Formula will use a RLV 5442S header or stock pipe and RLV 4100 silencer as defined in the KSUSA Briggs World Formula rules. Stock pipes may be cut and turned as necessary to fit the race car as long as the pipe still retains the original length, diameters and volume as the original stock pipe.
The Briggs World Formula KSUSA engine rules are available in downloadable form at: www.kidsprintusa.com.
ALL 2 Strokes Subject To CC Checks: To all my customers who are running on gasoline, be sure after about 3 races to clean the carbon from the top of your head and piston top to insure you tech out legal!! Also be sure you put the same head gasket back on and torque your motor to the correct spec. If you have problems doing this be sure to give me a call. THINK YOUR MOTOR IS GOING WEAK? You can check it yourself and save the freight and know yourself if you are having a problem. It is easy....get you some marvel mystery oil and run your piston to top dead center and fill the chamber full of oil to the top of the spark plug hole. If the oil leaks down in about 2 minutes past 2 threads in the head, your ring is weak and a upper cylinder job is needed!! Just an easy check for you to keep an eye on your motor so you will know when to send it back. If it doesn't go down any, or in about 5 minutes only 2 threads, you are good to go racing. GOOD LUCK TO ALL!!WIN WITH YELLOW FINS!
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