JAMAICA RACEWAY SENIOR SPORTSMAN

GAS CLASS MOTOR RULES

NOTE: Unless specified all parts are to be stock and unaltered. Parts may be teched Against a known stock part. Do not assume any part is legal because specific reference is not made in the tech manual. Obtain an answer from a track tech official

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#1. Remove clutch, chain guard, oil and motor mount. Check for tech paint or seals

#2. Remove air cleaner inspect for velocity, ram air, etc. ( IKF, WKA RULES )

#3. Remove exhaust inspect for porting, inspect for extra holes in muffler or header.

Muffler required.

#4. Remove flywheel shroud ,inspect for flywheel screen, may be on flywheel or on shroud,Inspect for head shroud, cylinder shroud, and coil vane.

#5. Remove fuel tank inspect for internal bowl position. Check for 1 or 2 stock gaskets.

Bracing of tank and repairing for leaks permitted. Cutting tank for tire clearance permitted. Old style tank may not be used on new style carb.

#6. Remove and inspect gas cap.

#7. Remove carburetor and inspect as follows:

a. Inspect for 1 or 2 intake gaskets. No sealer or paint.

b. Inspect swirl for position, if installed, then remove and inspect for alterations.

c. Tech: Carb flange bore is.726 max. Main bore .688 max. (no blue printing, boring honing, sandblasting, glass beading, polishing, tapering, etc.)

d. Inspect butterfly, shaft, screw, and felt washer. Butterfly shaft: Front of shaft .040 minimum and back of shaft .086 minimum. ( PER WKA-IKF-KART )

e. Air horn is 1.101—to—1.103-----MUST BE UNALTERED

f. Remove and inspect needle assembly and jet. ( jet .037 no go, may have recess or flat back

g. Tech idle hole .028 no go

h. Tech high speed hole .062 no go

i. Inspect short pickup tube for ( Screen Optional )

j. Remove diaphragm cover, inspect cover, diaphragm, spring, and cup.

k. Inspect long pickup tube for ( Screen Optional ) and steel retaining clip. No one piece brass tube.

L. Inspect carb body for alterations, extra hole, or passages, etc. After market device to reinforce a broken ear on carb permitted.

#8. Remove and inspect valve cover breather. ( disassemble if necessary )

NOTE: Air filter adaptor Refer to WKA, IKF, KART

#9. Remove and inspect for factory head bolt

#10. Tech head gasket for .043 minimum thickness. Check half way between head bolt holes. No coating or sealers. After market head gasket allowed.

#11. Check 3 places on head - .011, .408, .300 minimum. No machining, sand blasting, glass beading of head. Soft cabon and oil may be wiped with a rag before tech.

#12. Cylinder deck height .015 pop-up maximum at TDC. Check at wrist pin center line. Top of block may be machained

#13. Check cylinder bore for 2.607 maximum

#14. Check stroke from BDC to TDC – 2.4270 to 2.4470

#15. Set up degree wheel, pointer, dial indicator, and profile cam

EXHAUST INTAKE

.020______ ( 50-BBDC—45--BBDD .020________ ( 17-BTDC—14-BTDC

.050______ ( 38--33 BBDC ) .050________( 7 BTDC—ATDC )

.100______( 21—16 BBDC ) .100________( 10—17--- ATDC )

.150______( 2 BBDC--- 3 ABDC ) .150________( 29---36---ATDC )

.200______( 21--- 31 ABDC ) .200________( 55—64 ATDC )

MAX_____( .233” ) MAX_______( .233” )

.200______( 76 – 65 BTDC ) .200________( 43 – 33 BBDC )

.150______( 48 – 40 BTDC ) .150________( 13 – 6 BBDC )

.100______( 28 – 21 BTDC ) .100________( 6 – 13 ABDC )

.050______( 10 – 4 BTDC ) .050________( 23 – 31 ABDC )

.020______( 3-ATDC—6-ATDC .020________( 41-ABDC---44-ABDC

E-Z START_________( 45 – 60 ABDC )

E-Z LIFT___________( .013” MINIMUM )

E-Z LIFT___________( .019” MAXIMUM )

E-Z DURATION_ ( 30 DEGREE MIN. AT .001 DROP )

NOTE: All cam profile readings must be taken with zero valve lash. Rotate engine in the direction it runs only. Valves should have no clearance and no spring tension when checked.

#16. NO RAMP CAMS!!!!! WILL BE CHECK BY THE .020 CHECK ON PROFILE

#17. Remove intake valve, check for .30 degree face, 1.115 minimum diameter inspect for modifications. Minimum margin .025

#18.Tech intake and exhaust spring for 1.500 maximum length. Exhaust spring may be used on intake.

#19. Check upper retainer if installed for maximum lip thickness of .058. Brass retainer allowed. No back facing for upper retainer.

#20. Inspect for stock briggs lower retainer.

#21. Tech intake valve seat for factory installation, 30 degree angle, one angle, and 1.005 I.D. NO GO. Inspect port for modification. No gtinding, blue printing, glass beading, porting, holes, or cracks. Pressure test if necessary. NOTE: some blocks come from the factory with casting flash and some grinding marks in port. Excessive removal of material from port may result in disqualification, even if done by factory. We highly recommend you check your ports and get a track tech officials opinion if there is any question.

#22. Remove exhaust valve, tech 45 degree face, .990 minimum diameter and inspect for modifications. Minimum margin .025.

#23. Tech exhaust valve seat for factory installation, 45 degree angle, one angle,

.880 I. D. NO GO and inspect exhaust port for modifications. No grinding, blue printing, glass beading, porting.

#24. Intake and exhaust seats may be peened with a maximum of 12 center punch marks within .125 of O.D. of seat

#25. Stacking of stock valve guides allowed.

#26. Remove and inspect ratchet and flywheel washer. Inspect flywheel for alterations, no painting coating, broken fin, grinding, sandblasting, glass beading. No aluminum 3 HP flywheels. Minimum weight 5 lbs. 12oz. Stock briggs flywheel key, no offset keys.

#27. Check coil for maximum 5000 ohms – 2000 ohms minimum. Any plug connector ok.

#28. Remove side cover and inspect crankcase gasket, ball bearing, and stock foactory cam shaft alignment.

#29. NO chamfering of the cam side lifter bores. NO welding of lifter bores

#30. Remove and inspect lifters for alterations and reworking. Lifter O.D. 982 min. 1.005 max. Can be teched against known stock part.

#31. Oil dipper, NON TECH.

#32. Remove piston rod assembly from cylinder. Remove wrist pin, inspect for stock circlips, and separate from rod.

#33. Stock connecting rod only check length 3.1233--3.1333, oil hole non tech, inspect for honing alterations, reworking, etc. No .020 undersized rods.

#34. Piston, ring, and pin. Refer to WKA, IKF, KART, RULES

#35. Remove crankshaft from block and inspect for alterations, lightening, balancing ,polishing, or reworking. Some timing marks on 130232 engines are being drilled insead of punched. Bushing type PTO crankshaft #260938 may be turned down to allow the use of a bearing. Late model engines have a removable cam gear. The gear must be in place on an unaltered square key. Stock gear, no alterations.

#36. Inspect block for alterations and reworking, and stock briggs bushing, if installed in flywheel side. Repairing of blocks from broken rods ok, if not used to disguise modification. Removal of governor is ok.

#37. Any replacement bolt or fastener except coil bolts, rod bolts, head bolts, and carb butterfly screw permitted as long as original diameter is used.

#38. Stock briggs and Stratton engine rules legal block: 130202, 130232, 131232,

132232, 133230, 133232, 135230, 135232.

#39. Sleeving of cylinder block is permitted in all briggs and Stratton engine classes.

Coating or painting material are prohibited. Sleeve must be ferrous material and installed concentrically to stock bore.

#40. FUEL: Pump gas only. No 10 percent ethanol fuel. Tech to be done with digitron fuel meter or any test deemed necessary by track officials. Track fuel may be provided and tested. Fuel may be tested after each heat and /or feature according to track officials discretion.

JUNIOR RESTRICTOR PLATES: Junior I must run a .425 IKF restrictor plate. Junior II must run a .500 IKF restrictor plate. Must be installed between block and carb with flange into intake port. One gasket is required on each side of plate. Caution, engines may be shipped from briggs with two gaskets that appear as one. Horstman logo is clearly visible above carb when installed correctly. Air passageways for the purpose of bypassing the restrictor plate are not permitted.