Cover Note

These rules are in conjunction with all/any other rules laid down by the TADK Club and must be

read/used in conjunction with those rules.

Specifications

Single KT 100 Piston Port Engine only as manufactured by Yamaha with standard external

appearance (no left hand conversions) from carburettor inlet to barrel exhaust outlet. Piston port

engine must retain piston induction.

1. The use of painted or surface applied thermal barrier coatings on or in the engine/engine

components and on or in exhaust components is prohibited. The use of a fabric type

exhaust wrap is permitted from the head flange to the muffler connection (including the

spacer and flange on the muffler. Wrap must not be on the tapered section of the muffler.

2. The use of anti-friction coatings on or in the engine/engine components is prohibited.

3. External modifications, which do not in any way affect a performance gain, are legal

4. VHT paint may be applied externally to exhaust/muffler.

Legal Additions

Legal additions shall be limited to the following:

Air cleaner, chain guard, motor mount, direct drive gear, extension of carburettor jet needles,

carburettor return springs, third bearing and adaptor, temperature gauge and tachometer, fin

dampeners, fasteners, gaskets, joiners in spark plug leads, non-original spark leads, carburettor

diaphragm cover breather pipes, air cleaner mount, non original spark plug caps are allowable.

KT Ignition

The standard KT 100S (unmodified) ignition to be used.

Alternative ignition

The fitting of the following Modules as an alternative to the standard KT 100S ignition module is

permissible:

1. Yamaha, Victa, Atom, Delta, Wei/Shieh, Sig, Nova, PRD, and TCI., permitted.

2. Ignition key is a non-tech item.

Crankshaft and Conrod

1. Crankshaft must be the original KT 100S with a maximum stroke of 46.20mm.

2. The connecting Rod must be original KT100S, KT100J. The KSI Replacement rod will 

be allowable.

Exhaust Header Pipe

This item is not restricted to the original Manufacturer but must not have extraneous attachments,

fins or water cooling etc.

1. Modifications to fit exhaust temperature gauge is permissible.

2. Flex/pipe location flange must be visibly in line with the end of the header.

Cylinder

The cylinder must be of original Yamaha KT 100S manufactured materials only unless otherwise

specified.

1. The cylinder is not to have any additional / removable inserts / passages / tubes or dividers

    of any type.

2. Porting is allowable but must be only to the existing ports in their original intended layout. No additional ports

    or plugging of any ports. 

3. Threaded inserts are permissible to repair existing threads;

4. Studs may be replaced with bolts in existing location, or may have thread inserts to repair casting if thread

    has failed. Studs must be in original position.

Cylinder Head

Must be of original design with no additions (metallic or otherwise).

Minimum capacity of 11cc

Hemispherical combustion chamber, concentric with bore/spark plug.

Head Gasket

1. Must be of original cross section and material

2. Minimum thickness of 0.508mm (0.020” ).

Inlet Tract Length

Minimum inlet track length shall be 63mm measured from the outer carburettor adaptor face to the

piston wall. Phenolic spacer and alloy adaptor must be retained. Gaskets may be added to achieve

the minimum dimensions.

Phenolic Spacer:

To remain as moulded by Yamaha factory and conform to the diagram below. Drilling of the phenolic

spacer mounting holes is permitted. Sealing face may be re-faced.

Piston

Pistons approved are Strike, H Piston (this piston has a graphite coating), Yamaha, KSI, KSI Mk11,

JDP/Vertex, ARC (forged and cast).

Maximum piston diameter is 53.00mm.

Piston top and dimensions to conform to OEM shape and dimensions.

Carburettor:

1. Must be standard Walbro WB Series.

2. No additional holes or machining is permitted

3. Butterfly and shaft must be as manufactured.

4. It is permissible to repair the inlet seat and throttle shaft bore in the Walbro carburettor.

5. It is permissible to enlarge only existing fuel/air holes, but they may not be deleted or

relocated.

6. All air must pass through the carburettor venturi.

7. Measurement Code:

As cast maximum Venturi diameter 24.13mm.

As cast (area will extend from the front of the carburettor to the progression discharge jet which

must have all or portion of this jet in the cast area).

(iii) Maximum downstream diameter 25.7mm.

(iv) Butterfly shaft must be located at the bore centre.

(v) Minimum carburettor body length of 37.5mm.

Inlet Silencer

All Yamaha engines must run an air silencer box attached to the front of the carburettor.

Pressured Fuel Systems

1. Additional fuel pump or pressurised systems are forbidden.

2. Squeeze type pump between the fuel tank and carburettor is permitted.

 

ROTAX Kart Engine 

Rotax Engine

General

The rotax 125 engine should be of original spec's unless otherwise stated in the following rulings. Neither the engine nor any of its ancillaries may be modified in any way likely to improve performance, No polishing or grinding. The engine must  have the official Rotax stampings on the crankcase in two (2) places and also on the reed block face of the cylinder to be

eligible to compete..

Internal and External Additions 

1. No additional material may be added except in the case of engine repairs and shall only restore the engine or components to original specifications.

2. The use of painted on, liquid or paste applied thermal barrier coatings/ceramic coatings on or in the engine components and on or in the exhaust system is prohibited. No exhaust wrap permitted. A thermal-rated exhaust sealant is permitted at the junction between exhaust stub and exhaust pipe.

3. The use of anti-friction coatings in or on the engine/engine components is prohibited unless otherwise supplied OEM. The only exceptions to this are the gilnisil coating of the cylinder bore and the coating to the piston skirt.

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Legal Additions

Chain guard, motor mount, radiator mount, temperature gauge and tachometer/hour meter, exhaust gas temperature fitting.

If the rules do not cover something that can or cannot be done, then it cannot be done!

Non-tech Items

Fuel Filter, Air Filter (air box remains full tech item, all air passing into the engine must pass through the two original/genuine Rotax inlet tubes of the original/genuine Rotax air box), Radiator and Radiator Hoses, clamps pulse line, switches, ancillary mounts, fasteners, circlips, washers, bearings, spark plugs, gaskets, o-rings, piston pin, springs, seals, clutch drum, drive sprocket, rings, starter motor, clutch flywheel, thermostats and housings, spark plug brand and heat range. No alteration from original manufactures specification is permitted to fit a non-tech item. Non-tech items are approved based on the fact they do not alter or enhance performance.

Cylinder Head

Volume

Minimum of 11.0cc.

 

Squish

All Rotax Max engines competing in Rotax class to be running 1.0mm minimum squish.

Squish will be measured using lead solder wire and piston will be raised/lowered both clockwise and anticlockwise on both sides of the engine.

 

Combustion Chamber Insert

Identification code has to be 223 389. 223 389 1 or 223 389 2. No material may be added except to repair the spark plug thread and or spark plug seal surface.

Machined surfaces may be re-machined only if using cylinder 223997.

Cylinder head insert must retain both the squish band and visually spherical combustion chamber. O-Ring must be fitted.

The combustion chamber/squish area shall not protrude beyond the sealing ceiling face of the head insert.

"Rotax" and/or "Made in Austria" must be cast in the combustion insert.

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Spark Plug

Any brand or heat range

 

Thread Length

Maximum spark plug thread length shall be 20mm.

 

Piston

Uncoated or coated, aluminium cast piston with one (1) 1.0mm rectangular piston ring. Machined areas are: top end of piston, outside diameter, one groove for the piston ring, bore for the piston pin, inside diameter at bottom end of piston. Piston must conform to original Elko piston dimensions.

All other surfaces are not machined and have a cast surface.

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Gudgeon Pin

Gudgeon pin to be made of magnetic steel and same style as OEM.

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Cylinder

1. Light alloy cylinder with GILNISIL plating, configuration with one main exhaust port and pneumatic adjust valve.

2. Any replating is not allowed.

3. Maximum bore: 54.035mm (measured 10mm above the exhaust port).

4. Cylinder has to be marked with the Rotax logo, identification code 223 997 or 223996.

5. All ports and passages are cast finish except some pre-existing factory removal of flashing.

6. All ports have chamfered edges to prevent ring snagging.

7. Any additional machining is not permitted.

8. Cylinder must have the official Formula Rotax stamp on the inlet face.

9. Piston travel check using 5.0mm rod. Minimum 32.8mm, Maximum 33.8mm.

10. If you are using cylinder 223996 or any future cylinder volution, the cylinder must remain as supplied by the manufacturer and cannot be remachined

11. Height of cylinder must be 87mm with tolerance of -.05/+0.1 mm.

12. Due to manufacturing procedures some cylinders may have been machined on the exhaust flange

 

Cylinder Base Gaskets

1. Must be dimensionally the same size and shape as original and cannot be designed to decrease the size of the transfer ports.

2. Inlet System: Intake manifold is marked with the name Rotax and the identification code 267915.

3. No grinding or machining is permitted, however some factory flash removal may be present at the junction of the inside contour and the carburettor stop mounting face. This is a manual trimming operation consisting of a small corner break of less than 1mm in width.

4. Reed valve assembly is marked with the name Rotax and the identification code 22438 or 224389. The reed valve assembly is equipped with two (2) petal stops and two (2) reeds, each having three (3) petals. The maximum allowable width between the inside faces of the two (2) metal reed valve stops is 22.0mm. The thickness of the reeds is 0.6mm + - 0.08mm..

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Exhaust Power Valve

1. As supplied by the manufacturer with no modifications allowed.

2. Maximum thickness of Power Valve gaskeVs is 2.0mm.

3. Original spring must be fitted.

4. Any external non-original adjustment or blocking mechanism is illegal.

5. Additional fasteners or securing devices may be fitted/added.

6. Length of exhaust valve is 36.5mm +0.2mm/-0.3mm,

7. Width of collar is 4.8mm +/-0.3mm.

8. Exhaust valve evolution is approved ID 230260.

 

Crankshaft

1. As supplied by the manufacturer with no modifications permissible.

2. Stroke 54.5mm +/- 0.02mm.

 

Balance Shaft

1. No modification allowed.

2. Must be installed and operational.

3. Minimum weight of the dry balance shaft must be not less than 355 grams for balance shaft, Rotax part number 237 945 and 255grams for balance shaft, Rotax part number 237 949.

4. Balance gears must be installed and must be correctly aligned according to the instruction in the repair manual.

 

Conrod

1. As supplied by the manufacturer.

2. Any grinding/ polishing or modification is not permitted.

3. Conrod has to be marked with number "213" or "365" or "367" on shaft, 11.5.18

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Crankcase

1. As supplied by the manufacturer.

2. Zero grinding/polishing in the two main transfer passages.

3. Must have the official Formula Rotax stamp on the crankcase deck, either part no. 211870 or 211871 is permitted.

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Ignition

1. DENSO digital ignition only, no adjustment permitted or possible.

2. Ignition coil has the following marks close to the outlet of the high-tension cable, cast in the case. DENSO and 129000.

3. The ignition coil must have 3 pins at the terminal.

4. The only allowable spark plug cap is NGK Type TB05EMA.

5. Any modification to any part of the ignition system and/or crank-shaft to alter ignition timing or rev limiter is illegal.

6. The ignition pickup must be marked with the numbers 029600-0710, followed by a variable production code in the second line.

7. Battery must be a total of the nominal 12 volts only.

 

Carburettor

DELLORTO VHSB 34

1. The carburettor body, slide, needle, atomiser tube and atomiser insert (either spec 1 or spec 2 is permissible) to remain as originally supplied and cannot be subject to any modification.

2. No additions or additional machining filing, drilling or polishing etc is permitted to these items; this includes the bore/throat. "VHSB 34" cast in the housing of the carburettor. "QD" or "QS" stamped in the housing of the carburettor.

3. Atomiser tube stamped with "266 FN".

4. Needle stamped with "K 54" or "K 27" or "K98" only.

5. Slide marked #40 only.

6. The size of any hole or any of the following is unregulated: main jet, needle and seat, pilot jet, pilot jet emulsion insert choke jet.

7. The position of the float/float arms and the weight of the floats are unregulated.

8. All items (jets, needles etc) referred too must be present and operational.

9. With the exception of the choke, no changes or adjustments can be made to the carburettor once the engine is running.

 

Fuel Pump

1. Original MIKUNI diaphragm pump only.

2. Place of fixing is non-tech.

 

Intake Silencer

1. An original Rotax intake silencer must be fitted.

2. The original foam air filter may be replaced with either a flat style or cylindrical style filter providing all air to the engine passes through the original Rotax air box intake tubes.

 

Radiator

1. Alternative radiators other than genuine supplied radiators are acceptable and may be mounted remotely from the motor.

2. Additional cooling devices are not permitted. The removal of the thermostat from The cylinder head cover is acceptable.

 

Clutch

1. Dry Centrifugal Clutch - multi shoe aluminium or one-piece steel allowed using original design format components only.

2. Whilst on level ground the kart (with Driver in kart) must start to move under its own power, when the engine speed reaches 3000 rpm or less.

3. The use of a PRD clutch drum is permitted and Rotax sprocket as supplied by manufacturer. (Optional).

 

Exhaust System

Must be supplied by Rotax and cannot be modified except for,

1. the replacement of the silence absorption material and/or the addition of an exhaust gas temperature sensor fitting.

2. Standard engine/pipe coupling must be used.

 

Exhaust pipe with after muffler

1. Length of inlet cone: type a and type b: 592mm +/- 5mm (measured along the body of the exhaust pipe, (not the seam) from the beginning of the exhaust to the start of the cylindrical part).

2. Length of the cylindrical part of the exhaust pipe: type a and type b: 125mm +/- 5mm. Length of end cone: type a: 250mm +/- 5mm type b: 225mm +/- 5mm. Outside diameter of 180 bent tube: type a: 30mm +/- 3mm type b: 41mm + 1.5mm - 1.0mm (measured at beginning end of bend).

3. Hole diameter of end cap of silencer 21mm +0.2mm -0.Smm.

4. Painting/plating of the exhaust muffler is permitted with the exception of thermal barriers/coatings/paint.

5. NOTE: Any accidental damage to the unit will not incur a technical breach of these TADK Club Rules of Racing, however any attempt to modify or alter the exhaust system by cutting, or fabrication will automatically remove eligibility of the exhaust system.

6. Welding of the exhaust system to repair a crack, hole or to fit a patch etc. is permitted.

7. Only one exhaust/barrel gasket is permitted, maximum thickness of 2mm.

 

Exhaust Muffler

1. Noise isolating mat can only be replaced by an original Rotax spare part.

2. End cap rivets may be replaced with bolts/cap-screws etc.

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CADET 6.5hp Engine Rules

          Cover Note

          Internal and External Additions. 

          Testing procedure for RPM .

Cover Note

 These rules are in conjunction with all/any other rules laid down by the TADK Club and must be read/used

in conjunction with those rules.

These rules do not exclude the possibility of the club introducing some form of rev limiter at a later date.

1. Only stock standard 6.5 hp. stationary four stroke engines with a maximum of 212 cc allowed (if OEM capacity was 212cc). 2. Neither the engine nor any of its ancillaries may be modified in any way likely to improve performance, unless specifically      authorised as legal.

3. If it’s not written into the rules, you cannot do it.

Internal and External Additions

1. No additional material may be added except in the case of throttle connections and springs, engine repairs which shall only restore the engine or components to original specifications. An orifice plate can be stipulated by the TADK Club.

2. The use of thermal barrier coatings/ceramic coatings on or in the engine components is prohibited.

3. All governors & springs must be original to engines make and model.

4. Air box must be “as original”. No drilling or cutting permitted.

5. RPM cannot exceed 4200 rpm. This will be tested randomly or at end of any race.

6. OEM built-in 2:1 reduction gearbox and clutch permitted.

7. All karts must be fitted with kill switch in easy reach of the driver. Suggest using steering wheel mounted switch, either as well as, or instead of engine mounted. – (this allows driver to stop engine without taking eyes away from forward facing)

8. Low oil cut off sensor may be disconnected/removed.

9. An operable centrifugal clutch is mandatory.

Testing procedure for RPM

If deemed necessary, a test may be conducted.

Kart to be “blocked” so that rear wheels are off the ground. RPM meter to be connected to spark plug lead or ignition primary sensor connection.

Engine started and (if necessary) warmed up

Engine to be run to utmost rpm attainable (operator must be in control of brake pedal and applying slight pressure to the brake pedal to prevent “overrun”).

If Alfano or MyChron equipment used, highest rpm will be recorded. If a hand-held rpm indicator without highest rpm recording feature is used, the testing official must confirm with kart owner/driver that they agree with reading observed at time of testing.

The rpm testing equipment used on the day is the testing equipment- no questioning of accuracy.

The outcome of the test must be recorded and signed by both the owner/driver and the TADK Club official.

 

CADET Racket Engine Rules.

                                         Cover Note.

                                         Internal and External Additions.

 Cover Note These rules are in conjunction with all/any other rules laid down by the TADK Club and must be

                       read/used in conjunction with those rules.

1. Only stock standard Racket engines are permitted.

2. Neither the engine nor any of its ancillaries may be modified in any way likely to improve performance, unless

    specifically authorised as legal.

3. If it’s not written into the rules, you cannot do it.

Internal and External Additions

1. No additional material may be added except in the case of throttle connections and springs, engine repairs which

    shall only restore the engine or components to original specifications. 

2. The use of thermal barrier coatings/ceramic coatings on or in the engine components is prohibited.

3. Restrictor plates must be in place. Two sizes, 20mm diameter and 15mm. The 15mm diameter will be enforced.

    Oversized restrictor will mean disqualification from racing that day, points lost.

4. Squish 2.0mm.

5. Air inlet silencer box must be used.

6. Centrifugal clutch permitted.

7. All karts must be fitted with an approved "detent' kill switch in easy reach of the driver.

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