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1 Section N – N12 Rotax FR125 Max incorporating EVO Issue 2015-4 published 6-3-15

KARTSPORT NEW ZEALAND MANUAL

SECTION N – SPECIFICATIONS

RULE – N12 ROTAX FR125 MAX Incorporating EVO

Issue 2015-4 published 6-3-15

N12 Rotax FR125 Max N12.1 Engine Technical Specifications are under the control of KartSport New Zealand Executive in

conjunction with Rotax. The KartSport New Zealand Executive reserves the right to alter the class specifications to ensure fairness of competition, safety and the wishes of the competitors. Only written submissions will be accepted for changes, with the Executive acting on them if considered necessary. VARIANT OPTIONS:

• Pre EVO Rotax FR125 Max with option of Series 1, 2 or 3 (new) exhaust system. OR

• Pre EVO Rotax FR125 Max with full EVO Kit except for: new Series 3 exhaust system, new crankshaft, new con rod and new piston which are all optional. OR

• Complete new Rotax FR125 Max EVO engine with new Series 3 exhaust only. NOTE: No Mixing and Matching

• The mixing of pre EVO and EVO components is limited to: • A new EVO engine must be run with ALL components supplied including the new

Series 3 exhaust system. • A pre EVO engine with an EVO Kit upgrade must run with ALL EVO Kit components

except the new Series 3 exhaust system, new con rod, new crankshaft and new piston which are all optional.

• A pre EVO engine (circa Dec 2014 specifications) without the EVO Kit must run with ALL pre EVO components with the following exceptions: new Series 3 exhaust system, new crankshaft, new con rod and new piston are optional.

N12.2 The engine is a single cylinder, liquid cooled, reed valve 2 stroke. UNLESS IT STATES THAT YOU CAN DO IT, YOU CANNOT.

• Unless otherwise specified filing, grinding, polishing, surface treating, machining or lightening of any component is expressly forbidden. All measurements given in these engine rules are for technical references only; you must not machine any parts to the dimensions given.

• The addition of material to any component is not allowed. • Only genuine Rotax components that are specifically designed and supplied for the FR125 Max

engine may be used in or on the engine and its ancillaries, unless otherwise specified. The use of either “red” or “green” OEM gaskets is permitted.

• The engine is to be used with intake silencer, carburettor, fuel pump, radiator, wiring loom, ignition system, clutch, gears and exhaust system as supplied by the manufacturer.

• Any type of ignition switch may be used; it must in no way enhance the ignition system. • Unless otherwise specified position and method of mounting the battery, wiring loom, exhaust

system and fuel pump are free provided they are securely fixed and comply with Kartsport New Zealand Sprint chassis (Rule K1).

• The ignition coil must be mounted in the original position as supplied by Rotax.


• The use of thermal barrier coatings/ceramic coatings on or in the engine or exhaust system is not

allowed. • Fitting of helicoil type thread repair inserts to repair damaged threads is allowed, providing such

repairs are not used to derive any benefit other than rectification of damage. • The use of silicon type sealant between the ball and socket joint of the exhaust is permitted. • The use of ceramic / ceramic hybrid bearings or bearings containing any ceramic component, are not

permitted. N12.3 EXHAUST SYSTEM: Must be as supplied by Rotax and cannot be modified except for the

replacement of the silencer absorption material and the use of threaded fasteners in place of the rivets for securing the silencer end cap. The exhaust system may be welded for repair purposes. The weld must not exceed more than half the exhaust’s circumference at the point of the weld. It is permitted to paint the exhaust system with black paint. The use of any other coating or plating is not permitted.Replacement items must be OEM Rotax parts. Exhaust Headers: Standard exhaust headers(s) must be used. Two versions of original exhaust headers are legal to be used. Version 1, without gasket ring (left illustration) Version 2 (EVO) with gasket ring (middle and right illustrations) For version 2 the measurement (C) must be at least 15.5 mm.

The use of maximum 4 pieces of original Rotax exhaust springs, to fix the exhaust system to the cylinder is allowed. (a “safety wire” in the exhaust flange area is not allowed). Permitted modifications on the original exhaust systems are:

• Replacing the original rivets of the silencer end cap by 4 mm metric screws and corresponding locking nuts.

• Replacing the isolating mat (just one original isolating mat may be fitted) inside the silencer and the silencer end cap with perforated tube by original Rotax spares parts.

• Welding a socket (in a distance of 50-80 mm from the ball joint) on the top of the exhaust system for measuring the exhaust gas temperature (EGT).

Additional to the standard isolation mat a steel isolation mat (Rotax part no. 297 983) of the square dimension of 165 +10 mm is legal (not mandatory) to be assembled underneath the standard isolation mat according to the illustration. Clamp (1) must be fitted at a distance of 18+/-2mm, measured from the end of the tube. Clamp (2) must be fitted at the end area of the steel isolation mat. The measurement 10-12 mm from the end of the perforated tube to the beginning of the steel isolating mat is a specification for assembly purpose only! Both clamps (1 and 2) are mandatory to be fitted and tightened.


Exhaust pipe with after muffler as shown in illustrations. There are three versions of exhaust system: Version 1: tuned pipe and silencer

are one piece. The silencer is welded to the 180° elbow and the tuned pipe (top illustration).

Version 2: tuned pipe and silencer are one piece. The silencer is welded to the 180° elbow. Two springs fix the silencer to the tuned pipe (bottom illustration). Following measurements are valid for version 1 and 2: Silencer end cap, diameter of hole: 21,0 mm (maximum). Length of inlet cone: 592 mm +/-5 mm (measured on outside from beginning of exhaust pipe until beginning of cylindrical part). Length of cylindrical part of exhaust pipe: 125 mm +/-5 mm. Length of end cone: 225 mm, +/-5 mm. Outside diameter of 180° bent tube: 41mm +1,5 mm/–1,0 mm (measured at beginning and end of bend).

Version 3: tuned pipe with 180° elbow and silencer are two separate pieces. The silencer is fixed with 2 springs to the 180° elbow and two springs to the tuned pipe. The silencer can be turned that the 90° elbow outlet of the silencer shows either downwards towards the asphalt (preferred version for lowest noise emissions) or towards the back. It is also allowed to use the silencer end cap (without 90° elbow) and perforated tube of version 1 and 2.


Version 3 (EVO)

N12.4 INTAKE SILENCER: Intake silencer with

integrated, washable air filter has to be used with all parts as shown at the illustration and has to be mounted on the support bracket with two screws (in dry and wet condition).

• An 8mm maximum drain hole is permitted. • Intake silencer tube (pos 2) and carburettor

socket (pos 6) are marked with the wording "ROTAX".

• Intake silencer case bottom is marked on the inside with the Rotax part no. 225 015.

• Intake silencer case, top is marked on the inside with the Rotax part no. 225 025.

• Air filter (pos 4) must be installed as shown in the illustration between the two holders (pos 3) and must cover the complete area of the intake silencer case bottom (pos1).

• Two versions of air filters (pos 4) are legal to be used (Rotax 225051 or 225053).

• In wet conditions it is not permitted to attach anything to the intake silencer to protect the air inlet from water spray.

N12.5 CARBURETTOR: DELLORTO carburettor VHSB 34” cast in the housing of the carburettor.

”QD”, “QS” or “XS” (EVO) stamped in the housing of the carburettor. The complete inlet bore in the casting of the carburettor must show cast surface. All jets must be correctly seated and securely fitted at any time (tightened)! Settings of the carburettor adjustment screws (idle and idle air) are free. The position of the jet needle is free.

N12.5.1 Needle Valve Assembly: stamped "150". Needle of needle valve marked

with diamond symbol “INC" only.

N12.5.2 Start Jet: is stamped with the digits “60”.


N12.5.3 Optional Carburettor Plug Screw: marked "ROTAX" (ROTAX 261 030) is

legal to be used.

N12.5.4 Specific specifications for Dellorto VHSB 34 QS and QD

N12.5.4.1 Slide: must show with size “40” in casting and the bottom end of the slide must show cast surface.

N12.5.4.2 Jet Needle: stamped with K98 only. N12.5.4.3 Floats: Only floats marked “3.6 gr” or "5.2 gr" are legal to be used. N12.5.4.4 Needle Jet: stamped with “FN 266”.

Total length: 54.00 +/- 0.3 mm.

Length of bottom section: 11.50 +/- 0.2 mm


Top bore diameter 2.60 +/- 0.15 mm (measured 2mm inside)

4 x 4 cross holes diameter: Plug gauge 0.90 mm NO GO any of the 16 cross holes.

N12.5.4.5 Idle Jet: Only Idle jet permitted is stamped 60. Plug gauge 0.65 mm NO GO the bore of the idle jet 60.

N12.5.4.6 Idle Emulsion Tube: The only Idle Emulsion Tube permitted is stamped 60.

Plug gauge 0.65 mm NO GO the bore.


Plug gauge 0.65 mm NO GO any of the 4 cross bores.

N12.5.4.7 Carburettor Insert: must show stamping "8.5".

Angular bore: Plug gauge 0.60mm NO GO.

Vertical bore: Plug gauge 0.90mm NO GO.


N12.5.4.8 Atomizer: Remove atomizer from carburettor body by means of venturi tool

set (ROTAX 676 034); Atomizer, total length: 23.75 +/- 0.45 mm

Atomizer, length of cylindrical part: 15.75 +/- 0.25 mm

Atomizer, dimension of cutaway: 6.00 +/- 0.15 mm


Atomizer, diameter of cross bore: 4.05 +/- 0.15 mm

NOTE: 1-6-15 implementation for Dellorto VHSB 34 QS and QD carburettors.

N12.5.5 Specific specifications for Dellorto VHSB 34 XS (EVO) NOTE: All other items not noted are as per Dellorto VHSB 34 QS and QD specifications.

N12.5.5.1 Slide: must show with size “45” in casting. N12.5.5.2 Jet Needle: stamped with “K57” only. N12.5.4.3 Floats: Only floats marked "4.0 gr" are legal to be used.

N12.5.4.5 Idle Jet: Has to be stamped with “60”. N12.5.4.6 Idle Emulsion Tube: Has to be stamped with “45”. N12.5.4.7 Needle Jet: stamped with “DP267”.

Total length: 51.00 +/- 0.3 mm.

Length of bottom section: 33.0 +/- 0.2 mm


N12.5.4.8 Carburettor Insert: Must show stamping “12.5”.

N12.6 FUEL PUMP, PULSE LINE, FUEL LINES and FUEL FILTER: OEM MIKUNI diaphragm fuel

pump and components as supplied by Rotax only. Only one fuel pump permitted.

Fuel pump must be mounted on the bottom side of the support bracket for the intake silencer (see

illustration. Only one in-line fuel filter is permitted and this must be positioned in the fuel line between the fuel tank and the fuel pump. All fuel lines must be continuous (one piece without restriction, spigots, junctions, taps and similar devices) apart from the fuel tank pick up, the fuel filter and the fuel pump.

N12.7 INLET SYSTEM: Inlet manifold is marked with the name "ROTAX" and the identification code

"267 915". Some factory flash removal may be present at the conjunction 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 3 mm in width. No additional grinding or machining is permitted. The reed valve assy. is equipped with 2 petal stops and 2 reeds, each having 3 petals. The thickness of the reeds is 0.6 mm +/- 0.10 mm. Genuine Rotax Max reeds only.


N12.8 SPARK PLUG: DENSO Iridium IW 24, 27, 29, 31 or 34 or the NGK equivalent only. Shank length

shall be 20mm maximum. Original washer must be used. Spark plug cap must be marked with "NGK TB05EMA".

N12.9 IGNITION SYSTEM:

Digital battery ignition, variable ignition timing, no adjustments possible. KartSport New Zealand may use various test methods/equipment to determine the conformity of the ignition systems. Minimum length of ignition wire (high tension wire) is 210 mm from outlet of cable at ignition coil to outlet of cable at spark plug connector ( = the visible length of wire ).

N12.9.1 Exchange: Following a decision of the Stewards the Technical Officer(s) may be

authorized to require the exchange of the ignition coil (Denso ignition system) or electronic box (Dellorto ignition system) with a substitute item owned by KartSport New Zealand. The substitute item must be the same make and model as the item previously fitted to the competitor’s engine and must be returned to KartSport New Zealand when requested by the Stewards. Should an earlier return time not be nominated by the Stewards, the item must be returned to their original owners no later than the end of Technical Inspection for the event.

N12.9.2 Ignition Pick Up: The marking of the pick-up must

show the following numbers in the first line 029600-0710. A steel ball (diameter 3-5 mm) placed on circular surface of the sensor must stay in the center of the circular surface.

To fit the gasket (Rotax 431 500, thickness 0,8 mm) between the pick-up and the crankcase is an allowed option.


N12.9.3 Denso Ignition System: The casting of the ignition coil

has to show the following in casting “129000” and “DENSO”. Ignition coil must show 3 pins at the terminal. Connector housing of ignition coil must have either black or green color Version with extension wire (number 265571 engraved as in picture) is not legal to be used. Minimum length of the high tension cable is 210 mm (from outlet of ignition coil to outlet of spark plug connector = visible length of cable). The ignition coil has to be fixed by means of 2 original silent blocks to the gearbox cover. In case the frame collides with the ignition coil, it is an allowed modification to use a supplementary extension bracket (rigid, solid metal, mounted at the original fixation holes of the gearbox cover) to avoid any collide. To fit a second original mass cable (ROTAX part no. 264 910) is an allowed option.

N12.9.4 Dellorto Ignition System (EVO): Ignition coil with separate electronic box

(ECU, specific for every engine). Ignition coil and electronic box have to be fitted by means of the corresponding brackets and components according to the illustration.

The visual appearance of the ignition coil must be identical with the pictures. Ignition coil must show 2 pins at the terminal. The ignition coil is labeled with two stickers, “BRP 666820” and “NIG 0105”. The ignition coil is still legal to be used also if one or both stickers disappeared. Silent blocks should be used to mount the ignition coil. The ground cable of the cable harness has to be connected to the engine at the rear, left Allen screw of the cylinder head cover.

The FR125 Max electronic box is labelled with sticker “666814, 125 MAX evo” and is still legal if the sticker has disappeared. Full EVO loom including start/stop buttons must be used.


N12.10 BATTERY: As per Rule K1.37 or the genuine Rotax battery clamp part number 660221 or EVO battery mount. Only one 12v battery is permitted. Battery must be mounted on the left side of the chassis.

N12.11 STROKE: 54.5 mm +/-0.1 mm. N12.12 SQUISH GAP: 1.00 mm minimum. Measure as per Procedure Rule M12. N12.13 COMBUSTION CHAMBER INSERT: Cast identification code has to be "223 389" or "223 389

1" or "223 389 2" or 223 389 2/1" or “223 389 2/2”. Casted wording "ROTAX" and/or "MADE IN AUSTRIA" must be shown. No welding nor machining of this part is allowed.

Combustion chamber insert must conform to KartSport New Zealand Tech gauge. The crack of light between the template and the profile of the combustion chamber insert has to be the same over the whole profile. Carbon deposits can be removed before using the gauge. Heights of combustion chamber insert have to be 27.55 mm with a tolerance of +0.0/-0.1 mm (A) and 28.80 mm with a tolerance of +/- 0.2 mm (B).

Uncoated as well as red coated (EVO) cylinder head is legal to be used.

N12.14 PISTON and RING: Original, coated, aluminium, cast piston with one piston ring. The piston

has to show on the inside the cast wording "ELKO" and "MADE IN AUSTRIA". Machined areas are: Top end of piston, outside diameter, groove for the piston ring, bore for the piston pin, inside diameter at bottom end of piston and some pre-existing factory removal of flashing at the cut out of the piston skirt. All other surfaces are not machined and have cast surface.

B A


Original, magnetic, rectangular piston ring. Ring height : 0.98 +/- 0.02 mm Piston ring is marked either with "ROTAX 215 547" or "ROTAX 215 548".

"Window" type piston as delivered in the early days of production is no longer legal to be used. Any mechanical treatment or overwork is forbidden, changing the original surface is illegal (e.g. removal of carbon deposits).

N12.15 GUDGEON PIN: is made out of magnetic steel. Dimensions must be according to the

drawing. The minimum weight of the gudgeon pin must not be lower than 32.10 grams.

N12.16 CYLINDER: Light-alloy-cylinder with GILNISIL-plating. Any re-plating of cylinder is not

allowed. Cylinder with one main exhaust port and exhaust valve. Maximum bore of cylinder = 54.035 mm (measured 10 mm above the exhaust port). Cylinder has to be marked with the "ROTAX" logo. Cylinder with pneumatic timed exhaust valve. Cylinder has to be marked either identification code 223 993, 223 996 or 223 997.

N12.16.1: Height of Cylinder has to be 87.00 mm -0.05/+0.1 mm (measured with a digital vernier min. length 200mm).

N12.16.2: Cylinder Surfaces: All transfer ports and passages have cast finish surface except some removal (done by the manufacturer) of cast burr at the inlet passage, exhaust port and passages. All ports have chamfered edges to prevent ring snagging. Any additional machining is not permitted. The top edge of exhaust port may show some pre-existing machining from the manufacturer. The sealing flange for the exhaust socket may show signs of machining from the manufacturer. All ports have chamfered edges. Any additional machining is not permitted.


Cylinders marked 223 993, 223 994 and 613 933 the upper edge of the central boost port may show factory machining. The flange for the exhaust socket may show either cast finish or machined surface. Machined surface can be either flat or show a circular sealing bump. The top edge of the exhaust port may show either just a cast finish surface (left picture) or signs of a CNC machining (central picture) or signs of CNC machining in combination with signs of manual grinding (right picture).

The exhaust port may show partial manual grinding done by the manufacturer to eliminate minor casting defects and to eliminate the NIKASIL burr at the end of the NIKASIL plating.

N12.17 EXHAUST PORT TIMING: The "exhaust port timing" (distance from the top of the cylinder to

the top of the exhaust port) has to be checked by means of the template (ROTAX 277 397). Insert the template into the cylinder ensuring that the template is touching the cylinder wall and that the finger of the template is located in the middle of the exhaust port (highest point). Move the template upwards, until the finger is touching the top edge of the exhaust port. Insert a feeler gauge between the top of the cylinder and the template. It must not be possible to fit the feeler gauge specified (FR125 MAX: 0.75 mm). At cylinders 223 993 the cylinder is also legal if the template doesn´t fit in at all.

N12.18 EXHAUST POWER VALVE: If the piston is moved in direction top of cylinder and first time

covering completely the exhaust port, it must be possible to insert the exhaust valve gauge (ROTAX 277 030) until it stops at the surface of the cylinder (a feeler gauge of 0.05 mm must not be possible to fit in at any area around). Modifying the exhaust valve gasket (ROTAX 250 231) between the cylinder and the power valve housing is illegal.


As supplied by the manufacturer with no modification allowed. Two versions of original exhaust valve systems (pneumatic/electronic timed) are legal to be used. Both systems have to be used as supplied with all components fitted. Length of the exhaust valve (item 4 of pneumatic timing, item 2 of electronic timed exhaust valve) is 36,5 mm +0,20 mm/-0,30 mm. Width of collar is 4,8 mm +/-0,3 mm

Green coloured exhaust bellow (item 11 of pneumatic timed exhaust valve, item 10 of electronic timed exhaust valve, Rotax part no. 260 723) only is legal to be used.

Version 1, pneumatic timed exhaust valve.

Version 2, electronic timed exhaust valve (EVO) (crankcase vacuum used to close exhaust valve) Spring (13) below the exhaust valve piston (11)


At the electronic times exhaust valve also the version using the positive pressure in crankcase to close the exhaust valve is legal to be used.

Version 2, electronic timed exhaust valve (EVO)

(crankcase positive pressure used to close exhaust valve) Spring (13) outside the exhaust valve piston (11)

To fit the impulse nozzle “1” into the pressure hose is an allowed adjustment. The direction of the impulse nozzle inside the pressure hose is free. N12.19 CON ROD: Con rod has to show forged numbers "213", "365", "367" or “362”(EVO) on shaft.

Grinding or polishing of shaft of con rod is not permitted. Shafts of con rods "213", "365" and "367" are not machined and are copper plated.

Shaft of con rod “362” (EVO) is not copper plated and is blank (grey).

“1”


N12.20 CRANKCASE: As supplied by the manufacturer. Uncoated as well as black coated (EVO)

crankcases are legal to be used. No grinding/polishing is permitted in the two main transfer passages as well as in the crank-area. Crankshaft main bearing 6206 from FAG only is allowed (must be marked with code 579165BA or Z579165.11.KL).

N12.21 CYLINDER BASE GASKETS: genuine ROTAX

gaskets only. N12.22 BALANCE DRIVE: Only steel balance gears are

legal to be used. Balance gears must be installed and must be aligned according to the instruction in the repair manual. Mixing of steel balance gears of different width (6,0 and 9,0 mm) is strictly forbidden.

N12.23 BALANCE SHAFT: Balance shaft and balance

gears must be installed. Configurations of part no. 237 949 (equal with 237 948) only is legal. Surface (1) is not machined and must show cast surface. Measurement from centre of balance shaft to outer diameter of fly weight of balance shaft at defined length must not be lower than specified. The minimum weigh of the dry balance shaft must not be lower than: 255 grams for balance shaft ROTAX part no. 237 949 (equal with 237 948).

N12.24 CLUTCH: Both clutch element versions (item 6 with or without holes) as in illustration are

legal to be used. O-Ring (item 11 must be used). Old version clutch element can be either untreated or nitrated configuration. For 11 tooth sprocket, either the plain bearing (Rotax # 233850, 15x17x20) or (15x17x17.6 Rotax # 233855) must be fitted without any O-ring or Sealed needle cage bearing (15x19x17, Rotax # 632415) must be fitted with O-ring (12x2.5, Rotax # 950815). Non Genuine Rotax Max 17 tooth Drive Sprockets are permitted for SuperKart competition only.


Steel clutch and clutch drum of new clutch version must be within following specifications. Height of clutch: Minimum: 11.45 mm

Thickness of clutch shoe: Measurement has to be done at the 3 open ends of the clutch shoes, 5 - 10 mm from the machined groove (all clutch shoes must be completely closed at measurement - no

gap). No measurement may be below 24,10 mm.

Outer diameter of clutch drum: Diameter has to be measured with a sliding caliper just beside the

radius from the shoulder (not at the open end of the clutch drum). Minimum diameter: 89.50 mm.


Inner diameter of clutch drum: The inner diameter has to be measured with a sliding caliper. The

measurement has to be done in the middle of the clutch drum (in the contact area of the clutch drum). Maximum diameter: 84.90 mm.

Height of sprocket with clutch drum assembly: Minimum height: 33.90 mm.

12.25 CHAIN/CLUTCH GUARD: Must be fitted at all times. For Crankcase Rotax # 295913 (new style) the chain/clutch guard Rotax # 260772 must be used.

For Crankcase Rotax # 295911 (original style) either the chain/clutch guard Rotax # 260772 or any other third party chain/clutch guard of a similar design/effectiveness must be used.

N12.26 RADIATOR: The removal of the thermostat from the cylinder head cover is an allowed

modification. Radiator must be mounted with all components as shown in the respective illustration. Any non original device to control the air flow through the radiator is prohibited. The radiator has to be mounted on the right side of the engine. Blanking of the radiator is allowed (Rule K1.38). The use of repaired radiators is permitted. The filing of the crankcase is permitted to allow the easy fitting of the water connection. Coolant: See Rule L6.3. Three different versions as shown in the illustrations are legal to be used. Version 1 Cooling area: Height = 290 mm, Width = 133 mm Thickness of radiator: 32 mm


Version 2 Cooling area: Height = 290 mm, Width = 133 mm Thickness of radiator: 32 mm The support plate (pos. 7) enables two different mounting positions (height) of the radiator. Both mounting positions are legal to be used.

\

Version 3 Cooling area: Height = 290 mm, Width = 138 mm Thickness of radiator: 34 mm Radiator must be stamped on the side with the wording “ROTAX”. To remove the original flap is an allowed modification.

N12.27 LEGAL ADDITIONS: Limited to motor mount, water temperature gauge, tachometer/hour meter,

data logger. N12.28 NON TECH ITEMS: Fasteners, circlips, washers and exhaust retaining springs. The starter motor

shall be installed as originally supplied and be operable, but may be repaired and its parts not subject to technical inspection.

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