Rotax 125 Micro Max Homologation Approved - Karting … 125 Micro... · 2015-07-30 · TECHNICAL SPECIFICATIONS – JUNIOR (MICRO) – (A) FR 125 MAX (NON EVO) OR (B) FR 125 MAX (EVO)

110H NAL HOMOLOGATION FORM

ENGINE

NATIO Homologation N°

Manufacturer BRP-POWERTRAIN GMBH & CO KG

Make ROTAX

Model 125 MICRO MAX

Validity of the homologation 6 years

Number of pages 25 Plus Appendix This Homologation Form reproduces descriptions, illustrations and dimensions of the engine at the time that Karting Australia

conducted the homologation.

PHOTO OF DRIVE SIDE OF ENGINE PHOTO OF OPPOSITE SIDE OF ENGINE

Signature and stamp of Karting Australia

Les Allen National Technical Commissioner 27 May 2015

Copyright 2014 Karting Australia. All rights reserved. KA HOMOLOGATION NUMBER 110H 1

PHOTO OF DRIVE SIDE OF THE COMPLETE ENGINE

KA HOMOLOGATION NUMBER 110H 2 Copyright 2014 Karting Australia. All rights reserved.


PHOTO OF OPPOSITE DRIVE SIDE OF THE COMPLETE ENGINE


PHOTO OF THE REAR OF THE COMPLETE ENGINE


PHOTO OF THE FRONT OF THE COMPLETE ENGINE


PHOTO OF THE COMPLETE ENGINE TAKEN FROM ABOVE


PHOTO OF THE COMPLETE ENGINE TAKEN FROM BELOW


TECHNICAL INFORMATION

A

CHARACTERISTICS

The number of decimal places must be 2 or comply with the relevant tolerance. Tolerances & remarks

Cylinder

Volume of cylinder 125cm³ <125cm³

Original bore 54mm --

Theoritical maximum bore 54.08mm --

Original Stroke 54.5mm --

Number of transfer ducts, cylinder/sump 5 / 3 --

Number of exhaust ports / ducts 1 --

Volume of the combustion chamber 8.9cm³ minimum

Volume of the combustion chamber in the cylinder head 11.6cm³ minimum

Crankshaft

Number of bearings 2 --

Diameter of bearings 30MM 0.1mm

Minimum weight of crankshaft 2200 g minimum

All parts represented on page 17 photo

Balance shaft

Minimum weight of balance shaft 255g minimum

Percentage of balancing TBA % minimum

Connecting rod

Connecting rod centreline 100mm 0.2mm

Diameter of big end 26mm 0.05mm

Diameter of small end 19mm 0.05mm

Min. weight of the connecting rod 100g minimum


Piston

Number of piston rings 1

Min. weight of the bare piston 125g minimum

Gudgeon pin

Diameter 15mm 0.05mm

Length 45.6mm 0.15mm

Minimum weight 32.1g Minimum

Clutch

Minimum weight 1000g minimum

Of all the parts represented on the page 21 technical drawing

B

OPENING ANGLES

Of the inlet (main transfer ports) 119.5° 2°

Of the inlet (secondary transfer ports, for 5 transfer ducts engine) 120° 2°

Of the exhaust 178° 2°

Of the boosters 118° 2° * Angular reading by inserting a 0.2 x 5mm gauge.

C

MATERIAL

Cylinder head ALUMINIUM

Cylinder ALUMINIUM

Cylinder wall GILNISIL COATED

Sump ALUMINIUM

Crankshaft STEEL

Connecting rod STEEL-ALLOY

Piston ALUMINIUM


D.1 CYLINDER UNIT

EXPLODED DRAWING OF THE CYLINDER, CYLINDER HEAD AND EXHAUST MANIFOLD UNIT

* For 125 Micro Max / 125 Mini Max only!

To achieve the defined minimum squish gap, one Restriction Plate with same shape as cylinder base gasket in

combination with at least two cylinder base gaskets (one below the spacer and one above the spacer) must be

used.The squish gap must be measured with a certified slide gauge and by using a 3 mm tin wire (Rotax Part

No. 580 132).

Squish Gap for 125 Micro Max / 125 Mini Max only!

125 Micro MAX/evo minimum = 2,40 mm

125 Mini MAX/evo minimum = 2,40 mm

Without screws or gaskets. The aim of the exploded drawings is to identify the principles, the functioning and the whole mechanical unit

D

PHOTOS, DRAWINGS & GRAPHS

… Section D.1


DRAWING OF THE CYLINDER DEVELOPMENT

Indicate on the drawing :

B1/B2 = minimum thickness of the inlet (transferts) ribs.

A1/A2/A… = maximum inlet width measured at the chord.

E1/E2 = minimum thickness of the exhaust rib (if existing).

C1/C2/C… = maximum exhaust width measured at the chord.

DRAWING OF THE CYLINDER BASE without dimensions

PHOTO OF THE CYLINDER BASE

… Section D.1


DRAWING OF THE CYLINDER HEAD AND OF THE COMBUSTION CHAMBER without dimensions

PHOTO OF THE CYLINDER HEAD PHOTO OF THE COMBUSTION CHAMBER IN THE CYLINDER HEAD

… Section D.1


VERTICAL CROSS SECTION VIEW OF CYLINDER WITH LINER, without dimensions

PHOTO OF THE CYLINDER FROM ABOVE PHOTO OF THE CYLINDER FROM RH SIDE


... Section D.1

EXHAUST DUCT LENGTH

ANGLE in ° Minimum in mm

--° +/-1° -- mm

The L min. dimension will be the result of the value taken on the reference engine minus 5 mm.

Technical Drawing No.13

N/A TO 125 MICRO MAX

A: Centring guide centred in relation to the exhaust duct by the exhaust manifold fixation screws, with a total thickness of 20

+/- 0.05 mm and being drilled in its centre by a hole with a 5 mm diameter, H7 bore.

B: Control gauge composed of a shaft with a 5g6 diameter having a 2.5 mm radius at its end and a length = L min + 20+10.

TRANSFER DUCTS VOLUME

Transfer position on

5-transfer cylinder

Transfer position on

3-transfer cylinder

TRANSFER No.

VOLUME

in cm3

LH 1 RH 1

LH 2 RH 2

5

LH 1 RH 1

3

Transfer No. 1 LH --.-- +/- 5 %

Transfer No. 2 LH --.-- +/- 5 %

Transfer No. 3 or 5 --.-- +/- 8 %

Transfer No. 2 RH --.-- +/- 5 %

Transfer No. 1 RH --.-- +/- 5 %


... Section D.1

Technical Drawing No.13 bis

FRONT VIEW DRAWING – with dimensions

Minimum template Maximum template

Measurement ‘C’ must be minimum 15.5mm

Measurement ‘C’ must me maximum 16.5mm

Maximum template: internal profile of the gasket plane of the manifold

of the original cylinder plus 1 mm

Minimum template: internal profile of the gasket plane of the manifold

of the original cylinder minus 1 mm

Thickness: 5 +/- 0,05 mm

INTERNAL PROFILE OF THE EXHAUST DUCT

Templates of the internal dimensions of the exhaust duct: gasket plane of the manifold.


D.2 CONROD, CRANKCASE, CRANKSHAFT & PISTON

EXPLODED DRAWING OF THE PISTON, CRANKSHAFT, CONNECTING ROD AND CRANKCASES UNIT (exploded crankshaft)



...Section D.2

PHOTO OF THE CRANKSHAFT & CONROD PHOTO OF THE CONROD

DRAWING OF THE PISTON


...Section D.2

PHOTO OF THE INSIDE OF THE RH CRANKCASE

PHOTO OF THE INSIDE OF THE LH CRANKCASE

DRAWING OF THE CRANKSHAFT - CON ROD UNIT (DIMENSIONS incl. tolerances, big & small ends thickness, crank mass thickness & diameter )


D.3 BALANCE SHAFT & WATER PUMP

EXPLODED DRAWING OF THE BALANCE SHAFT, WATER PUMP INCLUDING HOUSING


…Section D.3


PHOTO OF THE BALANCE SHAFT PHOTO OF THE WATER PUMP IMPELLER

DRAWING OF THE BALANCE SHAFT (DIMENSIONS incl. tolerances)


D.4 REED VALVE & CLUTCH

TECHNICAL DRAWING (exploded view) OF THE CLUTCH ASSEMBLY

TECHNICAL DRAWING (exploded view) OF THE REED VALVE

The aim of the exploded drawings is to identify the principles, the functioning and the whole mechanical unit


… Section D.4

DRAWING OF THE REED VALVE (DIMENSIONS incl. tolerances)

DRAWING OF THE REED VALVE COVER (only basic engine)


D.5 EXHAUST SYSTEM

PHOTO OF THE EXHAUST MANIFOLD

Maximum inner diameter of exhaust socket is:-

- 18.2mm (125 Micro Max)

PHOTO OF THE EXHAUST

Exhaust for 125 Micro Max

TECHNICAL DESCRIPTIONS OF THE EXHAUST (Art. 8.9.3 of HR)

Weight in g - MICRO MAX: 2300G Minimum

Volume in cc +/-5 %


D.6 STARTER

EXPLODED DRAWING OF THE STARTING UNIT AND OF ITS HOUSING



Ignition homologation No. Dellorto Ignition System

Ignition homologation No. Ignition Coil is labelled with two stickers ‘’BRP 666820’’ & ‘‘NIG0105’’

Ignition homologation No. Electronic box is labelled with sticker ‘’666814, 125 MAX evo’’

Code F125 --/M/18 Color yellow

IGNITION SYSTEM

D.7 ELECTRICAL SYSTEM

TECHNICAL SPECIFICATIONS – JUNIOR (MICRO) – (A) FR 125 MAX (NON EVO) OR (B) FR 125 MAX (EVO)

AUSTRALIA - Version: 1 2 June 2015 Page: 1 of 36

Appendix A to ROTAX MICRO MAX Homologation Documents

The following notes are additional to the details contained in these Homologation documents for the ROTAX

MICRO MAX engine (the “Engine”) and are to be read in conjunction with the specifications and details contained

therein. They form part of the Homologation documents for the Engine.

The Engine must at all times be used and be presented in strict conformity with the specifications detailed in the

homologation documents. Unless otherwise expressly permitted by Karting Australia, only Rotax OEM parts

that have been manufactured and/or supplied by Rotax for the Engine are permitted to be used in the Engine

at any time.

Neither the Engine nor any of its ancillary components may be modified other than in accordance with the Rules,

these Homologation and Technical Specification documents.

UNLESS IN THE KARTING AUSTRALIA RULES AND/OR THESE HOMOLOGATION AND

TECHNICAL SPECIFICATION DOCUMENTS IT SAYS THAT YOU CAN, THEN YOU

CANNOT.

FOR AUSTRALIAN COMPETITION

GENERAL

1. EVO ENGINE INTRODUCTION INTO AUSTRALIAN KARTING

The introduction of the Rotax EVO Engines into Australia will be separated into two distinct categories:

a. Engines that are to be used in all Rotax Pro Tour National Series Competition Classes; and

b. Engines that are to be used in non-‐Rotax Pro Tour Competition Classes including; KA TaG, Tag

125, TaG 125 Restricted, Junior Max, Rotax 125 and DD2.

2. “NON EVO”, “UPGRADED TO EVO” OR “FULL EVO 2015”

a. A “FULL EVO 2015 ENGINE” (EVO) is a complete new Rotax EVO Engine including exhaust system

as homologated by KA in 2015 and that has been purchased from IKD after 1 January 2015.

i. A FULL EVO 2015 ENGINE must use all of the EVO Components supplied save that it is

permitted for an “EVO” Engine to use a cylinder head cover that is not red, and a

crankcase that is not black.

b. An “UPGRADED TO EVO ENGINE” (EVO) is a previously homologated Junior Max, Rotax 125 or

DD2 engine (“Older Engines”) that has been wholly or partially upgraded to EVO Engine

specification by the addition of any of the Performance Components listed herein.

i. Note that for Rotax Pro Tour Competition, if any of the Performance Components are

used on the Engine, all of the Performance Components must be used.

ii. Note that for non-‐Rotax Pro Tour Competition, the Engine can be partially Upgraded to

EVO Engine specification by the use of any of the Performance Components (in which

case it will still be considered to be an “Upgraded to EVO Engine”).



iii. For the sake of absolute clarity, the EVO Exhaust System and EVO Exhaust Socket are not

designated by Rotax or IKD to be Performance Components and are not required to be

fitted to an Upgraded To EVO Engine.

c. A “NON EVO ENGINE” (NON EVO) is a previously homologated Junior Max, Rotax 125 or DD2

engine (“Older Engines”) that has not been wholly or partially upgraded to EVO Engine

specification by the addition of any of the Performance Components listed herein.

i. A “Non EVO Engine” is permitted to use the “EVO” Exhaust System, “EVO” Exhaust

Socket, “EVO” Conrod, “EVO” Crankshaft, “EVO” Piston and “EVO” Battery Holding Unit

and Switches.

3. EVO PERFORMANCE COMPONENTS

All EVO performance components are external only. EVO Performance Components are:

a. Carburettor “VHSB 34 XS” (Rotax Part no. 295 060)

b. Dellorto Ignition System with Electronic Box (Rotax part no. 666 812)

Once an engine is determined to be either “NON EVO”, or “EVO” (Includes both “UPGRADED TO EVO” and

“Full EVO 2015” Engines) the relevant Technical Specifications outlined in this document apply to that Engine.

4. The introduction of the new Rotax EVO Engine to Australian competition will be done according to the

following principles.

5. Rotax Pro Tour Events

a. Rotax World Rules as approved by KA for Australia will apply to these events commencing at

Rotax Pro Tour Round 4, 2015.

b. EVO Engines will be permitted to be used in accordance with the homologation of these engines.

c. Previously homologated Junior Max, Rotax 125 and DD2 engines (the “Older Engines”) will

remain eligible for competition in Rotax Pro Tour events.

d. There will be no parity adjustments to equalize the EVO Engines and the Older Engines in the

Rotax Pro Tour.

e. Older Engines can be upgraded at any time to full EVO Engine specification using the EVO

Performance Components.



(A) FR 125 JUNIOR MAX (NON EVO) SPECIFICATION ONLY–WITHIN THE ENGINE SEAL

Squish Gap

A1.1

A1.2

FR 125 Junior Max: Minimum = 2.4mm

The squish gap must be measured with a certified

slide gauge and by using a 3 mm tin wire (Rotax

part no. 580 132). The crankshaft must be turned

by hand slowly over top dead centre to squeeze

the tin wire. The squish gap must be measured on

the left and right side in the direction of the piston

pin. The average value of the two measurements

counts.

Combustion

A2.1

Cast identification code has to be "223 389" or

Chamber "223 389 1" or "223 389 2" or 223 389 2/1" or

Insert “223 389 2/2”.

A2.2 Casted wording "ROTAX" and/or "MADE IN

AUSTRIA" must be shown

A2.3 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).

A2.4 The profile of the combustion chamber insert has

to be checked with a template (ROTAX part no.

277 390). The crack of light between the template

and the profile of the combustion chamber insert

has to be the same over the whole profile.

NOTE: If the combustion chamber insert fails the

template check as described herein, detailed

measurements of the combustion chamber insert

must be taken to determine conformity or non-

conformity of the component.

Piston with

Ring

Assembly

A3.1

A3.2

A3.3

Original, coated or uncoated, aluminium, cast

piston with one piston ring. The piston has to

show on the inside of the cast wording "MADE IN

AUSTRIA" (Image 1) and "ELKO" (Image 2).

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 (Image 3)

of flashing at the cut out of the piston skirt. All

other surfaces are not machined and have cast

surface.

Any mechanical treatment or rework of the piston

is forbidden, (e.g. removal of carbon deposits).

Cleaning without changing the original surface is

allowed.



A3.4

A3.5

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".

Piston Pin

(Gudgeon

Pin)

A4.1

A4.2

A4.3

Piston pin is made out of magnetic steel.

Dimensions must be according to the drawing.

The minimum weight of the piston pin must not be

lower than 32.10 grams.

Cylinder

A5.1

Light-alloy-cylinder with GILNISIL-plating.

Any re-plating of cylinder is not allowed.

A5.2 Cylinder with one main exhaust port and no

exhaust valve.

A5.3 Maximum bore of cylinder = 54,035mm

(measured 10 mm above the exhaust port).

A5.4 Cylinder has to be marked with the "ROTAX" logo

(see pictures).

A5.5.1 Cylinder has to be marked either identification

code 223 998, 223 994 (see pictures).

A5.5.2

Cylinder 223 999 is outlawed.

A5.6

Height of cylinder has to be 87mm -0.05/+0.1mm

(measured with a digital calliper).

A5.7.1

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



A5.7.2

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.

A5.7.3

On cylinders marked 223 994 the upper edge of

the central boost port may show factory

machining.

A5.7.4

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.

A5.7.5

The top edge of the exhaust port may show either

just a cast finish surface (Image1) or signs of

CNC machining (Image2) or signs of CNC

machining in combination with signs of manual

grinding (Image 3). The exhaust port may show

partial manual grinding done by the manufacturer

to eliminate minor casting defects and/or to

eliminate the NIKASIL burr at the end of the

NIKASIL plating (Image 3).



A5.7.6

A5.8

On cylinders marked 223 994 the exhaust port

may show factory machining all around.

FR 125 Junior Max: Cylinder 223 998 = 0.90 mm

Cylinder 223 994 = 1.10 mm

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 part

no. 277 397).

Insert the template into the cylinder, so 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

filler gauge between the top of the cylinder and

the template. It must not be possible to fit the

feeler gauge specified below.

NOTE: Take care to use the corresponding gauge

of the template (JUN, MAX or DD2) for the

respective cylinder.

Inlet System

A6.1

A6.2

A6.3

A6.4

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.



Crankshaft

A7.1

A7.2

A7.3

A7.4

A7.5

Stroke 54.5 mm +/-0,1 mm

Con rod has to show forged numbers "213",

"365", "367" or “362” on shaft.

Shafts of con rods "213", "365" and "367" are not

machined and are copper plated (Image 1). Shaft

of con rod “362” is not copper plated and

blank/grey (Image 2).

Grinding or polishing of shaft of con rod is not

permitted.

Effective from 1st June 2012, crankshaft main

bearing 6206 from FAG only is allowed for

Rotax National Series, State Championships or

events where Rotax is run as a standalone class

(must be marked with code 579165BA or

Z-579165.11.KL). This does not apply to

Restricted TAG, TAG & Sportsman style

classes.

Balance Shaft

A8.1

A8.2

A8.3

A8.4

A8.5

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 weight of the dry balance shaft

must not be lower than: 255 grams for balance

shaft Rotax part no. 237 949 (equal with 237 948).

Crankcase

A9.1

A9.2

As supplied by the manufacturer. No grinding or

polishing is permitted in the two main transfer

passages as well as in the crank area.

Uncoated as well as black coated crankcases are

legal to be used.



Balance Drive

A10.1

A10.2

A10.3

A10.4

Only steel balance gears are legal to be used at


events where Rotax is run as a standalone class.

Other events can continue to use the old style

plastic balance gears.

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.

Balance drive gear compartment must be vented

and connected to a minimum 100mL plastic

overflow bottle via plastic hose.

(A) FR 125 JUNIOR MAX SPECIFICATION ONLY – OUTSIDE THE ENGINE SEAL

It is the responsibility of the competitor to check his equipment (all components outside the engine seal as

mentioned below), to assure that his equipment is conforming to the technical specification below.

DENSO

A11.1

DENSO digital battery ignition, variable ignition

Ignition timing, no adjustment necessary and possible.

System

A11.2

The casting of the ignition coil has to show the

following in casting "129000-" and "DENSO"

(Image 1).

A11.3

Ignition coil must show 3 pins at the terminal

(Image 2).

A11.4 Connector housing of ignition coil must have

either black or green colour.

A11.5 The ignition coil has to be fixed by means of 2

original silent blocks to the gearbox cover. Only

in case of chassis component interference with

the original mounting location of the ignition

coil, a supplementary extension bracket, rigidly

constructed and fabricated of solid metal, of

minimum dimensions and attached to the

original case mounting holes, is permitted for

mounting of the coil.

A11.6 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). Ignition coil must be

in working condition (to be tested in case of

doubt).



A11.7

A11.8

A11.9

A11.10

The pick-up must be marked with the numbers

029600-0710, followed by a variable production

code in the 2nd line (Image 3).

HINT: In case of doubt, an easy check is to

place a steel ball (3-5 mm in diameter) on the

pick-up (engine side). The steel ball must stay

in the center of the pick-up surface.

Spark plug cap must be marked with

“NGK TB05EMA” (Image 4).

Battery must be fitted to the chassis with at

least 2 screws. Position of the battery is free.

The earth strap may be fitted with a connector

for ease of removal of the engine. Rotax Wiring

Harness must be OEM only, with no fittings or

repairs. The ignition coil can be relocated from

the crankcase as far as the OEM harness will

permit.

Centrifugal

A13.1

Dry centrifugal clutch with engagement maximum

Clutch at 4,000 r.p.m.

This means that the kart must start to move

before the engine speed reaches

4,000 r.p.m.

There are 2 versions of the steel clutch (Image 1)

and both are legal to be used. The older version

can be either untreated or nitrated configuration.

A13.2.1 Needle cage bearing 15x19x17 (Rotax part no.

632 415) must be fitted for 12, 13, 14 & 15 tooth

sprockets. Plain bearing 15x17x20 (Rotax part no.

233 855) must be fitted for 11 tooth sprockets.

(Image 2)

A13.2.2 O-Ring 12x2.5 (Rotax part no. 950 815) must be

fitted and must assure an appropriate sealing

between the clutch drum and the needle/plain

bearing.

A13.3 No extra lubrication or substance is allowed inside

the clutch drum, in addition to the grease that

originates from lubrication of the needle cage

bearing, and enters the clutch area.

See (Images) showing worst case scenario of

when grease exits the needle bearing area, even

with the O-Ring installed. Only the fixation nut and

the inside of the drum show signs of grease. The

running surface of the drum is completely dry.

When the plain bearing for 11 tooth sprockets is

used, the clutch area must be absolutely free of

grease or any additional substance.



A13.4.1

Steel clutch (both versions) and clutch drum must

be within the following specifications:

A13.4.2

Height of clutch: Minimum = 11.45 mm

A13.4.3

Thickness of clutch: Minimum = 24.10 mm

NOTE: 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, with no gap

showing).

A13.4.4

Outer diameter of clutch drum:

Minimum diameter = 89.50 mm

NOTE: Diameter has to be measured with a

sliding calliper, just beside the radius from the

shoulder (not at the open end of the clutch drum).

A13.4.5

Inner diameter of clutch drum:

Maximum diameter = 84.90 mm

NOTE: The inner diameter has to be measured

with a sliding calliper. The measurement has to be

done in the middle of the clutch drum (in the

contact area of the clutch drum).

A13.4.6

Height of sprocket with clutch drum assembly:

Minimum height = 33.90 mm

A13.4.7

The original Rotax clutch (3 spring) is eligible to

be used at any event until further notice.



Intake

Silencer

A14.1

A14.2

A14.3

A14.4

A14.5

Intake silencer with integrated, washable air filter

has to be used with all parts as shown in the

illustration and has to be mounted on the support

bracket with two screws (in dry and wet

condition).

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 must be installed as shown in illustration.

The original square type intake silencer is not

eligible to be used for Rotax National Series,

State Championships or events where Rotax is

run as a standalone class. It can be used in

Restricted TAG, TAG and Sportsman style

classes.

Carburettor

A15.1

A15.2

A15.3

A15.4

A15.5

A15.6

A15.7

Dellorto carburettor with “VHSB 34” cast in the

housing of the carburettor.

“QD” or “QS” is stamped in the housing of the

carburettor.

The complete inlet bore in the casting of the

carburettor must show a cast surface.

Carburettor Slide shows digits “40” in casting

Jet needle stamped with “K98” only.

Settings of the carburettor adjustment screws are

free.

The following two combinations of floats and idle

jets are legal:

Combination 1:

For carburettor insert 12.5 (as per illustration at

rule 15.16.1) floats marked with “5.2gr” must be

used. Idle Jet and Idle Jet Insert stamped with the

digits “30” must be used.

Combination 2:

For carburettor insert 8.5 (as per illustration at rule

15.16.1) floats marked with “3.6gr” must be used.

Idle Jet and Idle Jet Insert stamped with the digits

“60” must be used.

NOTE: Effective from 1st

January 2014, only

Combination 2 is allowed for Rotax National

Series, State Championships or events where

Rotax is run as a standalone class. This does not

apply to Restricted TAG, TAG and Sportsman

style classes.



A15.8

All jets must be correctly seated and securely

fitted.

A15.9 A minimum required size of Main Jet may be

determined for each race event by a

“Supplementary Regulation”.

A15.10

Needle Valve assembly stamped with the digits

“150” (Image 1)

A15.11

Needle of Needle Valve marked with diamond

symbol “INC” only (Image 2).

A15.12

Start Jet is stamped with the digits “60”.

A15.13.1 Needle Jet is stamped with “FN 266”.

A15.13.2 Total length of Needle Jet = 54.00 +/- 0.3 mm

A15.13.3

Length of bottom section of Needle Jet

= 11.50 +/- 0.2 mm

A15.13.4

Top bore diameter of Needle Jet

= 2.60 +/- 0.15 mm

(measured 2mm inside)



A15.13.5

4 x 4 cross holes diameter of Needle Jet:

Plug gauge 0.90 mm may NOT enter one of the

16 cross holes of the Needle Jet.

NOTE: Use jet gauge set (Rotax part no. 281

920)

A15.14.1

Idle Jet 30 and Idle Jet Insert 30 must be used

with carburettor insert stamped 12.5, as per

illustration at rule A15.16.1.

A15.14.2 Plug gauge 0.40 mm may NOT enter the bore of

the Idle Jet 30.


920)

A15.14.3

Plug gauge 0.40 mm may NOT enter the bore of

the Idle Jet Insert 30.


920)

A15.14.4

Plug gauge 0.40 mm may NOT enter one of the 4

cross bores of the Idle Jet Insert 30.


920)

A15.15.1



A15.15.2 illustration at rule A15.16.1.


the Idle Jet 60.


920)

A15.15.3




920)



A15.15.4




920)

A15.16.1

Carburettor insert must show stamping of either

8.5 or 12.5, as illustrated.

A15.16.2

Plug gauge 0.60 mm may NOT enter the angular

bore of the 8.5 carburettor insert only.


920)

A15.16.3

Plug gauge 0.90 mm may NOT enter the vertical

bore of the 8.5 carburettor insert only.


920).

A15.17.1

Remove atomizer from the carburettor body using

the Venturi Tool Set (Rotax part no. 676 034).

Total length of atomizer = 23.75 +/- 0.45 mm



A15.17.2

Length of cylindrical part of atomizer

= 15.75 +/- 0.25 mm

A15.17.3

Dimension of cutaway of atomizer

= 6.00 +/- 0.15 mm

A15.17.4

Diameter of cross bore of atomizer

= 4.05 +/- 0.15 mm

A15.18

Optional carburettor plug screw marked “ROTAX”

(Rotax part no. 261 030) is legal to be used.

A15.19

The two vent fittings must be connected with the

original 180mm air vent hose.

(Rotax part no. 260 260).

Fuel Pump

A16.1

The original MIKUNI Fuel Pump (diaphragm type)

must be used.

Radiator

A17.1

A17.2

A17.3

Single aluminium radiator, as shown in

illustrations below.

Radiator must be mounted on the right side of the

engine, with all components as shown in the

respective illustrations.

No additional non-original cooling device is

allowed.



A17.4

A17.5

A17.6

The removal of the thermostat from the cylinder

head cover is accepted.

For versions 1, 2 and 3, tape can be applied

around the radiator. Tape may not be removed

from the radiator during operation on the track. All

other means of air flow control through the

radiator are prohibited, except for the plastic flap

on version 3.For version 3, the removal of the

original plastic flap is accepted.

Version 1

Cooling area: Height = 290 mm, Width = 133 mm

Thickness of radiator = 32 mm

Version 2



Version 2 has two legal options to mount the

radiator to the retaining plate (see illustration).

Version 3



The word “ROTAX” is stamped on the side of

radiator.

Radiator

Coolant

A18.1

A18.2

Glycol base or soluble oil coolants are prohibited.

Radiator coolant system must be fitted with a

catch tank of minimum 100mL capacity to retain

radiator coolant overflow, in accordance with

Technical Rules Chapter1 Rule 9(h)(iii) 2



Exhaust

A19.1

Must be as supplied by BRP-POWERTRAIN and

System cannot be modified except for the replacement of

the silencer absorption material and the use of

threaded fasteners in place of the original rivets

for securing the silencer end cap.

A19.2 Just one piece of standard isolation mat is

allowed to be used. Can only be replaced with

genuine spare part (Rotax part no. 297 981).

A19.3.1 Additional to the standard isolation mat is a

special steel isolation mat which is legal, but not

mandatory. It is to be fitted underneath the

standard isolation mat, 10-12 mm from the end of

the tube, with both clamps mandatory.

A19.3.2 Steel isolation mat dimension = 165 mm +10 mm

A19.3.3 Clamp (1) must be fitted at a distance of

18 +/- 2 mm from the end of the tube.

Clamp (2) must be fitted at the end area of the

steel isolation mat.

A19.4 Exhaust pipe versions 1, 2 and 3 with after muffler

as shown in illustrations are legal to be used.

A19.5.1 Version 1

Tuned pipe and silencer are one piece. The

silencer is welded to the 180o

elbow and the tuned

pipe (Image 1).

A19.5.2 Diameter of hole of end cap

Maximum = 21.0 mm

A19.5.3 Length of inlet cone = 592 mm +/- 5 mm

(measured on outside from beginning of exhaust

pipe until beginning of cylindrical part).

A19.5.4 Length of end cone = 225 mm +/- 5 mm

A19.5.5 Outside diameter of 180o

bent tube

= 41 mm + 1.5mm / -1.0 mm

(measure at beginning and end of bend).

A19.6.1 Version 2

Tuned pipe and silencer are one piece. The

silence is welded to the 180o

elbow. Two springs

fix the silencer to the tuned pipe (Image 2).

A19.6.2 Diameter of hole of end cap

Maximum = 21.0 mm

A19.6.3 Length of inlet cone = 592 mm +/- 5 mm

(measured on outside from beginning of exhaust

pipe until beginning of cylindrical part).

A19.6.4 Length of end cone = 225 mm +/- 5 mm



A19.6.5

Outside diameter of 180o

bent tube

= 41 mm + 1.5mm / -1.0 mm

(measure at beginning and end of bend).

A19.7.1

Version 3

The tuned pipe with 180o

elbow and silencer are

two separate pieces. The silencer is fixed with two

springs to the 180o

elbow and two springs to the

tuned pipe.

A19.7.2 The silencer can be rotated so that the 90o

elbow

outlet of the silencer is pointing either downward

towards the asphalt (preferred for lowest noise

emissions) or upward towards the back.

A19.8

For measuring the exhaust gas temperature, a

weld on a socket on top of the exhaust, 50 mm

from the ball joint is allowed.

A20.1

Exhaust sockets version 1 and 2 are legal to be

used.

Version 1

Without gasket ring (Image 1)

Version 2

With gasket ring (Image 2)

Measurement (C) must be at least 15.5 mm

A20.2

The maximum use of exhaust springs to fix the

exhaust to the cylinder is 4 springs.



(B) 125 JUNIOR MAX EVO SPECIFICATION ONLY – WITHIN THE ENGINE SEAL

Squish Gap

B1.1

B1.2

125 Junior Max EVO: Minimum 2.4mm

The squish gap must be measured with a certified

slide gauge and by using a 3 mm tin wire (Rotax

part no. 580 132). The crankshaft must be turned

by hand slowly over top dead centre to squeeze

the tin wire. The squish gap must be measured on

the left and right side in the direction of the piston

pin. The average value of the two measurements

counts.

Combustion

B2.1

Cast identification code has to be "223 389" or

Chamber "223 389 1" or "223 389 2" or 223 389 2/1" or

Insert “223 389 2/2”.

B2.2 Casted wording "ROTAX" and/or "MADE IN

AUSTRIA" must be shown

B2.3 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).

B2.4 The profile of the combustion chamber insert has

to be checked with a template (ROTAX part no.

277 390). The crack of light between the template

and the profile of the combustion chamber insert

has to be the same over the whole profile.

NOTE: If the combustion chamber insert fails the

template check as described herein, detailed

measurements of the combustion chamber insert

must be taken to determine conformity or non-

conformity of the component.

Piston with

Ring

Assembly

B3.1

B3.2

B3.3

Original, coated or uncoated, aluminium, cast

piston with one piston ring. The piston has to

show on the inside of the cast wording "MADE IN

AUSTRIA" (Image 1) and "ELKO" (Image 2).

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 (Image 3)

of flashing at the cut out of the piston skirt. All

other surfaces are not machined and have cast

surface.

Any mechanical treatment or rework of the piston

is forbidden, (e.g. removal of carbon deposits).

Cleaning without changing the original surface is

allowed.



B3.4

B3.5

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".

Piston Pin

(Gudgeon

Pin)

B4.1

B4.2

B4.3

Piston pin is made out of magnetic steel.

Dimensions must be according to the drawing.

The minimum weight of the piston pin must not be

lower than 32.10 grams.

Cylinder

B5.1

Light-alloy-cylinder with GILNISIL-plating.

Any re-plating of cylinder is not allowed.

B5.2 Cylinder with one main exhaust port and no

exhaust valve.

B5.3 Maximum bore of cylinder = 54,035mm

(measured 10 mm above the exhaust port).

B5.4 Cylinder has to be marked with the "ROTAX" logo

(see pictures).

B5.5.1 Cylinder has to be marked either identification

code 223 998, 223 994 (see pictures).

B5.5.2

Cylinder 223 999 is outlawed.

B5.6

Height of cylinder has to be 87mm -0.05/+0.1mm

(measured with a digital calliper).



B5.7.1

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.

B5.7.2

All ports have chamfered edges. Any additional

machining is not permitted.

B5.7.3

On cylinders marked 223 994 the upper edge of

the central boost port may show factory

machining.

B5.7.4

The sealing 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.

B5.7.5

The top edge of the exhaust port may show either

just a cast finish surface (Image1) or signs of

CNC machining (Image2) or signs of CNC

machining in combination with signs of manual

grinding (Image 3). The exhaust port may show

partial manual grinding done by the manufacturer

to eliminate minor casting defects and/or to

eliminate the NIKASIL burr at the end of the

NIKASIL plating (Image 3).



B5.7.6

B5.8

On cylinders marked 223 994 the exhaust port

may show factory machining all around.

FR 125 Junior Max: Cylinder 223 998 = 0.90 mm

Cylinder 223 994 = 1.10 mm

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 part

no. 277 397).

Insert the template into the cylinder, so 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

filler gauge between the top of the cylinder and

the template. It must not be possible to fit the

feeler gauge specified below.

NOTE: Take care to use the corresponding gauge

of the template (JUN, MAX or DD2) for the

respective cylinder.

Inlet System

B6.1

B6.2

B6.3

B6.4

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.



Crankshaft

B7.1

B7.2

B7.3

B7.4

B7.5

Stroke 54.5 mm +/-0,1 mm

Con rod has to show forged numbers "213",

"365", "367" or “362” on shaft.

Shafts of con rods "213", "365" and "367" are not

machined and are copper plated (Image 1). Shaft

of con rod “362” is not copper plated and

blank/grey (Image 2).

Grinding or polishing of shaft of con rod is not

permitted.

Effective from 1st June 2012, crankshaft main

bearing 6206 from FAG only is allowed for


events where Rotax is run as a standalone class

(must be marked with code 579165BA or

Z-579165.11.KL). This does not apply to

Restricted TAG, TAG & Sportsman style

classes.

Balance Shaft

B8.1

B8.2

B8.3

B8.4

B8.5

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 weight of the dry balance shaft

must not be lower than: 255 grams for balance

shaft Rotax part no. 237 949 (equal with 237 948).

Crankcase

B9.1

B9.2

As supplied by the manufacturer. No grinding or

polishing is permitted in the two main transfer

passages as well as in the crank area.

Uncoated as well as black coated crankcases are

legal to be used.



Balance Drive

B10.1

B10.2

B10.3

B10.4

Only steel balance gears are legal to be used at


events where Rotax is run as a standalone class.

Other events can continue to use the old style

plastic balance gears.

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.

Balance drive gear compartment must be vented

and connected to a minimum 100mL plastic

overflow bottle via plastic hose.

(B) 125 JUNIOR MAX EVO SPECIFICATION ONLY – OUTSIDE THE ENGINE SEAL

It is the responsibility of the competitor to check his equipment (all components outside the engine seal as

mentioned below), to assure that his equipment is conforming to the technical specification below.

Dellorto

B11.1

Ignition Coil (same for all engine types) with

Ignition separate Electronic Box (ECU, specific to the

System engine type).

B11.2 Ignition coil and electronic box have to be fitted

by means of the corresponding brackets and

components according to the illustration.

B11.3.1

The visual appearance of the ignition coil must

be identical with the pictures.

B11.3.2 Ignition coil must show 2 pins at the terminal.

B11.3.3

The ignition coil is labelled with two stickers

“BRP 666820” and “NIG 0105”.

B11.3.4 The ignition coil is still legal to be used also if

one or both stickers have disappeared.

B11.3.5 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).

B11.3.6

The earth strap may be fitted with a connector

for ease of removal of the engine. Rotax Wiring

Harness must be OEM only, with no fittings or

repairs.



B11.4

B11.5

B11.6.1

B11.6.2

The pick-up must be marked with the numbers

029600-0710, followed by a variable production

code in the 2nd line (Image 3).

HINT: In case of doubt, an easy check is to

place a steel ball (3-5 mm in diameter) on the

pick-up (engine side). The steel ball must stay

in the center of the pick-up surface.

Spark plug cap must be marked with

“NGK TB05EMA” (Image 4).

The electronic boxes are labelled with stickers

(specific to the engine type) and are still legal to

be used also if the sticker has disappeared.

125 Junior Max EVO: “666812” and

“125 Junior MAX evo”

The electronic box has to be checked with the

ECU tester (Rotax part no. 276 230) according

to the following procedure:

1. Disconnect engine cable harness from

electronic box.

2. Connect ECU tester cable harness to

electronic box.

3. Connect energy cable of ECU tester

cable harness with the chargin

connector of engine cable harness.

4. The ECU tester will automatically detect

the type of the ECU and will start a

check program for the ignition timing

and the timing for the exhaust valve.

5. The ECU tester must show the

following results for 125 Junior Max

EVO:

“ECU TEST OK”

“125 Junior MAX evo”

Centrifugal

Clutch

B13.1

B13.2.1

Dry centrifugal clutch with engagement maximum

at 4,000 r.p.m.

This means that the kart must start to move

before the engine speed reaches

4,000 r.p.m.

There are 2 versions of the steel clutch (Image 1)

and both are legal to be used. The older version

can be either untreated or nitrated configuration.

Needle cage bearing 15x19x17 (Rotax part no.

632 415) must be fitted for 12, 13 and 14 tooth

sprockets. Plain bearing 15x17x20 (Rotax part no.

233 855) must be fitted for 11 tooth sprockets.

(Image 2)



B13.2.2

O-Ring 12x2.5 (Rotax part no. 950 815) must be

fitted and must assure an appropriate sealing

between the clutch drum and the needle/plain

bearing.

B13.3

No extra lubrication or substance is allowed inside

the clutch drum, in addition to the grease that

originates from lubrication of the needle cage

bearing, and enters the clutch area.

See (Images) showing worst case scenario of

when grease exits the needle bearing area, even

with the O-Ring installed. Only the fixation nut and

the inside of the drum show signs of grease. The

running surface of the drum is completely dry.

When the plain bearing for 11 tooth sprockets is

used, the clutch area must be absolutely free of

grease or any additional substance.

B13.4.1

Steel clutch (both versions) and clutch drum must

be within the following specifications:

B13.4.2

Height of clutch: Minimum = 11.45 mm

B13.4.3

Thickness of clutch: Minimum = 24.10 mm

NOTE: 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, with no gap

showing).

B13.4.4

Outer diameter of clutch drum:

Minimum diameter = 89.50 mm

NOTE: Diameter has to be measured with a

sliding calliper, just beside the radius from the

shoulder (not at the open end of the clutch drum).

B13.4.5

Inner diameter of clutch drum:

Maximum diameter = 84.90 mm

NOTE: The inner diameter has to be measured

with a sliding calliper. The measrement has to be

done in the middle of the clutch drum (in the

contact area of the clutch drum).



B13.4.6

B13.4.7

Height of sprocket with clutch drum assembly:

Minimum height = 33.90 mm

The original Rotax clutch (3 spring) is eligible to

be used at any event until further notice.

Intake

Silencer

B14.1

B14.2

B14.3

B14.4

B14.5

Intake silencer with integrated, washable air filter

has to be used with all parts as shown in the

illustration and has to be mounted on the support

bracket with two screws (in dry and wet

condition).

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 must be installed as shown in illustration.

The original square type intake silencer is not

eligible to be used for Rotax National Series,

State Championships or events where Rotax is

run as a standalone class. It can be used in

Restricted TAG, TAG and Sportsman style

classes.

Carburettor

B15.1

B15.2

B15.3

B15.4

B15.5

B15.6

Dellorto carburettor with “VHSB 34” cast in the

housing of the carburettor.

“XS” is stamped in the housing of the carburettor.

The complete inlet bore in the casting of the

carburettor must show a cast surface.

Jet needle stamped with “K57” only.

Settings of the carburettor adjustment screws are

free.

The only combination of floats and idle jets that

are legal is:

Carburettor insert 12.5 (as per illustration at rule

B15.15.1) floats marked with “4.0gr” must be

used. Idle Jet stamped with the digits “60” and

Idle Jet Insert stamped with digits “45” must be

used.



B15.7

All jets must be correctly seated and securely

fitted.

B15.8 A minimum required size of Main Jet may be

determined for each race event by a

“Supplementary Regulation”.

B15.9

Needle Valve assembly stamped with the digits

“150” (Image 1)

B15.10 Needle of Needle Valve marked with diamond

symbol “INC” only (Image 2).

B15.11

Start Jet is stamped with the digits “60”.

B15.12.1 Needle Jet is stamped with “DP 267”.

B15.12.2

Total length of Needle Jet = 51.00 +/- 0.3 mm

B15.12.3

Length of bottom section of Needle Jet

= 33.0 +/- 0.2 mm

B15.13.1



illustration at rule B15.15.1.

B15.13.2


the Idle Jet 60.


920)

B15.13.3




920)



B15.13.4




920)

B15.14

Carburettor insert must show stamping of 12.5, as

illustrated.

B15.15.1

Remove atomizer from the carburettor body using

the Venturi Tool Set (Rotax part no. 676 034).

Total length of atomizer = 23.75 +/- 0.45 mm

B15.15.2

Length of cylindrical part of atomizer

= 15.75 +/- 0.25 mm

B15.15.3

Dimension of cutaway of atomizer

= 5.75 +/- 0.15 mm



B15.15.4

B15.16.1

B15.16.2

Diameter of cross bore of atomizer

= 5.00 +/- 0.15 mm

Optional carburettor plug screw marked “ROTAX”

(Rotax part no. 261 030) is legal to be used.

The two vent fittings must be connected with the

original 180mm air vent hose.

(Rotax part no. 260 260).

Fuel Pump

B16.1

The original MIKUNI Fuel Pump (diaphragm type)

must be used.

Radiator

B17.1

B17.2

B17.3

B17.4

B17.5

B17.6

Single aluminium radiator, as shown in

illustrations below.

Radiator must be mounted on the right side of the

engine, with all components as shown in the

respective illustrations.

No additional non-original cooling device is

allowed.

The removal of the thermostat from the cylinder

head cover is accepted.

For versions 1, 2 and 3, tape can be applied

around the radiator. Tape may not be removed

from the radiator during operation on the track. All

other means of air flow control through the

radiator are prohibited, except for the plastic flap

on version 3.For version 3, the removal of the

original plastic flap is accepted.

Version 1





Version 2



Version 2 has two legal options to mount the

radiator to the retaining plate (see illustration).

Version 3



The word “ROTAX” is stamped on the side of

radiator.

Radiator

Coolant

B18.1

B18.2

Glycol base or soluble oil coolants are prohibited.

Radiator coolant system must be fitted with a

catch tank of minimum 100mL capacity to retain

radiator coolant overflow, in accordance with

Technical Rules Chapter1 Rule 9(h)(iii) 2

Exhaust

B19.1

Must be as supplied by BRP-POWERTRAIN and

System cannot be modified except for the replacement of

the silencer absorption material and the use of

threaded fasteners in place of the original rivets

for securing the silencer end cap.

B19.2 Just one piece of standard isolation mat is

allowed to be used. Can only be replaced with

genuine spare part (Rotax part no. 297 981).

B19.3.1 Additional to the standard isolation mat is a

special steel isolation mat which is legal, but not

mandatory. It is to be fitted underneath the

standard isolation mat, 10-12 mm from the end of

the tube, with both clamps mandatory.

B19.3.2 Steel isolation mat dimension = 165 mm +10 mm

B19.3.3 Clamp (1) must be fitted at a distance of

18 +/- 2 mm from the end of the tube.

Clamp (2) must be fitted at the end area of the

steel isolation mat.



B19.4.1

The only exhaust pipe legal to be used is the

version where the 180o

elbow and silencer are

1

two separate pieces. The silencer is fixed with two

springs to the 180o

elbow and two springs to the

tuned pipe (Image 1).

B19.4.2 The silencer can be rotated so that the 90o

elbow

outlet of the silencer is pointing either downward

towards the asphalt (preferred for lowest noise

emissions) or upward towards the back.

B19.5

For measuring the exhaust gas temperature, a

weld on a socket on top of the exhaust, 50 mm from the ball joint is allowed.

B19.6

Exhaust socket with gasket ring only is legal to be

used (Image 2). Measurement (C) must be at least 15.5 mm

B19.7

The maximum use of exhaust springs to fix the

exhaust to the cylinder is 4 springs.

2



Supplementary Rules specific for “Micro MAX”

to be read in conjunction with KA Technical Rules for

“Junior Max”

Micro MAX

Squish gap:

a) 125 Micro MAX Minimum = 2.40mm

b) To achieve the defined squish gap, a spacer (ROTAX part no. 626 420, same shape

as a cylinder base gasket) with at least two cylinder base gaskets (one below the

spacer and one above the spacer) must be used.

The squish gap must be measured with a certified slide gauge and by using a 3 mm

tin wire. The crankshaft must be turned by hand slowly over TDC (top dead center) to

squeeze the tin wire.

Recommended 3mm tin wire (ROTAX part no. 580 132).

The squish gap must be measured on the left and right side in the direction of the

piston pin.

The average value of the two measurements counts.

Ignition System:

Only the Dellorto Ignition System is legal to be used.

The electronic box is labeled with stickers and are still legal even if the stickers have

disappeared.

Sticker shows “666814, 125 MAX evo”

The ECU Tester has to show the following result:

“ECU TEST OK”

“125 MAX evo”



Radiator:

a) A specific "Micro MAX" radiator (ROTAX part no. 295 924 or 295 923) must be used

instead of the original radiator.

b) Radiator must be mounted with all components similar to the illustration version 2 or

3 for the 125 MAX engine. (see item

9.7.8 of the technical regulations 2014).

c) Cooling area:

height = 280 - 300 mm

width = 58 - 62 mm

thickness of radiator = 30 - 34 mm

Exhaust restrictor:

Only Exhaust Socket with gasket ring is legal to be used.

Diameter (A) must apply for the length (B) of at least 12mm.

Maximum inner diameter (A) of exhaust socket is:

18.20mm

The measurement (C) must be at least 18.5mm.



Exhaust system:

a) The specific "Micro MAX" exhaust system must be used instead of the original

exhaust system (see illustration below).

b) The inner diameter of the elbow outlet at the silencer end cover has to have a

minimum measurement of 21mm.

Cylinder:

a) The cylinder (ROTAX part no. 223 994) must be cast with two “Letters” within a circle on the drive side, and not a number.

b) Any combination of two “Letters” is acceptable. Photo is for illustration purposes only.