ISO 6855-2:2012

Mopeds - Measurement method for gaseous exhaust emissions and fuel consumption - Part 2: Test cycles and specific test conditions

This part of ISO 6855 defines test cycles for measurement for gaseous exhaust emissions from mopeds, as well as for determining the fuel consumption of mopeds as defined in ISO 3833, equipped with a spark ignition engine (four-stroke engine, two-stroke engine or rotary piston engine).

Cyclomoteurs — Méthode de mesure des émissions de gaz polluants et de consommation de combustible — Partie 2: Cyclomoteurs d'essai et conditions d'essai spécifiques

General Information

• Status: Published
• Publication Date: 19-Sep-2012
• ICS: 13.040.50 - Transport exhaust emissions
• ICS: 43.140 - Motorcycles and mopeds
• Technical Committee: ISO/TC 22/SC 38 - Motorcycles and mopeds
• Drafting Committee: ISO/TC 22/SC 38 - Motorcycles and mopeds
• Current Stage: 9093 - International Standard confirmed
• Start Date: 24-Oct-2023
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 6855:1983 - Road vehicles - Measurement methods for gaseous pollutants emitted by mopeds equipped with a controlled ignition engine
• Effective Date: 17-Oct-2009

Overview

ISO 6855-2:2012 - Mopeds: Test cycles and specific test conditions defines the laboratory procedures for measuring gaseous exhaust emissions and fuel consumption of mopeds with spark-ignition engines (two‑stroke, four‑stroke or rotary piston). This part of ISO 6855 specifies the dynamometer test cycles, warm-up routines, sampling/dilution arrangements and the specific conditions that ensure repeatable, comparable emissions and fuel‑use results.

Key topics and technical requirements

• Test cycles and warm-up: The standard prescribes urban-style cycles carried out on a chassis dynamometer with brake and flywheel. A warm‑up sequence of four consecutive 112 s cycles is run before the four-element main test (total main test duration 448 s).
• Sampling and dilution: Exhaust gases are diluted with air so that the flow volume of the diluted mixture remains constant. Continuous samples are collected (bag sampling / diluted mixture) to determine average concentrations of CO, unburnt hydrocarbons (THC), NOx and CO2.
• Type 1 (full cycle) tests: Detailed dynamometer operating procedures including gearbox use (manual, semi‑automatic, automatic), acceleration/deceleration behavior, speed and time tolerances (e.g., speed tolerance ±1 km/h, time tolerance ±0.5 s), ambient and test‑room temperature control (approx. 293–303 K), distance measurement accuracy and requirements for plotting speed vs time.
• Type 2 (idle) tests: Measurement of CO and THC emissions at idling for one minute, with gearbox/clutch positions defined for manual and automatic transmissions and analyzer stabilization criteria (steady value within one minute).
• Analysis and reporting: Gas analysis should be completed promptly (within 20 minutes after test end). Presentation formats for emissions and fuel consumption results are specified in Annex A and Annex B.

Practical applications and who uses it

• Vehicle manufacturers and powertrain developers - for certification, engine calibration and design verification.
• Emissions and fuel‑consumption test laboratories - to perform standardized dynamometer testing and produce comparable laboratory data.
• Regulatory agencies and type‑approval authorities - to evaluate compliance with national or regional moped emissions and fuel consumption requirements.
• R&D and environmental analysts - for benchmarking, fleet screening and lifecycle impact assessments.

Related standards and references

• ISO 6855-1:2012 - General test requirements (companion document)
• ISO 6855-3 - Fuel consumption measurement at constant speed (part of the series)
• ISO 4164, ISO 7116, ISO 3833 - referenced for engine power, maximum speed and vehicle classification
• European Commission Directive 97/24/EC is cited as equivalent test‑cycle origin.

Keywords: ISO 6855-2:2012, mopeds emissions test, chassis dynamometer, test cycles, gaseous exhaust emissions, fuel consumption measurement, Type 1 test, Type 2 test, bag sampling, CVS.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 6855-2
First edition
2012-09-15
Mopeds — Measurement method for
gaseous exhaust emissions and fuel
consumption —
Part 2:
Test cycles and specific test conditions
Cyclomoteurs — Méthode de mesure des émissions de gaz polluants et
de consommation de combustible —
Partie 2: Cyclomoteurs d’essai et conditions d’essai spécifiques
Reference number
©
ISO 2012
© ISO 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any
means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the
address below or ISO’s member body in the country of the requester.
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Tel. + 41 22 749 01 11
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Published in Switzerland
ii © ISO 2012 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Test cycle . 1
3.1 Introduction . 1
3.2 Type 1 test . 1
3.3 Type 2 test . 5
4 Presentation of results . 6
Annex A (normative) Presentation of results for gaseous exhaust emissions .7
Annex B (normative) Presentation of results of fuel consumption .11
Bibliography .15
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 6855-2 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 23, Mopeds.
ISO 6855-2 cancels and replaces ISO 6855:1983 and ISO 7859:2000, both of which have been
technically revised.
ISO 6855 consists of the following parts, under the general title Mopeds — Measurement method for
gaseous exhaust emissions and fuel consumption:
— Part 1: General test requirements
— Part 2: Test cycles and specific test conditions
— Part 3: Fuel consumption measurement at a constant speed
iv © ISO 2012 – All rights reserved

Introduction
This part of ISO 6855 has been prepared to provide details of the typical test cycles for measurement
of exhaust gas and fuel consumption. The measurements can be carried out by referring to this part of
ISO 6855 and ISO 6855-1.
INTERNATIONAL STANDARD ISO 6855-2:2012(E)
Mopeds — Measurement method for gaseous exhaust
emissions and fuel consumption —
Part 2:
Test cycles and specific test conditions
1 Scope
This part of ISO 6855 defines test cycles for measurement for gaseous exhaust emissions from mopeds,
as well as for determining the fuel consumption of mopeds as defined in ISO 3833, equipped with a spark
ignition engine (four-stroke engine, two-stroke engine or rotary piston engine).
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 4164, Mopeds — Engine test code — Net power
ISO 6855-1:2012, Measurement methods for gaseous exhaust emissions and fuel consumption — Part 1:
General test requirements
ISO 7116, Mopeds — Measurement of maximum speed
3 Test cycle
3.1 Introduction
The test cycle is equivalent to the test cycle specified in the European Union Commission Directive
[5]
97/24/EC .
The moped shall be placed on a chassis dynamometer equipped with a brake and flywheel. The test
shall be conducted over four elementary urban cycles lasting a total of 448 s without interruption.
Immediately before starting the first test cycle, the moped shall undergo four consecutive test cycles,
each lasting 112 s, in order to warm up the engine.
During the test the exhaust gases shall be diluted with air so that the flow volume of the mixture remains
constant. Throughout the test, a continuous flow of samples of the mixture shall be passed into one
or more bags so that concentrations (average test values) of carbon monoxide, unburnt hydrocarbons,
oxides of nitrogen and carbon dioxide can be determined.
3.2 Type 1 test
3.2.1 Operating cycle on the chassis dynamometer
3.2.1.1 Description of cycle
The operating cycles on the chassis dynamometer are indicated in 3.2.4.
3.2.1.2 General conditions for carrying out the cycle
Preliminary test cycles shall be carried out if necessary to determine how best to actuate the accelerator and
brake controls so as to achieve a cycle approximating to the theoretical cycle within the prescribed limits.
3.2.1.3 Use of the gearbox
The gearbox shall be used in accordance with the manufacturer’s instructions. If there are no
manufacturer’s instructions, the following rules apply.
3.2.1.3.1 Manual gearbox
At a steady speed of 20 km/h, the engine speed shall as far as possible remain between 50 % and 90 %
of the maximum speed. If this speed can be achieved using more than one gear, the engine is tested using
the highest gear.
During acceleration, the engine shall be tested using the gear which allows maximum acceleration. The
next higher gear shall be engaged, at the latest, when the engine speed has reached 110 % of the speed at
which the maximum net power output occurs. During deceleration, the next lower gear shall be engaged
before the engine begins to vibrate and, at the latest, when the engine speed has fallen to 30 % of the
speed of the maximum net power. The first gear shall not be engaged during deceleration.
3.2.1.3.2 Automatic gearbox and torque converter
The drive setting shall be used.
3.2.1.4 Tolerances
3.2.1.4.1 The theoretical speed shall be maintained to a tolerance of ± 1 km/h during all phases. Speed
tolerances greater than those prescribed are permitted during phase changes provided that the tolerances
are never exceeded for more than 0,5 s on any one occasion, in all cases subject to the provisions of
3.2.2.5.2 and 3.2.2.6.3.
3.2.1.4.2 A tolerance of ± 0,5 s above or below the theoretical times shall be allowed.
3.2.1.4.3 The speed and time tolerances are combined as indicated in 3.2.4.
3.2.1.4.4 The distance travelled during the cycle shall be measured within an accuracy of 10 m.
3.2.2 Procedure for chassis dynamometer tests
3.2.2.1 Special conditions for carrying out the cycle
3.2.2.1.1 The temperature in the premises where the chassis dynamometer bench is situated shall be
between 293 K and 303 K throughout the test, and shall be as close as possible to the temperature of the
premises where the mopeds were conditioned.
3.2.2.1.2 The moped shall as far as possible be horizontal during the test so as to avoid any abnormal
distribution of the fuel.
3.2.2.1.3 During the test, the moped speed shall be plotted against time in order to check that the cycles
have been performed correctly.
3.2.2.1.4 The temperatures of the cooling water and the crankcase oil may be recorded.
2 © ISO 2012 – All rights reserved

3.2.2.2 Starting up the engine
3.2.2.2.1 Once the preliminary operations on the equipment for collecting, diluting, analysing and
measuring the gases have been carried out, the engine is started up by means of the devices provided for
that purpose, such as the choke, the starter valve, etc., according to the manufacturer’s instructions.
3.2.2.2.2 The first cycle begins when the taking of samples and the measuring of the pump rotations
commence.
3.2.2.3 Use of the manual choke
The choke shall be cut out as soon as possible and in principle before acceleration from 0 to 50 km/h.
If this requirement cannot be met, the moment of actual cut-out shall be indicated. The choke shall be
adjusted in accordance with the manufacturer’s instructions.
3.2.2.4 Idling
3.2.2.4.1 Manual-shift gearbox
3.2.2.4.1.1 During periods of idling the clutch shall be engaged and the gears in neutral.
3.2.2.4.1.2 To enable the accelerations to be performed according to the normal cycle, the vehicle shall
be put in first gear, with the clutch disengaged, 5 s before commencement of the acceleration following
the idling period in question.
3.2.2.4.1.3 The first idling period at the beginning of the cycle consists of 6 s of idling in neutral with the
clutch engaged and 5 s in first gear with the clutch disengaged.
3.2.2.4.1.4 For the idling periods during each cycle, the corresponding times are 16 s in neutral and 5 s
in first gear with the clutch disengaged.
3.2.2.4.1.5 The last idling period in the cycle consists of 7 s in neutral with the clutch engaged.
3.2.2.4.2 Semi-automatic
...