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
Standards Content (Sample)
Mopeds — Measurement method for
gaseous exhaust emissions and fuel
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
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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
© ISO 2012 – All rights reserved iii
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bodies (ISO member bodies). The work of preparing International Standards is normally carried out
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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
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
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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.
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INTERNATIONAL STANDARD ISO 6855-2:2012(E)
Mopeds — Measurement method for gaseous exhaust
emissions and fuel consumption —
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).
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
The test cycle is equivalent to the test cycle specified in the European Union Commission Directive
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
220.127.116.11 Description of cycle
The operating cycles on the chassis dynamometer are indicated in 3.2.4.
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18.104.22.168 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.
22.214.171.124 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.
126.96.36.199.1 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.
188.8.131.52.2 Automatic gearbox and torque converter
The drive setting shall be used.
184.108.40.206.1 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
220.127.116.11.2 and 18.104.22.168.3.
22.214.171.124.2 A tolerance of ± 0,5 s above or below the theoretical times shall be allowed.
126.96.36.199.3 The speed and time tolerances are combined as indicated in 3.2.4.
188.8.131.52.4 The distance travelled during the cycle shall be measured within an accuracy of 10 m.
3.2.2 Procedure for chassis dynamometer tests
184.108.40.206 Special conditions for carrying out the cycle
220.127.116.11.1 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.
18.104.22.168.2 The moped shall as far as possible be horizontal during the test so as to avoid any abnormal
distribution of the fuel.
22.214.171.124.3 During the test, the moped speed shall be plotted against time in order to check that the cycles
have been performed correctly.
126.96.36.199.4 The temperatures of the cooling water and the crankcase oil may be recorded.
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188.8.131.52 Starting up the engine
184.108.40.206.1 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.
220.127.116.11.2 The first cycle begins when the taking of samples and the measuring of the pump rotations
18.104.22.168 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.
22.214.171.124.1 Manual-shift gearbox
126.96.36.199.1.1 During periods of idling the clutch shall be engaged and the gears in neutral.
188.8.131.52.1.2 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.
184.108.40.206.1.3 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.
220.127.116.11.1.4 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.
18.104.22.168.1.5 The last idling period in the cycle consists of 7 s in neutral with the clutch engaged.