Motorcycle testing and measurement: Difference between revisions

Revision as of 05:15, 24 December 2018

Revision as of 16:05, 18 September 2019

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{{refimprovemore citations needed|date=December 2009}}

[[File:2008 Sprint ST on the dyno at Ducati Seattle.jpg|thumb|upright=1.35|A [[Triumph Sprint ST]] on a chassis dynamometer]]

[[File:Suzuki Hayabusa at the Bonneville Salt Flats Speed Week.jpg|thumb|[[Suzuki Hayabusa]] at [[Bonneville Speedway|Bonneville Speed Week]].]]

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Motorcycle speed tests, especially at high speeds, are prone to variation due to human error, limitations in equipment, and atmospheric factors like wind, humidity, and altitude. The published results of two otherwise identical tests could vary depending on whether the result is reported with or without industry standard correction factors calculated to compensate for test conditions. Rounding errors are possible as well when converting to/from miles and kilometers per hour.<ref name=Ford2003>{{citation |last=

Ford |first=Dexter |title=Grudge Match |magazine=[[Motorcyclist (magazine)|Motorcyclist]] | issn=0027-2205 | publisher=Source Interlink Media |date=August 2003 |pages=34–35 |url=http://www.motorcyclistonline.com/features/122_0308_kawasaki_zx12r_suzuki_hayabusa/index.html }}</ref>

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==Engine power and torque==

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File:Boxsterdyno.png|Graph of power and torque.

</gallery>

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While the crankshaft power excludes these transmission losses, still the measurement is often made elsewhere in the drive-train, often at the rear wheel. A correction for the transmission losses is then applied to the measured values to obtain the crankshaft values. For motorcycles, the reported power and torque numbers normally pertain to the crankshaft. In directive 92/61/EEC of 30 June 1992 relating to the type-approval of two or three-wheel motor vehicles,<ref name="eur-lex.europa.eu">{{cite web|url=http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:31992L0061:EN:HTML|title=EUR-Lex - 31992L0061 - EN|author=|date=|website=eur-lex.europa.eu}}</ref> it is referred to as "maximum engine power", and manufacturers use similar terms. Historically, this convention may have come from the pre-[[unit construction]], wherein the crankshaft was directly accessible for measurements, and the gearbox might have come from a different manufacturer. However, when the engineering details of the transmission are known, the losses therein can be accurately quantified & corrected for. Explicit guidance on the homologation measurements and transmission corrections is given in directive 95/1/EC.<ref>http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:1995:052:0001:0040:EN:PDF</ref>

A main source of ambiguity and differences comes from the conditions the test was done at. These conditions include details like atmospheric conditions (temperature, pressure, humidity), tire pressure, but most importantly: the conditions of the motorcycle itself. Examples thereof are: was the alternator fitted?; was the air filter fitted?; what exhaust system was fitted? One would hope that manufacturers would test their motorcycles in normal running order, so the condition that they are sold in, and for which they obtained type-approval, but this is not always the case. Ducati, for instance, has chosen to publish more positive values, stating that "Technical data referring to power and torque was measured on an engine test stand at Ducati".<ref>{{cite web |url=http://ducati.com/bikes/superbike/1199_panigale_r/tech_spec.do |title=Archived copy |accessdate=2013-06-09 |deadurlurl-status=yesdead |archiveurlarchive-url=https://web.archive.org/web/20130704053908/http://www.ducati.com/bikes/superbike/1199_panigale_r/tech_spec.do |archivedatearchive-date=2013-07-04 |df= }}</ref> Their published values are typically 5% higher than the [[homologation]] values, in normal running order.

==Weight==

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While its weight is small compared to the other fluids discussed above (a few ounces), [[hydraulic fluid]] might be excluded during shipping. It is not safe to assume that it is either included or excluded in the reported dry weight. Hydraulic fluid might be found on a particular bike's front brake and reservoir, plus maybe a rear brake with a reservoir, and maybe also in a hydraulic clutch with its own reservoir.

[[Ducati]] has in the past used the term "Ducati weight", pertaining to a value excluding the battery as well as all fluids, but have since begun using "dry weight" for this.<ref>{{cite web |url=http://ducati.com/bikes/monster/1100__evo/tech_spec.do |title=Archived copy |accessdate=2013-06-08 |deadurlurl-status=yesdead |archiveurlarchive-url=https://web.archive.org/web/20130511070711/http://ducati.com/bikes/monster/1100__evo/tech_spec.do |archivedatearchive-date=2013-05-11 |df= }}</ref>

Beginning in 2009, the [[Japanese Big Four]] manufacturers and BMW began publishing the wet weight rather than dry, usually providing some explanation for what this means. Since then most other manufacturers have followed, in order to comply with EC directives that explicitly state that the values pertain to the vehicle in running order. Honda describes it as curb weight (aka kerb weight) and says this means the bike is "ready to ride." Others say all fluids are included and the fuel tank is at least 90% full. [[Erik Buell Racing]] gives "wet weight (no fuel)" for the 2012 1190RS motorcycle,<ref>{{cite web|url=http://www.erikbuellracing.com/motorcycles/1190rs/|title=1190RS « Erik Buell Racing|author=|date=|website=erikbuellracing.com}}</ref> while [[KTM]] gives a "weight without fuel approx."<ref>http://www.ktm.com/us/superbike/1190-rc8-r-usa/highlights.html#.UbLgxpz4KoY</ref>

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==Notes==

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==References==

{{commonsCommons category|Motorcycle testing}}

{{refbeginRefbegin}}

*{{Citation |url= https://books.google.com/books?id=igONw5YZvEUC&pg=RA6-PA40 |title= Aerodynamics 101; What looks fast isn't |magazine=[[Cycle World]] |date= June 1999 |last = Anderson |first= Steve }}

* {{Citation |last= Canet |first=Don |title=Tach Truths; Tall tales of the tachometer |magazine=[[Cycle World]] |publisher=[[Hachette Filipacchi Media U.S.]] {{Subscription required|via=[[Bondi Digital Publishing]]}} |issn=0011-4286 |___location=Newport Beach, California |date=July 2006 |volume=45 |issue= 7 |page=51}}

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*{{Citation|url=https://books.google.com/books?id=l2Zizg8I8p8C&pg=PA129|title=Motorcycle Tuning: Chassis|first=John|last=Robinson|publisher=Butterworth-Heinemann|year=1994|ISBN=075061840X}}

* {{Citation|last=Stermer |year=2006 |first=Bill |title=Streetbikes: Everything You Need to Know |publisher=MotorBooks/MBI Publishing Company |isbn= 9780760323625 |url=https://books.google.com/books?id=NMokiWY6E00C&pg=PA37#v=onepage&q=&f=false |page=37}}

{{refendRefend}}

{{Motorcycles}}

{{DEFAULTSORT:Motorcycle Testing And Measurement}}

[[Category:Motorcycle technology|*]]