ClassicMotorcycleMechanicsJune2020

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1/ 2/I’vealreadystrippedtheoriginal
engine(one)andworkedoutwhatthe
goodpartsarefromthatengine.NextI
inspectedenginenumberthree,which
hasonelockedcylinderanddecidednot
touseanyofthatmotor.Enginenumber
twoisnextandistheonethatisbest,
soIgowiththatasthebasemotor.In
theendIonlyusedtheselectorshaft
andaselectorforkfromtheothermotor
togetthisoneasperfectasIcan.
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3/ 4/IusedgenuineYamahasealsfromYambitsoverthereintheUK.Theywerewellpricedandthepartsarrivedinaweek,
despitethefireshere...IreplacedallengineandYPVSseals.5/Thecrankshaftisclosetoperfect.Iranalltheusualchecksonit
anditwaswithinspecifications.WorkingwithaJapaneselanguageservicemanualwasdifficult.Luckily,oneofmybestfriendsis
JapaneseandsheisamotorcycleexpertsoIcouldtextherimagesofpagestotranslateasIwentalong...Ialwaysthoroughly
lubeandcleanthecrankshaftofanyengineIassemble...6/Theoutputshaftrunsadoubleseal.Ireplacedtheouterseal.
7/ 8/ 9/Theselectorshaftseal,kickstartershaftsealandveryimportantly,thewater-pumpsealwereallreplaced.Thewater-
pumpshaftissacrificialanddoesn’trunabearing,sohadtobemeasuredtoensureitiswithinspecifications.10/OnceIwas
happywiththecrankshaftandbalanceshafttiming(markitondisassembly)andthesealswereinplace,IappliedThreebondto
thecasesaftercleaningthesurfacesthoroughlywithMethoandacleancloth.IalwaysrunsomeThreebondoverthesealouters
andIspraythethreadsofthecaseboltswithWD- 40 .Thecaseboltsarethentorquedtospecinorder.
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12/Istrippedandinspectedthegearboxand
addedthenewselectorclawsandoiledthe
bearings.It’saneasyjobtoslidethe 3 MA
gearboxinplace,mucheasierthantheRZV 500 R,
anRGVorinfactmostcassettegearboxesofthe
era:it’sareallyneatlittlesetup.The 6 mmbolts
andnutsaretorquedupinaclockwisedirection.
Makesuretheshaftsrotatefreely,thenfitthe
selectorshaft(withoilonit)andusinga
gearleverormultigripsontheshaft,runthrough
thegearsbeforegoinganyfurther,byspinning
theinputshaft.Ifthereisanissue,youneedto
knowrightnow,notwhenthebikeistogether.
11/It’snowtimetoquicklywipeaway
excessThreebondbeforeitsets.Then
makesurethecrankshaftrotatesfreely
andquietly.
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