CSC TT250 - Page 72

TT250Owner’s andServiceManual
www.CSCMotorcycles.com
71
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Weavoidtheaboveconditionsbyadjustingthevalves.Allwearereallydoingiskeepingthegapinthe
valvetrainwithinanacceptablerangeoverthelifeofanengine.Asthevalveandthevalveseatwear,
wekeepeverythingadjustedsothatwhentheengineis
atoperatingtemperaturewestillformagood
sealaroundthevalveseat.
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Differentenginesusedifferentapproachesforadjustingthevalves.YourTT250engineusesthebest
approachforeasymaintenanceandhighperformance:Itusesathreadedadjustorshaftwithalock
nuttosetandlockthe
valvegap.Inthephotoabove,that’swhattheuppertwoarrowspoint
to.Theseadjustorsarelocatedintheendsoftherockerarmsthatinterfacedirectlywiththevalve
stem.
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So,withallthattheorybehindus,let’sconsiderwhatwe’regoingtodohere:
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1. Wewant
togainaccesstothevalverockerarmsandtheiradjustmentscrews.
2. Wewanttheenginetobeatapointinitsrotationsuchthattherockerarmisonthecam’s
basecircle.Thismeansthecamisnotactuatingtherockerarm.Wewanttheengineto
have
thepistonat(orverynear)topdeadcenter,whichmeansthevalvesshouldbeclosed(whichis
anotherwayofsayingtherockerarmis onthecam’sbasecircle).
3. Withtheengineinthisposition,wewanttoloosenthethreadedadjustorlocknuts,wewant
to
setthevalvegapstothespecifiedgapof0.04mmto0.07mm,andwewanttotightenthelock
nutstolockthethreadedadjustorsatthisgap.Wealwaysmaketheadjustmenttothe
0.07mmsetting.Asthevalveandthecylinderheadwear,thegapwillgrowsmaller.
Settingit
tothe0.07 mmsettingallowsustokeepthevalveadjustmentinterval(thenumberofmiles
youcanridebetweenvalveadjustments)atareasonablyhighnumber.Initially,we’re
establishingthisintervaltobe500milesforthefirstadjustment,andevery2500miles
thereafter.
4. Whenwe’ve
completedtheabove,wewanttoputeverythingbacktogether.
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Mostoftheworkinadjustingthevalvesisassociatedwithjustgettingaccesstotheadjustors.The
adjustmentoperation(oncewehaveaccess)takesonlyafewmin utes.
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Whenyouadjustthevalves,youhavetostartwitha
coldengine.LetyourTT250cooldown
completely.
Removetherearbodypanelsontheleftandrightsideofthe
motorcycle.