Saito FG-90R3 - User Manual

5.Break-inMOSTIMPORTANT!!
●Prop-recommendation:Mejzlik-24”x12”.
●Use15:1fuel:oilratioforbreak-in.
●Nevermakethefuelmixtureleanduringbreak-in.Itcouldcauseseizureevenduring
idlingorlow-speedrunning.
●Beforestartingtheengine,openthemainneedleApprox.3turnsandtheslowneedle
Approx.5turnsCCWeachfromfullyclosed.
●Starttheengine(usingastarterisrecommendedforsafety).
●Runforabout5secondsatlowspeedtowarmup.
●Openthrottlegraduallyuptooverhalfopen.Inthemeantimeturnthemainneedle
CCW.ContinuetoturnthemainneedleCCWuntiltheRPMdeclines,keepingthe
throttleopenedoverhalf.
●ThenturntheslowneedleCCWtomakemixturemuchricher.
●Runinthisveryrichconditionfor1literoffuel..
●Now“initial”break-inisdone.
●Graspthepropbyhandandturnitseveraltimesinthedirectionofnormaloperation(CCW)untilthecarburetorgenerateshissing-like
sound.Afterhearingthissoundforabout5times,quicklyflipthepropapproximately10times.
●Removethechokebar.Thenpowerontheignitionsystemandflipthepropquicklytostarttheengine.Iftheenginedoesnʼtstart,repeat
thechokingprocedure.
Φ37.2mm 27.6mm 89.99cc
D24”~25”xP10”xP12”
Bore
Mainbody:3,161g/Muffler:157g/Ignition:250g
Stroke Disp.
Weight(Approx.) RPMRange
Approx.1,300-7,000rpm Maxonground Approx.6,000-6,500rpm
Propeller CM-6Plug
Optionalparts
Gasoline60-70㏄classApplications
Batteryforignitionsystem Voltage:6-8.4V,greaterthan1,000mA
・Limitgauge(0.1t)fortappetadjustment 1pc ・Spannerfortappetadjustinglocknut 1pc ・Carburetoradjustmentbar 1pc
・Sparkplug[CM-6](Attachedtotheengine) 3pcs ・Mufflerset   1set ・Chokebar  1pc
・Ignitionsystem(w/sensor)  1set ・Mufflerbracket   1set ・Plugwrench  1pc
・Standoffmount   1set ・Anti-looseningnut   1pc ・Hexagonalwrench  1set
Specifications
FG-90R3InstructionManual
2.Ignition
●Ignitionarrangement-Placethemainunitasfarfromotherelectrical
devicesaspossible.
(1)Plugcord(meshedhightensioncord)
Inserttheplugcapof(1)Plugcorddeeplyintotheplugof#1cylinder
tomakesureitwillnotcomeoff.Theothercapsandplugsshouldbe
installedbythesameway.(Refertocylinder#onthereverseside)
(2)Sensorcord
Connectwiththecordfromthesensorattachedtotheengine.
(3)Batterycord(black/redcord)
Useafullychargedbatterythathasadequatespec.(6-8.4V,morethan
1000mAisrecommended.).Betweenthebatteryandmainunit,make
suretosetaheavydutyswitchwhosecapacityishigherthan3A.
(4)Tachometercord
Connectthedigitaltachometer(Option).Otherwisetheconnectorisnormallyvacant.
ForCCW
Makerich
Main
needle
ForCW
Open
Throttle
lever
Standard
accessories
FuelTank
FuelLevel
ToOutsideoftheplane
Ventline
fuelsupplytocarburetor
Fuelfillerline
Ventline
Gasoline-compatible
tankstopper
Gasoline-compatibletubing
Filterwithweight
Setthecenterofthecarb
slightlyabovethefuellevel
Closeaspossible
Firewall
Standoffasrequired
Hollowoutreferringto
thecuttingsheet
PlugCap
SwitchCapacity:3A〜
Sensor
(2)Sensorcord
Battery
Voltage:6-8.4V
Capacity:1,000mA〜:
( 1)PlugCord
MainUnit
(3)BatteryCord
(4)TachometerCord
7.Tappetadjustment
Thevalveclearanceshouldbecheckedandadjustedafterbreak-inandeverytimeaftertwohourswhiletheengineiscold.Beforeadjusting
tappetgaps,tightenthescrewsaroundcylindersetc.
1.Removethesparkplugand
rockerarmcoversof#1
cylinder.Thenturntheprop
CCWbyhandtoplacethe
pistonatTDCofcompres-
sionstroke.
2.Loosenthelocknutand
adjustthegapbyhexago-
nalwrenchuntilyouget
thecorrectgap(belowpic)
forbothofintake&
exhaust.
3.Oncethegapisset,tighten
thelocknutandattachthe
plugandcovers.Dothesame
adjustmentforthe#3-#2
cylindersinorder.
4.Turnthepropbyhandtocheckif
thecompressionisenough.Ifthe
gapislessthan0,thevalveis
alwaysopenedsightlyandlose
compression.Thenadjustagain.
CorrectGap
Mustnotbeinserted
Closeto“0”withnolimit
Limitgauge
(0.1mm)
Loosenthelocknut
Adjustthegapturning
thesetscrew
TopDeadCenter
(Thestatebothvalvesareclosed)
Tightenthelocknut
tofixthesetscrew
Slowneedle
CCW
Rich
CW
Lean
Mainneedle
Throttle
lever
1.Fuel
●Thefuelismixtureofregulargasolineandhigh-quality2-strokeengineoil.
●[Exampleofoilrecommendation]
 ・KlotzKL-200OriginalTechniplate・DeluxeMaterialsPowerModel2T-Setc.
●Besuretousethemixture“gasoline:oil=15~20:1”byvolumeratio.(Ex.1000mlofgasolineshouldbemixedwithmorethan50mlofoil).
●Duringthebreak-inprocess,use15:1mixedfueltoensurethebestlubricationforinitialrunning.
●Anydamagecausedbythefuelused,inwhichtheoilratioislowerthan20:1willnotbecoveredbywarranty.
●Donotusegasolinecontainingethanol.Itmaycausenotonlypowerlossbutalsocorrosioninsidetheengine.
ver.Aug,2018
6.Adjustmentofcarburetorafterinitialbreak-in.
◇Needlereferenceposition(Setafterinitialbreak-in)
●Starttheengineafteradjustingtheneedletothefollowingreferencevalue.
●Mainneedle：Approx.2.5~3turnsCCWfromfullyclosed
●Slowneedle：Approx.4+1/2~5turnsCCWfromfullyclosed(Thenthrottleshouldbefullyclosed)
●Actually,thebestpositionoftheneedlesvarydependingontheprop,temperature,humidityand
soon.Pleaseadjustasnecessaryafterobservingtheengineperformanceduringflight.
◇Peakadjustment
●Afterstartingtheengine,warmupforapprox.30secondsatlowspeed.
●Achievethepeakatfullthrottle.
→TurnthemainneedleCWgraduallytothepositionwheretheRPMisgreatest(thepeak).ContinuingtoturntheneedleCWpastthepeak
couldleadtoseizuresoturnitslowlyandcarefully.IftheRPMsuddenlydecreasesafterpassingthepeak,instantlyturnthemainneedle
CCWtoagainincreasetheRPM.Otherwiseitcoulddamagetheengineseriously.
●OnceachievingpeakRPM,returnthethrottletolowspeed.Makeanoteofthepositionofmainneedleatthepeakatthattime.(How
manyturnsyoudidCWbasedonthereferencevalue.)
◇SlowneedleAdjustment
●AfterachievingpeakRPM,nextisslowneedleadjustment.OpenthethrottlefromlowRPMtofullthrottlequickly.
●TurntheslowneedleCCWslightlyiftheenginehesitatesforamomentorstallsbeforetheenginereachesmaxRPMbecausethemixture
istoolean.
●TurntheslowneedleCWslightlyiftheengineisslowtoreachpeakRPM(fullthrottleset)becausethemixtureistoorich.
●AdjusttheslowneedleasaboveuntiltheRPMfollowsthethrottlemovementsmoothly.Theimportantpointistoadjusttheslowneedle
AFTERthemainneedlehasbeenadjustedtoitspeak.
●Nowbreak-inatgroundlevelisdone.Adjusttappetsbythemethoddescribedlater.
◇Pre-flight/Flightadjustment
●Whentheslowneedleadjustmentisdone,checktheresponsebyrevvingupfromlowspeedtofullthrottlequicklyseveraltimes.
●OpenthethrottlefullyandturnthemainneedleCCWapprox.60〜90degreesfromthepeakposition.Thisistomakethefuelmixture
richerintheairwheretheRPMgethigherthanontheground.
●Afteralladjustmentsaremade,flyyouraircraftandfinetunetheengineaccordingtothesituation.Basicallytuningshouldbedonewith
themainneedle.Readjustmentoftheslowneedleisrarelyneededifthefirstadjustmentoftheslowneedlehasbeendonesuccessfully.
・Filterwithweight[G36-154] ・DurabletubeforGasoline(1m)[G36-155]
・Aluminumspinnernut[57T-30] ・Tappetadjustingkit[120S-161]・Digitaltachometer[G17-167]
3.Propeller
●RecommendedpropellerisMejzlik24x12.
●Useawell-balancedone.Neverusethepropellerthathasbeenscratchedordamagedevenifslightly.
●Asthepropelleriscompressedslightly,tightenthe6boltseveryhourofoperation.
4.Methodofchoke(Noneedwhenyouusestarter)
※Chokingisthemeansbywhichfuelisfedtotheenginewhenyoustartitby
handflipping.Thusitisunnecessarywhenusingstarter.Startingwithaelectric
starterisrecommendedforsafety.
●Inadvance,makeathinholeinthecowlingtoinsertthechokebar/slowneedle
adjustmentbar.
●Duringchoking,besuretoturnofftheignitionswitch.
●Asshowninthefig,passthechokebar(withM3.5threadonitstip)throughthe
holeinthecowling.ThenturnthebartoinsertintotheM3.5internalthreadat
thecenterofthethrottlelever.
●Fullyclosethethrottleandpullthechokebarandfixitwithacliporclampas
showninthefigsothatitmaynotgobacktothepreviousposition.
Cowling
Chokebarforinsert
M3.5screw
Throttlelever
Throttlevalve
(Movetotheleft)
Slowneedle
Chokebar
Temporaryfixed
byaclip

Summary

Fuel Requirements and Handling

Ignition System Setup and Connection

Propeller Selection and Maintenance

Choke Operation for Starting

Engine Break-in Procedure

Break-in Fuel Mixture Ratio

Use 15:1 fuel:oil ratio for break-in. Never make fuel mixture lean to avoid seizure.

Initial Engine Start and Warm-up

Open needles, start engine, run at low speed for 5s, then gradually open throttle.

Main Needle Adjustment During Break-in

Turn main needle CCW until RPM declines with throttle over half open.

Slow Needle Adjustment After Break-in

Turn slow needle CCW to make mixture richer, run in rich condition for 1 liter fuel.

Carburetor Adjustment Post Break-in

Carburetor Needle Reference Settings

Set main needle to 2.5-3 turns CCW, slow needle to 4.5-5 turns CCW from fully closed.

Peak RPM Adjustment

Warm up, then adjust main needle CW until peak RPM is reached. Avoid turning past peak.

Slow Needle Fine-Tuning

Adjust slow needle CW/CCW for smooth throttle response after main needle peak adjustment.

Pre-flight and Flight Adjustments

Adjust main needle CCW ~60-90 deg from peak for flight. Fine tune during flight.

Tappet (Valve Clearance) Adjustment

Tappet Adjustment Procedure

Check and adjust valve clearance when engine is cold. Tighten screws around cylinders first.

Setting Valve Clearance

Adjust gap using hex wrench until correct gap is achieved, then tighten lock nut.

Saito FG-90R3 Specifications

General

Brand	Saito
Model	FG-90R3
Category	Engine
Language	English