Generac Power Systems GTV99O User manual

Malual Part
No.OE2Oal
fr SERVICE
MANUAL
F
["J
*.1
POWER
P.O.
Box297
Phone:
[phone]
P nted
in
lJ.s.A
GiENEFIAC'
SYSTEMS, INC.
. Whitewater,Wl . 53190
GTV
-1990/760
V-TWIN
OHVIENGINE
Fax:.
(262)
472-6505
FirslEditionlssued
-bi/xrxx

?J
FOREWORD
This
manualhasbeenwritten andpublishedbyetHeUC@ pOWe
n
SYSTEMS,
lNc.to aid our dealers'mechanics,
company
servlce
per_
sonneland
general
consumerswhen servicingthe
products
des(ribed
herein.
Itisassumed
thatthese
personnelare
familiarwiththe servi(ing
pro_
cedures
torthese products,^orlikeor similar
products,
manu{actured
and
marketed
byGENERAC@
PowER
sYsTEM
s,lNc.lt isalto assumed
thattheyhavebeen
trained
inthe recommended
servicing
procedures
for the5e
products,which includes
the use
of mechanics
handtools
and
anyspecialtools
that might berequired.
Proper
service
andrepairisimPonant to the safe,
economical
and
reliableoperation
of the products
de5cribed
h€rein Thetrou'
bleshootirlg,
testing,
service
andrePair
procedures
recommended
by
cEtltnlc@ PowrR sysTEMs,
lNc.anddescribed
inthis manual
are
effective
methods
of performingsuahoperation5.
Some
oftheseoper-
ations
or procedures
may require
the use
of specialized
equipment'
Suchequipment
shouldbeused
when andasrecommended
we (outd not possibly
know oI andadvise
the sewice
trade of all
conceivable
pro(eduresot methodsbywhichaservice
might beper-
formed,
norot anypossiblehazards
and/orresults
ot each
procedure
ormethod,Wehavenotundertakenanysuchwideevaluation There-
{ore,anyone
who usesa Procedure
or methodnot recommended
by
themanu{acturer
must{irstsatisly
himselfthatneither
hissa{ety,
nor
the product'ssatety,
will be endangered
by the service
or oPerating
procedure
selected,
Atl information, illustrations and sPe(ifications
contained in this
manual
arebased
onthe latestproductinformation available
at the
iliili "'tri.n", However,
GENERAC@
PowER
sYsrEMs,
lNc'
reservesihe
rightto (hange,
alter orotherwise improve
the product
atanytime without Priornoti(e.
somecomponents
or assemblies
o{ the Product
degcribed
in this
manuat
may not be (onsidered rePairable.
Disassembly,
repairand
reassembly
oI such
components
maynot beinctuded
inthis manual'
Theengines
described
hereinmaybeused
to powerawide variety
oI Droducts.
Service
andrepairinstructions
relatingtoany such
prod'
uatsare
notcoveredinthismanual.Forinformationpertainingto use
of these
engines
with other products,
re{erto anyowne/s or service
manuals
pertaining
to said
products.

?., TABLEOF
CONTENTS
RULESFOR
SAFEOPERATION
DIMENSIONS
AND
FEATURES
4-CYCLE
ENGINE
THEORY
SEcTION
1:GENERAL
INFORMATION
SECTION
2:IGNITION
SECTION3;
CARBURETION
SECTION
4: GOVERNOR
CONTROLS
ANDGOVERNOR
SECTION
5:CYLINDER
HEADANDVALVES
SECT|oN
6:El.ECTRlc
SIARIER
SECNON7:
ALTERNATORS
SECTION8: LUBRICATION
SYSTEM
SECTION
9:
ENGINEDISASSEMBLY
SECTION
lO:CYLINDER
ANDCRANKCASE
COVER
SECTION
11:CRANKSHAFT
ANDCAMSHAFT
SECTION
12:PISTON,
RINGSAND
CONNECTING
RODINSPECTION
AND
ASSEMBLY
SECTION
13rENGINE
ASSEMBLY
AWORDABOUT
SPECIALTOOLS
Manyot theprccedurcs
depictedin thismanual
rcquitetheuseof special
tools.Someof
thetools
reouiredareavailable
asGenetac
patts
andatelistedassuchin thismanual.
ATTENTION!
cenerac
PowerSystems
doesnotapproveorauthorizethe
useolthese
engines-onAllTerrain
Vehicles
(AW"s);
go-carts,
motorbikes,aircraft
products,
personal
watercraft,
orvehicles
intended
foruse
in
(ompetitive
events.Use
oftheseengines
insuch
applicationscould
result
in
property
damage,serious
injury
(in.luding
paralysis),
oteven
death.
t

RULES
FORSAFEOPERATION
lfyou
donotunderstandany
podion
ofthismanual,con-
tad Cenerac
or your nearest
Generac
AuthorizedS€rvice
Dealerforstarting,operatingand
setulclng
procedures.
Throughoutthis
pubIcilion
andontags
anddecaGaffixed
tothe
engine,DANGER,
WARNING
andCAUTIONblocks
a€ usedtoaled
you
tospeclalinstrudion
about; panicu,
laropefalionthatmaybehazardous
if
performed
lncorrectly
orcarclessly.ObseNethem
carefully.
Thesesafetywarnings
cannoteliminate
the
hazards
that
theyindicate.
Stict
compliancewith
thespecialinsVuctions
whrle
per{or"l
ng
theserv
(
p
plLs
'comaor.Frse'
ara
majo.
Thefollowingdefinitions
applyio oANGER,
WARNING,
CAUTIONandNOTE
blocksfoundthrouqhoutthe
manua
Thesesafetysynbolsindicate
thefollawing:
DANGER:Afterlhis heading you canreadhan-
dling,installing,
op€rating
orsewicinginstructions
that,if not rtrictlycompiied
with,witt resuttin
personalinjnry
WARNING:
After
thisheading
you
canreadhan-
dling.
installing,
operatingorservicing
instructions
that,ifnotnrictlycompli€d
with,
mayresultin
per-
sonalinjury,
CAUTION:After
thisheadingyou
canreadinstruc-
tionsfor
handling,installing,
operating
orservi(ing
the
enginethat,il notstri.tly
compliedwirh,may
result
indamage
to€qu;pnent
and/or
property
NOTE:
After this heading you <anrcad explanatory
statements
that rcquirc specialemphasis.
These
symbolsindicate
thefolowing:
Points
outimportantsaiety
inlormationthat,ilnot
lollowed,
could
endanger
personal
saletyand/or
Prope
y
ofyourseli
andothers.
RULESFORSAFEOPERATION
StudytheseRIJLESFORSAFEOPERATION
carefu
ybefore
operalinq
orservicingthisequipment.Becomefamilia
rwth
TfpOWNFR'5N.4ANUA
adwith _eergirF Tl-eengrnecar
operalesa{€ly,
efficientlyandreliablyonlyifitis
properly
oper
ated
andmaintained.Many
accrdentsar€caused
by
failing
totolow simp
eandfundamentalrules
orprecauttons.
Generac
cannot
possiby
anticipate
every
possible
circ!m-
nance
thatmightinvolve
a hazard.
Thewarninqsinthis
manualand
ontags
anddecals
affixedtothe
equipmeni,arc
therelore,noi all-inclusive.
tfyouusea procedure,
work
method
oroperatingtechnique
Generacdoesnotspecifically
recommend,you
mustsatsfyyoLr6elf
thatlt is
safefor
you
and
olhers.Youmustalsomake
sLirethe
procedlre,
work
method
oroperaiingt€chnique
that
you
choose
doesnot
renderthe
enginetobeunsafe.
DANGERTDonottamper
with the engine
gov-
erned
tpeed.Highoperatingspeeds
aredang€rous
andincreare
therhkof personal injury
ordamag€
totheequipment.Operating
atlowspeedswith
heavyloadmayshorten
theengine'sljfe.
A Potential
explosionhazard.
A Potentialfiretrazard.
BEFORE
OPERATING
. Gasoine
shighlyFIAMMABLE
and
itsvaporsare
EXPLO-
slVE.
Donot
p€fmlismoklng,
openflames,
sparksorheat
rn
theareawhilehandlng
gasoline.
Avoidspilling
gasoline
onahotengine.
Complywithallofthe awsregutaiing
storage
and
handling
ofgasol ne.
. Slore
gasol
neandotherfuels
onlylncontainers
designed
andapprovedforthe
norageoi suchmateials.
. Add
gaso
in€ina
clean,welfventlated
area.Wipeupany
spllled
gasollne
immediatey.
t gasoline
hasbeenspiled,
letridry
completelybefo.estartirg
theengine.
. Donot
ovediIthelueltank.Alu/ays
alowroomforfuel
expansionll thetankisoverfilled,the fuelcanovedlow
ontoahot
engineandcauseaFIREor
anEXPLOSION.
. Allow
atlean two
(2)
feetofclearanceonalsides
ofthe
engine,even
whleoperating
it outdoors.or you
could
damagetrieengrne.
. Thofoughyinspecttheenqineforooseordamagedparts
beforeeachuse,
Do
nolusethe
engne
untladjustments
orTeparfsare
maoe.
. Checktheolllevelln
theengine
before
eachuse.
A Pobntial
electricat
shockhazard.

RULESFORSAFEOPERATION
The engine exhaust lrom thls ptoducl contains
chemicals known to the Stale of Calilornia io
cause cancer,birth d6fects, or other repro-
ductive harm.
Inspecttheengine
periodically.
Repairorreplacealldamaged
ordefective
parts
immediately.
Inspect
fuel
system
frequently
forleaksordamage.
Repair
orreplaceanydamagedorleakingcomponentimmediately,
Neverattemptto change,alterormodit theenginefuel
slstem
inanywaythatmight
affectsafetyorcompliance
with
applicablecodesandstandards.
WHILE
OPERATING
Thisenginewasdesignedandmanufacturedfor specific
applications-
Donot
attempttomodirytheequipmento.use
itforanyapplicationforwhichitwasnotdesigned.
GeneracPowerSystemsdoesnotapproveorauthorizethe
useoftheseengineson
AliTe(ain
Vehicles
(ATV3),go-cads,
motorbikes,alrcraft
pfoducts,personal
watercraft,orvehi-
clesintendedfor useincompetitiveevents.lJseof these
enginesinsuchapplications
could
resultin
property
damage,
serious
injury
(including
paralysis),
orevendeath.
Englneexhaust
gases
containDEADLY
carbon
monoxide
gas-
Thisdangerous
gas,
lf breathedinrufficient concen-
trations,
cancau5eunconsciousness
orevendeath,Operate
thisequipmentonlyintheopenairwhereadequateventi
lationlsavailable.
Donotinsertanyobject
thrcughthecoolingslotsof the
engine.You
coulddamagetheequipmentorinjure
yourself.
Donotoperatetheenginefanerthanihespeednecessary
to operatetheequipment.Donot
runtheengineathigh
speedwhennotoperating
theequipment,
Thisenginerequires
anadequateflowofcooingairforits
contrnued
proper
operation.Never
operaletheequlpment
insideanyroom
orenclosurewherethefreeflowol cool-
ingairintoand
outoftheequipmentmightbeobnructed.
Withouisufficienlcoolingairilow,theenglne
quicklyover-
heats.damagingtheengineornearby
propefty.
Donotsmokearound
theengine.Wipeupanyfueloroil
spillsrmmediately.
Neverleave
oilyorfuelsoakedragsaround
theengine.Keeptheareaaroundthe€nglne
clean
andlree
ofdebrls.
Keephands,feet,clothing,etc.,awayfrommoving
parts
of
thisenqine.
Neveroperatetheengine
(a)in
therain;(b)lnanyencosed
compadment;
(c)
if theenginespeedchanges;
(d)
if the
enginespa*s;
(e)
ifflame
orsmokesobservedwhilethe
engineisrunning,
Neverworkonthisenglneorhandle
anye€ctricaldevice
while
standlng
inwater,whiebarefoot,orwhilehands
of
feet
arcwet.DANGEROUSELECTRICSHOCKwiIresult.
SERVICE
INFORMATION
Seruiceonthisengine
withinandatlerthewaffanty
period
canbe
pedormed
byanyaulhozedservice
dealerSeruice
iechniciansarcfaclorytrainedand
capableoihandlingallservice
needs.
Whenconlaclinganaulhor,zedservicedealeraboul
pads
andservice.auAys_sllBlflhclgnllgE
nodelnumberand
serialnumberoi
your
unitas
given
onilsdala
plale
decal.Seetheilllstration
belowiorthelocationoithedecal.
Thewafiantyforthisengineisincludedinthe
0wnersmanuat.

DIMENSIONSANDfEATURES
MODfL GTV99O
TYPE I]LCEOLED 4-STREKE
lHV
BOREX STREKF 90 x7A
DISPLAC
EMENT 99?cc
CBMPRESSlEN
RAT]D 8.5'1
LUBPICAIIIN
SYSTEI.l
rUI
L PAES-UO]7'D V/LO\"/
!I . PPE\SLPf
SI.LIIE i
IGNlIIUN SYSTEI.I ELICTPDNIC
SPEAKfRLESS
CYL]NDER CAST IRDN SLEfVL-
S
IARTING
SYSTEM ELECTRICSTART
IIL CAPACITY C030mlV/FILTEP, 1750nl V/B FILTER
VE]GHT 454!a€/)]Dtbs

DIMENSIONSANDFEATURES

DIMENSIONSANDFEATURES

DIMENSIONS
AND FEATURES
P,/NOC2965A
P/N OC2955C
P,/N
OC2965t

+CYCLE
ENGINE
THEORY
ftheengineisto
run
properly,
four
(4)
eventsrnustoccurin
the
proper
sequenceanda!thecorecttime.These
eventsare
(a)
intake,
(b)
compression,
(c)
ignition
and
power,
and
(d)
exhaust.
A INTAKE
The
piston
istravellinqfromtopdeadcenter
(IDC)
tobottom
deadcenter(BDC).
The
cam
has
openedtheintakevalve.The
piston
s
downwardmovementinthe
cylindercreatesa
partial
vacuurninthecylinderAiratatmosphefic
pressure
isdrawn
intothecylinderthroughthecarburetorandismixedwithfuel
inthecalburetor.Thefuelairmixturcflows
thrcughtheopen
intakevalveintothecylinderWhenthe
piston
reachesBDC,
theintakestokeisover.
CrcNrT|oN
AND
powER
By
thetimethe
piston
reachesTDC
,combustionisakeady
in
progress.
Theintakeandexhaustvalvesremain
closedasthe
exprnding
gases
ofcombustion
force
the
piston
downwad.
D
EXHAUsr
Theexhauststroke
beginswhenthe
piston
has
rcachedBDC
and
has
starteditsupwardmovement.Theintake
valveis
closed.Theexhaunvaveis
opentolet
gases
escape.
B
coMPREsstoN
As
the
piston
reaches
bottomde6d
center
(BDC),
boththe
intake
andexhaustvalves
areclosed.The
piston
movesupward
toward
TDCand
thefuel-airmixtureis
compressed.lustbefore
the
piston
rcachesTDC,ignition
occLirs.

SECTION1:GENERAL
INFORMATION
SECTIONCONTENTS PAGE
MATNTTNANCESCHEDULE
.-........................-.......--.......
r-l
FUELANDOtLRECOMMENDAT|ON5.........-..-.................
1-l
Gasoline
.......................................................
...l-l
Lubrication..........................................................-.....
l'1
RecomrnendedOi1Type..............................................
1'1
ChanqeOi1..................--.............................-.-..........
1-1
Change
OilFi|ter..........-..--.......................-.................
1
-2
Cleaning
IntakeScr€en...........................-.-................
1-2
ReplaceSparkPlugs.................................................-
1'2
AirCeanerMaintenance
.........-.....-..........................
1_3
ServlceDualElement
Ai C1eanels..............................
1-3
TROUBLESHOOTTNG
.....................................................
1-4
5y5tematicCheck....--..................,..,,.,.......................
1-4
Checklgnition ..
...-........... I'
checklgnition
(Enqine
Running)..................................
1'
Checklqnition
(Fouled
PluqofotherCaules)..............
1-
Cylinder
B.
anc.
TFst....... ....l-
Cre.lFuer........................ .... ... .....
1-
CheckCompression......................................................1_
CylinderLeakdown
Test..............................................
1_
Thinqs
WhichAffectBothCylinders............................
1-
Thing!WhichAff€ctOneCy
lnder
..............................
1'
EQUtpI/tNr
AffEClrNG
ENGtNtOPtoATO\ .......... ......
HadStartinqorwi NotStar'1............................-.......1-
EngineWon'tstop......................................................
1-
Vibralion......................................................................
l-
PowerLoss......-...........................................................1-
Noise..........................................................-............-..1'
NOTE1
:Change oilandllleraft€rilrst8hours
oloperation
and
lhen
every100
hourslhercallsr.Chang€soonerwhen
opeEtng
undera
heary
load
or
inadusryordirty€nvionmenlorinhilh
ambienltemperature.
NOTE
2:Cleanmor€olienwhenoperalingin
didyordlsiycondillons-
Replace
canlsterslylelilterevery500hours.
NOTE3:PerlormthislaskONLYafrerlilst50hourc oiop€ration.Head
bollswillNOTneed
lunherrclorquing.
FUEL
ANDOItRECOMMENDATIONS
GASOL
NE:
Werecommendtheuse
ofclean,freshlead{reegasoline.
Arnin-
imumof85octaneis
recornmend€d.The
useol eadjree
gasoline
resultsin
fewercombustiondepositsandlongervalvelife.
Not€: Somefuels, called oxygenated or refonulated
gasolines,
arcgasolinesblendedwith alcoholsot etheE.
Ex.essive
amountsof theseblendscandamagethe luel
systemor cause
pertormanceprcUem' Do not use
gaso-
Iine which contains Methanol. lf any undesirable
operating
swptoms occu|,use
gasoline
with a lower pe'-
aentageof alcoholor ethei
Itisalsorecommended
that
gasolin€
be
purchased
insmall
quantities,
notmorethana
30daysupply.FRESHgasollne
min-
imizes
qum
deposits,
andalsou/illensurefuelvolatility
tailored
fortheseason
inwhichlheenginewillbeoperated.
LUBRCATON:
Oilhasfour
purposes.
ltcools,ceans,seals
andlubricates.
Duringnornraloperalion,
srnallparticlesofmetalfromthe
cylin
derwalk, pistons,
bearingsand
combustion
depositswill
gr:dually
contaminate
theoll.Dust
particles
from
theaLraLso
contaminaletheoil
formlnganabrasivemlxture
whichcan
cause
weartoal ofthe nternalmoving
pads
oftheengine,
lfthe
oilisnotchanged
regulary.Fresh
oilalsoassistsincool'
ing.Oldoilgradually
becomesthickandlosesltscooling
abi
iq/
aswellas
ilslubricatlng
qualities.
RECOMMENDED
OtTYPE:
Using
theproper typeand
weightofoilin
thecrankciseis
extremely
lmportant.Checktheoilbe{orc
each
useandchange
theo
Iregularly(s€eFigures1-1,
l-2
&
1-3).
Faiurcto
usethe
(o|ecl
o
I.
orLs:19d
-y
oi,
(dr
caJse
p
emarure
e19i-le
wea'
and
failure.
Useonly
high
qua
ry
deterqent
oilrated
wthAPIs€rviceclas-
siflcatlon
SF,SGor
SH.Therecommendedoilwelghts
incLude
the
{olowing:
. Duringsummer
months:SAE30.Anaccepta
blesubnitute
issAE
10w-30.Afterfi6t oll
change,
synthericoI G
1,1
MAINTENANCESCHEDUTE
Every
lElery I Every
I Houts125Hou6 50Hours
ChangeOilF
ller
Spa*Plug
CleanSpark
BeloqueHeadBols

SECTION
1:GENERALINFORMATION
. Durinq
winterr.onths
30.DONOTUSESAESAE
5W-30,Synthetic
sW-2
0or5W'
10w-40.
F -2A a 20 40 60 30 rou
c 30 .20 .10 ro 20 30
Temperature
Fange
orEv€cted
Us6
CHANGE
OIt:
Thecrankcaseoil
capacityis
about2030
ml
(2.
I qt)
withthe
oilfilterWithouttheflfter,
the
oilcapacity
is1750
ml(1.8
qt.).
Usenospecialadditives.
Makesur€
ihatthe
unit
iseverwnen
filling
withoil.DONOT
OVERFILL.
TMPORTANX
DONOTOVERF|LL.
Check
and maintainoil
level rcgularly. Changeoit and fittet aftet fi6t eight (8)
houtsof opetation.
Thereafter,
changeoil€nd
filter
everyt0O
hou6
oJopera
tion.
Ch:nge
oilmore
oftenil enqinei5
operatedindirtyor
dusty
conditionsor
f€n9ine
isoperated
und€rhealy
|oaosor
highambient
air
temperatures.
Removeoiidrainpllg
and
drainoitwhite
€ngife
is5r wdrin,
Figure
1-2.
Chanqe
oIfllter
(Figure
t-l)andreptace
dratn
ptuq
figurc 1-1.o fill Check
Remove
dipnick
andrefitlslowy
wthnew
oilof
proper
5€r
vr.e
classification
andviscositygrade.
R€fI to fu mark
on
dipstick.
When
checkng
oilevet,
dipst
ckmust
bealltheway
in
for
accurate
readtngs.
Start
and
run
engine
tocheckfor
oilleaks.
CHANGE
Ot FLTER:
Replace
oilf lter
€veryI
00hours.
Beforenstalt
nq
newI rer,
ightly
oilfilter
galket
with
fresh
cleanengineoit.
Screwfiier
onbyhand
until
gasket
cont.cts
filteradapter
Tighten
3/4to
one
fullturn
fadher,Fiqure
1-3.
Startandrun
engineatidlefor
30secondsand
stopengine.
Recheckoilevelandadd
ifrequired.
Reltartengineandcheck
for
oil
leaks.
figure 1-2.OilDrcin
figure1-3.
OilFilter
CLIANNGINTAKT
SCREEN]
Grass
partices,
chaffor
dirtcanclog
theatrcooting
system,
especially
after
prolonqed
serviceln
cLjttingdry
grass
orv€ry
driryar.
Continued
operationwith
acogged
cooling
synem
can
causesevere
overheatngand possible
englne
damage.
Fgure
14showsth€arcastobecieaned.Thisshoutdbea
reg-
uar marntenance
operation,or cleanntakescre€n
andol
cooler
finsafter
eachuse.
1-2

SECIION
1:
GENERAL
INFORMATION
REPLACESPARKPLUGS:
Replace
spark
plugs
every100hours
ofoperationorevery
season,whichever
occursfirst.Replace
spark
plugs
if elec,
trodesareburned
away,orthe
porcelain
iscracked.Setspark
pluggap
at.76
mm
(.030')
for
allmodels.Torquespark
plugs
to20.0
Nm
(180
in.ibs_).
Figute1
-5.
Setting
Spatk
Plugcap
tionsare
notcarcfully
followed,
dirtand
dunwhich
shouldbe
collectedinthecleaner,will
bedrawn
into
theengine.These
particles
are
highlyabrasive
andwillcausethe
plston
ringsand
cylinderboretowear
quickly.
As
the
ringsand
cytlnderbore
becomeworn,these
abrasive
particles
enter
thecrankcase
and
contaminatetheoil,forming
anabrasive
mixturewhich
willcausewear
onalloftheinternal
moving
pads.
Theaircleaneronevery
enginebrcught
inforacheckup
orrepairshould
beexaminedand
seNiced.tf
thearrceaner
shows
signsofneglect, showittothecustomef
beroreoean-
ing.Instructthecustomer
on proper
care,to assurelong
enginelife.
Note:Repla.eai .leaner gaskets
andmounting gaskets
that afe wom of damaged.to prcventdirt anddustfrcm
entering engine due to imryoper sealing. Replace
bent
air cleanermounting bracketif necessary,
SERVICEDUAL
ELEMENTAIRCLEANERS:
Removeandservicefoam
pre-c
eanerevery
25hours
orevery
season,whichever
occursfirn.setuice
canridgeevery
50hou6
orev€ry
season,whicheveroccursfirst.
SERVCECANSTERAIR
CLEANERS:
Cleantheairfilterelemen(s)with
compressed
airevery
50
hoursoreveryseason,whichever
occursfirst.
Replace
theair
{ilterelementG)every500hou6
orifdamaged.
Note: The air cleanet assemblies
on someequipment
may have been supplied by the equipment manufa.-
turei Seetheequipmentmanufadurels owne/s manual
for seNi.e infomation specili. to that prcduct,
TROUBTESHOOTING
lvostcompaints
concerningenglne
operation
canbeclas-
sifiedasoneoracombinationofthefollowlngi
2. Hardstarting
3. Lackol power
4. Runsrough
GENERAC Ch
SparkPluqType Part
No.
ResistorPlug
AIRCLEANERMANTENANCE:
Vrbration
Overheating
High
oi consumption
472341 RCt2YC 5.
6.
1.
WARNING:
NEVEROPERATE
ENGINE
WITHAIR
CLEANER
ASSEMELYOR
AIRCLEANER
CARTRIDGE
REMOVED.
FIREMAY RESULT.
Aproperly
5ervicedaircleaner
protects
lnternalpa(s
ofthe
enginefrom
dlrtanddun
pa.tic
esin
theairlfaircleanerinstruc-
Note:Whatappears
to bean enginemalfunction maybe
afault of the
powercd equipment Bthet than the engine.
lf equipmentissusped,
seeequipment
atlecting
engine
Figurc
1-4,Cleanlnhke Sqeen&OilCooletFins
SETPLUG
GAPAT0.76
mm
t-3

SECTION
.I:
GENERALINFORMATION
SYSTEMATICCHECKi
lftheenginewillnotstad
andthecause
of malfuncrionis
not€adilyapparen!
perform
asystematic
checkinthefolowing
orderl
1. lgnition
2. Fuel
3. Compression
This
check'up,
performed
in
asystematicmanneri
cdnusu-
allybedone
in
amatterofminutes.
ltisthe
quickest
andsurest
methodofdetermining
thecauseoffiilure.
Thebasiccheckup
procedure
isthesame
forallenginemodeh,
while
any
varia-
tion,bymodel,wiilbe
shownunderthe
subjectheading.
CHECKIGNITION:
lfsparkdoesnot
occurlookfor:
. Shortedignition,kill
wlre
. Twocosed
diodesinground
wireharness
. Incorrect
armature
air
gap
FIECK
lGNnoN
{ENGNERUNNING)I
ifengine
runsbutmisses
during
operation.aquick
checkto
determineif ignition
isor isnotatfaultcanbemadeby
installing
aspa*tesler
(Generac
p,t\l
OC5969)
betweenthe
spark
plug
lead
andeach
spark
plug,
Figuret-6.
Asparkmks
willbe
rcadily
apparent
whenthe
engineisrunning.tfspark
i5
good
but
engine
misses,check
forafouled
spark
plL'lg.
CHECK]GNITION
(FOULED
PLUGOROTHER
CAUSES):
To
checkforafouledspark
plug
oranonjunctioning
cylin-
der.attach
the
lpark
tener
(Generac
P/N
OC5969)between
the
spark
plug
lead
andeachspark
plug.
Stadandrun
engineat
topnolo.d
speed.Now
ground
onespark
plug,
Fig!ret
-7.
The
engineshould
continuetorunonthe
othercylinderRepeatthis
testwiththeother
cylnderlftheengine
willnotcontinue
to
runwhenmaking
thistest,the
cylinderthatlsNOT
grounded
isnotfunctioning
and/orthe
spark
plug
isfouled.
Installanew
spa*
plug
before
prcceeding.
f miss
contn!es,
problem
may
becarburetion
orcompression.See
CheckCalburction,
Check
Compression.
AlsoseeCyinder
BalanceTest.
Figvre
1-7.Checking
fot Fouled
plugs
CYLNDEREAIANCETEST
lf theenqineishardstadinq,
runsrough,
missesor tacks
power,pertorm
acylinder
balancetest
todetermirre
wnerner
boih
cylirdesareope.ai19
rctrerrfLlporenlrat.
ToolsRequircdi
1. Two
gnition
Teste6
(Cenerac
P/N
OC5969)
Attach
ani9nition
testerbetwe€n
thespark
plug
lead
and
each
spark
plug,
Fiqure
1'6.
Stadandrun
enginerunnln9
attopnoload
speedandnote
sparkatign
lionteste6.lfthe
spa.kisequat
atboth
jgniUon
testers,
the
problem
isnotigniton
related.
Asparkmiss
will
bereadilyapparent.Now
noteRPM
ofengine.Ground
outone
cylinderby
contactingignition
testerandagoodgrcund
on
engrne,Figufel
8.NoteRPMloss.
Then
ground
outthe
other
spark
pugandnoteiheRPNI
loss.lfthedifferencebetween
thetwocylind€rsdoesnot
exceed75RPNI,theamount
ofwork
thetwo
qlinde|s
aredoingshouldbeconsidered
equal.
figwe 1-6.Running
Check
J'
I
I
I

SECTION1:GENERALINFORMATION
I
lftheRPw
lossisgrcaterthan75RPIVthis
indicatesthatthe
grcunded
cylinder
withtheleastRPMlossisthe
weakestot
thetwocylinders.
Looktoth.tqlinderforaproblem.
Example:
EngineRPM
-Bothcylinders
=3400RPM
EngineRPM
-#1CylindetGrcunded
=3300RPM
Engine
RPIV
-*2 CylinderGrounded
=3100RPM
Conclusion:#1
cyllnderisweakestofthetwocylinders.
EXA[4PLE:
cyl.#1 cyl.#2 Diff.
Eng.+l 165PSI 160Psl 5Psl
Eng.42 175
PSI 155PSI 20Psl
lfcompression is
poor,
lookfor:
. lnsufficient
valveclearance
. Loosecyllnder
headbolts
. Blown
head
gasket
. Bumedva
ve5,valveseatsand/or
loose
valveseats
. warped
cylinder
head
. warped
valvestems
. Wornbofeand/or
rings
. BDken
conneding
rods
CYLINDER
LEAKDOWN
TESI
Acylinder
leakdowntener
maybeusedtotestthesealing
capability
ofthecompression
componentsofeachcllinderand
quickly
identitthe
prcblem
cornponent.
THINGSWHIC]]
AFFEEI-EO]ILIILNDIB!
l. Carburetion
2. Crankcase
vacuum
3. lgnitiontiming
a.
Apartially sheared
fl)4rvheelkeywilleffect
ignitioniimlng
andengine
Peaformance.
TH]NGS
WHICHAFFECT
ONECYLNDER:
1. Spark
plug
a.
a fouled5park
plug
mayindicatethatcarburetor
isout
ofadjustment.
2. Leakinspark
plug
wire
3. Head
gasket
4. lntake
manifod
a.Aleakateiiherend
ofthe
intakemaoifoldwlllonlyaffecl
onecylinder,
notboth.
5. Valves
6. RLngs
8. Cylinder
NOTE:A twin cylindet
engine
wi runwe ononecylin-
deraslong asthe
power rcquircdfor theappli.ation does
not exceedthepowet producedby the onecylinder
Figwe|-8.CylindetSalan.eTest
Thecy
inderbalance|enwillasodetecta
qlinderthat
isnot
functloning.
When
grcunding
outonecylinderthete
wil be
noRPIVloss.Whentheother
qlinder
ls
grounded
outthe
enqine
willsiop-
Thefuel
prcssurc
canbecheckedusingapressure tester
kit
(Generac
P/NOC7977).
Thiskt comeswithanlntormatve
'How
To'video.
CHECKCOIVPRES5ON:
lt
has
be€n
determlnedthrolghtestinqthatasimple.nd
accu
rateindicationofcomprcssion
canbemadeas
folows:
Removebothspark
plugs
andnsertacompresslon
gaugeinto
eithercylinder
(one
cylinderatatirne).
Turn
efglne
overwilh
enginestarter
untilthereisnofurtherncrease
in pressure.
Recordthisreading.
Rep€ai
pfocedure
onolhercylirder
and
rccord
thatreading.
The
d
Ifefencebeiweenbothcyinde6
shouldnoiexceed25%.
Morcthan25%indicatesossofcom-
press
on
in
the.ylinder
wth lower
presslre.
seeexamp
e.
1-5

SECTION
1:6ENERAL
INFORMATION
EQUIPMENT
AFFECTING
ENGINE
OPERATION
Frequently,
whatappearsto
bea
problemwith
engine
oper-
ation,
suchas
hardstarting,
vibration,
etc.,may
bethefault
oftheequipment
powered
ratherthan
theengine
itself.Listed
aAthemost
common
effectsofequipment
problems'
andwilat
tolook
forasthemost
common
cause.
HARD
STARTING
ORWILL
NOTSTARI
1. Loose
belt
-aloosebelt
likea
loosebladecancause
aback-
lash
effec-t,
whichwllcounteract
enginecranking
effort
2. starting
under
load
-see
i{theunit
isdisengaged
when
engine
isstarted;or
ifengaged,
shouldnot
haveaheavy
starting
load-
3. Check
remote
control
assembly
forproper adjustment-
4. Check
interlock
system
forshorted
wires,looseorcorrcded
connections,
ordefectivemodules
orswitches
ENG
INIWON'T
STOP:
1. Check
equipment
ignitionstop
swjtch.
2. Check
forlooseordisconnected
equipmentstop
swtcn
3- check
ground
wireharness
onengrne.
a.
SeeSection
2fortest
Procedure,
V]BRATION:
1. Unitloadout
ofbalance
-removeand
balance.
2. Mounting
boltsloose
-ughten.
r0wEe!05t
1. Bindordraginunit-
if
possible,
disengage
engine
andoper-
ateunit
manuallytofeelforany
bindingaction
2. Unitload
ha5excessdtag-
xol5E
1. Enginecouplingorpulley
-anoversize
or
worncouphng
canresultinknocking,
usuallyunder
acceleration.
Check
forfitortightness.
2. Equipment
needslub cation.

SECTION2:IGNITION
SECTIONCONTENTS PAGE
sPEClFlCATIONS..................
-.....--------------....-....
2-1
GENERAL
lNFORMAT|ON................................................
2-1
ARMATURES
Armatur€Testing................-.....................----..-.........2l
Removing
Amatures........................-.......................
2_1
lnstall
Armatures-.....................................................-.
2-1
AdjusiArmaturcAirGap..........................................
2-2
FL\1/VHEEL
RemoveFlywheel..-...................................-...............2_2
lnspectFlylvheel
KeyandKeylvays...........-................
2"2
lnstallFlylvhee1..........................................................2_3
ENGTNE
WtRTNGHARNESS.....................-......................
2-3
TeslingGrcundWircs............................................-...
2-3
EnginewirlngHarnessDiagram
................................
2-4
DiodeFailurcDiagnosis
...-.--.....................................
2-4
SPECIFICATIONS
FOR
GW-990/760
0HVtV-TW|NENGINE
MODEL5ERLE5................................................Gry-990t60
ARMATUREAIRGAP.....................................008',
TO.012'
(.20TO.30
MM)
FLYWHEELNUITORQUE
n:185..........--......................
.. ..- - .......150
FL\1/VHEELNUTTORQUE
NM............__.......................................-......................203.0
SeeSection
1ForSpatkPIugMainFnan.e
AndSpe<ifi<ations
GENERALINFORMATION
Generac
GTV-990,60OHVIV-Twin
enginesuseamagneto
ignltionran
ignitionamalurewithaseli-contalnedtransistor
module
(no
moving
paats).
Twomagneto
ignitionarrnatures
areused,withaflyljvheel
containingapermanent
magnet.
NOTE:
fhe magnetoignition synem rcquiresaminimum
of 350
RPMto ptoduce a consistentspa*.
ARMATURES
ARMATURETESTING:
Thecondition
oflheignitionarmatures
canbeaccu€tely
diag'
nosedusing
an ignitiontestet,
(Generac
P/N0C5969)as
descbedin'Trcubleshoot
n9' inSection
1.
REMOVNG
ARMATURES:
1. Removespark
plug
leads.
2. Removeintakemanifod
andcovel
intake
pofts.
3. Removerotating
screen
andblowerhousing.
4. Remove
armaturescrewsand lift off armature(s),
Figure2-1.
a.Disconnect
stopswltch
wires
atarmatures.
Note:The
flwheel doesnot needto be rcmovedto ser-
viceignition exceptto checkthe flwheel ket.
INSTATL
ARMATURES:
1- Turn
fylvheelsomagnet
isawayfrcmamatur€.
2. Install
ground
wireontotabterminalonarmature.
Note:
Makesurewires areroutedover afinaturemount-
ing posB
andaway
lrcm flwheel.
figute 2-2.Ins|.jrllingAnaturc
3. Assembearmature
toengine,
Figurc2-2.
a.
Mountingholesinarmature
areslotted,Pusharmature
awayfrom
fly\,vheelasfaras
possible
andtightenonesc€w
to holdafmaturc
inplace.
Figurc
2-1.RenovingAmature
2-1

SECTION
2:IGNITION
4. Repeatfor
second
armature.
5. Adjust
armatureair
gap.
ADIUST
ARMATUREARGAP:
1. Rotatefl!rheeluntilmagnetisunderamatur€laminalions.
2. Placethickness
9au9e,
.008"
-.012
"(0.20-.30 mm)
between
magnet
andarmature
laminaiions,Fgurc2-3
3. Loosen
mountingscrewso
magnet
will
pull
armaturedown
againstthickness
gauge.
a.
Torquescrcwsto 12.2Nm
(9
Jt.lbs.).
4, Rotate
flylvheeltoremovethlckness
gauge,
5. Repeatfor
secondarmatule-
Note: Routeamature grcund wire over breather tube
andaway from the flwheel. Figurc2-4,RemouingFIWheelNut
Caution:Flywheel
pulle.bolts
maydamagelighting
coilifturned
in
too
{ar.
cautionrDoNoTstrikellywheel
withahardobjed
ora m€taltoolasthismayGuseflywheeltoshat-
ter in operation.Alwaysuseapprovedflyl/vheel
Figure2"5.RenovingFl@heel
INSPECTFLYIVHEELKEYKEWVAYS.FLYIVHEELAND
CRANKSHAFT:
Check
flywheelkeyfordamage.Check fly\,vheel{or
cracks
orkeluaydanrage.Alsocheckcrankshaft
keylvaysand
taper
fordamage,Figure2-6.Repacecrankshaft,
ifdamaged.
A
A
FLYWHEEL
RE[,4OVE
FLY]/VHEEL:
1. Remove
fllavheelnutandwasher,Figure2-4.
2. Remove
fanretainerandfan.
4. Reinstall
flywheelnut.Turnnutdownflushwithtopof
mrea05.
5. Installfllu/heeT
puller
6. Tighten
puller
screwsequalyuntllfly\,vheelloosens.
Figure
2,5.
Figurc2-3,Adjusting
ai Gap
2-2

SECTION2: IGNITION
Figue2-6,Che.k
Hwheel Andeankshaft
INSTALLFL\ryVHEEL:
Note:CLEANflwheel and(ankshaft taperremoving all
oil, dirt or gtease.
1. Insertflylvheelkeyintocrankshaft.
2. Align
keywaysandassernbleflylvheeltocrankshaft.
3. Installwasherand
flylvheelnut.
a.Toquefly,vl/heelnutto203.0Nm
(150
ft.lbs.),
Fiqure2-7.
4. as5emblefanandretainerto
flywheel,Figure2 8.
a.Torquescrewsto
2l.7Nm
(192ln.
lbs.).
Figure2-7,TotquingFlwheel Nut
Figurc2-S.lnstaingFlywheelAndFan
ENGINEKILLWIRES
The
engine
killwiresconslstofa
grcund
wirewithadiodefor
eacharmatureand
aseparatewireforthecarburetorsolenoLd.
Theenginekillwiresareconnected
tothewirlngharness
pro-
videdbytheequipmentmanulacturer
Seeengine
wirediagram,
Page6-3.
TESTiNGGROUNDWIRES:
Usea DigitalMultimeter
(Figure
2-9)to testtheground
wires.
Theiollowingtestw
llbemadewiththemeterintheDiodeTen
IntheDiode
Test
position,
themeterwilldisplaythefoftvard
voltagedropacrcssthe
diode(s).lfthevoltagedropislessthan
0.7
volts,themeterwill
'Beep'onceas
well
asdisplaythe
volt-
agedrop.
A
continuous
toneindicatescontinuity(shoneddiode)
Anincompletecircuit
(open
diode)willbedisplayedas
'OL.'
2.3
Figurc 10.Digital Multinetel

SECTION2:IGNITION
'L tnsed
REDtestlead
into
yo+ receptacle
inmeter.
2. Insen
ELqCK
tenlead
intothe.,COM.
re.eptacle
In
meter
3. Rotate
selector
to >i nt(Diode
Test)posttio,r
4. hsert
REDtest
lead
clipinto
connector
.
A' (Fiqure
2_I
0).
Leave
attached
for
femainder
oftest.
5. TouchBLACK
tenlead
probe
toterminat
,8.,,
a.lfmeter
'Beeps'
once,
diode
isOK.
b.lf meter
makes: continuoLrs
tone,
diodeisdefective
Ghorted).
Replrce
ground
harness.
c.lfmeter
displays
'OL,' diod€
isdefective(open).
Replace
ground
harness.
6. Now
repeat
testfor
terminal
,
C,
, Results
must
be
thesame.
See
"DiodeFailwe Diagnosis-
betow
SPARK
PLUG
SPARK
PLUG
DIODE
figute2-11.
lgnitionWhing
Hamess
DIODE
FAITURE
DIAGNOSIS
IGNITION
KILLWIRE
ENGINE
GBOUND
HARNESS
POSITIVE
Ii4ETEB
TEST
LEAD NEGATIVE
I\4ETER
Figurc
2-10.Testing
Grcund
Whe
GROUND
WIRE
HARNESS
SWITCH
ON TURNED
OFF CAUSE
Engine
Runs
OnI Cy/jnder shuts
offoK I Closed
Diode
Engine
Runs
(Both
Cylinders) OnIy
One
Cylinder
shuts
Off I OpenDiode
(No
Spark) 2Closed
Diodes
Engine
RLins
(Both
Cylinders) Engine
Wont Shut
Off 2Open
Drodes
2-4