Rotax 377 User manual

I
,'
{-
I
OPERATOR'S MANUA L
TYPE 377, 447 AND 5O3
EOUIPPED WITH
EOSCH COI{
TACT BAEAKER
IGNrTtot! sYsrEn AND.'
AING CARBURETOR
ENGINES
I SSIJEI) JI'I-Y 1946
rHIS I'ANUAI, CONTAI'IS IITPORTANTSAFET!
INFORATIOX CONCER*II{O
TOIMENCINE.
TT'H TBE EIIOL\E At TI}iE OF RESALE.
AND I.IA IXTENAXCB
rT SEOI'LD RE AII

INDEX
PAGE
'I
SECTIOl'|
I
2
3
q
5
6
7
8
a
10
11
L2
13
14
15
16
17
1
1
3
5
6
7
8
10
10
11
1q
15
22
23
25
28
29
FOREl,lARD
SAFETY
FUELANDOIL
- ENGIIiE
REDUCTION
GEARBOX
STARTINGPROCEDURE
BREAKINPROCEDURE
CARSURETION
EXHAUSTSYSTEIIS
INSTRUIiIEI'ITS
IGNITIONSYSTEI{
SPECIAL
OPERATINGCONDITIONS
II1AINTENANCESCHEDULE
TROUBLE
SHOOTING
ENGINE
REPAIRLOG
LIGHTiNG
CIRCUIT
t.lIRIt'lc
DIAGRAII
TECHNICALDATA
,

sEcfloN1 trIRElIAtr)
?he ROTAX enqlne ls a! al:.-cool.eal 2 stroke engtne. C.i!efu1 and extenslvely
testeCl deslgfl and rugged clnstructlon as vell as the use of h19h quality patts
narrant rnar.lDle leuabl.ttty a'ld durablltty. Wlt}l ploper Eatntenarce anat cale
ard \rith the use of suitable fuel aDd o11, the engtne rill glve you trouble-free
serrxlce fo! eany years. the RmlX alesign incorporates t_he latest techn-tcal
devefopEents. In orile! to take advantage of future developrDents we resetve the
right to Da.keDodlflcatlons ln the ROTAX
atesLgn lrlttrout notlce.
I9!9 all fasteners are roet:ilc alth the exceptlon of t_he lnte!'lat threaat of the
Pla shaft (crarlshaft) r,hlch t6 l" naLtoDat flne ttread.
secrroH2 SAFETY
Safety ls everyone's buslness. Wehave lncluded sone of tie ttaportant safety
ttps here. but t}le tist ls not conptete. It lrould be lBpossibfe to l.lst every
way ln r'hlch oDe Eay I€ injured. Welroulal ratle! llsk youi ildlqratlon by
Eentlonlng that "!,htch everyone knows ls ilengerous,, than take the chance that
needless lnj\rry could occur. Pfease note the follonlng s],ubols tjrrouglrout tle
book:
/ll- Safety tlarnlng: Fallure to ob€y a safety $alnlng Eay result tn tnjury
to you or ot})ers.
I- InforDatlon vltal to the operatlon oi haintenance of your ploduct
(ln a-ll.claft ttils shoul.d also be cotlsldered necessa.ry fo! safety).
GENEITL SATETY POIMS
l, "."a afr:." DanuaL tioroughJ-y lrefole atteDptlng to opelate your engrne,
If you are doubtful about any polnts contact your engl.ne o! alrctaft
suppl1er.
llf Von are fitting the engiBe youtself, rather tlan pulchasLng rn atlcraft
t ltlt tfte englne afleadl' fltted, then please also ask your engine s\rppller
for a copy of t}le fnstallation Insthctlons.
I lf tft" englne u.ses a Rotax realuctlon qeart'ox and if you aie fittinq a
propeller yourself. you bust ensrre t.Lat the Eass tlohent of inertla of
tie pliopelle! 1s less tian 3OOO
xg o2 t! prevent probfens yith t}le
tolsional shoc& absorbe! ln tlle qeatbox.
lrte eronetfer Dust be bal.anceAto better than 1glan netre to plevent
vlbratlon probleDs anal ovelstlesslng of the &lve systeE. the balance
shoulil be perlod.ically checked as it can vary alue to Digrrtlon of irate!
,It}l-ln the plopeller. lhe balance should be checked [email protected] 1f tie
propeller Is da.naged, even lf lt ls only a snall chip.

-2-
I te al. englne uses a Rotax realuct{on gearbox, ensure that tie gearbor( ls
fllled nttn the colrect ol1. to the couect 1evel, before atteEptLng to
op€rate t-he englne. (See also sectlon olr reductlon gealbox, and Eaintenance
scheilule).
l".lot. you run the englne bake sule all englne controls are opeiatlve, tbat
you knor on anil off posltlons of throttle End lgnl.tlon, that they ale
easlly accesslble. and that you can operate thera lnstlnctlvely $lthout
hesltatlon. If a 'flybackr throttle ls fltteal, ensure tllat lt cannot
stlck ln alty opeD o! partly open posltlon.
,lct.cL.nvin" Eountlng systeE frequently as well as the drtve conponents,
fuel llnes, eiriDg, and fuel and air fllters. (see also baintenance schedule). -
ANever B1x fuef ln !n area tnat ls enclosed or lrhere fules coulal reach an
lNever refuef an alrcraft tf fuel could be spilled on bot engine codponents.
Use safety approved f\rel contalners ;ndl never transport fuef in .r unsafe
lerecf for fuet contaEtnatton. alr ventsr etc. Protect engine while not
ln use fron a'ly contaDinatLon entering erdlaust, fuel, o! carburetlon
systeD but be s\rre t! rebove storage protectlop before startlng englne.
rllMatntain you.r englne In top coDtlltlon, but nevert}leless be prepaleil for
lt to stop rundng at .nty tlne, I€ave yourself a rrey out in the event of
une)<pected fallure.
I x".'"t .ot t}}e eng1ne on Ure grounil wlth the propelLer turning riJlless you
ale ilolng so ln a lun-up area atnal can observe anyone o! anlthing entelilg
the danger area. In obsewe! ln a 6efe place iB a deflnlte asset.
,l*v.t leave you! allcraft or othet vehlcle unattenileil while the engln€
16 runnlng. If opelated by soroeone else you could be Eued even if the
u.se tas unauthollsed bV you.
lo.n - englne log andlenter alt operatlnq tlDe, but ln particula! any
unusual operatlon o! plobleDs. Do not fly unless you have corlected any
probleb and recoliled the correctlon tn the Logr.
l/l,*""r run the englne slthout grope! Ioading {e.9. propelle!).
l rllraF use genliine ROTAX
parts.

SECTION, FUELANDOIL
- ENGINE
FI,EL A petrol of octane nunb€! not belo$ MON83or ROIi9Obust be useal. In orde! to
eosule tlat tlles€ requirenents are bet, a { star ,*r+ fuel (\rhlch has a BirdEln
l,loNof 85) is reconnendeal 1n cleat Brltain.
OIL the englne Is designed to operate at a fue1./oif E1x ratlo of 50 to 1.
Do not be tenpted to lncrease the a.Eoutrt of oil - too lruch oi1 can cause plug
failute' excessive cajrt'on build up (possibly leatung to pre-lqnltion) and $i11
also reduce the octane lating of the fuef, !,lhlch could feaal to detonation anil
sevele engine daroage.
Any good quallty two atroke oll froro a leputable Eanufactutel shoul.al be satlsfactory,
but ha\dng choseD an ol1, ire woul.il recoDroend t-hat you stlck t! t}re sane branal- ttost
olls are compatlble, but wit}| the ad\,.ent of neir blends, s]'nthetics etc. Droblens
Eay occ\rr If you change brands.
It the engln lB to be oeed irverted (vith Bpark pl.ugB
Dot-rlttB dot.n) leleet r lrbricant yhleh features lqla carbon
depoaitE. OiI !€BIAre telds to drala to lor polnts, 1.e.
spark plug cavitl"!. Il tbis reEidue fallg to burn cl.ean
durlDg no!'Eal operation, plEg toqlirE rill occur, possible
pre-lgnitlon alro, I|a{tu.facturee of auitable lubricant6
rlll guaHntee tb,eir p!'qdust3 in yritirtg.
Fuel- contanlnatlon 18 a EraJor cause of engine failure.
The beet place to avolal contanination ls at the source. Once
Ln your fuel contalner, a very harzadous potenllal exists.
Use a clean aafety approved Etorage container. Filten
all fuel enterlng and leaving this eontainer. Do not over-fllt
.
contalner, allow for expansion.
/l' UARNING: Oalollne lc fla rable and exploaive under
certaln condltions. Alwaya perform proqedunea ln s nell ventl-
lated area. Do not snoke or allow open flalea or Eparka in the
vlclnlty. Never add fuel whlle engine le runnLng.

-4-
NIXINO PROCEDURE
glEP no.1: gelng a clean appnoved
container of knownvolune
filL coryect anount of
Lnto container.
Oil rnust be approved for
cooled engines at 50 3 1
ratloa.
SrEP
Eo.?r ldd fuel to obtein de6ired. ,
Dixture ratlo (water Eesh
filter).
I Fuel nuEt be rninlmun
!l.O.N, 8, or R.O.N. 90 octane
rEti.ng.
gfEP Fo. J: Replace contalner: cap and rbake
the contaLner. Thoroughly
agitate the container. Then
using a funnel vitb a fine
Deah acreen to prevent the
entry of xater and fqrci8n
particles, tranafelr Elxiure
frotn contafuer itrto tlte fuel
t&nk.
oll
r
al.r
aLx
?-4
a
-e"4
-e>
-a

sEcrtoN
4REDUCTION
GEARBOX
oII,
llf a RoTAXrealucllon gearbox ls fLtted to t}le engine, It Dust be f1l1ed lrtth
o11 to the coirect level lgQlg opelatlng tf|e engl.ne.
I U"" "r, EPgo EYPOIDgea! oll of sp€ciftcatton ePl - cL3 or hlgher (e.g.
lPl - 6.5 ls perfectly sat-lsfactory).
l alU aO. gearbox t]rrough tie vent plug to t-he 1o$e! of the two level screws,
lAfte! flfllng ensule that the leve1 screvs, the draln plug ard t}le vent plug
are all secured r'lth locklng wl!e.
' sllght seepage of oil froE t.|e output shaft o11 s€at is norlaal durlnq the filst
fes houls of operatlon, but should settle do$r! sr.rbsequertly. If slight oi1 loss
contl.Dues, dheck t-hat the sEall bleatber hole 1n the vent plug ls not blocked.
l""to.. every fltght a vlsual ihecx shoulal be lrade of ttre gealbox to engine
bounting, Also c:heck t})e pyopeller shaft bearings for play by glasplng one blaale
of t}!e propeller ln each hand anal locklng tfre plope11er fore and aft {Do Ig!
rotate the propeller. and Date sure the lgnltlon ls switched oFF before touchlng
tbe propelle!) .
|ft" e".tuo" oll shoultl be changed after tlte flrst 1o houls of operatloD.
lOecr orr level every 10 houls.
| ".-towo" geallrox Dourtlng bolts annualty or every 50 houls.
lUter fm hours anal subsequently every loo hours, the gearbox shoulal be reEoveCl
froE t}Ie engine anil checked for general rrea! and corlect shock absolt€r spring
preloail. Reflll l.lth fresh o1l afte! reflttlng to the engine. (lhls proceilure
lequlres speclal equipBeDt anal ls best left to yout deale! to calry out).

sEc'-eIoH
PnE-STAnlCltlcK
Before 6tartlng engine r'--ad
secbion dealing vrith sga|ting
and engine b:'eak-lrr thorouEhly. Tlreservice life of the englne
is lalgcly determined by howwefl you fol1o',{ lhese instructions.
Before stari::ng engir)e bc curc your it$Cellatign i6
complete, aecure and all. sontI'oi.s operalrc easily and sr,loolhly,
bhat yor-r
can operate tlrenlinstincbively,
Ah.lays enGure taat you a:e irr a oafc i:rrr1-uparea,
Ensure th:olrtle linkage al1ows p-isLotl
'ralve in carb to
botCon in idle po3ition. Scrcl. out idl.e 6pced adjusLrnent screvt
(no,JO, pageT) until, carb FiGtc,n
(no.f ) trol-Lons, Carefully turn
ln adjustment ecrew uitil it errgagee
piston anil turn in a further
t i t 7/2 ful1 :urns,
Check fuel Line i6 coDDected and tank ve::l is oDcn.
PNOCEDURE
On coLd engine apply chol(e frrlly. Leave t)rrottl-e a! idl.c
position. Openlng tbrottlc lrill greatly redlrce clroke effect
resultlng in hard -.tarting. llalre sure ignition sr.ritch is on and
you can ehut lt off lnstantl-y if necessary. Pufl starter until
firnly ehglBed anl tjien pulI ci,artly llrrouglr.
Above procedurc silould'oe rcpeated unt!1 cnglna be8ins
to "firerr.
Aa aoon as engiDe staltr, advfnce tlle throttle sIowly !o
Lotr speed anl renove clrol(e ac .jcon rs posoibl.e. P|olonged use
of choke can ca\lse er)Bine to fl.ood.
If lhe engilre falls to starl, DI ope:alr€6 orrl.yon one
cyllnder, clr:ck ithether the ignitio:r uriiing is disconnecLed fron
the spark plug protectors on flon thc sparl( plugs.
Eneure ahorting switch is in corirect pceition and Hired
correc lfy.
If preceedlng check6 do llot correct the pr.oblen, renove
the spark pluga alrd i[spect.
l{et Epirrk plxgs dcnotc flooded engine, Ileplace Uith dry
plugS and !'ernovc chokc.
Dry spark pl.ugs indlcatc no fucL in elgine. Inspect tank
fuel level, ;:uel valve and tank venlr. Rentovefloat bowl and
enaut
e fuel io presentr.
-6-
S-IAR,.|IIJGPROCIDURE
and
il

SECTION 6
for aircraft lnstallation
(in other appllcation8 proceea accordingly)
lhe break-in has to be perfonned xith the englne lnstal.led,
properly loaded. In case of an aircraft, anchor the plane to tbe
grqund. Run the engine according to the following graph:
-7-
BREAT- I,I{ PROCEDURE
tD3h.
r !000
rurl
t,5
I
0
2.2 ro It 20 ,o 1
5o
to
t0 t16!
(.ln)
/l Be Eure to uEe a aafe run-up area, to anchor aircraft at
tbose polnts appreved by the airfrane manufacturer, and to have
aoEeone present yho 1a abLe to shut off the engine instantly.
I ltt"" thls procedure the 1dle has to be adjusted. Then shor!'
take-off8 can be conducted. After a few sbort full-load take-offs,
but not later than 2 houra botaL running tine, the cyllnder head
nuta have to be re-torqued to 18 + 2q Nn (160 + 210 in.tb,). For
this procedure the cyLl.nder corl (if any) has to be taken off.
Engine tou8t be coLal for re-lotquing of head.
Toola: Serewdriyer, insert 1, (Eocket lrrench 1J), torque wrench.
Note: Uae a crosa aequence fot' tightenlng the nuta.
conslder both heads as one unj.t because they are joined by exhaust
and Eanifold8.
Ensure that covL bolts are torqued less than head bolts.
Ignition polnt rubblng bLocka wear rapldly during the fi!.at hour6
of operatl,on t1ll they 'rpolish in" on the cam of crar|lahaft, therefore
the pointr gap lay require adjustment after brea*-in (betr, 8 + 10 hr8)
! n"f"r to lgnition tirDing procedure. After initlal break-in adurt-
nent la pcrfotled, gnly norrral rnaintenance Ls requiled (see
Dalntenanec achedule).

After lO hour break-i.n perlod also titoroughly cieck spalk p1u9 conilLtloD,
reductlon gearbox bounting lruts, fan belt tenslon. exhaust nuffler
a1! & fuel flltratlon systeEs, electllcal nillng, ltghttng syBteD
relrlnd starte! lope conditLon and change realucttlon gearbox oil. On
a13o re-torque Dagneto houslng (fti'vheel). (See also Ealntenance
eDglne and
attachEent,
(1f uEed)
,
5O3 engLDe
schedule).
SECTION7 CARBURET
ION
Ihe BING calbutette! :[s a plston t]De carburetter stth f]oat ciaDber.
The carburetter can be adjusted by Jet replaceroent of varlous approveat sizes, by
adjustlng idle al!/f\rel Elxt\rre Bclew, carb ptston stop adjustDentr neeatle sizes.
and neeille c]lp positlon. lihe at!,/fue1 r0ixtule at tdle speed is adJusted by t_he
al.r adlusting scre* (see lllustration No,28). fhe ldte t.p.E. ts adjusted by the
calburette! plston adlustrent scre* (Lll. no. 30). Ii(yIE - these idle aauust_Dents
lnteract, so adjusting one Eay require EiDo! adlustjr€nt of the otber. Dullng
lnltial setting up, or lf the carbur.etter bas been natadjusted. the air adjustlng
scree (28) should be set \ turn out frord clcseal to start wtti.
I Note - The carbureto! rnust be in an exact right angte
positlon Ln relation to the crankshaft in both vlers fron top
and fro.0 the intake alde to ensure an equal nixture dietribution
to both cylinders.
Changing parts shoulal be done only after all other iterns
have been checked, and then by an experienced two cycle nechanLc.
Ensure that throtlle cable and lj.nkage do not stick and
that carb piston valve can be opened fully and closed to lhe
polnt where the piston adjustnent scretr no. JO controls piston
openl.ng and idle RPM. t'linor adjustnents can be nade at eable
adjustnent Ecrerr and lock rro. 12 and ng. 11.
A ge eertain that throttle linkage is not affected by engine
or alrfraJDe noveEent. This could change throbtte settings.
I nio lntake flltratlon and noise reduction devices rrust be
ln place for proper carbureticn, See section on sp:cial ,pera-
tlng conditlons. sPectaloPetatlng
conditlons, suchas severe cliEate o!
altltuile clange. nay regu1re dtffereDt Jettlng.
CoDtact your alealer.

EINo CARBURETOR
_ TIPICAL DESCRIPTION
(Note: this is not
,"0
"f
s
I
33€
32t
39
I
o
rt
-3I
-1
ll
31
37
ro--$a\t
f\l
lllt
112
i- |
_IA \
-J tt
- ---{ A
^ 19
----{ d-zo
BII'JG-double
float
c
arbure
to!
carburetor hcusing
carburetor piston
jet needle
holding p
late
plast i c spring cLrp
s
pi'ing
rubber ring
cover p
late
hex. screw
bex. nut
adjus
tment screvr
rubber gronmet
idler jet
needle jet
.81
/'\" \\
\i-r8 -
R--',
tl
U
29
15
r6
17
l8
21
25
nixing tube
nain jet
sieve sleeve
.float needle valve
clip
fLoat
float bra
cket
pin, float
gas
ket
float cbambe
r
spring cl.ip
O-ri ng
air re
gulat inl: screw
spring, adi
us
tment
screll
adj
ustrnent 3crew
b_30
xre
L)*
15)-
77) J1) venl line
12) starting piston tith
gaslte!
slee ve
spring, st arting
pi6ton
closure acrew
starting piston witb
gasket
)7) spring, starting
pis
ton
2
t
It
5
7
8
.,9
10
17
14
18
1q
22
))l
l8
)
39)
q0)
tl1
)
q2)
4t)
q! )
2J)
211)
27)
28) cfosure screw
choke lever assy,
hex, nut
lock washer 5
cyl. screw
ITIIKUNI
- lue I pump aEg
J0)

SECTIONBEXHAUSTSYSTEMS
Canslderable effort has gone lnto the oesign of the
ROTAXexhaust systeos. AnJ chan8es may severely deterLorate
perfornance, rellability, engine life, fuel economy, and the
system's ab{llty to reduce nolse to acceptable levela. Beware
of any acceEaary'systens that advertlEe an improvernent
over
the stock conponenta,
Af vlbratlon due to ihproper Drounting is any exhaust
systeru's worat ene,ny. Properly rnounted anil rflaintained, your
exhaust Bysten wlLl provide a long serviee life, Never renove
coupllng sprlng {ith a sharp object or one which can nark the
gptlng natenlal. A rounded screw-driver 6bank or a hook
fashloned fron 1/4'r bar stock ls ideal. Safety-{irlng of aprlngs
lE essentlal, as a broken spllng falling lnto t-lre proPeller corild cause sevele
danage. Flequently check Eprlngs for wear at the points of contact r'lti the
iooks and tie exlaust' Replace sprlngs when necessary'
sEcrloN 9 rNsrRUMENrs
fnatruments ""r, U" " valuable addi.tion if they are of
good qqal,lty, correctly insta1led, are nonitored, analthe
operator understands what they are telling him,
A Never uEea tachodeter tvhlch can cause
a short-cut on the
lgnition bysteE. AItet'natlvely use a tachometer
operating on the
llghting col1.
Al!. instruaents requinlng power source nust be oyerload
protected.
Al,1 wfuing and sensor leada nust be properly routed,
protected fron vibratl.ons and abraslon.
The 501 englne is designed and tuned to operate at 6150
fuu. load, full throttle.
The ,77 and 447 engines operete at 6500 fu1l loaal,
fuII throttlc.
a cyl.lniler head telopelatule guage elth a senso! unalelneath the sPark Plug seat
ls a useful accessory. ltre naxltlutD c'!'llnile! hea'l terperature Ls 25ooc'

SECTION 10
I
-r1-
IONITION SYSTEM
The ROTAXenglne ls equlppealritb a BoSCH
nagneto generator
12v 1q0wratlng, producLng the current neceEaary
for tbe
gpark analacceaaorl.es, The ignitlon unlt has been Eet to precise
toferancea by the factony. After lnitlal break-ln adiuetrcenta
&aLe no cha4gea_unlesa absolutely necesaary.
In case of trouble gbgerve the followlng:
If the l8|litlon faile intermittently or if tbere are other
troubleB that are due to neither 6park plug, nor external
conponenta, nor carburetor, the contact breakerB nay be the cause.
contacts nuat be clean and nust not be burnt, lrith new englneE
or nelr polnta the cam-folloFer of the ignitlon polnt aet weara
rapldly inltlally. Reaetting of contactB laay therefot'e be
nece6sary after eorne
tlme. The breaker contaets are accesaible
after removal of the retind starter and the starting pul1ey, Tbe
Eagneto hcuslnq (fl).rhee1) need not be re!,oved. Once carn follower has
ItpollBheil inn and points are re-adjusted, Bettlng6 Hill hold for
eonslcerable tl.me. To check vbether the ignition timing ie
qorrect there ls an affolt on the fan houslng, Further, there
are two Bc!'ibe rnarks on tbe magnetohousing, one for each
oyllnder, trhen the acribe rnark for the cytinder concerned llnes
up with the arrov, the lgnitlon points Bhould iust bave broken-
contact, thua triggering the lgnltlon Epark. If setting8 are
correct, thl.B would comespond to a firing point vrith.a tolerance
of between 1,81 and 2.r5 .nn ar .072 and .092 inch in pistor,
tflovementlglglg the piston reaches the top of tbe stroke. Use
a dlal indicator tool. in8talled in the spark plug hole.
I0NITION TII'1IN0 (mark6 procedure )
1) Dlaconnect spark plug pLres and remove6park pLugs,
2, Renovereirinal atarter assembly from engine,
the fan protector anal starting pulley.
Noter Thc gplg breaker point set controla the
pagneto alde g1ston anal the f!Jg! breaker point
then rernove
tlming of the
aet control a
the P.&q! Elqe plston.
,) Rogate crankshaft until breaker points vi61b1e thiough
fly{heel are fuLly opened, AdJust point Betting to .O72 to -ar6
lnch urlng a feeletr gauge and ecrew drlver', aa lllustratetl. Repeat
procedure for other set of points. AdjuEt both sldeE equally.

-L2-
NOTE! Breaker poLnt gap can change upon tightening. Always
recheck after t lghtenlng,
q) PulI back the rubber boot fron the double lead wire from
both external coils. Connect one end of a timing tight (flaEh-
tlght type) or a tone ti.nrer to the double lead wire connection
(nag elde). Connect the other wire to a good metal connection
en englne (ground).
5) Turn titning instrunent on. Insure tbat igniti.on switch is on,
Rotate crankshaft untiL mag side piston approaches top dead
centre and tl.ming narks align, The timing light shoultl fluctuate
or tone signal vary, If not, then slacken the tuo arhature plate
retalning acrewa and Totate the ptate till markEand tining
fluctuatlon a1ign, then retighten retaining Ecreqs.
NOTE: Tirning may change upon tightening screwa, Recheck and
correct as neeessary,
6) Dlsconnect timing instrunent wire from nag side connection,
then reconnect lt to the double wire conneetlon on polrer take
off colL nlre Leading fron engine. Rotate crankshaft until
PTO
side piston approaehes top dead centre, As soon as tining
rnarks allgn, tlmlng light should fluctuate, or tone signal sound
level Ehould vary.
NOTE: If neceaaary to adjust, proceed as followa:
- if tinlng is too early, decrease breaker point gap toward
Lower llmlt, 1.e. 0, 30rutr
( . o12''), then recbeck timlng,
- lf tlrDl.ng Is too late, increase breaken point gap toward
upper IInit, i,e. 0, 4o mn ( . oI5n), then recheck tininB.

Too ear Turn arnature plate
clock ise Too earIYi Decrease Point gap
\,/ \
mark
Too late: Turn armature Plate
' counie
r- closkwige Too late: fncrease point gap
?) l,ihen
correct tlntng ls achleved, check Pole shoe breatavay gap. The gap lrust
be iritlin I to l?En or o.3 to 0'69 ln' (see tllustlation) \r'hen
the nark on
fllruhee1 colresponCs 'ritlL nark on fan housinq'
If t-he breala$ay gaP ls out of tolelance' the f1! dbeel InaYhave
cranlshaft ' Fe!0ove
f:)a'teef and insPect taPe! and key' RePair
edge
cardb oa!"d
striP
o
8) once cottpteteil. leconnect afl wlres, replace "v" belt pulley and starter cup'
Replace rerlnil stalte! aIId fan ProtecEol'
NOIE: !'lag ana PTO coifs are wire'l lnversety fol correct outPut of lqnitton' If
ln alodbt, c$eck willng iliagra&'
NotE: - uagneto houslnq (fl)rvheel) ltut
- On 5O3 englDe only, hex nut u22 x 1'5 ls not seclre'l wlth locrrrE anil sholl'l
be re-tolqueal (9o NI'l - 8oo Lb'ln') after ttle flrst 10 houls and then after evely
20 hours.
turneal on the
lf necessarY.
.c9

-1{-
SECTICN
II SPECIAL
ffiATINC
$DITI0,S
Fl.oat flyinq off watet 16 a falrly lare occurrence ln Gleat alitaln, but 1f you do
fly off water tlere ale dangers to your engine you \.,onrt experience on land. SoDe
of t-hese danger6 ale t ate! lngestion on tale-off or landing due to spray anal splash,
tracklrlg of hlgh ten-slon spark, corroslon, electrolysls, and lrolst of all
unlntentional aubEerslon, slnllar probleDs can exist 1f flytng close to tle coast
or off beaches, s'hel.e salt anal sand can afso be a hazald.
rhe htgh carboD content of htgh quality bearlngs, crar*shaft etc. are highly
susceptlble t! colroslon. Slmthettc olls, although good lubrtcants, often attract
Eolsture rathe! than repel lt.
I e gooaquallty air intale systeD {1.e. K & N oll- lDpregnated fllter} will
plevent Ioost plobleEs.
lO.y rfft.t eleEents {paper tt'pe ) are not acceptable especially 1D rootst
condltions. They FiII a.bsolb rat€r and choke the engine causing over rlch
carburetlon Dlxto.res whlc-tr result ln enqlne Dolrer foss.
I e pre-flignt spray over tfre exposed lgnltlon coroponentsl,ith a water :.epelent
splay wtU help to plevent elect).lcal plobleEs ilue to t{ate! anal salt.
NOTE: lrost englnes are fttted vith nolse leductlon kit consistlng of an lntE-ke
sllencer and after Euffler. ReEoval of the lntake silencer {of fltttng, if t}le
engine vas supplied l'it})out one,) v111 necessltate alteratlons to t}le carburetter
calibratloD. Englne danage could lesult if carburetler ls not ,etted correctly.
EnquLre at your ileale:. for nore lnfornation.
I on aircraft equipped
wftn englne cowllngs you must ensure blowe! lnlet size ls
not restricteC aid exit lE double ehe lnlet area. there shoulai be no circulatton
b€tween Lr,1et and exit on col'11nq.
CARBT'RTTTERICING In coDEon nLtl all sildla! calburetters, tclng 1n t-be throat
of t!,e carburetter can occrE unde! certaln conditlons, partlcularly Fben tl1e alr
tebperature ls lcw and the hreidity hlgh. Excessive lcing can cause rough rLnrinq,
a stickitlg tirottle, and posslbly total engine failure. Even slight lclng, '"_hich
oay be undetected, caD cause ploblebs as lce fofireal 1n the carburettor lrill $elt .)
rlhen t}e englne ls stopped. and can tric}le dolrn lnto t-he float chaDber whlch bay
teail to a blocked Jet and an englne fa11u!e on the subsequent flight. A carburetter ':
heatlng systeE ts avatlable to countelact t}|ls lctng plobleE. If a heating systeE
1s not fitted, elthe! avolil operating ln condltlons \rhere tcing nay occur, or, lf
you suspect 1cln9, make frequent ple-fught checks to dete&lne whether there are
,ate! &opfets ln tne float chaEb€r by renovlDg the boul anal lnst)ectlng b€fore each
fltoht.

sEcrroN12
A l**"t* rt ls recoro'enitetl
co[ponents or systeEs not coveretl
IlAINTENANCESCHEDUI.f
you have deale! assistalrce pe!loalically for
by thls 'lanual.
I Ot""onr,""t spark plug leaals fo! afl Ealrtenance anal tnspectlon plocedures.
once per week for a norDal duty cycle or avelage fllght.
largely on the typ€ of duty the engine ls subjected to.
Englne rl,eat is dependent
Severe or lnterEdttent engine operatlon will result ln Duch nore laptd engine wea!
per hou! tian steaaly coDtinuous operatlon. ff the englne l.s not gotng to be useal
for 20 to 30 ilays o! Eore, consuft storage procedules ln thls sectlon.
Thorough ltspections and checks rcust be nade aluring the
| ".*". tlnes are based on avelage use, assuning englne is rrrrr at' least
flrst houls of
tn tolerance.
operatlon, to ensure that all components have reEaiDed t19ht and
Fal]ure to do so coulil leaal to pletiature englne fatlure.
lhls ls an a.bbrevlateal Eaintenance schedulei partlcular procedures are explatned ln
Eo.e detall else}fiere ln thls Eanual.
PRE-FIIGIIT qEECK Eust t!€ callled out before every fllght.
Vlsual check of engine anal gearlrox for loose nuts anal bofts, oil leaks, locse
wlring connections, chafed wlres, security of spark plug caps, security of
plopeller Eouttt1ng. securlty of fuel 1ines.
Oreck propeller for chtps and ot-he! dabage.
Check propeller shaft bearing for play - lf any play is evident do not fIy.
Check exhaust s)stem for cracks, check exlaust Dountlngs and coupling spflngs.
Check fafl belt has not broken by tutrdng englne using tewind starte! obsetvlng
cooling fan turarlng.
If prevlous flylDq condltlonE have beeD ltkely to cruse calburetter icing. unctlp
carburetter float chaDber anil check for water conta.Etnatton.
}FTER FIFST EOUR (GROU}ID RI'NNTNG
BREAX IN ONLY)
A;l!!<t.:rhrrYAi+ai
Carry out pre-fllght cte* above.
AT:IER EIRST 2 HOUT5
Re tolque englne ct'llnder heatl.
rFiFp FIFiT q ur,rD:
Fe_trEh!en Exbaust nanifoLdscrews.

AI"IER FTFST 10 EOI'Rs
Check contact brea.ker polnts gap anal lgnitlon tlnlng
check condition of spark plugs
Check englne and redrctlon gearbox Dounting nuts
drect fan belt tensloh
Check al! ftltratton syslen
Check fuel ft ltratlon syste$
check for locse lruts and bolts
or€ck llghting systeB (1f useil)
Check conilitlon of reirlnd starte! lope
Re torque Eaqneto housing (fl!'wheel) nut (5o3 englne only)
chaDge redDctlon Eearttox o11
Carry out t-hofough pre-fllght check as above.
EVERYIO I]OI,IRS
Re torque agneto houslng (fl]'whee1) nut (5o3 engtne only)
EVERY50 FOUF.S
oR ANNUAILY (which€ve! cones flrst)
check conalltlon of spalk plugs
check red\.ctjon gearbox 011 1evel
cieck fan belt tension
check fuel flltration systeD
aleck ai! filtration systeE
EI/ERY 20 EOURS
Check contact br€aler polnts gap
d)eck tgnitton ttDlng
Decarbonlse lf necessary
Fe torque c)'l1nder head nuts
Re tolque gearbox Eountlng nuts
Re tolque englne nountlng nuts
ReFlace sFark plugs if lrecessary
EVERY1OOEOURS
oR EVERY 2 YEI\RS {whicheve! coDres first)
.i
I
Check reduction geatbox for *ear antl sbock absorbe! sprlng preLoaal
check alaphragns and gasket in fuel PUmp- rePlace lf necessaly
EVERY 2oo SOURS, OR S@NER IF A IPSS IN POWER IS SUSPE(TED
Check cyllnaler bores for $ea! or daDag€
Check plstons fo! wear o! da.Dage
check pl6ton lings for sticklng tn tiell grooves
ca!!y out coErpresslon check
.j
)-

I
f-r7-
.
i:
SPARK
PLUCS: Due to varying fuel properties etc.' check every
10 houra of operation. Beplace aa required or annuafly,
- proyiding spark plug heat range and the carburetor
callbration are correct, the spark plugs will have a bro!.nish
tinge at the electrodea of both spark plugs after full load
operatlon, One sooty spark ptug by itsetf usually lndicates
a baal
plug or faulty ignition system to that plug in a sound
englne. If both plugs are sooty ith oil. deposits, carbu!'ation
and air syaten ahouLd be checked.
A1ways change both plugs if possi.ble,
Never interchange plugs fron one cylinder to the other.
If both pluBs have I'white'r electrodes with I'me1t'r
droplets'
firet suspect lean nixture. If calibration is correct and there
lg no evldence of nanifold leaks ot' lack of fuel, change the
plugE to a colder range. Do check if cooling systen is operatlng
correct ly .
AI ntt..,tton; Heavy oi1 deposits on the electrodes and
Lnsulator cause englne troubles and have to be renoved regularly
(every 10 hours ) ,
ff, after cleaning or changing the spark pfug8, you still.
have an ignitlon problem, check to see if only one cylinder is
affected or both are. Somethought to what is common
to both
aystens or only one will isolate the problen more efficiently,
If no external fault is found, the ignition uni.t nust be checked.
Never clean 2-cycle spark plugs with abrasive cleaners.
Renenber to correctly gap yourplugs with a wire gauge -
0,{ to 0,5 n[! or ,015 to ,020 in, spark plugs rnust be torqued
to 27 Nn or 240 in.lb.
.i
i
t
aeg
I

-re-
lio nct operate tlre engine if the rewind starter itj defecti.;e. I
t
@
9
ob,u
ttl
JI}
a
c{,lLr1,l0slsrEM
I
fnspect fan belt tensl.on every 10 hours. Replase belt if
frased or can be ten3loned no Longer to epecification.
The tenslon of the V-belt can be adjusted by shins betHeen
the \t-belt pulley half and the fan (resp, the protection sheaye
on 503). The V-belt lB correctly tensioned xhen lt can be
dep,-ee$€al
8 +.9 EE (1/{i)with nortral finger presaure (in the
Eldd-r.e
betxeen the 2 V-belt sheaveE).
REI.'IND STARfER
Check cord candition every 10 hours. Replace when worn
or trayed.
To ehange the starter rope, follow the pr:ocedure outlined
(the nunbers etated in bracketa refer to the illust.ation).
Flrsg rg,oove the rewind slarter assernbly fron the engine.
s?cond, rerDve the snap rins (9), loop spring (8),
clrclip (7), pawl lock (6), and the ta,r (5).
Pull out the ata.ter rope fully to the end, hold atarter
hcueing (1) and rope sheave (J) together in their pcsition.
There is an apening in the rope sbeave, The key clanp (4)
vlslble r'n ibe opening has to be puehed out in the oppoeite
serse of tbe pulling dj.rection. Pull the rope out of the rope
iheave,
Tben insert the new star-ter rope inlo the -a
pe shea?e! rrcunt
r.he key c1€Lnpin the saj-ne
position as it !.'asbefire and !,eniount
the partB 5, 6, 7, 8, and 9.
Jl L:;....,1ilgri Do not rer0oee spring container (2), this might
cause in,;'qries,
\o
d