Rotax 377 User manual

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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.