06_Fuel and Lubrication System

8/4/2019 06_Fuel and Lubrication System

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CONTENTSFUEL SYSTEM ............................................................. 6s 1FUEL COCK ................................................................. 6- 2FUEL PUMP ................................................................ .6- 3CARBURETOR .............................................................. .6_ 4

CARBURETOR CONSTRUCT/ON ................................ .6- 4SPEC/F/CA T/ONS ..................................................... .6_ 6I.D. NO. LOCA T/ON ................................................... 6- 8DIAP HR AG M AN D PISTO N OPE RAT ION .....................6 - 8SLOW SYSTEM ..................................................... .6_ 9TRA NSIE NT ENR ICHM ENT SYS TEM ...........................6 - 9MAIN SYSTEM ........................................................ .6_fOSTARTER SYSTEM .................................................. .6_11FLOAT SYSTEM ..................................................... .6_11REMOVAL .............................................................. .6-QDISASSEMBL Y ........................................................ .6-QNEEDLE VALVE INSPECTION ................................... .6_13FLOAT HEIGHT ADJUSTMENT ...... ......................... .6_13REASSEMBLY AND REMOUNTING ... ......................... .6_14BALANCING CARBURETORS ......... ......................... .6_15

LUBRICATION SYSTEM ....................... ......................... .6_17O/L PR ES SU RE . ............................. ......................... .6_17OlL FILTER .................................... ......................... .6_18OIL SUM P FILTER ........................ ........................ ..6_18LUBRICATION SYSTEM CHART ...... ......................... .6_19


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6-1 FUEL AND LUBRICATION SYSTEM

FUEL SYSTEMA vacuum operated fuel pump is used to supply fuel from the fuel tank to the carburetor. The pu mp isnecessary as the fuel cock is mounted lower than the carburetor fuel bowl. In addition, the pump assuresan adeq uate supply of fuel to the engine unde r the steepe st climbing conditions as well as while runningacross rough terrain.

No. 2 carburetor

Fuel

Fuel pump


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FUEL AND LUBRICATION SYSTEM 6-2

FUEL COCKA valve is provided at the top of the fuel cock lever and can switch over to OFF, ON and RES.With the valve ON (normal), the main passage opens. With the valve OFF, both holes close.

ON position RES position

ON

WARNING:Gasoline is very explosive. Extreme care must be taken.Gaskets mu st be replaced with new ones to prevent fuelleakage.INSPECTION AND CLEANINGIf the fuel strainer is dirty with sediment or rust, fuel will notflow smoothly and loss in engine power may result. Clean thefuel strainer with compressed air.


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FUEL PUMPVacuum pulsations from the carburetor intake tract are used to operate the pump diaphragm . Whenvacuum is applied to the diaphragm, fuel is drawn from the tank into the diaphragm s chamber. As positivepressure is applied, the spring forces the diaphragm back, pushing the fuel through the outlet to thecarburetor.A series of check valves is used in the fuel flow route to allow the fuel to move in only one direction,through the pump bod y.

Negat :ive

Fuel from fuel cock

Fuel to carburetor

Positive 1

FUEL PUMP INSPECTIONIn case of fuel leak at fuel p ump or air leak into the fuel line,check the following items:* Broken diaphragm* Malfunction of check valve* Loose screws on fuel pumpIf any defect is found, replace the fuel pump assem bly with anew one.


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CARBURETORCARBURETOR CONSTRUCTION

No . 2 (FRO INT) CARBURETOR

($ Syncronizing cable@ Thrott le valve@ Thrott le valve shaft

return spring

0 Needle valve

@ Seal ring

@ Main jet@ Main jet holder8 Pilot jet@$ Starter plunger@ Balance screw@$ Coasting valve0 Fuel hose@$ Breather hose@ Carburetor top cap@$ Piston valve spring

@ Jet needle stopper plate@ Spacer@ E-ring@$ Jet needle@ Washer@$ Spring@ Piston valve@$ Needle jet


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No. 1 (REAR) CARBURETOR

@ Fuel hose@ Coasting valve@ Drain screw@ Gasket@ Float pin@ Float0 Needle valve@ Filter@ Main jet@ Needle valve stopper screw

0 Pilot jet@ Balance screw@ Thrott le valve@ Throttle stop screw@ Thrott le valve shaft@I Thrott le valve return spring0 Pilot screw$$ Starter plunger@& Fartburetor top cap

IS on valve spring

@ Breather hose@ Jet needle stopper plate@ Spacer@ E-ring@ Jet needle@ Washer0 Spring@$ Piston valve@ Needle jet


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SPECIFICATIONSCARBURETOR CARBURETOR

I SPECIFICATIONITEM E-02.04. 15,21,25,28,34 ICarburetor type MIKUNI MIKUNI

BS36SS (No. 1) BDS36SS (No. 2)Bore SIXI.D. No.Idle r/min.

36 mm c45coo t

1100f100r/min. tFloat height 27.7fl.Omm 9.1 f 1 .O mmI1 -09 20.04 in) (0.36 f 0.04 in )IMain jet (M.J.) # 132.5 #I20Main air jet (M.A.J.) 1 .B mm tJet needle (J.N.1 5FlOB-3rd 5D49-3rdNeedle jet (N.J.) 1 P- 4 tThrottle valve (Th .V .) #115 cPilot jet (P.J.) #47.5 #40By-pass (8.P.) 0.8 mm x 2PCS 0.8 mm x 3 PCSPilot outletValve seatStarter jet

(P.0.)W.S.)(G.S.1

0.8 mm 1 .O mm1.5 mm t# 25 # 22.5 7Pilot screw (P.S.) (PRE-SET) (PRE-SET)l-3/8 turns back l-l/B turns backI 1

Pilot air jet (P.A.J.) No.1 : (# 70). No.1 : (# 65).No.2: (2.0 mm) No.2: (I .2 mm)Throttle cable playChoke cable play

0.5 - 1 .O mm(0.02 - 0.04 in) t0.5 - 1 .O mm(0.02 - 0.04 in) t

CARBURETORSPECIFICATION

ITEM E-03Carburetor type MIKUNI MIKUNIBS36SS (No. 1) BDSSBSS (No. 2)Bore size 36 mm tI.D. No. 45ClO tIdle r/min. 1200 + 50 rlmin. cFloat height 27.7fl.Omm 9.1 * 1 .O mm(1.09 * 0.04 in) (0.36 * 0.04 in)Main jet (M.J.) # l3Z i # ir_? iMain air iet (M.A.J.) 1.8 mm tJet needle (J.N.) 5E72-1 st 5D47-1 stNeedle jet (N.J.1 P- 7 p rThrottle valve (Th .V .) #I25 # 110Pilot iet 1P.J.) #Y i #Y UBy-passPilot outletValve seatStarter iet

(B.P.) 0.8 mm x 2PCS 0.8 mm x 3 PCS(P.0.) 0.8 mm 1.0 mm(V.S.1 1.5 mm t(G.S.) #25 #22.5

L

SPECIFICATIONITEM E-33Carburetor type MIKUNI MIKUNI

BS36SS (No. 1) BDS36SS (No. 2)Bore size 36 mm tI.D. No. 45C20 tIdle rlmin. 1200 + 50 rlmin. tFloat height 27.7 * 1 .O mm 9.1 + 1 .O mm(1.09 f 0.04 in) (0.36 f 0.04 in)Main jet (M.J.) # 132.5 #/f?L?.iMain air jet (M.A.J.) 1.8 mm tJet needle (J.N.1 5E73-1st 5D47-1 stNeedle iet

I(N.J.) / P-q P-7 t

Throttle valve (Th.V.) #125 # 110Pilot jet (P.J.) #Y #Y UBy-pass (B.P.) 0.8 mm x 2PCS 0.8 mm x 3PCSPilot outlet (P.0.) 0.8 mm

1 n--Valve seat (V.S.1 1.5 --Starter jet (G.S.) L

06_Fuel and Lubrication System

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