Honda G28 Horizontal Shaft Engine Repair Manual

G28 (ALL) A FEW WORDS ABOUT SAFETY SERVICE INFORMATION The service and repair information contained in this manual is intended for use by qualified, professional technicians. Attempting service or repairs without the proper training, tools, and equipment could cause injury to you or others. It could also damage the engine or create an unsafe condition. This manual describes the proper methods and procedures for performing service, maintenance, and repairs. Some procedures require the use of special tools. Any person who intends to use a replacement part, service procedure, or a tool that is not recommended by Honda, must determine the risks to their personal safety and the safe operation of the engine. If you need to replace a part, use genuine Honda parts with the correct part number, or an equivalent part. We strongly recommend that you do not use replacement parts of inferior quality. For Your Customer's Safety Proper service and maintenance are essential to the customer's safety and the reliability of the engine. Any error or oversight while servicing an engine can result in faulty operation, damage to the engine, or injury to others. For Your Safety Because this manual is intended for the professional service technician, we do not provide warnings about many basic shop safety practices (eg, Hot parts- wear gloves). If you have not received shop safety training or do not feel confident about your knowledge of safe servicing practices, we recommend that you do not attempt to perform the procedures described in this manual. Some of the most important general service safety precautions are given below. However, we cannot warn you of every conceivable hazard that can arise in performing service and repair procedures. Only you can decide whether or not you should perform a given task. Important Safety Precautions A WARNING Improper service or repairs can create an unsafe condition that can cause your customer or others to be seriously hurt or killed. Follow the procedures and precautions in this manual and other service materials carefully. A WARNING Failure to properly follow instructions and precautions can cause you to be seriously hurt or killed. Follow the procedures and precautions in this manual carefully. • Make sure you have a clear understanding of all basic shop safety practices and that you are wearing appropriate clothing and using safety equipment. When performing any service task, be especially careful of the following: 0 Read all of the instructions before you begin, and make sure you have the tools, the replacement or repair parts, and the skills required to perform the tasks safely and completely. 0 Protect your eyes by using proper safety glasses, goggles, or face shields any time you hammer, drill, grind, or work around pressurized air or liquids, and springs or other stored-energy components. If there is any doubt, put on eye protection. 0 Use other protective wear when necessary, for example, gloves or safety shoes. Handling hot or sharp parts can cause severe burns or cuts. Before you grab something that looks like it can hurt you, stop and put on gloves. • Make sure the engine is off before you begin any servicing procedures, unless the instructions tell you to do otherwise. This will help eliminate several potential hazards: 0 Carbon monoxide poisoning from engine exhaust. Be sure there is adequate ventilation whenever you run the engine. 0 Burns from hot parts. Let the engine and exhaust system cool before working in those areas. 0 Injury from moving parts. If the instruction tells you to run the engine, be sure your hands, fingers, and clothing are out of the way. • Gasoline vapors are explosive. To reduce the possibility of a fire or explosion, be careful when working around gasoline. 0 Use only a nonflammable solvent, not gasoline, to clean parts. 0 Never drain or store gasoline in an open container. 0 Keep all cigarettes, sparks, and flames away from all fuel-related parts.

open more bookmarks ' -' click to condense the PERFORMANCE ! ···· ··0 DIMENSIONAL D L ..... D WIRING DIAGRAM 1±1·· ·· 0 SERVICE INFORMA 1±1···· 0 TROUBLESHOOTING MAINTENANCE DISASSEMBLY & SERVI DISASSEMBLY CH P.I~~~~~.~.I:J.L.:..... ....... . . !i :N:§:P.:g:¢.fi : 9.:Ni MUFFLER/AIR CLEANER RECOIL STARTER/FAN C FLYWHEEL GENERATOR G28 (ALL) ODNTROL !iOX GREEN BOX UNK$ Click here to go to this page in the manual

G28(ALL) FEATURES 1. OHC Higll r•erformance Engine Thi~ engine is a 4 cycle engine employing ttn OHC de sign superior in vol umetric e fficiency, and producing 2.8 horsep.ov.~f' wi th minimum fue l consumptiou. 2. Quiet Versatl~ Engirt(' _, Concenttntoo in Design for Loft' Speed Pcrfonnancc Having a greater dri\'ing fo r(..'C at low speed range and q,li~ ope ration with minimum of vibrations, it is a powerful rugged engine whi~h displays the full ~rit~ of the 4 cycle SYstem. 3. W~ttcr.Proof, Dllstproof Engiu An oil bath air cleaner is provid~:d on to p of the completely cnclo.~ed type engine and a tabyrinth pack- in £ on the magneTo to pf~\'tl"tl dust Ellld wute1 fmrn enl~:ring the cne:in~,;. The entire unit can bo wa.~hed -with water wi1hnut worry nf water wetting the engine. 4. Horlr.ont~J D~sign \l'iCh Low C~nl~r of Gmvity The engine bady is de!'.igncd a!) a hrorizontal ty('lf wit h low ccnier gravity {) rovidinc ut n1osr safety in operation with .minimum vibraiion. 5. ·"uto~ru~lic Centriflll¢ CluldJ As an aucoma.tic centrifugal clutch is iocorpo raced, making tl1~ engin~ easy to slltr( ewn with 11 road. Under ex.;essive lO<t d the clu~ch operates without :.li\lling the cnsine.. Further, a work mu.:hinc t::tln be ~topp«.>d by operation of the throttle only. (,, Easy Bnudling It is desisned lo op~:rate easily by nnyon~;: (tluoltle, fud cock, t:ngine swil«:h and ..:huke lever art: in\er- luckcd on a single control mounted 011 the panel). 7, Hi1;:hly Vcr:iatile (hi; '-'nginc <."an IJt- widely USI."CJ to p<JWCr Wltlc:r pump, ~c:ncrator, liLWrJ m<J\'Cf, p<JWCr<:U ~prayer, tirJd numerous other ust:S.

·= G28 (ALL) SPECIFICATIONS <=INDEX 1. f:nll:in~;: Sf"X"ilicalioo:~: (G 28 F) Model T~pe Type of fuel Coolirl!;: sys1em Numher of cylinder and type C~de Toral piston rcpla~·emcnl !'!ore X Stroke Continuous r111(..-d horsepower Ma:.timutn 11r>rst:powt:r M<tximum tarq11C Dim<:nsion (l~ngrh x widlh x height) 0 1)'" Wf'll',(lf Fuel c:Jnsmnplion Compression ralioJ Valve arrangement Ty~ ..,r curnbustlon cbamber Type of piston Number Qf pls1on rings Irllet vJlvc (Opell A. T. JJ. C. Clns\: A. D. D. C. Exhaus~ v~J.,e {Open B. B. D. C. Close ll. T. D. C. !gnirion syslern Ignil[oa timing Starling sy~1em Spark plug Stoppin!! sy:;t(;m Carburewr S~d go11cmor Lubricant capacity Air dt-ane r LtlbrK:alion sys 1em Clutch tyf!t r Shuft diame1er PTO RPM (<t~ _Mux .. hor:scpowt:r) lfl.otalmg ~ohre(;llon Pow~r ~ncra1ing systr:m Fuel lallk cupHdty Air cleaner oil c:apaciry lksniption Gasoli11e Fon:~d air cooled Single cyli11der, l•ori,vlitill type, go inclined 4 67 cc (4.09 CLI in.) 49 X 35.6 mm (l.9J x 1.40 in.) 2.0 P.l'/5,000 rpm H HP/6,000 r[1m 0.37 kg··m (2 . 6B lb- ft.)/4.000 r~'nl 32.4 X 29S X 323 mm (12:.76 X 11.?3 X 12.72 in.) 14.S kg (32.0 lb) 300 ¥/HP/h ( 0.661 lb/111-'/h) lU O.,erheacl camshaft typ~ O"al ~hEI~ Aluminum .alloy, fta1 l1e.1d type 2 compression ria~;:s ;md l oil r[ng 10" ( at 1.05 mm lirt) ~o· (al 1.05 mm lifl) 1 j• (a I 1.0~ mm lit't) 1 o· (31 1.05 mm lift) Hi;;h tensivn deo.:tri~: ignition 30' IJ. T. D. C. (tixccl) Recoil starter C-6 HB (NOK) Fu el cod; in1crloding t_!ipc (~witclo gr0undins systelll) lloriwntal buucrlly type Centrifugal weigh! type 0.7 l!tt'rS (0.74 U. S. l(l •• 0.1'>2 Imp. C ft .) Oil bath type For~d. splash Au1omatic ~:emrirugal cype (I 23 F D, FD WD 19 rum (0.748 in.) J,OOO rpm Clockwi~c G 28 LJ ' l9 m.m (0.74$ in.) 4. 2:<.0 rpm Coumcr clockwise rlywhecl magnclo system 2.5 liters (0.66 U. S gill.. 0.55 Imp. gal.) 40cc (I+ OZ)

G28 (ALL) PERFOIL'\fA NCE Cl!nVE 10 1-- -- ..... , ..... _.,.-_.,. - - ---, I I zsr~-- . I Ma dmum hc · se;JOws-r I i I 2 8PS!6.00Urpm / n ....: 1 1).29 0. 28 w ;;;;;;) r 0. 27 (Y ~ 0 0.26 1- 0.2~ 0 24 C .23 0.22 0.6~ 300 0.60 -· - - CRANfQitiAFI SPLW 3.5 40 4.~ 5.C ':1. ) 6.0 >~ !OJ PTD ~PEUJ lor G28Ll is 3.0 15 4.0 4.28 >~ :o ~ PfO Sf'fFfl ftll f28 F.~(){J 1.75 ?. 00 2. 25 i.'.JO . 2 .. 75 -- J OO X i0 3 CR~N~SHAI r s~EED Fi£. 1- 1 Otll ['Lil ch;~r:t~::t<.~ri~:ic c: ur ve 1. !' [)wer curw); ~md < ll'e developed from lest t!ngine equippL•d wilh s1andarll ••i• · ck•an~r. mullkr. and <ill o1h~1· power com.uming devices and ~ re c orr~c:tcd to standard sea lcv~::l atmos pheric pressure <Jf 2.9.92 in. of Hg and a temperature of 6n°f ( 15 °C). 2. Pmdu(:Jit•n cng)nc. =, when .~hl('lped, wJJI dcliclof') nor Je:.~.~ rhMl 9f>% of rhc max inmm R. H. P. Afrcr run inw reduce fri~tion, it will dcvcl o~ not less than 95% of ma ximum H. H. r. J. Engine powc:r will rlecrea~«: arproximately 1.5·;,; for each 1 OOOft (JOOM I a bull\.'. sea level and I % l'or each 10"1-' (6"C) abm·e s.tanc1atd ~emperature of GO"F (15"C). 4. Tests were con ducted in conf o rmance wilh SAE St11ndnrd J 607.

,. ---- - G28( ALL) DIMENSIONA L DIAGRAM I <=INDEX Thrt:t· View Din•cosional Drar;ing ~ PTO SHAFT FOR G 28 ED. FD. (CHAIN T YPE) 1e1 __.... G\ ;:; r-t. , ~:- l ~; 11--i-~--------.i -~-=-1 -· •• J ____________ ________ _ fj - -- !.30 (56.3 1 I ' ·- > Q ~. ~ -- ,... ' " g • A -ro£:- _____ l t~ PTO SHAFT F OR G 28 D ( GEAR T YPE) I ~---1-'' \ ( . : I 'I l I ·- - e~ii.lt --- ~ -11 ·- ·-·I I ,...to : I (1 (},8~- • 0 "' I l oOrl- ' . ··- -~, . - ~ ~h - ·~m - . 1 . ' - ' :. · . 4i L. ~ I .; ~ I I ;:~ ~-- . .. ' 1'7 .. __ .. ._ --,~ -;. .I i' ~~;;; ~-·· . ~ : . I ~ . ~~.: ~..a - ·r S -=l-L - ~.-- . -··- I ..J. -~ :·~ -- r- · ..- ', 1 C 33 ' : iJ!:~l I _ ,., _ ... "' .:-··- r-_,_ ._ ___ --i}/ .~-~---= _._, _ __ _ IJnit : inch (mm) ?: ~1a rk G 28 EO. FD

6 G28 (ALL) DAJLY Al\U I·'ERlODICAL lNSPl';CfJONS It IS ut' utmost imponan~ to rw;rfo r111 proper in~pr.: liuu UI IU mai11t~uan~.;c to kt:~J) lh· .: G 28 cngin:; m the bes: o per~ttin!!- condi tion. DA ilY IN$~ECTI O"' (·.~ hich is w be pc ·1l\1rmeJ d<.~i ly hy the us~ r hctorc opmm ng the er1g10c} PER 10 1)1 . CAL INSPECTIONS (1\'h ich •tn :· to be pc: 1 fo rm:,;J "t th e sp::c rllcd i n:CQI'al~ hy !hi:: :-;erv icc ~hor) L DAlL\ ' L~SPE.CrL01\ In f'Cr forming ~he d?J ily mspccri c. • :J, :l ilk rour;jdf ill:.: f'o llo win&: qucst. = or. s ;mel 1 hcn che.;-1.; !hose specific itt>ms to assun• thut the conditio ns arc s:li isfa clory. a. 1 '5 the en~inc oil fi ll ed ro t he f'l TOjlCr lcl•cl ' b. Is there ~llflicicnt fuel in 1 ht: lllnl: '! Ti l nk capi!ciry ~ :u ]Hers (O.rili I J. S. gal., 0. 5~ Imp. g:r!.) ~ - Arc oil th e i!i lpcrt;\rJI cornpon~nts secu rely ti_i!ht ... ·nci.l' l 2. PERIOD!( '.\L I.\ SPEL:TlO~ Pc1 roJCll tht: peri odica l oper,n inn by the ~hcdu k ;;huwn in t he chart bclo\11. --._._ t-lc •u :. I l ! -------- 26 50 HI() ~- l1ems -~- - -- Cbanr.c engine oil I • I • I I -· -- --.- Clc:!ni nf-1 011 ba t11 air cleaner ~·il ur 1 ll • • • chnng~.: oil ! l ··- -- - - r\I.! Ju"t cc~.rht:rr ro r • ·- -- - r- -· - -- ~. \.l ean : mr:l adjLI~I ;;park pl ug · Af 1 er 20 0 h Nll l ':l of Ol~la\ion rette~t the he ms innicat~d bye . 15ll I 2{10 .. I • I --~--- I ·-·- - - - • . Whc- n pe rforming d~ry work (h:m owhg, n~owing. ctc."l , rcrlace C' il a1 a short er mtc:rva llc\c ry Ill ho urs or d<t iiYJ. · Ched :111d rcHU th..: ~;ugm1: I.J il f:\'Cry 20 hOllrS. • When the V b i:H i~ sl ighlly wofll, make n: pl accment t:a rly. • Cle:1n 1hc 011 ~imim:r pt:dodka ll y.

G28 (ALL) LUBRICATION Lubrication prevents w~ar a;~d seizure of the con - !act surfaces of the rotating :1nd slidin~ part&. It also ~rves to cool the p: tr tl> f rom !he heat pmdu- ced by rric!ion. Op~rating the cn~:im: with insufficient engine o il will deYcl op cngin;: s;:ilurc or excessive w~;ar, rc~ultini!! in ;: h:)rtc: r scn•icc: li fe ur the cngim:. I. Engine <JiJ d1ang~ and r('tlllin~ <D R<=movc the oil cap and the drain holt , and th~n dri!in the oil completely from the engine. (The oil will drair1 fasler while the en~;lt\e is s t[JI warm.) (Fig. 1-3, 1-4) ® Tighten 1 he drain bolt ~ecurcly and refill with new oiL After overhauling the engine, r efi ll t~ crankcase with 0.7 liters (0.74 U. S. q ! ., 0.62 Imp. qt .) or new en- iine oil, however, ror oil cha nges or repl- enishment, refill according 10 the oil level gau~e. Fill with oil up to the upper l~vel nun lt.. C l\ t he ga u ge with the engine in a lc'ic:l positi on. Check 1he oi l l evel without screwing the cap in. (Fig, 1- 5) To fac:ilitate use on 11ariou$ types of machines and also to < lllain higher \lersatility, two drain plu~ are provided. 2. Oil Use oil which corn;:spond8 to MS or DO in the API ~~ervicc classification. Tht.: ~radc of oil used should be sdectcd to conform with \he outside temperature. - SAE IOW/30 may be used a ll sea11on reg-ar- dl<;.-ss of outside temperature. 3. Genuin.: parts HONDA genu ine pa rts arc manufactured with high quality cOJ'I t rol and strict illSJ)~lion. If these genuine parts arc not used it not only reduces the service l ife of the components but also adversely affects the perfo rmance of the engine. fig. 1-J (i) Dr jjin h:1h Fig, 1-4 ('1) Oil C<~P ® @ Fig, 1-1 (!) Oil gauge ® Upper level @) LW't'r kvcl :.~ ro ~ ~1~\l~~@jjiJ ' - . · .• . • l'::J...:: Fig, HI

8 'I I' 0 I Fig. l-7 (i) Oil pa n ~ Elcrnr:nl :~ Air cl1..11111:r 1.~ Fig, 1 -S (f) Air cl eaner covtr ~ Oil level <3, Bre; nh.. ·r tube fig. 1-9 (f) J\llanmcnt marl: Fig. 1- 10 (j) Fillt?r ~1.1ge G28 (ALL) --- <=INDEX CLEAKING THE OlL BATH ArR CLEANER A~D CHANG- ING THE OIL When the oil in the ra n t c:comts dirty, the o il ~iscosity wi ll be lowere!d :1nc1 du~t in lhe o il will pass through the p las ti c wool element and re su lt in premalure wear of the en gi ne compcmen rs. Therefore, changing and checkin~ the oil and cleaning the air cltaner should be performed nt pc: riOI.Iic interval. Remove t he air cleaner covc:r oil pan and air ck-unc:r e~ment. and then wash them in ~ac:olinc or ke rosene. (Fig.l -71 The specified c~p:-Jcity of the oi l (un to the stepped section of the oil pan) i~ 40cc (t..!.. OZ.i. Excr- 3 ci!:C C.1re n01 to fi ll above lhc l>pct.~i ficc.l Jc,..cl. Overfi lli ng wiH cuuse malrunclion of the engi11e by O \'crt1 owins inlu t h..: c11~ inc:. Cfig. J - 8} \1) T~ppc1 Mjust'll'\('nt The tapper clcaranL'C h:t s 11 great cfft:ct on the va lv e t 1rning. If the clc:<1rancc is insufficit:nl the va lve may he prevented from fully closin~~:. thu~, rcsu (r mg in im; uiTrcie nl compression. On t he other hand, an excessi~ tappet d enranc:e will produce tapp;:\ noise and result in noi5;1 eng,jne otx:ration. 1' he fappet cl~ar unce wi ll CJ iso have a varying degree of dTecl on the: engine power output. engine oper al iun nuLl engine noise. Adjvshncnl . I. Rcmo -..e the fan CO\'Cr and align the flywheel ·'T' mark with the spc:ciftcd aligning m:1rk (Fig. 1 -9). 2. Hemove t he tupper cap alld ched t he dearaace hetwccn the adju!iting screw and the 11:1 l 11e. If the adju:> ting screw is pushing the 11a l.-e. r...,latc th~ fl ywheel one full 1um and then nli~n the ·• r· mark (piston is at T. D. C. of the wmpres!'. ion stroke). Loosen tlle adjust- ini :H.:rew lock nut and make the adjustmcnl wi til I he adjus ti ng ~crew to obtain the standard cle~ll'(lnce of 0.05 rru11 (0.002 in.) (for both i11let and eJthau~>L l (Fig. l- 10) 1'\0(e : (l) The :.tdju!ltrocnl 111\.ISI be amde with a cold n.gine and the clenrance dlo•ld be mtllsuri!d 'filii £1 feeler gauge. (2) 'When Joc .. i•lg tfK" adjusting scr('v, hold !be S('tew to pre, ·ent iU; turnln~.

G28(ALL) (::.i) lgnirlon Timing Adjustmrnl Improper ignition timing, r~gardlc.~'- or the accur- acy of rh~ val~e timing or the prllper c:omrm:g.'lion rres!'.ure, will not pmvide a <;ati~factory eng1ne performance. Improper ignition riming wlll cau'\e overheating and backfiring ~nd resnll in adverse eft'tcts on engin~ performance. (I) Rernovt: the fan co~;cr and the starter pullc:y, then align the "F'' mark on the flywheel with the ~pecified aligning mark. At th i~ time, check to make sure that !he contact breaker points arc just $ti1.rting to open. (l;ig. I - II) Ignition Timing Adjustment with ;, Te ster Connect one of leads of the tester with the black primary lead of the engil"le, ground the otht:r lead of the tester to the engine and tht:n align the "F' mark: with the sp~ified aligning mark. The l::~mp of the testt:r will light Itt rhi~ nme lf the points are properly fldju:;tcd. (Fig 1-12) Perform ahe adjustmel!l by luuscning !he COJ11a ct breaker lock screw and rnovin8 the ba~e plare. (fig. 1- 13) Open (B. T. D. C.) 10 " IN Close (A. B. D. C.) 1 Oe ----- --·-.-- -.-. -· Open (B. B~ D. C.) 15~ EX - - --- -- Close (A. T. D. C.) lOQ Fig, l-11 (1; .<\lignini! mark Fig, I -12 (j__'; Pri mar .1' k.u.i (mack) Fig, 1-13 CD Screw @ Ac.lju~ting loca1i on wi th ~crt::w dri~er (~) roinl surface l':!) He<:omc ra~rcr ® Be\:ome ~lorer

Honda G28 Horizontal Shaft Engine Repair Manual

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