Nu50-Crankcase-Crankshaft

CRANKCASE/CRANKSHAFT NU50· NU50M

98 Dale of Issue: NOli•• 1981 10-0 e HONDA MOTOR CO., l TO. ri/)HON'DA NUSO·NUSOM 10. CRANKCASE/CRANKSHAFT

SERVICE INFORMATION 10-1 CRANKSHAFT INSPECTION 10-3 TROUBLESHOOTING 10-1 CRANKCASE ASSEMBLY 10-5 CRANKCASE SEPARATION 10-2 CRANKSHAFT REMOVAL 10-3

SERVICE INFORMATION GENERAL - The lollow"'9 parts musll)e removed before separating the crankcase:

Engine Page 5-2 - Mounting bracket - Genter stand Oil pump Page 2-5 Reed valve Page 4·9 KIck Slaner driven gear PageS·l1.17 Alternator Page 7-2 Cylinder head, cylinder Page 6-2, 3

. In addition 10 the above, remove the following parts when the left crankcase halve must be replaced:

Rear wheel Page 12-2 Final reduction Page 9·2

SPECIFICATIONS -.-- __._n__ . ITEM . STANDAf!!?__ (in) SERVICE LIMIT mOl (inl CONNECTING ROD BIG END SIDE 0.60 (0.024) CLEARANCE CONNECTING ROD BIG END RADIAL CLEARANCE 0.05/0.002) CRANKSHAFT RUNQUT A 0.15 (0.0061 B 0.10 (O.OO4J I

TOOLS

$ped,1l Crankcase Puller 07935-1870000 or modified 07933-1470000 seal And Case Assembling Tool 07965-1480010 Bearing Remover \ 07936-3710600

Common Attachment. 42 x 47 mm 07746-0010300 Pilot, 20 mm 07746-0040500 Driver 07749-0010000 Bearing Remover Handle 07936-3710100 Bearing Remover Weight 07936-3710200 TROUBLESHOOTING Abnormal engine noise 1. Worn main journal bearing 2. Worn crankpin bearing 3. Worn transmission bearing

Date of Issue: Nov., 1981 99 © HONDA MOTOR CO., lTD. 10-1 CRANKCASE/CRANKSHAFT NUSO· NUSOM

CRANKCASE SEPARAnON

Perform the following operations: Engine removal (Page 5·2) Oil pump removal (Page 2-5) Rced valve removal (Page 4·91 Rear wheel removal (Page 12·21

Remove the engine mounting bracket. RenlOve the center stand bracket.

Remove the cylinder head. cylinder and piston {Page 6·2. 31. Remove the alternatOl. (Page 7·2). , Remove the kick Haner driyen gear (Page 8-11, 171 . • Remove the final reduction usembly (page 9-2).

Remove the crankcase attaching bolts.

100 Date of Issue: Noy" 1981 10-2 © HONDA MOTOR CO., LTD. HONDA.

CRANKCASE/CRAN KSHAFT

R CASE 07933-147 Attach the special 100I on the ng. ht crankC

CASE PULlER 07935-1870000 CRANKSHAFT REMOVAL mnk""" the special toO I on the left Attach I h crankcase. shown.Remove the crankshah from the e

C T INSPECTION RANKSHAF 'de de",n" t he connecting. rod big end $1 with iI feeler gauge. .

SERVICE LIMIT: 060mm. (0.024 m)

. Nov., 1981 Date of Issue. TOR CO., lTD. @HONDAMO '0' 10-3 NU50· NU50M CRANKCASE/CRAN KSHAFT

Measure tile connecting rod big end radial clearance a, twO points in the X and Y directions.

SERViCE LIMIT: 0.05 mm (0.002 in)

Set the crankshaft on a stand or V·blocks as shown and read funout using it dial gauge.

The actual runout is of the total indicator reading.

SERVICE LIMITS: A: O.15mmlO.006in) B: 0.10 mm 10.004 in)

60mmr---'--60mm A B

Spin the crankshah bearing by hand and check for PLAY play. The bearing mUsl be replaced if it is noisy or .-== PLAY has excllssivc play. I' -t 11'111 TOOLS (Bearing Installation) :C ')l Common Attachment, 42)< 117 mrn 07746-0010300 Pilot, 20 mm 07746-0040500 - fj--- f- Driver 07749-0010000 I u( '2J f-U- RADIAL AXIAL

CRANKCASE ASSEMBLY Wash the crankshaft in soillen! and blow dry wilh compressed air. Check for cracks or other laulu. Remove all gasket material from the crankcase mating surfaces. Dress lInv roughness or irregutaliries Wilh an oil Slone. Apply clean cr'lgine oil to all moving and sliding sul1aces.

SEAL AND CASE ASSEMBLING TOOL 07965-1480010 Install the crankshaft Into the left crankcase. , j NOTE lubricate 'hi! crankshah main and journal bearings with Honda 2·stroke injector oil or eQuivalent.

SEAL AND CASE ASSEMBLING TOOL 07965-1480010 InSlall a new gasket and the dowel pin 10 [he crank· case m311ng surface and i1sremble Ihe crankcase halves. Assemble the removed parts in Ihe reverse order of remol/al (Page 10·:H.

Date of Issue: Nov" 1981 103 <&:l HONDA MOTOR CO., lTD. 10-5