Cylinder Head; Cylinder And Piston - Yamaha CW50L Service Manual

I..o Ic-01 I..o°.-I
__ CYLINDER HEAD • Piston wall
1. Eliminate: Wear/Scratches/Damage --*Replace.
• Carbon deposits
Use a rounded scraper (_)
NOTE:
Take care to avoid damaging the spark plug
3o,ool threads. Do not use a sharp instrument. Avoid _ .J 3o7oo, J
scratching the aluminium.
__________o_ f._---- _, 6. Measura:
J 2. Inspect: • Piston to cylinder clearance
• Cylinder head warpage ..................................................... **
Out of specification --* Resurface, Piston to cylinder clearance measurement
•****************************************************** steps:
Warpage measurement and re-surfacement First step:
steps: Measure the cylinder bore "C" with a cylinder
Attach a straight edge C) and a thickness bore gauge.
gauge (_)to the cylinder head. NOTE:
Measure the warpage limit. _ ___- /I Measure the cylinder bore "C" in parallel to and
_o Warpage limit: _ at right angles to the crankshaft, Then, calculate
/ I t,e veraoeo, t,e ea ure
If the warpage is out of specification, resur-
face the cylinder head. P'_"X] Standard Wear limit
NOTE:. Cylinder 39.993~ 49.912mm 40.10 mm
Rotate the head several times to avoid removing
3 too much material from one side. 3o7oos Bore "C" (1.574~ 1.575in) (1.579 in)
Taper _ 0,006 mm
CYLINDER AND PISTON "T" (0.0002in)
1. Eliminate: C=Maximum D
• Carbon deposits T = (Maximum D1,D3or Ds) -
Use a rounded scraper C) (Maximum D2,D4or Ds )
2. Inspect:
• Cylinder wall If out of specification, replace cylinder, pis-
Wear/Scratches --, Replace. ton and piston rings as a set.
3O4O01
Sand3" Eliminate:in crisscross Do not sand exces-
r,l,2nd
step:
• Carbon deposits __ • Measure the piston skirt diameter"P" with a
Fromthe piston crown (_)and ring grooves 0. micrometer.
.;,, ,_:: 4. Remove: @ 5 mm (0.2 in) from the piston bottom edge.
• Score marks and lacquer deposits
From the sides of piston. _ Piston Size: I
Standard:
I
NOTE: 39.952 ~ 39.972 mm
a pattern. I (1.573 ~ 1.574 in)
3o7oo3 sively. 3o_oo6
I
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