Cylinder Head/Valves Troubleshooting; Cylinder Head/Valves Tools; Excessive Smoke; Excessive Noise - Honda 2000 XR50R Service Manual

CYLINDER HEAD/V ALVES
TOOLS
Valve spring compressor
Valve spring compressor attachment
Valve guide driver, 5.0 mm
Valve guide reamer, 5.0 mm
Valve seat cutters
Seat cutter, 24 mm (45
0
IN)
Seat cutter, 20.5 mm (45
0
EX)
Flat cutter, 24 mm (32
0
IN)
Flat cutter, 21.5 mm (32 0 EX)
Interior cutter, 22 mm (60° IN/EX)
Cutter holder, 5 mm
TROUBLESHOOTING
07751 -00 10000
07959 - KM30101
07742-MA60000
D7984 - MA60001
or
07984- MA6000C (U.S.A. only)
07780 - 0010600
07780-0011000
07780- 0012500
07780 - 0012800
07780 -0014202
07781 - 0010400
- These are commercially available in U.S.A.
• Engine top-end problems usually affect engine performance. These problem can be diagnosed by a compression test or by
tracing engine noises to the top-end with a sounding rod stethoscope.
• If the performance is poor at low speeds, check for white smoke in the crankcase breather tube. If the tube is smoky check
for a seized piston ring (Section 8).
Compression too low, hard starting or poor performance at
low speed
• Valves:
- Incorrect valve clearance
-Burned or bent valve
-Incorrect valve timing
-Broken valve spring
-Uneven valve seating
• Cylinder head:
- Leaking or damaged head gasket
-Warped or cracked cylinder htlad
• Worn cylinder, piston or piston rings (saction
8)
Compression too high, overheating or knocking
• Excessive carbon build-up on piston crown or on combus·
tion chamber
Excessive smoke
• Cyli nder head:
- Worn valve stem or valve guide
-Damaged stem seal
• Worn cylinder, piston or piston rings (section 8)
7-2
excessive noise
• Cylinder head:
-I ncorrect valve clearance
-Sticking valve or broken valve spring
-Damaged or worn camshaft
-Loose or worn cam chain
-Worn or damaged cam chain
-Worn or damaged cam chain tensioner (section 10)
-Worn cam sprocket teeth
-Worn rocker arm and/or shaft
• Worn cylinder, piston or piston rings (section
8)
Rough idle
• l ow cyli nder compression
•
•