Bajaj Discover 100M Service Station Manual page 168

ENGINE ASSEMBLING - IMPORTANT SKILL TIPS
Discover DTS-Si
Service Station Manual
Valve Lapping
A. Carry out valve leakage test for intake and exhaust valves.
• Position the camshaft in such way that both the valves are completely closed.
• Fill some quantity of petrol inside intake port.
• Apply slight pressure on intake port with the help of palm.
• Check whether petrol is leaking through valve & valve seat mating surface in
combustion chamber.
• If the petrol is passing through valve & valve seat mating surface (contact
area) this indicates valve seat leakage.
• Repeat the same procedure for exhaust valve.
B. Valve Lapping.
• Check the condition of valve seat and valve face.
• Hold the cylinder head in a fixture / vice firmly. For light pitting marks
• Smear fine lapping compound on valve seat and valve face.
• Pour a drop of oil on the valve seat.
• Fit valve into valve guide.
• Hold the valve with the help of lapping stick.
• Rotate valve in one direction only by applying light
lapping stick.
• Check the condition of valve seat and valve face.
Carry out the same lapping procedure by using first coarse and then fine
lapping compound. After lapping, clean valve, valve seat and cylinder head
complete thoroughly. Assemble the cylinder head and carry out the leakage
test to confirm that there is no leakage.
C. Decarbonize and clean cylinder head combustion chamber valve seat and
valve face by acetone & fine emery paper.
137
pressure with the help of
For deep pitting marks
Dealer Development Center
Akurdi Pune