cracked lands. Examine each ring groove for
burrs, dented edges and wear. Pay particular
attention to the top compression ring groove,
as it usually wears more than the others.
3. To check piston wear, measure the outside
diameter ofthe piston with a micrometer. Take
the measurement 3/16 in. (5 mm) above the
bottom ofthe piston skirt, at a right angle to the
piston pin bore (Figure 70). If the diameter of
the piston measures less than the wear limit in
Table 1, have the piston reconditioned or
install a new piston.
4. Measure piston-to-cylinder clearance.
T h e m o s t a c c u r a t e way to check
pistonlcylinder clearance is to measure the
inside diameter of the cylinder just above its
bottom edge where it will have undergone the
least amount of wear, then subtract the piston
diameter as measured in Piston Inspection,
Step 3. The clearance should be within the
range specified in Table 1.
Y o u c a n a l s o m e a s u r e installed
piston/cylinder clearance with a feeler gauge
near the bottom of the cylinder (Figure 71).
The piston should be just free enough to slide
with a light push (with no rings on the piston).
This method is not as accurate as micrometer
If a cylinder has not worn past the acceptable
inside diameter limit and installing a new
piston will bring t h e clearance within
Property of www.SmallEngineDiscount.com - Not for Resale