Measuring The Piston/Cylinder Mounting Clearance; Checking The Piston Ring End Gap - Husqvarna FC 250 2017 Repair Manual

17 ENGINE
17.4.16
17.4.17
198

Measuring the piston/cylinder mounting clearance

310368-10

Checking the piston ring end gap

310347-10
Info
O
Piston size is marked on the side of the piston .
-
Check/measure the cylinder.
-
Check/measure the piston.
-
The smallest piston/cylinder mounting clearance equals the
smallest cylinder bore diameter minus the largest piston
diameter. The largest piston/cylinder mounting clearance
equals the largest cylinder bore diameter minus the smallest
piston diameter.
Guideline
Piston/cylinder - mounting clearance
Size I
Size II
Wear limit
-
Remove the piston ring from the piston.
-
Place the piston ring in the cylinder and align with the piston.
Guideline
Below the upper edge of the
cylinder
f)
Measure end gap with a feeler gauge.
Guideline
Piston ring end gap
Compression ring
Oil scraper ring
If the end gap is greater than the specified value:
-
Check/measure the cylinder.
If cylinder wear lies within the specified tolerance:
-
Change the piston ring.
-
Mount the piston ring with the marking facing toward the pis-
ton head.
(0 p. 196)
(0 p. 197)
0.030 ... 0.052 mm (0.00118
... 0.00205 in)
0.032 ... 0.055 mm (0.00126
... 0.00217 in)
0.070 mm (0.00276 in)
20 mm (0.79 in)
I :5 0.40 mm (:5 0.0157 in)
I :5 0. 70 mm (:5 0.0276 in)
(0 p. 196)
..
..
..