Piston Rings/Ring Grooves; Piston Ring Gap; Piston Assembly - Triumph Rocket III Classic Service Manual

Crankshaft
Piston Rings/Ring Grooves
1.
Check the pistons for uneven groove wear by
visually inspecting the ring grooves.
2. Clean the piston ring grooves.
3. Fit the piston rings to the pistons. Check, using feeler
gauges, for the correct clearance between the ring
grooves and the rings. Replace the piston and rings if
outside the specified limit.
Checking Piston Ring to Groove Clearances
Piston ring/groove clearance
Top - standard
0.02 - 0.06 mm
Top - service limit
0.16 mm
Second - standard
0.02 - 0.06 mm
Second - service limit 0.16 mm
Piston Ring Gap
Note:
•
Before final assembly the piston ring gap, when
fitted in the liner, must first be checked.
1.
Place the piston ring inside the liner.
2. Push the ring into the top of the cylinder, using the
piston to hold the ring square with the inside of the
bore. Continue to push the ring into the bore until
the third groove of the piston is level with the top of
the liner around its full circumference.
cbxx
Aligning Piston Rings using the Piston
3. Remove the piston and measure the gap between
the ends of the piston ring using feeler gauges.
Piston ring end gap tolerances
Top - standard 0.20 - 0.35 mm
Top - service limit 0.55 mm
Second - standard 0.30 - 0.50 mm
Second - service limit
0.675 mm
Oil control - standard 0.20 - 0.70 mm
Oil control - service limit 0.875 mm
Note:
• If the end gap is too large, replace the piston
rings with a new set
• If the gap remains too large with new piston
rings, both the pistons and barrels must be
replaced
•
If the gap is too small, check the cylinder bore
for distortion, replacing as necessary. Do not
file piston rings!
Piston Assembly
1. Clean the piston ring grooves and fit the piston rings
to the piston.
Note:
• The top ring upper surface is marked 'N' and
can be identified by a chamfer on the inside
edge.
5.18
SelVice Manual- Rocket Ill/ Classic / Touring