WATERAX
MARK-3 Owner's Manual
03/2016
– Page 36 of 52
Piston/Cylinder Matching
During engine top end repair, it is highly recommended to match the piston with the cylinder in order to
obtain the correct piston/cylinder clearance. To facilitate the matching process, a color scheme is used:
red piston matches with red cylinder; green piston matches with green cylinder. Each piston and cylinder
grade has its unique item number.
For optimal engine performance, reliability and durability, it is very important to have the correct
piston/cylinder clearance. A clearance that is too tight can cause the piston to seize. An engine with a
clearance that is too loose will generate less power, more noise and may accelerate engine wear.
The piston/cylinder clearance is defined as the difference between the cylinder bore and the piston
diameter. See the table below for instructions on how to measure the cylinder bore and piston diameter:
To determine the cylinder bore, use a calibrated
dial bore gauge and measure the cylinder bore at
a distance of 5 to 10 mm above the exhaust port.
See image.
To determine the piston diameter, use a calibrated
micrometer and measure the piston diameter at a
distance of 24 mm from the bottom of the piston.
The measurement should be taken perpendicular
to the piston pin axis (piston is oval).
See image.
Notes:
•
Measurements should be taken in a temperature controlled room adjusted at 20 °C [68 °F].
•
Measuring instruments must be calibrated.
Depending on the type of cylinder (Nikasil coated or cast iron sleeve), the required clearance will vary:
Piston/cylinder
clearance
Cast Iron Sleeve
Cylinder
0.06 - 0.08 mm
.0024 - .0031 in
Nikasil Coated
Cylinder
0.04 - 0.06 mm
.0016 - .0024 in
ID
ITEM NO
DESCRIPTION
QTY
- 801273* CYLINDER & PISTON KIT NIKASIL
-
1 801270* R-332R 185CC PISTON W/RINGS STD SIZE RED GRADE
1
2 800009
R-324 185CC NEEDLE BEARING
1
3 800030
R-328 185CC GUDGEON PIN
1
4 800028
R-329 185CC CIRCLIP
2
5 701233* R-257NR 185CC CYLINDER NIKASIL RED GRADE
1
* Note: Factory matched Nikasil cylinder and piston kit. Kit grade may be red or green.
