ENGINE
CS-2511TES
251Ts, 251TCs
57
8-1 Testing cylinder compression
NOTE:
Test cylinder compression when engine is
cold.
1. Move ignition switch to STOP position.
2. Open cap cover and remove spark plug (Refer
to “3-2 Testing spark“).
3. Remove valve core (A) from compression gauge
91037 (B) and insert valve core (A) to adapter
X681-000000
(C) with valve core driver (D).
4. Connect adapter (C) and compression gauge (B).
5. Install compression gauge (B) with adapter (C)
in spark plug hole and tighten by hand. Pull starter
several times to stabilize reading on compression
gauge.
6. If pressure is lower than approx. 75% of
standard compression pressure (Refer to “1-2
Technical data”), inspect cylinder bore, piston and
piston ring for wear or damage.
7. If pressure is more than approx. 125% of stan-
dard compression pressure, inspect cylinder
combustion chamber and exhaust port, piston
crown, and muffler for carbon deposits.
NOTE:
Compression pressure varies with volume
of compression gauge tip occupying cylinder com-
bustion chamber. When you use other than the
tool 91037 (B) and adapter X681-000000 (C), it is
recommended to measure and note compression
pressure of brand-new engines as standard pres-
sure in advance.
B
A
C
D
B
C
