SRM-420ES, SRM-420TES
T410S, B410S
T410TS, B410TS
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ENGINE
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6-1 Testing cylinder compression
NOTE:
Test cylinder compression when engine is
cold.
1. Move ignition switch to STOP position. Then re-
move spark plug.
2. Install compression gauge 91037 (A) in spark
plug hole and tighten by hand. Pull starter several
times to stabilize reading on compression gauge.
3. I f p r e s s u r e i s l o w e r t h a n a p p r o x . 75% o f
standard compression pressure (Refer to “1-2
Technical data ”), inspect cylinder bore, piston, and
piston rings for wear or damage.
4. If pressure is more than approx. 125% of standard compression pressure, inspect cylinder combustion
chamber and exhaust port, piston crown, and muffl er 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 (A), it is recommended to measure and note
compression pressure of brand-new engines as standard pressure in advance.
6-2 Cleaning cooling air passages
1. Inspect air intake grid (A). If blocked with leaves
or other debris, clean out debris as required.
2. Remove muffler cover (B), cylinder cover (C)
and starter assembly (D). Remove inner cylinder
cover and fan cover.
3. Inspect cylinder cooling fins (E) for blockage
with dirt or dust.
4. Clean them with wooden stick or plastic stick or
compressed air as required.
WARNING DANGER
Always wear eye protection when using
compressed air for cleaning. Otherwise,
eye damage can occur from fl ying particles.
B
D
C
A
E
A