Technical Information - Honda HHT25S Owner's Manual

Low Power or Engine Speed Won't Increase
Possible Cause
Air filter is dirty or clogged.
Fuel filter is dirty or clogged.
Throttle cable is out of
adjustment, broken, or bent.
Spark arrester screen
clogged.
Grass is wrapped around the
output shaft and/or cutting
attachment.
Blade or Cutting Line Head Won't Stop Turning When the
Throttle is at the Slow Position
Possible Cause
Fault in the throttle control or
cable; throttle cable out of
adjustment or bent.
Idle speed is too fast.
Broken or worn clutch
springs, or faulty clutch
system.
Blade or Cutting Line Head Won't Turn
Possible Cause
Worn or broken clutch,
broken drive cable, worn or
broken gear case parts.
Excessive Vibration
Possible Cause
Loose cutting-line head or
blade nut.
Cutting-line is not wound
properly or has unequal line
lengths.
Damaged blade.
26
Correction
Clean or replace the air filter.
Replace the fuel filter.
Adjust the cable or replace it if
necessary.
Clean the screen.
Move the ignition switch to the
STOP (O) position and disconnect
the spark plug cap from the spark
plug. Remove grass from the
output shaft and cutting attachment
area.
Correction
Check the throttle control parts;
adjust or replace the cable if
necessary.
Adjust the idle speed.
Replace the clutch springs or
replace or repair other clutch
system parts.
Correction
Replace or repair faulty
components as needed.
Correction
Tighten the cutting-line head or
blade nut securely.
Rewind the cutting-line and cut to
equal lengths.
Replace the blade.

TECHNICAL INFORMATION

This section contains important information about serial number
locations, high altitude operation, and emission control systems.
Serial Number Locations
ENGINE
SERIAL
NUMBER
FRAME SERIAL NUMBER
There are two serial numbers, one for the trimmer and one for the
engine. Record these numbers in the space provided. You will need to
have these numbers available when ordering parts or making
technical or warranty inquiries (page 28).
Engine serial number: _____________________________
Frame serial number: ______________________________
Date of purchase: _________________________________
Carburetor Modifications for High Altitude Operation
At high altitude, the standard carburetor air-fuel mixture will be too
rich. Performance will decrease, and fuel consumption will increase. A
very rich mixture will also foul the spark plug and cause hard starting.
Operation at an altitude that differs from that at which this engine was
certified, for extended periods of time, may increase emissions.
High altitude performance can be improved by specific modifications
to the carburetor. If you always operate your trimmer at altitudes
above 5,000 feet (1,500 meters), have your servicing dealer perform
this carburetor modification. This engine, when operated at high
altitude with the carburetor modifications for high altitude use, will
meet each emission standard throughout its useful life.
Even with carburetor modification, engine horsepower will decrease
about 3.5% for each 1,000-foot (300-meter) increase in altitude. The
effect of altitude on horsepower will be greater than this if no
carburetor modification is made.
NOTICE
When the carburetor has been modified for high altitude operation,
the air-fuel mixture will be too lean for low altitude use. Operation at
altitudes below 5,000 feet (1,500 meters) with a modified carburetor
may cause the engine to overheat and result in serious engine
damage. For use at low altitudes, have your servicing dealer return
the carburetor to original factory specifications.