Technical Information · issue 29 of 1998
Chainsaws in General: Fixed Jets (special accessor
IssueTI 29/1998
Full text
Page 1 of 2
Technical Information
29.98
Fixed Jets for Carburetor =³High Altitude Jets´
If necessary, adjustable carburetors with a==============³Adjustable´ carburetor with semi-fixed jet
³semi-fixed jet´ may be set leaner, down to =============Eex~mpleW=ea=NV=^F
H = 0, to suit the lower air volume at high
altitudes.
The so-called “semi-fixed jet” in these carburetors
ensures a minimum supply of fuel. The semi-fixed
jet may be a separate jet (screw or press-fitted)
or an additional bore in the valve jet (see
“Carburetors” handbook).
It is a fact that engine power decreases as
altitude increases.=qhe additional, altitude-related
enrichment of the mixture can be compensated for
001TI001 KN
by using a leaner carburetor setting. If the range
of adjustment down to H = 0 is not sufficient to 1 2
counteract the over-rich mixture at very high
~ltitudesI=it=is=possible=to=inst~ll=~=fixed jet with
1 =s~lve jet
a smaller bore=E“high altitude jet”).
2 =pemi-fixed jet (screw-fitted)
The optional “high altitude jets” listed in the table
are available for this purpose. Each of these
optional jets is designed for a specific carburetor
=========================================================Carburetor with fixed jet
type.
(example: WT 360)
Important notes
Use only the type designation stamped on the
carburetor body =e.g. WT 426= to determine the
correct part number.
The replacement of fixed jets should be carried
out only by trained personnel.
Special care must be taken with press-fitted jets:
• Use a pin punch of the right diameter
001TI002 KN
• Position jet squarely in bore and press home 1 2
(for correct position see “Carburetors”
handbook)
• Do not damage end face of jet while pressing 1 =s~lve jet
home 2 =cixed jet (screw-fitted)
• Recommendation: Do not reuse jets that have
===been=pressed=outK=====================================Warning: Do not use fixed jets with a smaller
bore =³high altitude jets´ at lower altitudes
=========================================================because they make the mixture too lean and
can cause engine damage.
)29.98 - 2
=Carburetor========================Fixed jet =³high altitude jet´===================Model
Part No. Bore dia. (mm) Part No.
WT 283 B==========NNOP=NOM=MSNM===Fixed jet 0.50================NNOV=NON=RSMM======MOPI=MOR
WT 323============NNOM=NOM=MSMS===Fixed jet 0.58================NNOT=NON=RSMO======MMV
WT 325 A==========NNPM=NOM=MSMM===Fixed jet 0.50================NNOV=NON=RSMM======MNT
WT 326 C==========NNOV=NOM=MSMS===Fixed jet 0.42================NNOP=NON=RSQO======MOM=q
WT 360============NNOP=NOM=MSNN===Fixed jet 0.44================NNOP=NON=RSRP======MOP=i
WT 396============NNOP=NOM=MSNP===Fixed jet 0.42================NNOP=NON=RSQO======MOP=i
WT 403 A==========NNON=NOM=MSNM===Fixed jet 0.52================NNON=NON=RSMO======MOS=mol
WT 426============================Fixed jet 0.46
1121 120 0650 1121 121 5601 026
WT 493 A==========NNON=NOM=MSNP===Fixed jet 0.50================NNON=NON=RSMP======MOS
WT 498 A==========NNOP=NOM=MSNS===Fixed jet 0.50================NNOV=NON=RSMM======MOP=`
WT 503============================Fixed jet 0.48
1123 120 0614 1123 121 5630 021
C3A-S31D==========NNOR=NOM=MSRN===Fixed jet 0.56================NNOR=NON=RQMT======MPS
1125 120 0613
C3A-S38A==========NNOR=NOM=MSNT===Fixed jet 0.56================NNOR=NON=RQMT======MPQ
C3A-S39A==========NNOR=NOM=MSNR===Fixed jet 0.56==========fo 1125 121 5407 036
WJ-65=============NNOO=NOM=MSNS===Fixed jet 0.60================NNOO=NON=RSMU======MSQ
WJ-66=============NNOO=NOM=MSOO===Fixed jet 0.62================NNOO=NON=RSMP======MSS
WJ-67=============NNOO=NOM=MSON
WJ-69=============NNOO=NOM=MSNU
C1Q-S37A==========NNPO=NOM=MSMO===Fixed jet 0.40================NNPO=NON=RSQM======MNV=q
HD 14=============NNOU=NOM=MSOQ===Fixed jet 0.66================NNOU=NON=RSMR======MQS
HD 15=============NNOU=NOM=MSOR===Fixed jet 0.66================NNOU=NON=RSMR======MQQ
HD 16=============NNOU=NOM=MSOP===Fixed jet 0.66================NNOU=NON=RSMR======MQS
HD 17=============NNOU=NOM=MSOO===Fixed jet 0.66================NNOU=NON=RSMR======MQQ
HD 18 A/B=========NNOT=NOM=MSMQ===Fixed jet 0.54================NNPM=NON=RSMM======MOV
HD 19 A/B=========NNOT=NOM=MSRM===Fixed jet 0.54================NNPM=NON=RSMM======MOVI=MPV
HD 21 A/B=========NNOT=NOM=MSMR===Fixed jet 0.54================NNPM=NON=RSMM======MPV
HT 7 A============NNOQ=NOM=MSMT===Fixed jet 0.88================NNOQ=NON=RSMS======MUQ
HT 11 D===========NNOQ=NOM=MSMU===Fixed jet 1.00================NNOQ=NON=RSMP======MUU
HT 12 A/B=========NNOQ=NOM=MSRM===Fixed jet 1.00================NNOQ=NON=RSMP======MUU
Spare part for USA only
1998 Andreas Stihl Andreas Stihl - D1/MTK-sc
Technical Documentation 6381 Page 2 of 2
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