Machine Tuning; Carburetor; Principles Of Carburetor Tuning; Carburetor Specifications - Suzuki RM250 Owner's Service Manual

4- 1 MACHINE TUNING
MACHINE TUNING
CARBURETOR
The carburetion of your motorcycle is carefully
selected after extensive testing . You wi ll find
that the carburetion will function smoothly un·
der many varied operating conditions. For best
results we recommend that the adjustments and
carburetion jetting be left " as is " from the
factory .
Some riders may operate their motorcycle un-
der extreme operating conditions such as; very
high altitudes or extreme cold and hot temper-
atures . In these circumstances the jetting of the
carburetor or other adjustments may need to be
altered slightly . Riders who are not familiar with
the operation and jetting procedures of the
KEIHIN carburetor should have their local autho-
rized Suzuki dealer perform these alterations,
Mechanically experienced riders can alter the
carburetor settings based on the following in-
formation and specifications .
Carburetor Specifications
Bore
38 mm
Main jet
# 180
Jet needle R 14 70NS-3rd
Cut-aw ay #5
Slow jet
#52
Air screw
1-1f2turns out
Float height 16,0 mm (0.55 in)
Setting parts # 175.# 178. # 185 and
main jet: #1 90
PRINCIPLES OF CARBURETOR TUNING
Carburetor Components and Functions
The carburetor consists of a number of parts as
shown below, The asterisk (*) marked parts are
precisely machined, w hich meter the intake air
(oxygen) and fuel so that the air/fuel mixture ra-
tio is controlled accurately. They can be divid-
ed by three operation-related groups; pilot (slow)
system , intermediate system and main system,
and they achieve their functions in each cor-
responding throttle opening range , It is neces-
sary to have a full understanding of them for
proper carbu retor tuning,
5.
Choke/idle adjust
knob
6.
* Air screw
7.
*Main jet
1. Top cap 8. *Slow jet
2. Spring
9.
Float
3 . *Jet needl e 10. Needle valve ass 'y
4 .
Throttle valve 11 .
Clip