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Spark Plug Heat Ranges

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					                        Spark Plug Heat Ranges

SILVERSTONE/BERU DENSO , ND                          NGK                    BOSCH             CHAMPION

                             W22ESZU                 B7EV                                     N4G

S5                           W24ESZU                 B8EV, B8EGV            W08CS             N3G

S9, S7                       W27ESZU                 B85EGV                 W08CS

14Z-3CU Ultra                W29ESZU , IW29          B9EV, B9EGV                              N2G, N86G

                             W31ESZU , IW31          B95EGV                 W07CS             N59G, N84G

                             W34ESZU , IW34          B10EV, B10EGV          W07CS             N57G, N82G

                                                     B105EGV                W06CS

                                                     B11EGV                 W06CS



NOTE:
These are the equivalent heat ranges found through track and dyno testing, they will not necessarily match the
manufacturers listings.




                    Setting up your 2-cycle Tillotson Carburetor.
With today's state of the art motors and stinger type exhaust systems, the following information will
      help you achieve the desired results that you need from these motors. Before mounting your
 Tillotson carburetor check the pulse track from the carb mounting surface and make sure that this
          track through the carb adapter , gaskets and etc is clear and in line with each other.
 Set the low speed needle at 1+1/2 turns out and the high speed needle at 1+1/8 turns out. Adjust
the throttle stop screw on the carburetor so that it just cushions the butterfly when the throttle valve
 goes closed. Do not set the carburetor so that the engine will idle as this will cause the engine to
                        lean out in the corners and anytime you are off the throttle.



                         Track tuning your Tillotson Carburetor.
     If the carburetor settings are too rich ( too much fuel ) the engine will falter at that section of the
  track corresponding to that particular range of the carburetor settings. A spluttering or irregular
firing sound will be heard. This sound is also called       4 stroking. If this sound occurs at low speed
 while at full throttle, such as coming out of a tight turn, it is usually due to the Low Speed adjusting
needle being turned out too far. If the sound occurs at high speed while at full throttle, such as on a
 straightaway section of the track, it is due to the High Speed adjusting needle being out too far. In
    either case, needle adjustments must be made inwards gradually, in approximately 1/8 turn
 increments. It is best to adjust the Low Speed needle first for best overall low speed performance
                          and then follow with the final high speed adjustment.

If the engine does not 4 stroke or give the too rich firing sound, any place on the track, it could be
because the engine is running too lean ( not enough fuel ). This is easily checked by opening the
needles out in 1/8 turn increments until the engine 4 strokes.        In general, the optimum
performance and engine reliability will occur at carburetor settings just slightly leaner than the point
where the engine will begin to 4 stroke.


If you find that the engine will not chop off clean or is slow to come back from high rpm's when you
lift the throttle, this is a sign that the pop-off pressure in the carb is too high. The cure for this is to
lower the pop-off pressure. If you experience loading-up problems, this is a sign that the pop-off
pressure may be too low. The cure for this is to raise the pop-off pressure. As a general rule of
thumb, the pop-off pressure will be from 8 to 12 lbs, and is a tuning factor that you can adjust for
the altitude of your racetrack and the type of racing that you do.


        Plugs: Too hot, too cold or like baby bear just right!
       How can you tell if a plug is too hot, too cold, or "yes" just right? Let's assume that you
       have a general idea on the correct plug for your application, Take the vehicle out on
       the track, run it at race speed and race temperature for several laps. Then bring the
       car into the pits hot and shut it off-no idling. To read the plug, you need to look at both
       the insulator and the electrode. The table below was given to me by Gary Hartman
       many years ago. I don't know where he got it, or if he wrote it, but it has been very
       helpful to me.


    Spark Plug Condition                                         Indications
    Normal - correct heat range       Insulator nose white or very light tan to rust brown. Little or no
                                     cement boil where the center electrode protrudes through the
                                     insulator nose. The electrodes are not discolored or eroded.
                                     Insulator nose dark gray or black. Steel plug shell covered with
    Too cold - use hotter plug
                                     tar-like deposit.
                                     Insulator nose chalky white or may have satin sheen. Excessive
                                     cement boil where center electrode protrudes through the
    Too hot - use colder plug        insulator nose. Cement may be white or meringue-like. Center
                                     electrode may 'blue' and be rounded off at the edges. Earth
                                     electrode may be badly eroded or have a molten appearance.
                                     Insulator nose blistered or fused. Center plug and remove
    Pre-ignition - use a colder plug piston and electrode and side electrode burned or combustion
                                     chamber deposits melted away.
                                     Fractured insulator nose in sustained and/or richen mixture
                                     extreme cases. Insulator nose covered in tiny beads of
    Detonation - retard timing       aluminum leaving the piston. Excessive cement boil where
                                     center electrode protrudes through insulator nose. Specks on
                                     plug shell end.

Don't forget, only read the plug when it's new and has been run hot and brought into the pits and
shut off - no idling.

				
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