JETTING: Always remember to change one carburetor component at a time and keep a record of your changes and effects

JETTING - HAMMER STYLE

JETTING: Always remember to change one carburetor component at a time and keep a record of your changes and effects.

IDLE to 1/4 THROTTLE: The AIR JET, PILOT JET and FUEL SCREW are most effective in this range When you want a leaner mixture use a LARGER AIR JET, SMALLER PILOT JET or turn the FUEL SCREW in. The opposite holds true for a richer mixture.

1/4 to 3/4 THROTTLE: The JET NEEDLE is the most effective component in this range. Raising the needle by lowering the "E" clip position at the top of the needle will richen the mixture. Lowering the needle will lean the mixture.

WIDE-OPEN THROTTLE: Changing the MAIN JET affects this range. Select the size, which offers the best wide-open throttle performance, then there is the option to install one size larger MAIN JET for ideal engine longevity.

FUEL SCREW:

(TM 33) This screw is located at the bottom of the float bowl, the screw meters fuel and opening the screw (counter-clockwise) out results in a richer mixture.

AIR JET, PILOT JET, FUEL SCREW, AND SLIDE CUTAWAY:

Keep in mind that the fuel screw gives a good indication of a properly sized Air Jet and Pilot Jet. The Air Jet and Pilot Jet calibrate the mixture from both the idle bypass and the idle orifice. If the idle screw is properly adjusted, but the engine does not have good response when the throttle is snapped wide-open, it is usually a sign of a lean mixture and the Air Jet/Pilot Jet will need to be replaced with one size (richer) and the fuel screw re-adjusted. Consequently, if the throttle is only partially opened, such as in a trail riding situation, and the sled loads up (slow to build rpm) when the throttle is returned to wide-open, it is usually a sign of a rich Air Jet/Pilot jet. If the Air Jet or Pilot Jet does not clean up this part of the circuit, the slide can be substituted for one with a different cutaway (not recommended). The higher the number, the larger the cutaway will be, allowing more air to the nozzle leaning the mixture and, conversely, a smaller cutaway will richen the mixture with a greater effect up to 1/4 throttle.

JET NEEDLE:

Straight diameter section - By going to a thinner needle, there is a larger area between the jet needle and the needle jet supplying a richer mixture. Length of the straight section - This determines at which point the needle taper will start relative to the clip position. If you have to run a needle in the highest clip position (needle raised out of nozzle), a needle with a longer straight section should be used. Needle "E" clip position - This works in conjunction with the length of the straight section. If the engine is too rich above 1/4 throttle, raising the needle "E" clip (effectively lowering it into the nozzle) will lean the mixture. Needle Taper - A larger taper will result in a leaner mixture in the first half of the taper and a richer mixture in the last half of the needle. Needle Jet: The needle jet (nozzle) controls the fuel/air mixture up to 3/4 throttle. How it overlaps with the jet needle depends on the jet orifice inner diameter, air bleed holes and type of nozzle. Most modern Japanese carburetors use a fixed needle jet (nozzle) assembly, which cannot be removed, but with the TM 33 replacement is possible.

Caution: this is where MOST burn-downs occur. To see where you are on the "MID" (needles) run the engine half throttle on a long straightaway hit the kill button or turn key off while holding throttle in "MID" position (USE EXTREEM CAUTION NOT TO CRASH INTO ANYTHING OR ANYONE ELSE). Then pull the spark plugs. The parts of the plug you should be looking at are the positive electrode and first 1/4 of the ground electrode. Best power will usually result in a cardboard colored insulator tip and light colored ring around the tip of the positive electrode. For the ground portion should be a light cardboard color running no more than halfway towards threads. The first three threads should be oily if you’re running the correct heat range.

MAIN JET:

Fully load the engine (wide-open throttle) on a long straightaway or long hill, hit the kill button or turn key off while holding throttle wide-open (USE EXTREEM CAUTION NOT TO CRASH INTO ANYTHING OR ANYONE ELSE). Then pull the spark plugs. The parts of the plug you should be looking at are the positive electrode and first 1/4 of the ground electrode. Best power will usually result in a cardboard colored insulator tip and light colored ring around the tip of the positive electrode. For the ground portion should be a light cardboard color running no more than halfway towards threads. The first three threads should be oily if you’re running the correct heat range. Keep in mind that the different types (race gas or aviation) and different brands of gasoline can give different readings.

Exploded view TM flat slide (http://www.sudco.com/Diagrams323728/exptm.gif ) Buy the Sudco Mikuni book if you want to tune.

The Original " Hammer"

Totallyamaha is not responsible for any damages that these modifications may cause to your vehicle; any modifications are your responsibility if you choose to do so. We are providing information ONLY. Some of these modifications may VOID your warranty and that is your responsibility to look into. The Totallyamaha users have passed along most of the information found on this site. If you have any questions or concerns about anything on this site talk to your dealer before using any of the information. Totallyamaha will not be liable for any damages or personal injury from any modification performed from this site.