Snowmobile Polaris (2006 year). Manual - part 25

4.10

CARBURETION

provided in the head of the jet needle. The chart at right shows 
the variation of fuel flow based on the height of the “E" ring.

NEEDLE JET

The needle jet works in conjunction with the jet needle to 
regulate fuel flow rate. An air bleed opening in the side of the 

needle jet brings in air measured by the air jet. This air 
initiates the mixing and atomizing process inside the needle 
jet. Mixing is augmented by a projection at the needle jet 
outlet, called the primary choke. The letter number code 
stamped on the jet indicates jet inside diameter.

THROTTLE OPENING VS FUEL FLOW

4.11

CARBURETION

MIKUNI TM38 FLAT SLIDE 
SERVICE

DISASSEMBLY

1.

Remove the carburetor from the engine before
disassembling. Clean the outside of the carburetor
thoroughly with solvent. Do not use compressed air to dry
at this time. The float chamber could become pressurized
resulting in damage to the floats or inlet needle and seat.

2.

Remove all top cap screws (1), top cap (2) and gasket (3).

3.

Locate the arm screw (4) and loosen it just enough to move
the arm (5) out of the way so that you can remove the
needle (6) e-clip and the plastic washer from the throttle
slide.

NOTE:  Keep track of the plastic washer (G), and 
place it so it is on the top of the throttle valve when 

installing the needle and e-ring back into the 
carburetor.

4.

Inspect the needle (7), e-clip (8), and plastic washer (9) for
wear.

5.

Remove the four screws (10) on the funnel face.

6.

Turn throttle shaft so the throttle slide (11) slides open all
the way. 

7.

With slide fully open, pull funnel (12) out from the bottom
first. Inspect the gasket (13).

8.

Check for wear on the faces of the slides,.

CAUTION

W

EAR

 

EYE

 

PROTECTION

 

WHEN

 

USING

 

COMPRESSED

 

AIR

 

OR

 

WHEN

 

USING

 

CLEANING

 

SOLVENTS

. R

EVIEW

 

ALL

 

FUEL

 

SYS

-

TEM

 

WARNINGS

 

LOCATED

 

AT

 

THE

 

BEGINNING

 

OF

 

THIS

 

CHAP

-

TER

 

BEFORE

 

PROCEEDING

.

1

2

3

4

5

6

7

8

9

10

11

12

13

4.12

CARBURETION

9.

Inspect e-rings, plate, spring, and rings (14) connecting the
slide to the lever if needed.

10. Remove water trap/drain plug (15) and single screw (16)

on the bottom of the carburetor.

11. Remove and drain the float bowl (17).

NOTE:  Float bowl will not come off unless the water 
trap/drain plug and screw are removed.

12. Remove the two screws (18) holding the float/needle and

seat assembly (19) in position and remove this assembly.

13. Inspect the contents for wear and debris.

14. Remove and inspect the main jet (20), pilot jet (21) and

starter jet (22) and clean them out.

15. Remove the air jet screw if so equipped.

16. Clean out all passages in carburetor body with carburetor

cleaner. Dry all passages and jets with compressed air.

17. Replace gaskets and any parts that show wear or damage.

18. Repeat steps 1-18 for disassembly for the other carburetor

if needed.

ASSEMBLY

1.

Install the main jet (20), pilot jet (21) and starter jet (22).

2.

Install float/needle & seat assembly (19).

3.

Place carburetor in an inverted position.

4.

Connect a pressure tester (PN 2870975) to fuel inlet
fitting. Apply 5 psi pressure and observe for one minute.
The needle and seat should hold pressure indefinitely. If
the pressure drops, carefully inspect the needle and the
needle seat. The needle can be replaced (needle comes

14

15

16

17

18

19

20

22

21

4.13

CARBURETION

with float and seat).

5.

Carefully inspect float bowl gasket and replace if
necessary.

6.

Install float bowl (16) on carburetor with water trap/drain
plug (15) and single screw (16) on the bottom of the
carburetor.

7.

If throttle slide was removed, install throttle slide (11) so
that the wider face is facing the engine side of the
carburetor.

8.

Install the funnel gasket (13) and funnel (12) onto the
carburetor. You will have to lift the throttle slide up and
place the smaller face into the funnel area.

9.

Install funnel screws (10).

10. Install the e-clip (8) in the desired position on the jet needle

(7).

11. Slide the plastic washer (9) on the jet needle so that it is

positioned to rest on top of the throttle valve when
assembled.

12. Install carburetors on engine.

13. Synchronize the carburetors. See “THROTTLE VALVE

SYNCRONIZATION” on page 4.13.

14. Replace top cap gaskets (3), cover (2) and screws (1).

15. Check throttle lever free play. See “THROTTLE LEVER

FREE PLAY” on page 3.24.

CARBURETOR 
SYNCRONIZATION

THROTTLE VALVE SYNCRONIZATION

Mikuni TM style carburetors are synchronized at wide open 
throttle with out the engine running. The MAG side carburetor 
is the adjusting carburetor, the PTO side carburetor has a non 
adjustable set screw on the throttle shaft. The PTO carburetor 
is considered the base carburetor. All adjustments are made to 
the MAG carburetor

1.

Remove the air box.

2.

Remove the carburetor tops.

3.

Hold the throttle wide open with the bellcrank on the
carburetor.

4.

The bottom of the throttle valve should be flush with the
top of the carburetor intake area.

5.

If they are not flush, hold the PTO carburetor flush with the
top of the intake area of the carburetor. 

6.

Turn the throttle slide synchronization screw until both of
the throttle slides are flush with the top of the intake area
of the carburetor.

7.

Once the PTO carburetor side is flush, loosen the Phillips
head screw, located under the top cover on the MAG
carburetor.

8.

While holding the PTO carburetor slide flush to the top of
the carburetor, rotate the synchronization nut clockwise to
raise the slide and counterclockwise to lower the slide.

9.

Adjust the synchronization nut until it is even with the
PTO slide.

10. Once this is flush, lock the locking screw.

11. Replace the tops of the carburetor.

12. Install carburetor back onto the sled.

13. Install all cables. 

14. Install all vent lines, and fuel lines.

Throttle slide sync screw

Lock Screw

Sync Nut