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Thunder Slide Jet Kit
J031412013-11-01
GENERAL
Kit Number
29935-98A
Models
For model fitment information, see the P&A retail catalog or the Parts and Accessories section of www.harley-davidson.com (English only).
Kit Contents
See Figure 6 and Table 1.
WARNING
Rider and passenger safety depend upon the correct installation of this kit. Use the appropriate service manual procedures. If the procedure is not within your capabilities or you do not have the correct tools, have a Harley-Davidson dealer perform the installation. Improper installation of this kit could result in death or serious injury. (00333b)
NOTE
This instruction sheet references Service Manual information. A Service Manual for your model motorcycle is required for this installation and is available from a Harley-Davidson Dealer.
NOTE
Harley-Davidson® motorcycles equipped with some Screamin' Eagle® high-performance engine parts may not be used on public roads and in some cases must be restricted to closed course competition. This engine related performance part is intended for racing applications and is not legal for sale or use in California on pollution controlled motor vehicles. Engine related performance parts are intended for the experienced rider only.
WARNING
When servicing the fuel system, do not smoke or allow open flame or sparks in the vicinity. Gasoline is extremely flammable and highly explosive, which could result in death or serious injury. (00330a)
Carburetor Removal
See the Service Manual. Remove the Carburetor in EVO model motorcycles.
INSTALLATION
Thunder Slide Installation
1. See Figure 1 and Figure 6. Remove the carburetor top. Remove the slide spring, spring seat, jet needle and metal vacuum piston slide.
1Vacuum piston slide with diaphragm
2Jet needle
3Slide spring
4Slide spring seat
Figure 1. Vacuum Piston Chamber Slide Components
2. Carefully remove the original rubber diaphragm from the metal slide by gently pulling at the edge of the diaphragm in a circular motion until diaphragm is out of the stock slide retaining groove. The stock rubber diaphragm will be installed on the Thunder Slide.
3. To assemble the stock diaphragm on the Thunder Slide, first install the larger slide retainer (9) with the radial grooves facing up on the slide. You will notice that the slide has a collar on the top which you will have to push the larger retainer past.
4. Lay the diaphragm on the larger retainer in the same direction it was on the stock slide.
5. Press the small slide retainer (8) with the grooves facing down, on top of the diaphragm. You should hear a "snap" as it all goes together. Make sure it is flat and secured on top of the slide and that the diaphragm is centered.
DYNOJET Kit Installation
NOTE
These are recommended starting points. Jet changes may be required during tuning.
1. See Figure 2 and Figure 6. Place the carburetor upside down on a bench. Remove the carburetor float bowl. Remove the stock main jet and emulsion tube, sometimes referred to as the main jet holder. verify that the Needle Jet does not fall out during this procedure. Replace the stock emulsion tube with the new DYNOJET emulsion tube (14) provided. When the DYNOJET emulsion tube is fully seated, there will still be threads visible. Install the new DYNOJET main jet provided. Use the BJ165 main jet with a completely stock bike. Use the BJ175 main jet with an aftermarket slip-on and airbox. With a complete aftermarket exhaust with a high flow baffle and airbox use the BJ185 main jet. With extensive engine modifications, ie: cams, head work, airbox and high flow aftermarket exhaust, it may be necessary to use the BJ195 main jet.
1Main Jet Holder/Emulsion Tube
2Needle Jet
3Main Jet
Figure 2. Stock Carburetor Jets and Holder
2. See Figure 6. Install the E-clip (6) on groove #3 of the new DYNOJET needle (5). Install the new Thunder Slide (7), new Dynojet needle (5), needle (10) spacer, with needle retainer and new Dynojet slide spring (15) into the carburetor body, making sure the slide spring is aligned properly.
NOTE
During the next step, care must be taken not to drill through the Idle mixture screw. The Idle mixture screw is directly underneath the plug, be ready to pull back on the drill the instant you break through the plug.
3. See Figure 3 and Figure 6. Locate the Idle mixture plug (1). If you see a Idle mixture screw head not plugged, proceed directly to the adjusting procedure. With the plug drill bit (16) provided, carefully drill through the the plug. Use the screw (17) provided to secure and remove the plug.
4. Carefully turn the mixture screw clockwise until it seats, then turn out 3-1/2 turns.
1Idle Mixture Plug
2Main Jet
3Pilot/Slow Jet
Figure 3. Idle Mixture Plug Location
NOTE
If the Idle mixture screw setting exceeds 3.5 turns to achieve low speed drivability when running a free flowing aftermarket exhaust and/or other modifications, install a larger pilot/slow jet.
Thunder Nozzle Installation
1. See Figure 4 and Figure 6. With the carburetor float bowl removed, using a vise, clamp onto the stock accelerator pump nozzle. Remove it by twisting and pulling it out of the float bowl. Remove the stock check valve.
Figure 4. Stock Float Bowl and Accelerator Pump in Vise
2. See Figure 5 and Figure 6. Install the new check ball (12) and the new brass weight (13) into the float bowl. Press the new DYNOJET Thunder Nozzle (11) into the stock pump nozzle hole and lightly tap it into place with a soft hammer. The spray hole in the nozzle should face the brass float bowl drain tube.
3. Carefully install the float bowl gasket and the float bowl.
1Thunder nozzle
2Thunder nozzle spray location
Figure 5. Stock Float Bowl and Thunder Nozzle Installed
Carburetor Installation
For installation procedures refer to the "Carburetor" section in a the Service Manual for Carbureted EVO model motorcycles. Use the fuel hose clamp (18) provided.
NOTE
Prior to performing any jetting changes, verify the carburetor and manifold are installed correctly and there are no intake leaks. Also make sure the float is adjusted correctly (Refer to the "Fuel System" section in the Service Manual for float adjustment procedures).
TROUBLESHOOTING GUIDE
NOTE
Proper idle before troubleshooting is required.
NOTE
BEFORE STARTING THE MOTORCYCLE: Check fuel line and vacuum line. Open and close the throttle checking for smoothness and full operation. Check accelerator pump action to make sure actuation rod is installed correctly in float bowl. Turn on fuel petcock and check for any fuel leaks.
Check on Initial Start-Up
  1. BEFORE STARTING THE MOTORCYCLE: Check fuel line and vacuum line. Open and close the throttle checking for smoothness and full operation. Check accelerator pump action to make sure actuation rod is installed correctly in float bowl. Turn on fuel petcock and check for any fuel leaks.
  2. Start the engine, turn the handlebars from lock to unlock to verify cables are routed properly.
  3. Blip the throttle 2 to 3 times to verify linkage is not sticking.
  4. Check the engine kill switch for correct operation.
After completing your installation and following the proper safety precautions, the machine should function properly with noticeable performance gains. If the machine functions well, but does not seem to have any performance gain, try needle positions on either side of the base settings to improve performance. If the machine has more pronounced troubles in function and performance, read through the troubleshooting guide. Find the problem description that best matches your trouble, and perform the recommended adjustment procedures. In some cases, more than one description closely resembles your problem. If so, perform each of the adjustment procedures in the easiest manner or the most logical conclusion.
Start and Idling Problems
(Pilot jet must be stock)
  1. Motorcycle will not start cold. It is important to know that your bike will start and idle without your needle, slide, or main jet installed. DYNOJET kits do not alter your stock idle circuit, or the starting circuit. Also check:
    1. Fuel in the float bowl.
    2. Choke plunger for proper operation.
    3. verify throttle plate is closed. Check throttle play.
    4. Vacuum leaks (vacuum hose and area around intake manifold).
    5. Float bowl is not flooding over with gas (float damage, or dirt in needle valve).
  2. Motorcycle will not start hot. It is important to note whether the bike starts hard only when you let it sit for a period of time, or starts hard any time when hot. Both of these conditions are usually "rich" problems. If you have trouble after the bike sits, then check for gas tank venting problems. Also check:
    1. ldle mixture screw turned out too far.
    2. Float bowl is not overflowing with gas.
    3. Pilot/ Slow jet (not stock).
  3. Motorcycle idles rough until it reaches normal running temperature:
    1. Idle mixture screw set too "lean". Turning counterclockwise will enrich mixture.
  4. Motorcycle idles well until it reaches normal running temperature, then idles rough and possibly stalls.
    1. Idle mixture screw turned out too far.
    2. Pilot/Slow jet (not stock).
    3. Choke plunger or choke cable not returning to closed position.
  5. Motorcycle starts, but does not idle at all.
    1. Idle mixture screw turned out too far.
    2. Vacuum hose disconnected.
    3. Pilot/Slow jet plugged.
    4. Manifold air leak.
    5. Idle turned down too far.
  6. Motorcycle starts, but does not idle at all. Bike seems to rev slowly off idle with possible black smoke.
    1. Idle mixture screw turned out too far.
    2. Pilot Air Jet plugged.
    3. Choke not returning to off position.
    4. Pilot/Slow jet (not stock).
    5. Fuel leaking past needle valve.
  7. Low speed and cruising problems: (Engine does not accept throttle past idle, engine accepts past throttle but pops through carburetor, engine surges when holding steady speed, engine is very cold-blooded and choke has to be left on for a long time).
    1. Check that main jet is drilled completely.
    2. Check for vacuum leaks.
    3. Check vacuum hose for leakage.
    4. Check float level is not too low.
    5. Check accelerator pump operation.
If the above check out, then raise the needle one groove at a time and retest.
Acceleration Problems
Proper idle must be established before off idle troubleshooting is carried out.
  1. Engine accelerates from down low, then goes flat. Seems to be worse in high gears.
    1. Check needle installation, there must be three washers above the E-Clip.
    2. Check needle shroud installation.
    3. Drag pipes will always cause problem.
    4. Poor choice of cam will cause flat spots in midrange. If the above check out, lower needle one groove at a time and retest.
  2. Engine accelerates to red line but flattens out. Seems to be worse in higher gears and when hot.
    1. Check parameters on fact sheet (main jet size for your application).
    2. Check intake air flow. Many aftermarket filters do not flow as well as stock ones.
    3. Check exhaust flow. Some aftermarket pipes flow much worse than stock ones, but may be noisier. If the above check out, lower the main jet size.
  3. Engine seems sluggish when accelerating in low gears or when cold. Seems to be better when rolling and in high gear.
    1. Try restricting the air entering the air filter. If problem gets better, then try going to a larger main jet.
  4. Bike functions normally with the exception of popping when decelerating.
    1. Check exhaust leaks and intake leaks. If the above check out, try enriching mixture screw slightly, making sure bike idles smooth.
For Technical assistance: Contact your DYNOJET distributor or call Dynojet U.S.A. (800)-992-4993
2191 Mendenhall Dr. Suite 105
North Las Vegas, NV 89031
Tel: 702-399-1423
Fax: 702-399-1431
8am-5pm Pacific Time
Monday through Friday
Service Parts
Figure 6. Service Parts
Table 1. Service Parts
Item
Description (Quantity)
Part Number
1
Main Jet
BJ165
2
Main Jet
BJ175
3
Main Jet
BJ185
4
Main Jet
BJ195
5
Fuel Needle
DNO891
6
E-Clip
DE0001
7
Thunder Slide
DTS006
8
Diaphragm Retainer Upper
DTS002
9
Diaphragm Retainer Lower
DTS004
10
Needle Spacer
THNR01
11
Thunder Nozzle
THNOZ2
12
Check Ball BB
#1/8
13
Check Ball Weight
DW070
14
Emulsion Tube
DET007
15
Slide Spring
DSP088
16
Plug Drill (not shown) DD
#5/32
17
Screw (not shown)
DS0001
18
Clamp (not shown)
9946
19
Stock Part
20
Needle hole
21
Float bowl
Note: In order for this kit to work properly, your pilot circuit must be completely stock.