Differences

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-====== IH: Carburetor, Intake Manifold & Exhaust Systems ======
-===== Sub-Documents =====
-* . . . [[techtalk:ih:carb02a|Finding and fixing the cause of the degradation that leads to intake manifold leaks]]
-====== Tillotson HD Carburetor (1966-1971) ======
-  * On January 15, 1968, the MoCo issued a service checklist to aid in testing and repairing (instead of returning for warranty) Tillotson carburetors due to some dealers having difficulty diagnosing problems on 1966 → Sportsters & 1967 → Electra Glides.
-  * Before disassembling the carb to correct any (non)performance, it should first be established that external adjustments have been made and are correct. In many cases, the intermediate and idle speed needles are incorrectly adjusted cause poor performance.
-  * Correct adjustment can be determined in the shop and verified by a road test:
-  * Adjustments (a tachometer is recommended):
-    - Seat idle and intermediate needles, gently, and open both 7/8 turn.
-    - Start the engine and warm up for at least 3 minutes at fast idle.
-    - Set the engine throttle so that the engine runs at app. 2000 RPM.
-    - Without changing the throttle setting, turn the intermediate needle slowly in the direction which produces the highest RPM. The engine should not miss or surge at this position.
-    - Back off the intermediate needle 1/8 turn to slightly richen the mixture. This is the correct intermediate needle adjustment.
-    - Readjust the idle needle & the idle speed stop screw to produce a smooth idle at desired speed (900-1100 RPM).
-  * All these tests should be performed (in sequence) before further disassembly or repairs are made.
-  * Testing (prior to removal from engine):
-    - The accelerator pump should be inspected for proper operation. Remove the air cleaner and prime the carburetor by inserting a toothpick through the small hole in the bottom of the plastic pump cover and gently work the diaphragm several times. Operate the throttle lever (both rapidly and then slowly several times with the fuel valve turned on. The pump should deliver a strong & constant jet of fuel with each stroke. Failure to do so indicates defective diaphragm valves or pump plunger.
-    - In cleaning of high, intermediate and low speed channels, the following procedure, most likely, will dislodge any loose dirt lodged in the passages. Remove high speed screw plug located on rear side of carburetor, opposite intermediate adjustment
-====== Keihin Carburetor - Butterfly or Non-CV (Late 1976-1987) ======
-===== Lean Condition Adjustments from the MoCo (1979) =====
-  * During the mid 1979 model season, HD makes a recommendation to dealers for corrective measures regarding the carburetion and [[techtalk:ih:engctl01#breakerless_electronic_ignition_system|ignition system]] on (1100, 1200 and 1340cc) models with emissions control design changes. They operate with leaner air/fuel mixtures and are more sensitive to carburetor mixture settings / ignition spark. ((HD Service Bulletin #M-739 dated November 3, 1978))
-  * For proper carburetion it is recommended to check the following items as corrective measures for irregular running and spit-back which are symptoms of an excessively lean mixture. Also check for proper ignition.
-    * Check to see that the intake manifold seals and band clamps are installed properly. Using a squirt can with stanisol or kerosene, squirt some on these connections with the engine idling and see if there is any change (increase or decrease) in RPM which would indicate an air leak.
-    * The air cleaner backing plate must be flat against the carburetor flange gasket surface and the air cleaner mounting brackets must be adjusted and tightened properly per the FSM with no air leakage at the carburetor mounting flange.
-===== High Altitude Modification Kit =====
-  * Carburetor modification kits (including jet(s) and an accelerator pump stop screw) were made available for 1200cc, 1340cc and 1000cc models to provide leaner fuel mixtures when operating at elevations above 4000 feet sea level. ((HD Service Blletin #M-730 dated June 15, 1978))
-    * Normally, leaner fuel/air mixtures are required for proper engine operation as the elevation above sea level increases. This high altitude kit (27096-79 for 1979 XLH (XL), XLCH, XLCR-1000) should be installed where there is evidence of a rich condition causing loss of smooth combustion, stumbling on acceleration or such other carburetor issues at high altitudes.
-    * The kit for Sportsters includes a #160 main jet, accelerator pump stop screw and the front down tube on the frame.
-    * Install and adjust the acc pump stop screw to extend 1/8" past hole in lever.
-  * Note, any motorcycle modified for high altitude operation must be converted back to standard if operated at altitudes below 4000 feet. An overly lean condition can cause engine damage.
-\\
-===== Welch Plug or Expansion Plug =====
-  * Inspection:
-    * A close inspection around the walls of a welch plug can reveal possible leaks.
-  * Removal: ((HD Service Bulletin #518 dated September 10, 1965 pg OC-189))
-    * Whenever a welsh plug is removed, a new one should be installed in it's place, especially since a large part of the time, removal of one means destroying or deforming it.((1959-1969 HD Sportster FSM))
-    * Drill an 1/8" hole thru it (just deep enough to break thru to the other side) off center and pry it out with a small punch. Be careful not to drill too deep which could destroy the nozzle assembly or casting. While prying it out, be careful not to damage the casting counter-bore edges around the plug.
-  * Installation: ((HD Service Bulletin #518 dated September 10, 1965 pg OC-189))((1959-1969 HD Sportster FSM)).
-    * The plug should be seated  with a flat end punch that is slightly smaller than the diameter of the plug. The plug should be flat and not concaved to assure a tight fit. If leakage is suspected due to a rough or damaged welch plug seat in the casting, apply a small amount of epoxy or suitable sealant to the edges after installing it.
-    * Installation Recommendations from Hubbard Spring [[http://www.hubbardspring.com/install_reco.php?cid=45]]
-  * Some Welch Plug dims: [[http://www.hubbardspring.com/index.php/category/43/cupped-plugs-and-cupped-plugs-pierced-catalog
-]]
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