- Setup.jpg (76.08 KiB) Viewed 1461 times
1 - Main Jet
2 - Idle Jet
3 - Power Jet
4 - By-Pass Screw
5 - Volume Control Screw
6 - Fast Idle Adjuster Screw
7 - Fast Idle Cam
8 - Accelerator Pump Adjustment Nut
9 - 12V Electric Choke Connection
10 - 12V Idle Fuel Cut-Off Solenoid
11 - GL1100 Vacume Advance Connection
12 - Choke Adjustment Reference
IN - Fuel Inlet
Ck - Choke
Tc - Throttle Cable Attach
X - Vacume Ports Not Used
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10.1 - Initial Carburetor Set-Up
This section covers the Solex 30PICT/3, 30PICT/4, 31PICT/3, 31PICT/4, 34PICT/3, Brosol H30/31, Bocar and Pierpoint carburetors with two idle adjusting screws on the left side.
Foreword
Jetting calculations for these carburetors to your Honda GL1000, GL1100 and GL1200 Goldwing engine can be found on our webpage using the "Single Carburetor Jet Calculator" button and are determined first through calculation then verified through actual testing using our '78 GL1000, '83 GL1100 and '84 GL1200, all utilizing our Jessco Weber Single Carburetor Manifold and no other.
This "Initial Carburetor Set-Up" information is applicable only to a properly jetted carburetor for the engine in use and specific to our manifold, yet applies to most other intake manifold designs normally found for these engines. Of course, a competent design and a high quality of craftsmanship is assumed in the construction of your particular manifold.
These carburetors are often times set-up incorrectly. In our experience using the Brosol H30/31 carburetor on our manifold (both heated and not heated tests of the same manifold) using our Jessco Solex Adapter on our 1978 GL1000 Goldwing daily rider, we've come to know this combination with exclusivity as applied to the GL1000. Without question, our heated manifold tests were always superior in performance than when we ran the manifold with no heat. With a properly set-up carburetor on our heated manifold, performance criteria consistantly rose above the same criteria for a unheated manifold. Fuel, once atomized by the carburetor, remained atomized and in suspension from throttle valve to intake valve under all conditions with our heated manifold during testing. Proper fuel atomization (carburetor set-up) for intial start-up and running is the purpose of this section. Further tuning after Initial Carburetor Set-Up and running is covered in the Single Carburetor Performance chapter and is specific to our intake manifold only.
Note: Prior to adjusting the carburetor, the valves, points and timing should be set, and set in that order. Start with a cold engine and end with it warm to set the valves, points and timing (in this order) and then set the choke with engine cold before setting the carburetor base and running idles. In setting the choke you are setting the throttle valve in a reference position designed for all adjustments made to the idle and primary circuits. *If you adjust your idle using the Fast Idle Adjuster Screw (6) as has been done previously on PICT/2 carburetors, you will not be able to properly tune your carburetor and all performance criteria will be compromised.
Initial Carburetor Set-Up
Note: Correct idle speed is very important with these carburetors, which is more complicated (and much more sensitive) than the earlier PICT/2 types. These /3 carbs have three separate fuel circuits in them (only two in older /2 carburetors), four circuits for the /4 carbs, and the 1150-1200 rpm idle is designed so the airflow through the carburetor is balanced for the idle circuit fuel flow. That's why they have both Volume Control (5) and Bypass (4) Screws (the earlier ones had only one: Volume). This way the idle speed can be set correctly using the Bypass Screw (4) without touching the Fast Idle Adjuster Screw (6) on the throttle arm, which has to be set exactly right.
Make sure the gasket at the base of the carburetor is sealing properly as well as the gaskets or O-rings for the manifold (no vacuum leaks). Install the air filter assembly so the carburetor sees actual airflow under its use.
Turn the ignition ON and allow the Choke (Ck) to warm until fully open, then switch the ignition OFF. Do not "blip" the throttle, or otherwise work the throttle valve to excess in attempting to open the butterfly as fuel will enter the manifold unneccessarily with every blip. Give it 3-5 minutes to warm depending on ambient temperature. Alternatively, adjust the choke to a fully open position.
The first step is to set the throttle valve. Back out (counter-clockwise) the Fast Idle Adjuster Screw (6) located at the top of the throttle arm on the left side of the carburetor.
Note: "Fast Idle Adjuster Screw" is a misnomer - ***this screw it is NOT used to adjust the idle speed!*** The Fast Idle Adjuster Screw (6) works with the Choke (Ck) to give a smooth idle on a cold engine and sets the the throttle valve to the correct position for the idle circuits when not in use. As the choke warms up, the choke valve in the throat of the carburetor opens and the Fast Idle Adjuster Screw (6) moves down the steps of the choke Fast Idle Cam (7) via throttle "blipping" reducing the engine idle speed and gradually closing the throttle valve at the same time. Screwing the Fast Idle Adjuster Screw (6) in more will increase the idle speed, yes, but doing so messes up the Volume Control Screw (5) and Bypass Screw (4) adjustments that control the idle mixture. ***This destroys the idle geometry*** and the bike won't run right.
With the Choke (Ck) held in the fully open position (Fast Idle Cam (7) at its lowest point) place a piece of notebook paper or a 0.003" feeler gauge between the lowest step of the choke Fast Idle Cam (7) and the Fast Idle Adjuster Screw (6). Slowly turn the screw in until you feel drag on the paper or the feeler gauge. Then remove the paper or feeler gauge and turn the screw in precisely 1/2 turn - no more! This sets the throttle valve open the required 0.004", so you can use the Bypass Screw (4) to set the idle speed correctly. From this point on, leave the Fast Idle Adjuster Screw (6) alone.
Next, set the volume of gas available at idle speeds. This is done using the Volume Control Screw (5). The Volume Control Screw (5) controls the AIR volume, not the fuel volume. Screwing it in reduces the air and makes the fuel/air mixture richer. And of course turning the Volume Control Screw (5) out increases the concentration of air and makes the mixture leaner.
Note: The Volume Control Screw (5) is the smaller of the two adjusting screws, located on the left side of the carburetor just above the Idle Fuel Cut-Off Solenoid (10). The Volume Control Screw (5) is NOT used to set the idle speed - that's the job of the Bypass Screw (4).
Before setting the Volume Control Screw (5) per the step below, turn the Bypass Screw (4) in GENTLY until it bottoms out - you don't want to open the seat area up. Now unscrew it EXACTLY 2 turns.
Screw the Volume Control Screw (5) in GENTLY until it bottoms out - again, you don't want to open the seat area up. Now unscrew it EXACTLY 2-1/2 turns. These are the initial start-up settings for all engines.
Start the engine and let it warm up, making sure the automatic Choke (Ck) is fully open before proceeding. Your engine may not idle at this point if warm, so be at the ready.
Now set the idle. This is done by controlling the volume of air going by the Bypass Screw (4). Remember, the Bypass Screw (4) is LARGER than the Volume Control Screw (5).
Next, turn the idle Bypass Screw (4) whichever way (most likely out) to set the idle at 1150 rpm.
Go back to the Volume Control Screw (5) and adjust it SLOWLY to obtain the fastest (smoothest running) idle speed (this is usually out - counter-clockwise). You should not have to turn the screw much outside the range of 2-3 turns total (1/2 turn in/out from the basic 2-1/2 turn out setting).
Turn the Volume Control Screw (5) screw back IN (clockwise) SLOWLY until the engine speed drops by about 20-30 rpm (slightly leaner). If you don't have a tachometer, listen until you can hear the engine speed just start to drop, maybe as little as 1/10th of a turn on the Volume Control Screw (5). The Volume Control Screw (5) is capable of very precise metering with very small fractions of a turn.
Go back to the larger Bypass Screw (4) again to reset the idle speed to 1150 -1200rpm.
Final Note: If you find it difficult or impossible to make these adjustments work, you could have stripped threads on any of these adjusters, a damaged seat area for the adjuster screw, a damaged needle valve or O-ring, or a vacume leak at the throttle shaft bushing, base gasket or intake manifold gaskets or O-rings. If there are any pin-holes, bad welds or cracks in the manifold then air can be sucked into the manifold causing the air/fuel ratio to become lean. This can cause (among other things) carburetor adjustment to be impossible.
Initial Set-Up of the carburetor is now complete.
