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Old 04-06-2014, 07:53 AM   #1249
Big B
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Joined: Jan 2006
Location: Victoria Down Under
Oddometer: 242
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Just used my Harmoniser using Grok's instructions, it was a breeze! Even given I had done a complete carby rebuild!

Thank Grok great big of Kit!

Originally Posted by Grok View Post
I'm going to jump in here.. Not too sure if it's a good idea because I don't own a Ural and the last one I tuned is a distant memory. This information will probably be useful for AIRHEAD OWNERS as well. If anyone thinks I'm full of crap or omitted something please do correct me.

There are 3 types of adjustments for balance and carb tuning.
1. Carburetor idle mixture
2. Idle balance and RPM combination.
3. Higher-RPM balance.

Do a careful valve adjust first. It helps immensely for smoothness.
Warm the engine to operating temperature, then shut it off.
Put a BAF (big ass fan) on it while doing the adjustments.

The first thing we are going to do is a rough idle balance and RPM adjustment. This will make sure the carbs are working roughly equally and are running on the idle jets instead of the main jets. This is in preparation for adjusting the idle mixture. If the bike is generally running well, this step 1 may not be necessary.

PURPOSE: make sure carbs are contributing roughly equally and are operating on the idle jets by adjusting idle balance and RPM in Harmonizer balancer mode.

Disconnect the vacuum line from the left carb and remove the cap from the right. plug on the Harmonizer hoses and push the red button. After some seconds, the Harmonizer will finish it's calibration routine and stand ready in balancer mode. Put the petcock in prime position (this will bypass and defeat the vacuum shutoff function). Start the motor and blip the throttle a couple of times. Make sure there is a very small amount of slack in the cables. Adjust the idle stop screws (not the idle mixture screws) such that the Harmonizer shows balanced at around 1000 to 1100 RPM. You don't need to be too accurate here. We're going to redo it later. Shut off the motor.

PURPOSE: Optimize idle mixture for each carb by adjusting for max vacuum in Harmonizer gauge mode.

Here's where we adjust the idle mixture for each carb. In the previous step we made sure both carbs were contributing roughly equally and were running on the adjustable idle jets. Disconnect the Harmonizer hose from the right carb and put the cap back on. At this point the Harmonizer should be connected with one hose only, yellow port to left carb. Put the Harmonizer in gauge mode by holding the button pressed until you see "gauge mode" and releasing the button. Start the engine. On the Harmonizer display you will see a left-zero graph and a numeric display that shows vacuum in inches of mercury along with the tach reading. The object is to adjust the idle mixture screw on the left carb such that the vacuum reading is as high as you can make it. Make small adjustments and give the Harmonizer a few seconds to settle after each small tweak. Once you've maximized the vacuum reading for the left carb, shut off the motor. Disconnect the Harmonizer from the left carb, replace the vacuum petcock hose, and remove the cap from the right carb. Connect the Harmonizer yellow port the the right carb. Still in gauge mode, repeat the process of adjusting the idle mixture screw for maximum vacuum on the right carb. Shut off the motor.

PURPOSE: Fine tune idle balance after messing about with the idle mixture adjustments in step 2.

Step 3 is basically a repeat of step 1. The Harmonizer is in balancer mode and both hoses are connected. The object is to adjust the idle stop screws such that the Harmonizer show a balanced condition and the RPM's are within specifications. Shut off motor.

PURPOSE: Adjust relative cable lengths such that the carbs are balanced above idle, while the cables are in control.

Make sure both cables have a small amount of slack - maybe 2mm or so.
Put the Harmonizer in balancer mode if it has automatically turned itself off. Restart the motor.

Adjust the relative cable length by adjusting ONE of the cable adjusters (the right side is traditional) such that the Harmonizer shows a balanced condition at around 3000 RPM or so.

That should do it!
Shutoff motor. Disconnect Harmonizer, replace petcock hose and vacuum cap, shutoff pectock.

Bask in your achievement!
Big B
93 R100GSPD

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