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I don't know why I have'nt figured this out before. Even our manuals don't mention this. We've all been told you can't move these screws and then put them back to their original settings. This may help you if you've moved the screws from their original factory settings and want to put them back, but you can't remember where they were.
When the factory sets the screw, they "more often than not" put a "nick" in the carb body that's in line with one side of the screw slot. If your's don't line up, then they've been moved before. This nick will not tell you the # of turns out a screw is, but keep in mind on the VM carbs, the pilot screws (underneath) are generally 3/4 to 1 1/4 turns out FROM THE FACTORY. The side air screws are generally 1 1/2 to 1 3/4 turns out. The mixture screw on CV carbs is generally 1 1/2 to 2 turns out. I have yet to see factory settings of a full turn under or over the above settings, so you can see that the nick should help you in putting the screws back to where they were.
As a side note regarding the VM carbs. The factory/emissions people don't want you to turn the side air screws but they are actually intended for fine tuning, especially when you ride in higher elevations. If you have trouble with re-starting and low speed riding in high elevations, try turning the screws OUT about a 1/4 turn or so. Return them when out of the high elevation.
The mixture screw on CV carbs can also be adjusted to help with elevation problems, except you would turn the screw IN to counter the richening effect high elevations have on jetting.
Of course if your bike has engine mod's and has been re-jetted correctly, these screws will not be in their factory settings. When tuning, the side air screws (VM) and mixture screws (CV) should be set to achieve the highest rpm possible and then re-set the idle to about 1,100 rpm with the idle screwknob. With the VM carbs, adjusting the pilot screw (underneath) will effect the mixture, so you have to re-tune the side air screws after making adjustments to the pilots screws. You may not notice any change in settings, but you should always do the re-check anyways.
When the factory sets the screw, they "more often than not" put a "nick" in the carb body that's in line with one side of the screw slot. If your's don't line up, then they've been moved before. This nick will not tell you the # of turns out a screw is, but keep in mind on the VM carbs, the pilot screws (underneath) are generally 3/4 to 1 1/4 turns out FROM THE FACTORY. The side air screws are generally 1 1/2 to 1 3/4 turns out. The mixture screw on CV carbs is generally 1 1/2 to 2 turns out. I have yet to see factory settings of a full turn under or over the above settings, so you can see that the nick should help you in putting the screws back to where they were.
As a side note regarding the VM carbs. The factory/emissions people don't want you to turn the side air screws but they are actually intended for fine tuning, especially when you ride in higher elevations. If you have trouble with re-starting and low speed riding in high elevations, try turning the screws OUT about a 1/4 turn or so. Return them when out of the high elevation.
The mixture screw on CV carbs can also be adjusted to help with elevation problems, except you would turn the screw IN to counter the richening effect high elevations have on jetting.
Of course if your bike has engine mod's and has been re-jetted correctly, these screws will not be in their factory settings. When tuning, the side air screws (VM) and mixture screws (CV) should be set to achieve the highest rpm possible and then re-set the idle to about 1,100 rpm with the idle screwknob. With the VM carbs, adjusting the pilot screw (underneath) will effect the mixture, so you have to re-tune the side air screws after making adjustments to the pilots screws. You may not notice any change in settings, but you should always do the re-check anyways.
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