Originally Posted by
av8tor1977
Well, this will probably get me in trouble but.... Everyone seems to think that the spring holds the throttle plate centered and it does not. That spring works in torsion to close the throttle; not in compression to hold the shaft. If it were in compression to hold against the shaft, it would push the shaft and plate over against the other side of the carb; not center it. Some carbs have a "C" clip on the opposite side that helps locate the butterfly plate and shaft, some don't. But in any case that spring doesn't do it. Now I will go along with the argument that leaving the spring on may damp some vibrations and help prevent carb throat wear, but that spring is there to close the throttle, not tension/push sideways against the throttle.
Oh boy, I can imagine the comments on this one....
AV8TOR
Well this will be one of the very few times I disagree with you and then only partly. Agree though, quite a few Walbro carbs use "C" clips or other methods to center the butterfly in the bore. These are a very positive means of centering the shaft and the carb could care less whether the spring was there or not. On some of the WT and WJ series carbs, that darn spring is the only thing that centers the shaft when the carb is open. Even disconnecting the spring allows the shaft to float along its length and the butterfly can tear up the bore. Then there are carbs that have a "C" clip on one side and only the spring on the other or a combination of the above. The point here is that Walbro uses many combinations of parts to locate the shaft along its length to center the butterfly. Some will never wear out and it seems some are designed to fail early. Leaving the spring in place seems to help for those carbs that don't have other means of locating the shaft.
This is really one of those subjects that has no real right and wrong ...... everyone just do what works for you. If a carb bore wears and it becomes difficult to find a reliable idle speed and mixture, you know the method used on that particular carb was wrong and a lesson will be learned. I know most things I have learned in this hobby were learned the hard way and I adjusted my methods accordingly. All part of why we are in the hobby in the first place I guess.