Maybe penetrating fluid dripped on the shaft to seep in between the shaft and the inside bore of the pillow bearings to start with.
Next making some kind of jig to hold each part separately. Like even though it seems both pillow bearings are stuck, just try moving one at a time a short distance latterly toward the nearest end of the shaft. Eventually moving them both off the shaft and get a new shaft.
Also the areas of the shaft that are next to the immovable pillow bearings that you are trying to move them over, you may try to remove burs first by sanding using fine emory cloth.
I have had a really bad time with the collars that have set screws and mark up the shaft and pulleys would get stuck in the areas where they had just been removed from. I switched to half split collars (bushings) that have a set screw that only tightens the split area so that it immobilizes the collar. There is no set screw that hits the round of the shaft with these collars. Then all of the pulleys have keys and they are the only things marked up by the set screw ends. The keys are replaceable and cheap to replace and this is how I make sure things are removable.
Occasional fine sanding and oiling the steel shaft is still necessary once in a while as I also have windsurfing year round as a sport in salt water and the water vapor gets on my bike.
There are probably some other ways others may have to add, but hope this will help.
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I'm still wondering myself if the trouble I have with getting the centrifugal clutch of mine on the engine crank shaft turned around 180 degrees (the bell on the inside) can be solved short of modifying the crankshaft keyway slot nearest the crankcase cover oil seal.
The key way cut on the engine crankshaft closest to the crankcase cover oil seal is a rounded sloped cut. I have had to modify the key to get it almost fully installed. Its not quite there, just 1.3 mili-meters short of having the end of the engine crankshaft even with the centrifugal clutch pulley.
I have had the people at Max Torque the manufacturer of my centrifugal clutch mention that turning the clutch around is OK to do as the shoes on the one I have are symmetrical and grip either way. I want to have it install like this so I have the belt further away from the engine so I can fit the flat idler pulley I am to get in the mail tomorrow.
I'll be checking with Briggs and Stratton what they know of this too. Any help appreciated!
Art Fish Mobile Motor Bike prior Motor Bike DIY'er build to add side car maybe?
See posts #93 and #94 on page 10 for pics of the problem
http://motorbicycling.com/showthread.php?p=454501#post454501
http://motorbicycling.com/showthread.php?t=29678&page=10
MT