If you try to swap the XJ forks to a XS without using the XJ balance tube, you have to make a choice; air assist OR adjustable damping, you can't have both.
If you want the adjustable damping, you have to retain the XJ fork caps and dampers, but you no longer have any way to put air into the forks. The 'air assist' springs used in the air forks are considerably 'softer' and require at least 3-4 lbs of pressure to equal the non-air springs. This is why if using the aftermarket Progressive springs that fit all XS/XJ forks, no air is needed; they're 'stiff' enough already, although you could add air for 'tuning' if possible. A set of OEM non-air assist 'standard' springs (with a preload spacer) will work the same way. You can 'tune' the forks by changing the amount of oil in them; less will make them softer in initial movement, more oil stiffer. By changing the oil level, what you're really doing is changing the air volume in the forks; more oil = less air, and vice versa. The less air, the faster it compresses to a given pressure.
If you want the adjustable damping, you have to retain the XJ fork caps and dampers, but you no longer have any way to put air into the forks. The 'air assist' springs used in the air forks are considerably 'softer' and require at least 3-4 lbs of pressure to equal the non-air springs. This is why if using the aftermarket Progressive springs that fit all XS/XJ forks, no air is needed; they're 'stiff' enough already, although you could add air for 'tuning' if possible. A set of OEM non-air assist 'standard' springs (with a preload spacer) will work the same way. You can 'tune' the forks by changing the amount of oil in them; less will make them softer in initial movement, more oil stiffer. By changing the oil level, what you're really doing is changing the air volume in the forks; more oil = less air, and vice versa. The less air, the faster it compresses to a given pressure.
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