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andyvh1959 · 12-17-2017, 02:22 PM

Done this on non-cruisers, but should apply: manufactuers put in the least amount of oil needed in the forks. So the old guide was to go with LIGHTER oil, but a lot more oil. The oil level is set with the springs out and fork fully compressed, pour in oil to within 1.5" from the top. The lighter oil keeps the bike responsive to small bumps. The added volume decreases the air above the oil that acts like the final "spring" because air can be compressed. The lower air volume helps to reduce bottoming. Also, preload is critical to reduce sag. Fit spacers at the top of the springs to keep sag to about 1/2". Years ago we'd use VW Bug valve springs as spacers.

12-17-2017, 02:22 PM	#12
andyvh1959 Advanced Member Join Date: Dec 2017 Location: Green Bay WI Posts: 759	Done this on non-cruisers, but should apply: manufactuers put in the least amount of oil needed in the forks. So the old guide was to go with LIGHTER oil, but a lot more oil. The oil level is set with the springs out and fork fully compressed, pour in oil to within 1.5" from the top. The lighter oil keeps the bike responsive to small bumps. The added volume decreases the air above the oil that acts like the final "spring" because air can be compressed. The lower air volume helps to reduce bottoming. Also, preload is critical to reduce sag. Fit spacers at the top of the springs to keep sag to about 1/2". Years ago we'd use VW Bug valve springs as spacers. Last edited by andyvh1959; 12-17-2017 at 02:26 PM.
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