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de-airing front forks

882 Views 3 Replies 3 Participants Last post by  Abes_CW
i'm a little fed up with my front forks. they loose air just sitting there. is disabling the air assist as simple as replacing cap or plugging off the air ports? i'm sure I have to add some additional fluid but i can adapt.
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I apologize now to the rest of the world for the Imperial units used below...

I just abandoned the air-assist feature of my '79 CX500 forks last weekend. These were apparently an aftermarket setup, with one Schrader valve feeding two 1/8" tubes, one to each fork cap. The tubing fittings were a spring-loaded press-in type. The system would not hold air, even for a minute. I used soapy water on all of the fittings and could not find any leaks.

I'd submit that a leaking air setup wouldn't necessarily allow the air inside to compress with upward slider travel, making them even softer.

I used a couple of different size screws to hammer into the springy press-in part of the fittings on the fork caps to get them out; since the springy parts spin, drilling wouldn't have done anything. I then plugged the holes with JB Weld epoxy, and put a 3/4" long spacer made from 1/2" galvanized water pipe under the cap in each fork. I wish they had been a bit longer, since the Windjammer on the front adds a reasonable amount of weight and the tired stock springs are working harder than they otherwise would.

Just thinking about air assist, and guessing at an approximate 1 square inch of internal cross-sectional area of the fork tube, even 10 psi (and it was mentioned in another thread that 6-10 psi might be the proper range) would result in a preload of about 10 lb. I'd say that I pushed down with a lot more force than 10 lb. when I was re-installing the fork caps with those spacers, so I think the air assist isn't doing a whole lot unless your springs are already pretty close to the stiffness you need. At that point it might be good for fine tuning.
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