XS2 fork mysteries, need help

tmikeyb

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So, I bought a 1972 XS2 that looked somewhat unmolested, except that it had extended fork tubes, which turned out to be extended by 5 inches. I bought a very rough 72 parts bike that had good looking fork tubes, that I thought I'd use. When I disassembled the forks on the parts bike, I was surprised to find 2 different diameter sized damper assemblies. I assumed that one leg was 34mm and the other 35mm. But both measure 33.9 O.D., so I assume that means 34mm. The top cap bolt fits both legs, and the length, & ODs are the same, so I couldn't figure out the different hydraulics. When I look in the bottom of the 2 legs, it looks pretty obvious that someone bored one of the legs to accept the larger diameter damper piston. The one with the larger I.D. at the bottom shows pretty obvious tool marks. So, I disassembled the extended tubes and found that they also had the larger diameter hydraulics in both of them, but the O.D. of the legs is the same as the others, 34mm. Both of them also appear to have been bored from the bottom up to the lower bushing. So, I have 2 sets of the larger dampner assemblies, and one of the smaller. Was this a common thing to do back in the day? i.e. bore the smaller tubes to accept the larger piston & associated parts? I can look at the ends of the tubes side by side and clearly see that the metal is thinner on 3 of the tubes. It seems like my simplest way out is to take my 1 fork tube that still has the smaller bottom hole and have it bored to match the other one. That's simple enough, but my question is: how do I know that the metal at the bottom of the tube is strong enough? I guess it was apparently strong enough on the extended tubes, and one of the stock tubes that were bored. What would my other options be?
 
All of my fork pieces look exactly like yours. It's just that the parts that go in the lower end with the piston and circlip are too large a diameter to fit into the bottom of the tube. I suppose that I have a weird problem.
 
Can you post pic’s of what you have? One of the members will recognize what you have.
 
Here are some pics. These 2 fork tubes are identical except for the inside diameter from the bottom end up to the internal bushing. The one with the larger hole has tool marks that make it appear that it might have been bored to size. The picture of the 2 fork pistons shows the 2 different sizes. The smaller is 1.022 inches, the larger is 1.099 inches. The 3rd pic just shows the other pieces that go into the cavity at the bottom of the fork tube. I have 3 full sets of the larger diameter components, but only 1 partial set of the smaller diameter components. It seems to me that both legs should have the same pieces, but I'm no expert. It would be easy enough to bore the leg with the smaller diameter to match the other one. My only concern would be strength of the thinner metal. Just for info, the extended 34mm legs that I removed also had the larger diameter hole at the bottom, for the larger diameter pieces. IMG_2687.JPGIMG_2688.JPGIMG_2689.JPG
 
Need pics of the fork legs. XS2 legs are 1 year only. Both right and left are different from any other year.
 
Aren't the left and right identical on a 72 though???
Nope. Totally different. The internals are the same, the legs themselves are different. 72 legs are 1 year only same with 73. 74-75 I think are the same. 76 different again.
 
72 legs are 1 year only same with 73.
Greg, I thought the ‘72-73 are the same. Inner tubes and internals, same part #’s. ‘74-75 tubes were also interchangeable with the TX500 according to the parts #’s, however not the internals. Maybe someone with parts on the bench could get a measurement for the pistons to compare to the ones tmikeyb has.
 
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This is from a XS2. 72 and 73 are the same, larger bore. 74,75 are the same, smaller bore.
1712182984611.png
 
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