Rear Master Cylinder Puzzler

arfingdog

XS400 Enthusiast
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Northern Virginia, USA
When I got my bike, a 79 XS400F, the rear master cylinder was in parts in a tub. Inspection showed a leak in the reservoir, which I believe I fixed by "welding" the plastic with a soldering iron. The seals look great. But here's the puzzler: the piston (55mm) seems to be too long for the bore. Am I doing this wrong? In the bore goes the spring (40mm, 12mm fully compressed) big end down, then the cap-like-thing, then the piston with the groove end out to receive the slotted washer and then the snap ring. When I compress all of that fully, the piston groove with the slotted washer is still not far enough down to allow the snap ring go into the groove in the housing. Could I somehow have the wrong piston? Or am I just an idiot? Or perhaps both? Picture attached.
 

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  • Rear MC parts.jpg
    Rear MC parts.jpg
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Ding ding ding ding! I think I have my own answer, and it is B: I am an idiot. The slotted washer and snap ring go around the middle part of the piston, not the end! I'd be happy to have someone confirm and mock me if they wish! ;-)
 
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