Found source for discontinued 77-79 front caliper pistons
I have a '78 GS 750 and when I went to rebuild the front calipers found that the pistons are discontinued. Mine were trashed. Only Wemoto (in UK) carried a replacement, was going to be pricey. I did some research and found out that the Yamaha XS series and Honda GL 1000 both used nearly the same size piston along the way. Stock size for the gs750 '77-79 is 41mm tall and 38.10mm OD, The XS/GL replacements I found are either 38.0 or 38.1mm OD, and 41.25 to 41.3 mm tall.
I went with these from HVC cycles in the US, they are stainless, 38.0mm OD and 41.25mm tall http://www.hvccycle.com/brake-caliper-pistons.html $27.75ea P/N HVC200106-5. I did not find the larger diameter 38.10 pistons from other makers until after I placed my order, or I would have gone with them to stay with factory spec. Although these are 0.1 mm under spec, they sealed nicely with new factory seals, function great, and have not leaked.
Here are the sources I found, hopefully this will simplify the search from some others on here. Most of these are stainless, but not all.
These should work for GS 750's from 1977-1979, B, C, E, EC, EN, and N models. This is just my research, so double check your specs and see what will work for you. I am just listing what worked for me, if you choose to go with any of these you assume all of the risk for the change. I only used HVC cycle, and can not vouch for any of the other manufacturers.
I went with these from HVC cycles in the US, they are stainless, 38.0mm OD and 41.25mm tall http://www.hvccycle.com/brake-caliper-pistons.html $27.75ea P/N HVC200106-5. I did not find the larger diameter 38.10 pistons from other makers until after I placed my order, or I would have gone with them to stay with factory spec. Although these are 0.1 mm under spec, they sealed nicely with new factory seals, function great, and have not leaked.
Here are the sources I found, hopefully this will simplify the search from some others on here. Most of these are stainless, but not all.
These should work for GS 750's from 1977-1979, B, C, E, EC, EN, and N models. This is just my research, so double check your specs and see what will work for you. I am just listing what worked for me, if you choose to go with any of these you assume all of the risk for the change. I only used HVC cycle, and can not vouch for any of the other manufacturers.
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