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Originally posted by hampshirehog
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they look like these.........
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that is an option. the pistons are wierd, they have some kind of material inside the pistons, almost like brake pad material.
they look like these.........
1978 GS1085.
Just remember, an opinion without 3.14 is just an onion! -
I've not seen that before.
Is the material proud of the steel piston like in the eBay image? Is it possible that it is compressing during application and then expanding upon release so while the piston retracts the insert material is taking up the rollback amount. That would still not explain why there is pressure in the hydraulic side that is relieved during bleeder opening.Comment
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yeah the material is about 2mm proud of the piston itself. i dont really think this material would compress otherwise this kind of problem could happen from the factory on new bikes. they are genuine Kawasaki pistons.
i will investigate more tomorrow1978 GS1085.
Just remember, an opinion without 3.14 is just an onion!Comment
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I may be wrong here, but I think that material inside the piston takes the place of and does the job of the old anti rattle springs and plates.
I agree though, I dont see it causing a problem.
Maybe a stupid question, but is your disc running true, exactly in the middle of your caliper carrier, not slightly off to one side maybe?Comment
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the disc is dead in the middle of the caliper and is 100% running trueOriginally posted by Flyboy View Post1978 GS1085.
Just remember, an opinion without 3.14 is just an onion!Comment
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ok, just tested the caliper on an old RF900 disc, 5mm thick but it measures 4.7mm due to wear. the caliper works fine now, releases the disc when lever is pulled and released, so something has to be shaved. gonna try the "material off the pistons first see how hard that is, if not then a trip out to get the pads skimmed1978 GS1085.
Just remember, an opinion without 3.14 is just an onion!Comment
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Crazy to skim 4 pistons per caliper. I'd deal with the pads.Ed
To measure is to know.
Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182
Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846
Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf
KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-ResurrectionComment
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I would deal with the pads also rather then the complexity of those pistons.
But more of an issue with me is do you still have residual pressure in the hydraulics with the thinner disc relieved by opening the bleeder?Comment
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You sure the pistons are all the way back in to the cailper body. Maybe cracking the bleeder as suggested would give you that little bit more you need???MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550
NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.
I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.Comment
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SUCCESS......... i have shaved off 1/2 mm off the "material" on each of the pistons. it is almost like hard wood sort of composition and was easy to file down.
All back together again and bled through and it works perfect.
Jack, i think the residual pressure was due to the pistons being pushed out but not quite reaching the roll back point so they were being pushed out but didnt have the rollback action from the seals, so they just sat there until pressure was released,(by the bleeder).
anyways, all sorted now, many thanks for all your help and ideas everyone.....1978 GS1085.
Just remember, an opinion without 3.14 is just an onion!Comment
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