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Brake disk switch
- ThatGPzGuy
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- More Sparky than Speed Racer
Jim
North GA
2016 Yamaha FJR1300ES
1982 GPz750 R1
1974 Kawasaki H1
1976 Kawasaki KZ400
1979 Yamaha XS650 cafe'
2001 KZ1000P
2001 Yamaha YZ426
1981 Honda XR200 stroked in an '89 CR125 chassis
1965 Mustang
1967 Triumph GT6
1976 Bronco
"If you didn't build it, it's not really yours"
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- Bluemeanie
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1980 KZ650F1, Bought new out the door for $2,162.98!
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- Patton
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Plummen,
It is an issue of the drilled disks being thinner than the solid disks.
Come to find out that the drilled disks wear more rapidly, are thinner and lighter, and should bolt right up if bolt patterns match as the pistons will compensate.
Lots of folks drill holes in the larger single front disc.
1973 Z1
KZ900 LTD
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- Patton
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Plummen,
It is an issue of the drilled disks being thinner than the solid disks.
Come to find out that the drilled disks wear more rapidly, are thinner and lighter, and should bolt right up if bolt patterns match as the pistons will compensate.
And lots of other folks leave their solid undrilled thinner oem dual front discs in stock showroon condition.
Can't prove it either way, but have heard drilled disc performs better in wet condidtions, And also heard whether drilled or not has no significant difference in rate of wear. Perhaps drilled performs cooler which could reduce chance of disc warp.
1973 Z1
KZ900 LTD
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- Patton
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650ed wrote:
In addition to the diameter be sure to check the thickness of the disks. I know some models were different than others, but I don't know the details. Ed
The stock 650 rotors are 7 mm thick and have a 6 mm service limit, the Z1R rotors are 5 mm thick and have a 4.2 mm service limit. The difference in thickness didn´t present any problems when I did the swap though.
FSM for '73-'76 900's and '77-'78 1000's shows oem disc thickness on single front disc models of 6.9-7.1mm with service limit of 6.0mm. And shows '78 D1/Z1R cafe racer with mucho-drilled dual front discs (without specs -- so am guessing same as other dual front disc models).
FSM for dual drilled front discs '79 KZ1000 shows oem drilled disc thickness of 4.9-5.1mm with service limit of 4.5mm for both A3 standard model and D2/Z1R-II cafe racer model).
FSM supp for KZ900LTD (dual front discs) shows standard front disc thickness of 4.9-5.1mm with service limit of 4.5mm.
FSM supp for KZ900LTD shows standard single rear disc thickness of 6.9-7.1mm with service limit of 6.0mm (same as single front disc models).
So it seems all the large fours from '73 through '79 used same thickness on single front disc models (through '78) and same thinner thickness on all dual front disc models (regardless of whether drilled or solid).
Addition -- and also seems the thicker single rear disc thickness remained constant at least through '79 on the large fours.
1973 Z1
KZ900 LTD
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- OnkelB
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... And shows '78 D1/Z1R cafe racer with mucho-drilled dual front discs (without specs -- so am guessing same as other dual front disc models).
[/quote]
I think the service limit is stamped into the Z1R discs I have, I´ll check it tomorrow.
77 KZ 650 B1, 82 GPz 1100 B2.
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- Qdude
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77 KZ 650 C1.
77 KZ 650 C1.
Crashed-Repaired, Pods, Kerker pipe, re-wired core bundle, lamp upgraded, homemade rectifier, solid state regulator , Dyna-s ignition, repainted, slightly modified, year-round commuter
Honda Metro 85 mpg Scooter. Dont laugh I will throw it at you
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- OnkelB
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77 KZ 650 B1, 82 GPz 1100 B2.
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- Qdude
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Much thanks !!
77 KZ 650 C1.
77 KZ 650 C1.
Crashed-Repaired, Pods, Kerker pipe, re-wired core bundle, lamp upgraded, homemade rectifier, solid state regulator , Dyna-s ignition, repainted, slightly modified, year-round commuter
Honda Metro 85 mpg Scooter. Dont laugh I will throw it at you
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