1979 sf special front brake m/c size

gray am I

XS650 Enthusiast
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mechanic doing some work on my bike commented that he thought that the nissin 11/16 front master on my special was too large and he thought it should be a smaller size is this the original sizing for this Australian twin disc special or is he right?
 
11/16 bore is 17.46 mm. I think that's too big. The stock 14 mm bore as used on the single caliper brakes here in the US work ok for a single but an 11 of 12 mm works much better. They do work well with a dual disc set up.
I have two bikes set up with dual disc. The 75 uses 5 mm thick slotted rotors. The 81 uses 7 mm slotted rotors.
The calipers and rotors are stock Yamaha parts.
Upgrading the brake lines from the stock rubber to braided stainless steel lines is well worth the cost. Rubber has a lot of stretch to them. The braided lines don't. All your lever effort goes to operate the brakes instead of losing part to swelling the rubber lines.
Leo
 
mechanic doing some work on my bike commented that he thought that the nissin 11/16 front master on my special was too large and he thought it should be a smaller size is this the original sizing for this Australian twin disc special or is he right?
I think both of those statements are true.
Was running this
madness front brake first version.jpg
with the stock US spec single disk 14mm MC and it worked well.

Changed to this set up
brake detail.jpg
losing about 8 pounds! of unsprung rotating mass. Still using the 14mm MC. :thumbsup:
Aftermarket 14mm MC's are dime a dozen and with SS lines should be a very noticeable and pleasant improvement in brake feel and control.
 
I think both of those statements are true.
Was running this
View attachment 137344
with the stock US spec single disk 14mm MC and it worked well.

Changed to this set up
View attachment 137343
losing about 8 pounds! of unsprung rotating mass. Still using the 14mm MC. :thumbsup:
Aftermarket 14mm MC's are dime a dozen and with SS lines should be a very noticeable and pleasant improvement in brake feel and control.
What rotors are those? Very nicely done!
 
What rotors are those? Very nicely done!
Later Yamaha sport bike FZ600 to 1000cc 89-93 something like that. Flea bay, they are either the right ones or a totally different design. You need to use 6 to 7mm spacers tween the flange and rotor to line up with the stock caliper.
DSCN0482.JPG DSCN0479.JPG brake rotors spacer poa 013.JPG
 
This master cylinder was on the bike when I purchased it. xs 650 master cylinders seem to come in all different sizes so I assumed this larger diameter was an original fitment for the Australian twin disc models. Can anyone tell me what the correct original diameter for my 79 special should be?
 
thanks my 79 is a nissin 11/16 (17.46). I thought it was the original so some time back I had it resleeved in stainless as I couldn't find another,
 
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