Author Topic: Master Cylinder Piston Sizes  (Read 1500 times)

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Offline spiritof67

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Master Cylinder Piston Sizes
« on: August 08, 2013, 06:52:51 PM »
First, does anyone have a spec on what the m/cyl piston sizes are for 1970-74 CB750's?

Second, what standard looking m/cyl is generally used for street use/double front disc setups? I always used my standard m/cyl - but I heard that a similar Kawasaki one was actually a better fit for street use.

Third, will an 11mm piston Magura m/cyl work OK for a street use/double disc setup?

Thanks to all, and bless the anoraks!

Offline scottly

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Re: Master Cylinder Piston Sizes
« Reply #1 on: August 08, 2013, 08:06:02 PM »
The stock MC piston size is 14mm for all year 750s.
The stock MC works well with '76 and earlier 38mm dual calipers, but starts to get a bit of a soft feel with 77/78 42.8mm calipers for some folks.
An 11 mm piston would be too small, unless it had 150% more travel than the stock piston.
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Offline Djfob

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Re: Master Cylinder Piston Sizes
« Reply #2 on: August 08, 2013, 09:12:14 PM »
Piston size is actually stamped underneath m/c
78 CB750k

Offline spiritof67

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Re: Master Cylinder Piston Sizes
« Reply #3 on: August 09, 2013, 01:38:28 PM »
Thank you. Have a nice Magura 11mm m/cyl and no bike to use it on. I used stock m/cyl on many double disc CB750's (we really didn't have any alternative in 1971...) but was unsure re: piston size. It was always my understanding that Z1 Kawas had a 15-16 mm piston m/cyl but I never saw proof of that.