Author Topic: Help IDing brake master cylinder  (Read 332 times)

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Offline zabzob

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Help IDing brake master cylinder
« on: August 10, 2022, 09:21:49 PM »
My bike was a bit of a frankenstein when I got it, with the quite common Harley rear rim swap, Vetter fairing etc. Way back when I first made it road worthy in 2012, I remember buying a master cylinder rebuild kit, disassembling the crusty old MC, lining up all the parts, and finding that the piston was completely different. Mine was replaced by something with a built in brake light switch, so there is no pressure sensor in the brake line. That is steel braided right down to the caliper. Anyway, it's leaking a bit, and I'd like to get a proper rebuild kit, but I'm having trouble IDing it. Here are some pictures:

https://i.imgur.com/tbC34Ur.jpg
https://i.imgur.com/184d56O.jpg

The stamping on the bottom is a little hard to make out. It's 2 K 2 and then Ø 14, which I'm guessing means 14 mm diameter. I believe the rubber parts from the rebuild kit I bought fit, and I just reused the piston.

Any help would be appreciated. Thanks!
1975 CB750K5

Offline bryanj

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Re: Help IDing brake master cylinder
« Reply #1 on: August 11, 2022, 01:00:47 AM »
Looks like an early gl1000 but i think they are bigger than 14mm dia
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

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Offline zabzob

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Re: Help IDing brake master cylinder
« Reply #2 on: August 11, 2022, 11:22:07 AM »
There are a lot that look similar, but I can't even find pictures of another one with the built in switch. Looking at parts fiches for GL1000 and no joy yet. Somebody must know! I guess I don't really need to know the exact model, just which rebuilt kit to get. This might end up with me disassembling it and buying one that "looks right."
1975 CB750K5

Offline scottly

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Re: Help IDing brake master cylinder
« Reply #3 on: August 11, 2022, 11:29:34 AM »
The K8 750 master was 14mm, and had a built-in switch. The GL had an 11/16" (17.5mm) master.
Don't fix it if it ain't broke!
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Offline zabzob

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Re: Help IDing brake master cylinder
« Reply #4 on: August 11, 2022, 01:41:25 PM »
@scottly that looks like it! Ordering the correct kit now.
1975 CB750K5