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Main Area => General GS500 Discussion => Topic started by: herennow on March 05, 2026, 09:09:41 AM

Title: New brake M/C
Post by: herennow on March 05, 2026, 09:09:41 AM
So my master cylinder window was leaking, I cant find the slightly smaller suzuki window  (the standard 18mm ones do not fit our bikes)

So for 40 bucks from Ali, I bought the whole shebang... Looks like decent quality too surprisingly.

Title: Re: New brake M/C
Post by: herennow on March 27, 2026, 03:06:36 PM
MC looking good, except I came to install it and the thread for the banjo bolt was M10x1.25mm  Rather than M10x1mm they did in Japan.

Now waiting for a banjo bolt to arrive in the post, then  BRRM BRRM, I hope
Title: Re: New brake M/C
Post by: Rallyfan on April 02, 2026, 07:00:30 PM
This is what I suspect:

You bought an M/C that is intended for an offroad quad or ATV.

This means that the M/C has a fitting for an M1X1.25 banjo bolt.

If the existing banjo bolt doesn't fit, does that mean that our bikes use an M1X1.0 banjo bolt?

Could you please elaborate on the thread and size (length) of the banjo bolt you ended up using?

Thanks!
Title: Re: New brake M/C
Post by: herennow on April 04, 2026, 10:07:37 PM
I was surprised, it was a VERY close copy of our AJP master cylinders (they went bankrupt some time back), right down to interchangeability with the original electrical switch and mirrors. Its a copy of the suzuki part.

Overall length of the bolt was 28mm. M10 x 1.5, original one was 1.0

gs1.jpg


This is the problem, they used a really cheap shitty little plastic sightglass held on with a circlip, time and light will kill it.

As they are bankrupt, no more replacements, I will try to get my old one machines to take the new size sight glasses.

mc sight.jpg

Title: Re: New brake M/C
Post by: Rallyfan on April 06, 2026, 10:54:13 PM
SIGHT GLASS TOPIC: Have you tried a 12mm sight glass into your old, authentic master cylinder's reservoir?

I think our OEM sight glasses are 12mm.

Measure yours but I bet I"m right -- and if I am, then the sight glass is easy to find even though it's not 18mm. (12mm is common on dirt bikes and older ATVs; you'll be able to find it locally I bet).

BANJO BOLT TOPIC: So have you been able to buy a banjo bolt that fits both the brake line and the new master cylinder?
Title: Re: New brake M/C
Post by: herennow on April 07, 2026, 10:58:44 PM
Nope, sight glass is 14 mm at the body and around 17.25mm at the crown where the oring sealed. the part that cracked on mine. The dimensions of the banjo bolt given above worked perfectly. Lever is nice and firm.

Reminds me, I must plug in the brake switch wires.went for a test ride without them plugged in DOH!

Also I really gotta change those 23 year old brake hoses!!!!!

gs10.jpg