Chinese master cylinder for $13.30 AU easy replacement. A guy from another site found these, a few variations on fitting them. You just need a 6mm to 8mm barb hose reducer, a new hose, a new brake pedal bolt with a recessed head do this with a Burr grinder electric drill or a lathe. I ended up moving the lock nut to the rear of the bolt so I could fit an aftermarket boot $4.00 Au.

I will be forever grateful to Martin for telling me about this master cylinder.  For the first time since I took it under my wing, my RT has a firm brake pedal.

It's amazing how easy it was to install this $7 master cylinder and how the results were so much better than what I got for the $200 I wasted on the OEM master cylinder.



It didn't take much longer than a rebuild to modify and install this master cylinder.  With the black paint it looks OEM.

One note: With the reservoir hose entering at the bottom of the master cylinder, some air is going to want to stay in the hose.  To make bleeding faster, I had to "milk" the air bubbles out by squeezing the hose until no more bubbles came up to the reservoir before pumping the pedal to bleed the system.

Could you share where you got the Master cylinder and Boot from Martin?

Source of M/Cyl is Ali heaps of them but you need the one with the slotted mounting holes shop around and you might even find a cheaper one. Look up universal or Honda Or Yamaha I paid $13.33 Au shipped to OZ. I also have one as a spare. https://www.aliexpress.com/item/Audew-Universal-Rear-Motorcycle-Dirt-Pit-Bike-Hydraulic-Master-Oil-Brake-Reservoir-Cylinder-Gold/32601326433.html?
The source of the boots is Glen a really nice helpful guy from Stainless Steel Sleeving Shop 22/193 South pine Rd Brendale Ph O7 3889 6669 boots are $4.00 Au. He also sleeves front M/Cyl's in stainless guaranteed and tested $200.00 Au. Once done replacement rubbers are $10.00 Au. And he will ship. Turn around on M/Cyl sleeving is approx 2 weeks.
He does not like doing rear M/Cyl on Bricks as invariably the plastic fitting that goes to the reservoir breaks and he has to make a new one out of brass with an "O" ring seal. A local brake place in Lawnton made up the brake hose on the spot $60-$70.00 I think. The 6mm- 8mm barb hose reducer I made on my ancient lathe but these can be had on Ebay. If you need any more information just ask.
Regards Martin.

Thanks for that I will have a look. All the best. John.

Glen could also be a source for M/Cyl cup rubbers.

Thanks Martin that is good info for me and many others. BTW welcome to our Knuthaus

The first picture posted is the final version with the larger boot. In order to fit the boot I had to slot the end of the bolt and move the lock nut to the rear. In order to move the locknut to the rear a small amount of metal has to be ground off. The added benefit is that now all of the contact area between the M/Cyl and the brake adjuster bolt is fully covered.
Regards Martin

Is there anyone else not seeing Martin's photos?

By the way Martin +1 on what RickG said, another great example of the value of this forum with members around the world contributing ideas and information.

Cheers

I can't see them

MartinW wrote:The first picture posted is the final version with the larger boot. In order to fit the boot I had to slot the end of the bolt and move the lock nut to the rear. In order to move the locknut to the rear a small amount of metal has to be ground off. The added benefit is that now all of the contact area between the M/Cyl and the brake adjuster bolt is fully covered.
Regards Martin

Hey Martin!

We can't see the pictures.
You have linked them to your Computer Hardisk but you have to upload them.

Maybe this link helps
https://www.k100-forum.com/t998-posting-pictures-and-movies

Cheers

Thanks Laitch and Chocolate I am trying some may say very trying.Now all I have to find how to delete an image

 Now I can see the pictures, thanks.

If you go back in to edit your post, in the edit pane just put your cursor behind the photo you want to delete and backspace it out, then immediately hit the preview button and it will save your change, repeat as necessary. At least that is how I do it.
I need to use the preview button a lot before I send to tidy up my spelling and my tablet's auto correction.
Cheers

Thanks fellas for the welcome glad to contribute, as a new member I might not be able to remove pictures. I  tried your method Gaz and I can't lock the cursor in behind. Maybe one of your nice forum facilitators will clean up my mess otherwise I'll wait until my daughter visits.
Regards Martin.

MartinW wrote:...as a new member I might not be able to remove pictures. Maybe one of your nice forum facilitators will clean up my mess...
Regards Martin.

Done.


PS, just click 'edit', when you see the empty box where the image should be, press 'backspace', repeat until ghost images are toast, then 'send' to save your work. What Gaz said.

Thanks TWB I've tried a couple of times when my daughter visits i''ll get her to have a look.
regards Martin.