14mm rear master cylinder
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Hi guys I’m looking at upgrading the rear master cylinder to a 14mm what do you guys use or recommend there are the ones from china
@gary76 Before going down that route I'd recondition your stock M/Cyl as well as the rear caliper and possibly upgrade the rear brake hose to an HEL. I'd hesitate doing any "upgrades" until you've got the stock setup as good as it can possibly be.
The Yambits rear master cylinder repair kit is good but I'd go genuine for the rear caliper pistons and seals as the quality of some of those eBay kits can be a bit patchy. I bought an eBay rear caliper rebuild kit once, cleaned the caliper completely including the seal grooves, put it together and bled it and there was a small dribble of brake fluid on the back of the pad on the piston side. Wiped it off and it came back several times, so I cleaned up the (old) genuine piston/seals and put them back in as I wanted to go for a ride that evening and it cured it, no issues for a couple of months whereupon I bought new genuine ones.
When doing the master cylinder, replace the O-ring and circlip where the plastic reservoir elbow fits with genuine and clean behind this as it gets scabby and blocks the tiny hole inside it. Take your time getting the plastic elbow out as it might be stuck in with more corrosion. New reservoir membrane (Yambits) is also a good shout. HEL rear main hose is a good fit but use the original banjo bolts as these have more threads than the HEL ones. The reservoir hoses on DTRs are now getting on for 30 years old so it's a good idea to change this but you can't just use any old length of rubber hose as the fluid seeps through it at a molecular level (looks like condensation when the rest of the bike is bone dry); Tygon 2375 is what road racers use for non-pressurised brake fluid connections:
There's nothing really wrong with the stock rear brake on the DTR but like a lot of things on bikes it's very sensitive to how it's maintained. A lot of people neglect the sliding pins which allow the caliper to float when the brake is applied and the rubbers/pins are well worth buying genuine and keeping well greased. Another thing that used to help me is, when going out for a ride with a freshly lubed chain, try and drag the rear brake fairly regularly for about the first 5 or so miles as chain lube goes everywhere including on the disc rotor face nearest the wheel. Doing this burns it off until the chain has flung off the excess and makes the brake noticeably better for the rest of the ride and it's also worth giving the rotor a wipe off with some brake cleaner when you're back home cleaning the bike and re-lubing the chain etc. with it on the workstand. Take out the pads and give them a blast off with brake cleaner regularly as well.
