Front Brake

Yes, I run an 11mm from an XT/TT225 on one of my bikes and a 1/2" from a 550 Vision on the other. I got both off eBay for around $20. It may take a while to find a nice 11mm one because coming off a dirt bike, many are really trashed, lol. Here's the 11mm on my '78, a little "weathered" but so is the whole rest of the bike, so it fits in well, lol .....

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..... and the 1/2" one on my '83 .....


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The only parts that I needed to replace were the screws for the tops. Both give better brake "feel" and modulation, but the 11mm gives a bit more of it than the 1/2" one. However, this is at the expense of more lever travel, but I've grown used to it.
I've found a lot of MC on ebay that say they're XT225 but they're new parts and I don't think they're OEM so not sure just what they are. While it looks like 11mm is what most on the forum recommend, the parts don't indicate piston size so I don't know what they are.

Also, I'm having trouble finding any with the brake light wire & not sure if I'd be able to connect the stock wiring.

I found this one & it looks like it might work but not sure. Maybe someone can enlighten me?

https://www.ebay.com/itm/4027871485...t15kiqXOu3qUGtnsBGQ16JIy0e|tkp:Bk9SR7TrprbOYg
 
You'll have to ask about bore, cuz a lot of that aftermarket crap just uses a random "too big" bore.
One aftermarket "XT225" MC had a 16mm bore! One listing with the same UPC as yours shows; Piston 9/16(14.3mm) :^(
 
While it looks like 11mm is what most on the forum recommend, the parts don't indicate piston size so I don't know what they are.
Look close at 5twins pics. The bore dia. is cast into the body.


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Yes, the original Yamaha ones are marked. I wouldn't get a Chinese aftermarket one. The Yamaha units are very high quality. Neither of mine required a rebuild kit, only a thorough cleaning. As I mentioned, all I replaced were the top cover screws. It may take some time and searching to find one. The window for checking the fluid level is often trashed. But keep searching, one will pop up eventually. I've scored 3 or 4 over the years, all about $30 or less. They are the Nissin brand and that should be marked as well .....

TTR225MC3.jpg
 
Unless we are talking about a 100% original bike, I would not bother with the stock MC. Like I have mentioned before, on my -74 RD350A, I have a 13 mm Brembo MC, and the RD has the same 2x48 mm caliper as all disc brake XS models up to and including 1976. With a single braided hose, this gives a really good brake feel and power. As the Brembo MC has a microswitch for the brake light, you can remove that monstrous brake light switch and use a single hose. Lighter, neater and more functional IMHO. You may want to retain the short steel line at the caliper though, to avoid fender clearance issues.
Do you have a picture of the Brembo MC
I just need something to start my search for one with
Thanks !!
 
Here are some pics, a bit poorly lit...
In any case, these 13 mm Brembo were used on any SINGLE DISC Ducati from 92-93 onwards. 600 Monster and 600 SS, some 750 SS and 750 Monster.
 

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Yes this procedure is not so easy on the early caliper, you can't retract the pistons with a c-clamp like you can on the late caliper.
Could you elaborate on the procedure for the early calipers? My '75 is giving me fits trying to get that last little bit of air out of the system.
 
Could you elaborate on the procedure for the early calipers? My '75 is giving me fits trying to get that last little bit of air out of the system.
They are harder, haven't done it alot on the early ones but forced caliper pistons back. pumped out, repeated a few times worked for me. been kinda thinking of a great early piston retraction method but haven't found a brilliant solution. :cheers:
Recent work has been drum fronts....
 
PS if you block ONE piston from moving the other has to travel, pump a few times switch the piston you block, repeat.
Just like a late model best to bleed, pump with no or old pads and caliper not mounted. Pay attention to where the cross over passage between the pistons is, orient caliper so any trapped air can go up and out.
 
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:twocents: that whole tie the lever to the handlebar thing is a legend, and is of no particular use.
But what do I know? I've only R&R'd 30 -or 40 front brakes.
I'll go hide now.
I used to say the same. Actually, I believe "bullshit" was how I described it.
Now I'm of the opinion that tying the lever back has (limited) value. Keep in mind this only applies if you can actually pump the lever up and get a good brake, but...
When you squeeze the lever, you build up pressure... 'cause a liquid not compressible. But air is. Tiny air bubbles will get compressed down in size. In most(?) cases, small enough to work their way up the hose to the tiny compensator port in the master. When you finally untie the lever, they should float up through the port and into the reservoir. So yeah, if you've got most of the air out, enough to build up pressure, but still a little spongy until you pump it, go ahead and try. Worth a shot.

But... I've never actually tried it, so take all this with a grain of salt. :rolleyes:
 
I get the same effect; turn bars so MC is up hill, wallk away, then a couple squeeze releases after an hour or three, a few bubbles usually come up. Open the reservoir cover to watch, see for yourself.
Not a bad idea in the spring after a layup either.
 
I used to say the same. Actually, I believe "bullshit" was how I described it.
Now I'm of the opinion that tying the lever back has (limited) value. Keep in mind this only applies if you can actually pump the lever up and get a good brake, but...
When you squeeze the lever, you build up pressure... 'cause a liquid not compressible. But air is. Tiny air bubbles will get compressed down in size. In most(?) cases, small enough to work their way up the hose to the tiny compensator port in the master. When you finally untie the lever, they should float up through the port and into the reservoir. So yeah, if you've got most of the air out, enough to build up pressure, but still a little spongy until you pump it, go ahead and try. Worth a shot.

But... I've never actually tried it, so take all this with a grain of salt. :rolleyes:
I've never gotten most of the air out.
 
Yes, the original Yamaha ones are marked. I wouldn't get a Chinese aftermarket one. The Yamaha units are very high quality. Neither of mine required a rebuild kit, only a thorough cleaning. As I mentioned, all I replaced were the top cover screws. It may take some time and searching to find one. The window for checking the fluid level is often trashed. But keep searching, one will pop up eventually. I've scored 3 or 4 over the years, all about $30 or less. They are the Nissin brand and that should be marked as well .....

View attachment 251023
I feel confident with anything having 'Nissin' stamped on it.
 
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