ZTL2 8 Piston brake caliper Master Silynder Problem

Dear Freins..

This is south korea.

I have a xb12scg 2008.

I've recently had accidents twice after replacing spare parts I bought in ztl2 8piston brake caliper from twinmotorcycle in Netherlands .
The reason was because I lost control when I applied the front brake at low speed, toughly rolling front wheel and handlebar
(At high speed, I feel its brake capability is superior to 6 piston and there's no problem.)
The two accidents were all the same outbreak at low speed, losing control with the urgent braking.
At first, I thought it was unavoidable, but I happened to meet the same situation, I came to think it may be a problem from ZTL2 8 piston brake caliper.
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​The model I bought from you is ZTL2 8 piston brake caliper but I omitted 8 piston master cylinder, so I used BREMBO 19*20 item Korean Garage recommended, not using the one twinmotorcycle recommended.

I guess Brembo master cylinder' pressure mayn't match ZTL 8 piston brake caliper's pressure.

Now, after two serious accidents, I'm experiencing tough situations that may stop me riding the bike again, so I have some more questions.

1. Using the spare part twinmotorcycle recommended, can't it brake the bike urgently like Brembo master cylinder? Otherwise, is it just the characteristic of ZTL 8 piston?
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2. If I use LSL, Steering damper, can the handlebar controlling at low speed be better than now?


HD Sporster was my first motorcycle and I brought BUELL from USA in 2008 by myself because I thought I may be more satisfied with it. I'm really into the motorcycle.

There's a limit in Korea in seeking the advice since it's rather rare in Korea. (For reference, Buell registered in Korea is less than 5, and total quantity is just about 20. And mine has even acquired the eco label.

I still want to ride Buell but I have no choice but to give if I cannot solve this problem.

Up to now, I have enjoyed Buell thanks to the advice from Buell forum. And now buell forum is the only alternative, I look forward to freinds advice.

Thank you..


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I have the same bike , with the 8 piston cal, I use the compatible buell master cylinder, and it works Great. That Brembo might be a larger bore I dont know, You might want adj your lever so its not so sensitive for panic braking.
https://www.ebay.com/itm/Buell-8-Pis...lU2TIZ&vxp=mtr

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Thank you for your reply.
Did your bike have any big problems with heavy braking at low speeds?
It would be nice to compare the specifications of ZTL2 Master Master Sylinder and Brembo.
Is there any way to know the ZTL2 master sylinder specification?

The 19mm Brembo is fine for the ZTL2 caliper. I'm with Lunatic though, I believe its a lever problem.

Do you have OEM levers on the bike?

If it's not original, make SURE that when you install the lever it's not depressing the master cylinder piston. It may activate the brake and not release pressure.

Anyone has the diameter for the pistons on the ZTL2?

Brembo M50 4 pot calipers are Ø 30mm and two calipers in a system makes total Ø:240mm where Brembo recommend the 17RCS.

Brembo M4 4 pot calipers are Ø:34mm and two calipers in a system makes total Ø:272mm where Brembo recommend the 19RCS.


I just fitted the Brembo RCS on clutch side and want to do the same for right side MC.
I was first thinking that it has to be the 19RCS 18-20 ratio lever. But Brembo recomends the 17RCS 18-20 ratio up to Ø:258mm total. (max 32mm pistons).

You need a 19mm bore for the ZTL-2. That is what produces the correct amount of pressure to the ZTL-2 caliper.

Lever ratio will only change the levers total throw to whatever you personally prefer.

Do I? What do you base that on? Do you have the 19mm on ZTL setup?

From what I can see in this tread TS say 19x20 may cause abruptly feel. And one post may indicate that the original MC are 12.7mm. When Brembo states that 19mm are for 32mm+ pistons and bigger.

I interpret that as the ZTL's could be a missmatch with 19mm MC. Maybe even 17mm. I would like to know diameter before i come to any conclusion and spend $300+

Guess I just have to use the evening driving up to my calipers and measure it.


I know ratio only change throw. Then it also makes the feel of the lever to be more or less abruptly. And it could be that 19mm 18-20 ratio MC will be to sensitive no matter what ratio you put it in. Then smaler bore would be better?

M/C bore size doesn't just magically produce more or less pressure, sort of. It does, but at a different amount of piston travel. So what you are trying to do it get the amount of M/C piston TRAVEL correct. That will make your lever be in a good spot and the effort required to get it there with your hand what you prefer.

The smaller M/C bore for the ZTL caliper won't have enough piston throw to build enough pressure on the ZTL-2 caliper to even stop the bike with the lever touching the grip. I tried that as an experiment once, and that was the result.

When Buell went to the ZTL-2 caliper, they also went to a 19mm master cylinder. I have a 19mm EBR radial master on both my '08 STT that I upgraded to ZTL-2 and also on my EBR that came stock. They both work very well.

IMO ,20mm would be a good choice if you like a very stiff/short throw lever but NOT smaller than the 19mm that works fine. 18mm will leave you with not enough travel when the brakes get hot.

I know the Brembo M/C is a big expense, so it pays to get the right one! I have an extra stock EBR 19mm radial M/C you can either try it and send back or just buy from me. PM me if you're interested.

Jan-E28: are you running stock levers now?

Thank you for the feedback and offer.

I'm sorry to say that I don't run anything like it today. Not even a Buell :topsy_turvy: Its for a -85 cafe racer build. So its more for show then hard racing. Doubt that I see close to any fade limit. But I do want the best match when I first go for such a expensive system. Whole front will be combo of XB12/1125r parts.
I already did a good deal on a Brembo RCS clutch lever for the wire to hyd conversion and want same lever for right side.


I measured on the caliper now and it's 4x30mm and 4x26mm = 224mm total.
I think the only correct thing would be to ask Brembo what they think. And watch for a used one. And If I have to go for a new one take the one shop recommends so it would be easy for return/swap if it turns out to be wrong.