Honda CBR 250 Forum banner

21 - 33 of 33 Posts

·
Super Moderator
Joined
·
6,931 Posts
The RH lower fork case is the same for both ABS and Non-ABS bikes, however the caliper mounting brackets are different... did the ABS caliper that you ordered off of e-bay include the bracket?
 

·
Registered
Joined
·
28 Posts
Typically, I think modulation is handled best via pressure, not distance, so that would be my main concern that you are headed down the wrong path.

However, I know that what works for me, may not be the best for you, and I don't think there is anything dangerous or inherently bad about what you want to do.

Another issue is hooking a single MC up to 2 inputs on the caliper, if, indeed, the center piston is controlled independently of the other two. You'll need a Y-connector of some sort.
 

·
Registered
Joined
·
1,096 Posts
Thanks for the feedback I really do appreciate it all. I am not so set in my ways that I HAVE to do this or that and am one of these people that post up looking only for reinforcement of my sometimes whimsical mod choices. I really do enjoy brainstorming especially when those few folks that actually know what they're talking about chime in; it makes the world go round. Plus I know that I'm new here and you may assume that this is my first bike and there's no way to confirm that I actually know what I'm doing.

From what I can tell the outside two pistons (27 x 35) are independently controlled by the front master cylinder. The center piston (22 x 27) is controlled by the rear MC. So based on Soul Searcher's specs the increase in fluid displacement is ~33% (lemmy99 got it!). In my experience increasing fluid requirements on a same size MC piston softens the lever. And this is where I have an issue with the current setup; it's the lever feel and travel. Nothing more.

Also it seems that folks are jumping to conclusions and making assumptions that I want more overall braking power. This is not the case. As many have stated the brakes are "just fine" and can no doubt lock up the brakes at will. What I do not like is the feel and lack of, to me, modulation. I would like more bite and for that a sintered pad is the answer. The SS lines are of course going to provide consistency and by reducing expansion and thus sponginess but with the MC/piston ratio the way that it is I can't see how an SS line would have much effect on the lever feel.

A side benefit to the ABS caliper is the larger pad. An even smaller benefit is the increased surface are for more heat dispersion which of course has a downside of more weight.

But back to my goal if someone has a suggestion on how to soften the lever and improve modulation without changing out the caliper or master cylinder than please let me know. Ideally I would like to go with a 4-piston caliper but that would almost certainly require a new, larger, MC. So to me, for now, the triple piston caliper that is already molded to (hopefully at least as I haven't checked) mount to the fork tubes of the CBR appears to be an ideal option.

Because ss lines have a smaller diameter .... Hence you have mor feel & don't swell under load like the stock lines.
 

·
Registered
Joined
·
4 Posts
Abs have 2 pistons in front cayse it uses it simultaneously
While if u install it in non abs both pistons presses hard and u're history
To increase braking you can change the brake fluid to DOT4
 

·
Registered
Joined
·
23 Posts
Discussion Starter #25
The RH lower fork case is the same for both ABS and Non-ABS bikes, however the caliper mounting brackets are different... did the ABS caliper that you ordered off of e-bay include the bracket?
Yes it does. That 's a good point to make, thank you. Obviously the rotors are different so I still need to make sure that the offset of the non-ABS rotor and the centerline of the ABS caliper match up. I have swapped out the rotors and calipers on other bikes in this same fashion and had to find other compatible rotors to use because the offset of the original rotor caused the placements to be up against one side of the caliper.

Typically, I think modulation is handled best via pressure, not distance, so that would be my main concern that you are headed down the wrong path.
Can you explain more about the "via pressure, not distance" comment? I'm not sure what you mean? I would think increasing area (through larger and more pistons) would decrease pressure making the lever feel softer (or maybe I have that backwards). What do you mean by distance?

Another issue is hooking a single MC up to 2 inputs on the caliper, if, indeed, the center piston is controlled independently of the other two. You'll need a Y-connector of some sort.
The center piston is operated independently and has a completely separate line and bleeder. I thought about a Y-connector or other hard line going from the bleeder of the center piston to the other but I think what I will likely do is just get a second line and a double banjo bolt (like pictured) and use the stock MC. I'm actually hoping for a secondary benefit in that under light lever usages, because of the small center piston size, that the center piston will engage first for light braking. Then under harder braking the outer pistons will engage and then under even hard braking the opposite pad will engage effectively giving me 3 stages of braking "power". At least that's the theory but I never got my PhD in fluid dynamics.
 

Attachments

·
Registered
Joined
·
28 Posts
Can you explain more about the "via pressure, not distance" comment? I'm not sure what you mean? I would think increasing area (through larger and more pistons) would decrease pressure making the lever feel softer (or maybe I have that backwards). What do you mean by distance?
I mean the feel, and how your brain interprets pressure vs distance. People tend to be pretty good and applying varying amounts of pressure and knowing the relationship better. They are less good at judging distance traveled without looking.

For example, if you take a thing that measured how hard you push on something and put pressure on it, then you try to double that pressure, without looking, you'll likely get close. If you did the same thing, but measuring a change in distance, you probably won't be as accurate.

Of course, it's not quite that black and white. I'm sure some people are better at gauging distance. Also the type and range of movement or pressure makes a big difference.

As a rule, tho, I prefer modulation via lever pressure over lever movement.

On the flip side, a lever that moves is more comfortable than having to squeeze the life out in order to stop.
 

·
Registered
Joined
·
3,226 Posts
front brake does have a 'smooth' feel when used for slow speed slowing etc,
but thats not a negative on this motorcycle.. it will 'bite' with very light
pressure tho, just touching it at about heart beat rate, which shows
its potential.. as aufitt points out, she will or can do stoppies..

my emergency response was accelerating thru 2nd when a bloke stepped out
in front from behind a stopped truck, passing it uphill in my home street,
no time for other options etc.. this was a full stoppie, on a steep upsloping
road [my home street, about to prep for a park not far up ahead]..

she has standard brakes yet responded very well to a totally
unrehearsed or even slightly anticipated strong immediate stop..

just saying, standard cbr250r front brake works well..

yet,, rational modifications or even functional variations
are still within honda road motorcycle design intentions
[imo], even if this example seems an unusual and
not particularly well thought out example of it..

bottom line tho must be to encourage the general idea of it..
within the specific context here, of experimenting with
a well designed system that can and has stood
between the stoppie and 'splat'...
 

·
Registered
Joined
·
23 Posts
Discussion Starter #28
I mean the feel, and how your brain interprets pressure vs distance. People tend to be pretty good and applying varying amounts of pressure and knowing the relationship better. They are less good at judging distance traveled without looking.

For example, if you take a thing that measured how hard you push on something and put pressure on it, then you try to double that pressure, without looking, you'll likely get close. If you did the same thing, but measuring a change in distance, you probably won't be as accurate.

Of course, it's not quite that black and white. I'm sure some people are better at gauging distance. Also the type and range of movement or pressure makes a big difference.

As a rule, tho, I prefer modulation via lever pressure over lever movement.
On the flip side, a lever that moves is more comfortable than having to squeeze the life out in order to stop.
Ah, gotcha. Thanks!

yet,, rational modifications or even functional variations
are still within honda road motorcycle design intentions
[imo], even if this example seems an unusual and
not particularly well thought out example of it..
Thanks? My thoughts are that this bike was meant for two specific purposes; 1) a great first bike and 2) to commute on. I think it does both of those spectacularly. I am just trying to make minor modifications here and there to match me as a rider.

I started breaking everything down last night and will test mount today. The center piston is noticeably smaller than the other two so it should engage much earlier (relatively) than the other two. That is yet to be seen. My main concern is that the lever travel will be too much. If I put this caliper on and the MC is not up to par I will not be then swapping the MC. I'm not about to go down that rabbit hole as there is no need for it. The bike stops fine I'm just looking for a little more travel in the lever and ideally better feedback. We shall see soon hopefully. I'll post some pics tonight.
 

·
Registered
Joined
·
23 Posts
Discussion Starter #29
Abs have 2 pistons in front cayse it uses it simultaneously
While if u install it in non abs both pistons presses hard and u're history
To increase braking you can change the brake fluid to DOT4
You should already be using DOT4 fluid. At least my M/C cap, as many modern bikes, already call for DOT4. Maybe in other countries they use DOT 3 because it's cheaper(?).
 

·
Registered
Joined
·
23 Posts
Discussion Starter #30 (Edited)
Challenge #1 overcome easily. As I suspected the bracket mounted up perfectly and there is no noticeable offset problems between the pads and the rotor. I will know that for certain once the new pads I ordered are delivered on Saturday. I'm sure once I do that resistance to swap over the single line I already have to run the outer two pistons will be futile. A double banjo bolt has been ordered and the search is on for a suitable second brake line.

Does anyone know the length of the non-ABS front brake line?

Also, unfortunately, just by eye-balling it, the caliper mount points to the bracket is different which means I will not be able to transfer the ABS caliper to the non-ABS bracket. I will likely trim the ABS bracket down since the sensor mount won't be needed and it will save some weight (maybe negligible). Or I might keep it there as those left over threaded holes would be AWESOME for a GoPro camera mount!!!
 

Attachments

·
Super Moderator
Joined
·
6,931 Posts
... Obviously the rotors are different so I still need to make sure that the offset of the non-ABS rotor and the centerline of the ABS caliper match up. I have swapped out the rotors and calipers on other bikes in this same fashion and had to find other compatible rotors to use because the offset of the original rotor caused the placements to be up against one side of the caliper.
Both the ABS and Non-ABS bikes use the same front brake disc/rotor. The difference is that the ABS equipped bikes come with the wheel hub drilled and tapped for mounting the Pulser Ring... so Honda has a different part number for the front wheel on an ABS bike.

... Also, unfortunately, just by eye-balling it, the caliper mount points to the bracket is different which means I will not be able to transfer the ABS caliper to the non-ABS bracket.
But you already knew that the ABS & Non-ABS mounting brackets were different (see post #21).

With the ABS Caliper and ABS mounting bracket, everything... caliper, pads, disc, will line up without issue.

The $64,000 question is whether or not the Non-ABS Master Cylinder will push enough fluid to operate all three pistons before the lever bottoms out against the handle bar.
 

·
Registered
Joined
·
23 Posts
Discussion Starter #32
Both the ABS and Non-ABS bikes use the same front brake disc/rotor. The difference is that the ABS equipped bikes come with the wheel hub drilled and tapped for mounting the Pulser Ring... so Honda has a different part number for the front wheel on an ABS bike.
Ah, good to know, thank you!

But you already knew that the ABS & Non-ABS mounting brackets were different (see post #21).
Yup, definitely knew they had different part numbers but that could be because of several reasons. I knew they were going to be different from the get-go because of the need for the ABS sensor mount. I was hoping that the caliper mount points were the same (which they are). The ABS caliper's mounting holes are a few millimeters apart than those of the two piston caliper[/QUOTE]

The $64,000 question is whether or not the Non-ABS Master Cylinder will push enough fluid to operate all three pistons before the lever bottoms out against the handle bar.
Exactly what I hope to find out! All I need now is a second line of the proper length.
 

·
Registered
Joined
·
2 Posts
Ah, good to know, thank you!



Yup, definitely knew they had different part numbers but that could be because of several reasons. I knew they were going to be different from the get-go because of the need for the ABS sensor mount. I was hoping that the caliper mount points were the same (which they are). The ABS caliper's mounting holes are a few millimeters apart than those of the two piston caliper


Exactly what I hope to find out! All I need now is a second line of the proper length.
[/QUOTE]


Hey mate, looks like an old thread but I was wondering how you went? As I have a 2011 cbr250r front end that I'm retro fitting to a 1979 kawasaki z250a. I was unsure of how to make the abs caliper work, I have the calliper and the two lines that go to a "block" and that is all. Hopefully you are still around and able to help. Cheers.
 
21 - 33 of 33 Posts
Top