FJR brake master cyl worth it?

I have the parts to go to a '93+ front end on my '92, & intend to install a set of FZR1000 4 piston calipers I have lying around. I already bought a new '92 master cylinder, but have not yet installed anything. I bought the new '92 master cyl before I read as many of the FJR master cyl posts as I could 'search,' & now I am thinking of returning the '92 and going with the FJR, but to my reading, I am not entirely sold on the benefits of the FJR. Would those who have experience with a 4piston caliper/FJR installation provide some input?

Some people say, 'the 4 or 6 piston calipers work OK w/the stock master cyl,' while others seem to believe the FJR master cyl provides an additional edge of function. I am aware the FJR lever has multiple positions, but once you set it for the size of your hands, isn't that it? Then I see where Garrett has ongoing problems. Since the stock '92 has ~5/8" bore & is only a two piston design, and the FJR is 4 piston & a smaller bore, I would think the stock '92 pushes plenty of fluid to move the larger swept area of the 4 pistons.

Where exactly does the advantage of the FJR master cyl figure in the design? I am trying to justify the restocking fee but if there isn't a great difference, then I won't bother, and will stay w/my new '92 master cyl. I read many exclamations of "really-great feel now w/R1 calipers/FJR master cyl,' but what can anyone offer to make me return my new '92 master cyl for the FJR? My hand size fits the '92 w/no problems, I don't need the lever to be closer to the grip. Thanks to anyone who comments.

Fire-medic said:

I have the parts to go to a '93+ front end on my '92, & intend to install a set of FZR1000 4 piston calipers I have lying around. I already bought a new '92 master cylinder, but have not yet installed anything. I bought the new '92 master cyl before I read as many of the FJR master cyl posts as I could 'search,' & now I am thinking of returning the '92 and going with the FJR, but to my reading, I am not entirely sold on the benefits of the FJR. Would those who have experience with a 4piston caliper/FJR installation provide some input?

Some people say, 'the 4 or 6 piston calipers work OK w/the stock master cyl,' while others seem to believe the FJR master cyl provides an additional edge of function. I am aware the FJR lever has multiple positions, but once you set it for the size of your hands, isn't that it? Then I see where Garrett has ongoing problems. Since the stock '92 has ~5/8" bore & is only a two piston design, and the FJR is 4 piston & a smaller bore, I would think the stock '92 pushes plenty of fluid to move the larger swept area of the 4 pistons.

Where exactly does the advantage of the FJR master cyl figure in the design? I am trying to justify the restocking fee but if there isn't a great difference, then I won't bother, and will stay w/my new '92 master cyl. I read many exclamations of "really-great feel now w/R1 calipers/FJR master cyl,' but what can anyone offer to make me return my new '92 master cyl for the FJR? My hand size fits the '92 w/no problems, I don't need the lever to be closer to the grip. Thanks to anyone who comments.

Click to expand...

I have my stock master cylinder ('92) with SS lines and 6 piston tokico front calipers. I have no issue with being able to put pressure on the calipers, I can use 1 finger to stop but it's is hard, two fingers are what I use most of the time.

plenty of people aside from me LOVE the fjr upgrade. the 'feel' of the master once it does engage i like a lot better than the stock one. i had both on today and remembering the stock one made me put the fjr back on even with its 1/2" of free play or whatever...

Thank-you for the feedback, guys.

A different sized master cylinder piston will alter the lever ratio (how much effort is required to move the caliper pistons) which will change the feel of the lever.

Have a look here for an explanation and how to calculate the 'sweet' spot.

MaxMidnight said:

A different sized master cylinder piston will alter the lever ratio (how much effort is required to move the caliper pistons) which will change the feel of the lever.

Have a look here for an explanation and how to calculate the 'sweet' spot.

Click to expand...

agreed. a 5/8" to 16mm shouldn't be a huge difference though eh? its like 1/8 of a mm.

the fjr has some free play before pressure builds anyways, confirmed by a test with the hole plugged with a bolt.

i'm looking at the chart now. pretty cool. does it matter that we have 2x calipers though? anyone know the stock piston size on the later models? Can someone measure quick?

Thanks, 'MaxMidnight,' I have read the doc & it is helpful. I have also read your UK forum comments & they are informative.

My question is, "what Yamaha master cyl has a 12 mm bore & the hole for the rear view mirror?" The same question for a 1/2" bore, too.

Using the chart from your post, and aiming for something in the 23:1 to 27:1 range, for my 4 piston (32 mm ea.) Tokico FZR1000 calipers, it looks like a 12 mm piston should fall close to the 'sweet spot' at 28.44:1. If I use the '93 VMax 5/8" (anyone correct me if this measurement is wrong) master cyl for the front brake, the ratio becomes a miserable 16.25:1! From the chart doc: "...ratios lower than 23:1 produce a lever feel so "wooden" as to have little, if any feel."

Going to a 1/2" bore would give me 25:39:1 which appears to be very acceptable, according to the chart. So, I assume that the easiest master cyl's. bores to find from Yamaha may be 12 mm, 1/2", 14 mm ('03 FJR 1300), or 5'8" (stock '93 VMax?); '04-05 FJR non-ABS, 15 mm; '04-05 FJR w/ABS, 16 mm (thanks, Mike, for the link below)

http://www.vmaxforum.net/showthread.php?t=2231&highlight=master+cylinder&page=7

Below is a chart using the four pistons measuring 32 mm ea. from my FZR1000 calipers & the ratios by master cyl bore (according to the referenced doc):

12 mm 28.44:1
1/2" 25.39:1
14 mm 20.9:1
15 mm 18.2:1
16 mm 16:1
5/8" 16.25:1

So I need to cross-reference to find out what bike application has the 1/2" bore to put me close to the 'sweet spot,' & still have at least a blank for a mirror stem if not a threaded hole? I think one way to get this info would be to use a rebuild kit cross-reference to find what bike uses a 1/2" bore master brake cyl. Replacing the stock 5/8" bore with the 1/2" bore looks like the best shot.
The only thing I am not sure about is that the chart person references the 'sweet spot' for single piston & for two-piston opposed calipers, but does not specifically state 4 or 6 piston opposed 'sweet spot' values. Anyone have more-specific information on the 4 & 6 pot calipers' 'sweet spot' ratios/ranges?

This is all interesting stuff, and I appreciate the assistance.

Any comments/suggestions?

p.s.: I did send a note to the 'Vintage Brake' person, I will post the response when I get it.

from the link I put in the previous post, to save some mouse clicks:
(courtesy of) [email protected]
This is the info I found when I was researching last year.

Here is some updated info on FJR masters

16mm=0.629"
5/8"=0.625"
14mm=0.551"

Another FYI on FJR bore diameters:

03' thru 05' all have the same bore diameter in the clutch master. 14mm

03' is the ONLY year the FJR had a front brake master with 14mm bore

04'-05' FJR front brake masters are 15mm

04'-05' FJR front brake masters for ABS equipped bikes are 16mm.

you may be better off to pursue the master, then just get bar end mirrors or the like...

gamorg02 said:

you may be better off to pursue the master, then just get bar end mirrors or the like...

Click to expand...

Yeah, of course you are right. I was just wondering about if someone knew the sweet spot ratio for 4-pots & what Yamaha bike had a 1/2" bore for the brake cyl.

It appears that there is a different ratio depending on # of pistons:

single moving piston (the old Honda SOHC original style);
twin moving piston (two same-sided of the caliper pistons pressing against a stationary side of the caliper, like the Honda 600 F2),
single-opposed piston (actually two pistons opposite each other & both move;
twin-opposed piston (two pistons opposite each other & four move);
and triple-opposed pistons (three pistons opposite each other & six move).

If you read to the end of the Vintage Brakes article, he makes some mention of this but is incomplete as to the 4 or 6 piston calipers.

Fire-medic said:

Yeah, of course you are right. I was just wondering about if someone knew the sweet spot ratio for 4-pots & what Yamaha bike had a 1/2" bore for the brake cyl.

It appears that there is a different ratio depending on # of pistons:

single moving piston (the old Honda SOHC original style);
twin moving piston (two same-sided of the caliper pistons pressing against a stationary side of the caliper, like the Honda 600 F2),
single-opposed piston (actually two pistons opposite each other & both move;
twin-opposed piston (two pistons opposite each other & four move);
and triple-opposed pistons (three pistons opposite each other & six move).

If you read to the end of the Vintage Brakes article, he makes some mention of this but is incomplete as to the 4 or 6 piston calipers.

Click to expand...

yea i'm not sure how to calculate the 4 piston opposed all moving type...

I may be overthinking all of this as I just took a look at the master cyl. bore on the FZR1000 (1987) I have from which series the donor calipers came, and the bore is 5/8"! So evidently the ratio with that size is OK as that is the O.E.M. spec. So just by going to HH pads & steel-braided quality lines & keeping the stock VMax master cyl size should be OK. If you want the adjustability of the lever, go w/the FJR.

OK, I heard back from the person who has the chart on his website. My question & then his response:

"So can you provide any information as to the sweet spot for 4 piston(two-opposed) calipers? Thanks."

(His response)
"Typically, they are in the 33-34:1. Most will use a 16mm conventional or a 19mm radial master cylinder. It looks like you are only counting the pistons in one caliper. The numbers in the parentheses are the number of active pistons. (2) means one single-sided caliper w/ 2 pistons. (4) means one opposed piston caliper with 4 pistons. Double the number on the chart for dual calipers." (emphasis mine)

For my 32mm four-piston calipers, of which there are two, & a 5/8" bore for the master cyl:

2(2 X 16.25)=32.5

So it looks like the factory was doing what it should in the first place. Hope this additional info helps.

yea, the fjr at 16mm is about right and really shouldn't act all that different from the 5/8"

just for completeness, b/c the OP wanted insight into the R1/R6 caliper-FJR1300 master setup.

Fire-medic said:

...I read many exclamations of "really-great feel now w/R1 calipers/FJR master cyl,' but what can anyone offer to make me return my new '92 master cyl for the FJR?...

Click to expand...

here mathematically is why the configuration feels "sweet"

1. The R1/R6 caliper has two 30mm pistons and two 27mm pistons.
   • This calculates out to : 2*(pi*(30/2)^2) + 2*(pi*(27/2)^2) = 2558.8272163489 mm^2 of effective area
2. The "sweet spot" ratio is 33-34:1 for a dual caliper setup
   • Let's shoot for 33.5:1
   • Therefore, the single-caliper-"sweet spot" ratio of interest is (33.5/2):1 = 16.75:1
3. So the bore of master cylinder that will supply the sweet-spot ratio has:
   • a cross-sectional area of: 2558.8272163489/16.75 = 152.7658039611 mm^2, and
   • a diameter of: 2*sqrt(152.7658039611/pi) ~= 14mm

Any 14mm master will do, but, like the previous posts and another thread have stated, the 2003 (not '04 or '05) FJR front brake master:

1. has reservoir that resembles stock V-Max,
2. has adjustable-lever capability,
3. has mirror mount like stock V-Max, and
4. most importantly, has a 14mm bore

QUOTE]
I've got 4 pot Nisssen calipers with stock master. The brakes function great. But, there is little travel, so feel is limited.
I noticed Garrett's masters have a better feel and a little more travel than the stockers, after riding his bike. It's an upgrade I plan to do now. The pad movement is very small, pads are already touching the rotors. I believe the FJ's delivers the smoother feel and longer travel because of the smaller bore.
Nothing like trying something before spending the money.I attempt this on most mods I do, if possible.
Steve-o

ninjaneer said:

just for completeness, b/c the OP wanted insight into the R1/R6 caliper-FJR1300 master setup.


here mathematically is why the configuration feels "sweet"

1. The R1/R6 caliper has two 30mm pistons and two 27mm pistons.
   • This calculates out to : 2*(pi*(30/2)^2) + 2*(pi*(27/2)^2) = 2558.8272163489 mm^2 of effective area
2. The "sweet spot" ratio is 33-34:1 for a dual caliper setup
   • Let's shoot for 33.5:1
   • Therefore, the single-caliper-"sweet spot" ratio of interest is (33.5/2):1 = 16.75:1
3. So the bore of master cylinder that will supply the sweet-spot ratio has:
   • a cross-sectional area of: 2558.8272163489/16.75 = 152.7658039611 mm^2, and
   • a diameter of: 2*sqrt(152.7658039611/pi) ~= 14mm

Any 14mm master will do, but, like the previous posts and another thread have stated, the 2003 (not '04 or '05) FJR front brake master:

1. has reservoir that resembles stock V-Max,
2. has adjustable-lever capability,
3. has mirror mount like stock V-Max, and
4. most importantly, has a 14mm bore

Click to expand...

FYI, same master on 01-05 FZ1, may be easier to find on ebay....

https://www.partzilla.com/product/y...?ref=c24bc07766002c06e89c5b799bbbc4e32bb2c8e7

...but, the mirror mount sits back in the way, won't let the bar clamp snug up to the switch gear., which jacks the lever position inboard, not even with the end of the grip.......... I'll probly file mine off.

...plus the FZ1 has the same blue puck brake calipers as the R1, and it has the super-cool looking blue puck 2 piston rear caliper, also...... making the 01-05 FZ1 the one-stop shop.