Fazer Blue Spot Caliper

So the lever feels too firm or too mushy? Do you know what the diameter of the caliper pistons are? Those are two piston calipers and not 4 correct?
 
Hi Travis
Lever is way too firm, Im presently running a 14mm bore size master cylinder off a Suzuki bandit. The Fazer blue spot is a 2 piston opposed caliper, 2 different size pistons but the average is about 28mm. Had a look on the chart from vintage bikes and the nearest ideal master cylinder bore size would appear to be 11mm.
Cheers Kev
 
You mean vintage brakes? This chart: http://www.vintagebrake.com/mastercylinder.htm

I would imagine that 4 pistons opposed would require the same ratio as 2 pistons opposed. Maybe I’m not thinking about this correctly but I think the stock ratios were closer to 9:1 for single piston calipers and 18:1 for 2 piston opposed calipers for the XS650s. The specs for my 2007 FZ1 say one piston is 27mm and the other is 30.2mm. That averages by area to 28.64mm. It has a 16mm master. Going by that, I have a ratio of about 25.65 to 1. The 16mm master has an area of about 200mm^2 so if wanted to push half as much fluid (since you have one caliper instead of two) you’d want a master with an area of about 100mm^2 (assuming they have the same stroke). So yeah an 11mm master cylinder (95mm^2) is about right.

Are the stock XS650 ratios just way too firm? Or maybe they are that way because the rotors are smaller, wheels larger, and brake pads were crappier back in the day so you need a lower ratio than what people run now on modern sport bikes. Since your rotor is a little bigger than stock (isn’t it?), but you still have a 19” wheel, maybe go with an 11mm or 12mm master. Would suck to get an 11mm master and find it’s too mushy.
 
I'm pretty sure a lot of dirt bikes have 11mm master cylinders.

Try 2003 KX125, 2006 Suzuki RM-Z250, 2008-2010 Yamaha WR250, 2000 VTR 250
 
"For 2 piston opposed calipers, I like ratios in the 27:1 range, feeling some line and caliper flex. For a firmer lever, use 23:1. I think ratios lower than 23:1 produce a lever feel so "wooden" as to have little, if any feel." quote from Vintage Brakes.
Looking at the Vintage Brake chart, my 14mm master cylinder with 4 x 28mm pistons gives a ratio of 16:1 and a 11mm master cylinder would give a ratio close to 26:1, very close to the ideal ratio of 27:1
Hope Ive read this right :confused:
I think the 14mm would work with a twin disc set up, as on your FZ1, giving a ratio of 32:1 tho 16mm is better at 25:1
Got to be worth a shot at a second hand 11mm dirt bike master cylinder off ebay tho :wtf:
 
yeah I think you've got it all figured out. An 11mm or 12mm master cylinder should work well. Buy one on ebay and let us know how it works!
 
Found a nice 11mm front master cylinder from a Triumph Legend TT2000, its a nissin make and has a mirror mount too :thumbsup: cost £15 off ebay
Hopefully get it fitted this weekend & let ya know what its like
 
I was hoping to get it all done over the Christmas break but they sent me the clutch master cylinder by mistake :doh:
So I didn't get the front break master cylinder until after the holidays :banghead:
Hoping it will give a bit more feel to the lever :bike:
 
while we are on the subject, is there any other bikes brake rotors that fit the bolt pattern of the xs?

There is a list of rotors in this message thread at Do The Ton:

http://dotheton.com/index.php?topic=6437.0

It's a list of larger diameter rotors, but the bolt circle and the fit on the XS650 is confirmed. The diameter of the FZR 600 rotor is the same as the XS650 (298mm). If you are making your own bracket, you could go to a larger rotor if you want.

That list was also posted in a message at 650rider. Here's the original message link (according to Google) which doesn't work, but has the message or thread number:

http://www.650rider.com/index.php?name=Forums&file=viewtopic&p=42928

Here's the TinyURL link to the cached page: http://tinyurl.com/y8vdn5d

The message thread at 650rider also had a list of some compatible 298mm rotors. Hope this helps!
 
thanks very much, now time to go bug my ducati friend for a rotor.

edit:

what about the rear rotor - trying to get a matching set :p
 
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If you live in the US you could send the drawings or CAD files to Fabricator Kevin, http://www.fabkevin.com , and he will whip you up a bracket in no time at all. He isn't the cheapest but his work is impeccable and he stands behind is work.
He has made me several items over the years and I can tell you his workmanship is first class and his knowledge and customer service is topped by none.
 
Yeah fabkev doese do some killer work and he is one stand up guy I got to meet him at smokeout 10 in rockingham last year ,great guy in person too:thumbsup:
 
Hi All
Im new to this site but Travis asked if I could post pictures & details of my brake conversion.
The disc is available new from Mikes XS or one of the european outlets such as www.xs650shop.de in Germany & bolts straight on, comes with an aluminium adaptor to offset the disc to the correct position and can be used with the original caliper if you want.
The Fazer Blue spot caliper came from ebay and the mounting adaptor I made.
This was CNC machined and I will post pics of the CNC co-ordinates etc... I have the drawings on Mastercam so can easily post any other dimensions anyone may need, just let me know
Cheers Kev

Dude that looks awesome.
 
Yeah I bet. When I bought my bike it had some issues. One of them being that the front disc brake caliper was locked up. So I just bought a new one. If I had only seen this before hand. I would have so done this mod. Oh well. Good work!
 
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