Twinpot Brake Upgrade on GS550E - GS750C - GS1000C

[salty_monk]

So... bought some parts with this in mind a year or so back & when TKent approached me with a suitable test bike I sent them to him to bolt up...

This uses a 310mm Honda Blackbird Rotor along with a single bracket & spacer kit.

The holes in the rotor are the correct PCD (bolt circle) so only need enlarging to 8mm.

Caveat - The rotors are quite rare - I paid $150 for a good set (obviously you only need one).

I have 1 rotor here on the shelf - first come first served at $75 plus shipping.

This mod will fit any of the single rotor brake models that come stock with a 290mm rotor I believe (apart from L, GL, or T variants).

For the GS450 Twins - This same mod can be done but with the CBR F3/F4 295mm rotor (these are more common).

This mod uses the same Kawasaki Twinpot caliper as used in the other upgrades & the same brackets (but only one side obviously!).



Price on the brackets - $47 shipped.

As usual - Stock bolts with blue loctite.
You'll need to source 1 x M10 bolt & nut for the third hole (fine thread preferred but not essential).
Stock line will work.
Stock Master will work.
Speedo Drive dust shield may need trimming by 4mm.

[posplayr]

Clean looking mod

[tkent02]

After riding a week, a few hundred miles…

Much much better than the original single front brake, but not quite as good as the twinpot Kaw setup on dual brake bikes. I would say it's about the same as the best dual brake bike with stock Suzuki brakes, and better than most of them. One or two fingers except for the absolute max effort braking riding two up takes three. I would prefer to have it a little stronger, so two fingers is all I would ever need, like the newer bikes. It does seem to be getting stronger as the pads bed in more, but it's not quite there.
I may try a smaller diameter master cylinder, could try better pads too. These are GG pads, but inexpensive ones. Not sure yet. Maybe just need stronger fingers.

On a 1000 I'd want to go dual brakes, on a 750 maybe, but on a 550 it seems fine to me, or just almost fine. If it were just a hair stronger it would be fine.

Overall I like it, it's a lot lighter than the dual brakes, or the original single brake. Don't have to buy different forks, just one disc, one caliper, one set of pads, one line.
It's that much easier and quicker to install.

[gsgeezer]

I bet you're spoiled, now!

[tkent02]

I noticed the calipers are not located exactly right, a few mm of the pad is hanging off the side of the disc. A slightly larger disc would work better, I think 320mm instead of 310 would be perfect, but it might be a hair too big, might need to be turned down a tad. I don't know what discs are available in the correct offset.
I moved the master cylinder in on the bars about an inch, so now my finger hits the lever farther out from the fulcrum. Increased the braking for a given finger pressure quite a bit.
It's also getting stronger as the pads bed in.
I think a better design MC or even just a smaller bore MC would have it working very well.

Yeah, I'm spoiled.

[hotrodalex]

I've finally collected all the parts to do this upgrade and finished other more pressing projects, so hopefully next weekend I'll knock it out!

[hotrodalex]

I did indeed get it done that weekend, just haven't gotten around to posting about it.

- CBR1100XX Blackbird rotor from ebay
- front left caliper from a 2000 Kawasaki Concours ZG1000A from ebay, practically new pads included
- SS lines from Slingshot Cycles (http://www.slingshotcycles.com/GS550_c_95.html)
- Speed bleeder from Slingshot (SB7100)
- Stock master cylinder

And while I was at it, I replaced the wheel bearings too. Bike stops much better, although the MC seems to be on the small side. Lever travel is fairly long, but easy effort.

[salty_monk]

Just sent another single bracket set out yesterday... Looks like this variant is working well with the back corner of pad chamfered (to stop it building an edge).

[malanosa]

I'm interest in doing this upgrade on my '80 550E, but have a few questions.

Is there a consensus on whether a 310 mm or 320 mm rotor is a better fit?

I know this information is somewhere on the forum, but would someone kindly post here what other calipers would work, besides the 2000 Kawasaki Concours calipers that hotrodalex used?

Is anyone happy with their master cylinder after doing this? Tkent02 says he would try a smaller one, while hotrodalex says stock might be too small.

Thanks for any help you can provide!

[salty_monk]

That is a Blackbird rotor. So far I am yet to find a 320mm that would work but it would be better as with this you need to file a chamfer onto the top corner of the pad so it doesn't wear to an edge (slight overhang).

You can get the brackets from me.

Yes that is the only caliper that works with the brackets.

[salty_monk]

From member Jabcb's research this should work:

I found MetalGear’s eBay store: https://www.ebay.com.au/sch/mgear2003/m.html

The 88-97 Honda NTV650 rotor: http://www.ebay.com.au/itm/MetalGear...-/162121183600
OD: 320mm
ID: 62mm
bolt circle: 78mm with 6 holes
bolt hole: 8.5mm
offset: 22mm

Doesn't look like it will need the rear hub spacer. The rotor won't be quite central in the caliper because the offset is slightly off but not enough that it will cause a problem (you get a similar mismatch when using the GS550 rotor on GS1000E GS1100E etc forks & plenty have run that for many miles).

[malanosa]

Thank you!

So it sounds like the best fitment would be the 320 mm rotor from the 88-97 Honda NTV650 and the caliper from a 2000 Kawasaki Convours ZG1000A.

Maybe the rotor could even be modified with light grinding or a small spacer to get it perfectly centered in the calipers?

[limeex2]

Are there different calipers that will fit GS wheels? Calipers that squeeze from both sides would be superior. Probably would have reconfigure everything I suppose. Who makes a smaller 1/2 bore master cylinder? Most have 5/8 bores. I believe EX500's use them

[jabcb]

I’m not a Honda expert. Honda’s designations for the NT650 & NTV650 are confusing.


EBC lists disc for:
Honda NT 650 J/K/L (Bros) 1988-1992 as MD1124LS which is 320mm
Honda NT 650 V2/V3/V4/V5 Deauville as MD1008 which is 296mm
Honda NT 650 VW/VX/VY/V1 as MD1008 which is 296mm
Honda NTV 650 J/K/L/M/P/S/T/V 1988-1997 as MD1021LS which is 316mm

https://ebcbrakesdirect.com/motorcycle/honda/nt-650-j-k-l-bros/1988-1992/36837

https://ebcbrakesdirect.com/motorcycle/honda/nt-650-v2-v3-v4-v5-deauville-note--linked-brake-system.-fit-all-three-sets-at-pad-change/2002-2005/36839

https://ebcbrakesdirect.com/motorcycle/honda/nt-650-vw-vx-vy-v1-deauville/1998-2001/36838

https://ebcbrakesdirect.com/motorcycle/honda/ntv-650-j-k-l-m-p-s-t-v/1988-1997/36840

I have an EBC catalog spreadsheet from 2008.
It lists the MD1124LS for models:
NT 400 Bros (NC25)
NT 650 J/K/L (Bros)


Also have an EBC catalog pdf from 2009.
It lists the Honda part numbers corresponding to the MD1124 as:
45120-MN8-000
45120-MN8-910


My local Honda dealer’s online parts manual does not list these two #s as valid.


cmsnl.com lists the two #s as valid.
The NT400 Bros 1988-1990 Japan uses 45120-MN8-000 or 45120-MN8-910
The NT650 Bros 1988-1990 Japan uses 45120-MN8-000 or 45120-MN8-910


From what I’ve found so far.
The Honda NT650 Hawk sold in the US uses a different disc.
I didn’t find any used NT400 Bros or NT650 Bros front discs on worldwide eBay.
Looks like the MetalGear 21-079-GL & EBC MD1124LS will both work.

[salty_monk]

Not much room for opposed piston Calipers... Twinpot sliding pin is about as good as it gets with any kind of safety margin