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How-To add Brembo caliper and a 18" spoked rim

Discussion in 'The Garage' started by Bushyeyed1, Mar 21, 2020.

  1. Bushyeyed1

    Bushyeyed1 Cafe Racer XS650.com Supporter Top Contributor

    9C0B1EBA-D21C-4F38-A0E4-9A6DAAE1087E.jpeg This will just be a thread to show how I was able to change rim size and upgrade the brakes on the front end of my 1980 XS650G. Results may be different for other year/models and different brands of parts used. I will try and include all the research information I was able to find and a list of the parts I purchased to complete the job. The following process is for the Brembo with 40 mm not 65 mm spaced mount holes.

    Here is the list of parts I purchased to complete the job;

    - 40mm Rightside Brembo Caliper #20.5165.68 ( I bought mine used off ebay; you can see the models that have them OEM at the link below.)

    - Brembo brake pads #107.4426.45

    - 320mm Aprilia Mana 850 front right brake disc (See below link #51 for multiple types of 320 mm discs, but also understand there is more available that isn't on the list. Just verify the caliper has an outer diameter of 320 mm an inner Diameter of 64 mm, a disc thickness of about 5 mm, obviously 6 holes sized 8.4 mm and a hole Circumference 80 mm.)

    - Motolanna 10mm spacer and mounting bracket for the 40mm Brembo P4 brake caliper


    - Dorman M8-1.25 x 35mm hex bolts #981-435D or similar type from your hardware store. This will be needed to make up the difference created by the spacer for mounting the disc to the hub; Need 6 bolts for the wheel hub.

    - Hillman M10-1.50 x 30mm Allen bolts #43116 or similar type from your hardware store. This is the correct size to mount the caliper to the bracket and fork. The yamaha stock bolts have different thread pattern and the Brembo bolts were a little too long. You will need 4 of these bolts.

    - Mikesxs spoke kit #19-0067

    - Takasago 18" / WM3 / 2.15" or similar size REAR rim. I opted for a cheaper brand than the excel rim, but it looks quality to me. Also the WM3 type rim matched my actual rear rim style so I would recommend you research this before you purchase a rim. I only saw the gutter style rims on Mikesxs. Also I am not sure if the 2.5" wide rims will fit, because the caliper was close to the spokes on the 2.15” rim. The spoke kit from mikes is for a rear rim to a front hub so make sure your purchase a rear rim.

    Shouldn't have to mention it, but you will need these following parts;

    - A 18" FRONT tire I opted the size 100/90-18 and think it looks good and doesn't throw off the speed-o-meter judging off one of those digital radar speed checkers I drove by on the side of the road.
    - A 18" Tire tube
    - A 18' rim strip
    - Brake fluid
    - wheel bearing/brake grease
    - wheel balancing weights

    These parts may not be needed but I had these fitted before this project.

    - Braided brake line (might as well) you can pick your poison, but I used some chinese brand and I have had them for a while now since before this set up with no issues. I have shorter handle bars so I have a 39 cm for the top line and I can't remember the length for the lower line. I want to say it was 50 cm, but they have plenty of sizes available so just make sure it has a little slack.

    - Master cylinder (why not) most Ducati single disk run a 13mm and if your going to do a dual disk then 16 mm is a good size.

    I was able to true my rim and spokes myself, but if it wasn't so expensive to do in Hawaii ($125) I would have paid someone to do it. Also paying someone to mount tire and balancing tire will save you some headache and keep you from scratching the new rims. If you do spoke your own rim make sure you number all the spokes on both sides. I started from the valve stem hole and number with the rotation direction of the wheel. I kept the spokes for the inside and outside separate and it made it easy knowing which was an odd number spoke or an even number spoke. Also I didn’t take off all the spokes before installing the new ones so I didn’t forget how they were installed. You will need to remove the rotor disc or it will be in the way of getting the spokes on and off.

    Bleeding the brakes was so much easier with a kit I purchased from O'rielly's the brand is Performance Tool #W80625. I will never go back to the old 20 oz plastic coke bottle and tube, but you could probably make something that doesn't create such a mess.

    Also I opted to put a washer between the dust cover and fork leg on the right side to ensure that the spokes didn't get too close to the brake caliper once the nut was torqued down to hold on the wheel.

    The bike rides smoother and is easier to lean into a curb now with the wider 18" tire in the front. Also the brakes perform way better than the stock caliper set up. Feel free to ask me any questions on here so we can share with the rest of the group.

    Attached Files:

    Last edited: Mar 22, 2020
  2. jetmechmarty

    jetmechmarty XS650 Guru Top Contributor

    I’m assuming the increased brake performance will be huge. I’ve collected the caliper and master cylinder for this upgrade.
    gggGary and Bushyeyed1 like this.
  3. Bushyeyed1

    Bushyeyed1 Cafe Racer XS650.com Supporter Top Contributor

    Yes Marty it definitely does work a lot better and I am sure if you end up doing a two caliper and dual disc setup then even better. I don’t feel like my bike goes fast enough to need a dual disc set up, but that’s just my opinion at this moment. I mean don’t get me wrong my bike does the ton and up, but for now the single disc works well for me.
  4. arcticXS

    arcticXS XS650 Guru Top Contributor

    A neat setup for sure! Most use Ducati discs, but that Aprilia disc sure looks nice as well as lightweight.
    I have one question though. Is the swept area of the disc wide enough for the entire brake pad, or is there some overhang?
    gggGary and Bushyeyed1 like this.
  5. Bushyeyed1

    Bushyeyed1 Cafe Racer XS650.com Supporter Top Contributor

    Hard to get a good picture, but in my case the Aprilia Mana 850 disc is a perfect fit. I almost got a Ducati monster disc, but liked the minimalistic look of the Aprilia floating disc. There is so many other after market brands that look good too.

    Attached Files:

    gggGary and arcticXS like this.
  6. arcticXS

    arcticXS XS650 Guru Top Contributor

    Also, you are using an MC from bikes with dual discs. What is the bore? In my experience, a single 4 piston Brembo caliper works best with a 12 or 13 mm bore MC. On my XS with the "65 mm" caliper, I use a Brembo 13 mm MC.
    And on my drilled stock disc RD350 with oem type 2x48 mm piston caliper (same as 72-76 XS), I also use a Brembo 13 mm MC. On both those bikes, the brakes were vastly improved.
    gggGary likes this.
  7. Bushyeyed1

    Bushyeyed1 Cafe Racer XS650.com Supporter Top Contributor

    @articXS the master cylinder I have been using for a while now is a 16 mm piston bore. I can't remember why I went with this diameter, but it has worked better then the stock master cylinder. It is good advice though so that others may get a 13 mm piston bore instead. I can tell you that the brake light switch engages once pressure hits the brake lever with the one I have installed. I don't feel like I have to squeeze too hard if anything it may help with the sudden dive that can be caused by the front brakes.
    Last edited: Mar 22, 2020
    gggGary likes this.
  8. arcticXS

    arcticXS XS650 Guru Top Contributor

    An overly large MC may actually make the brakes more "grabby" and more tricky to modulate. The difference between 13 and 16 mm is actually pretty large.
    Assuming the same lever geometry, a 13 mm MC will give 50% more clamping force at the caliper than a 16 mm, for the same effort. 16 mm MC is commonly used for 2-caliper setups with 4 piston Brembo calipers like yours.
    Bushyeyed1 likes this.
  9. Bushyeyed1

    Bushyeyed1 Cafe Racer XS650.com Supporter Top Contributor

    That’s why I started this thread so everyone who wants to do this modification will have all the information they need.
    gggGary and arcticXS like this.
  10. 650Skull

    650Skull Dinosaur Lives Top Contributor

    Nice thread and write up...........2 words......TECH MENU..............
    gggGary and Bushyeyed1 like this.
  11. arcticXS

    arcticXS XS650 Guru Top Contributor

    I just remembered that braking power is also influenced by wheel size, or more precisely the tyre rolling diameter. With all other things being the same (disc, caliper, pads, brake line and master cylinder), an 18" wheel will give a more efficient brake than a 19" or 21" wheel. It just comes from the leverage ratio between disc and wheel.
    gggGary likes this.
  12. jetmechmarty

    jetmechmarty XS650 Guru Top Contributor

    I have the Brembo caliper and master cylinder from my wrecked V11 EV. Moto Guzzi matched them. Only the line will require replacement.
    gggGary likes this.
  13. Bushyeyed1

    Bushyeyed1 Cafe Racer XS650.com Supporter Top Contributor

    I have been patiently waiting for my new master cylinder to come in. It will definitely look better and the master cylinder bore size is 12.7 mm.
    arcticXS and gggGary like this.
  14. jetmechmarty

    jetmechmarty XS650 Guru Top Contributor

    Pandemonium also has the caliper adapter. They has used Brembo calipers as well.
    gggGary likes this.
  15. Bushyeyed1

    Bushyeyed1 Cafe Racer XS650.com Supporter Top Contributor

    gggGary likes this.
  16. SEd27

    SEd27 XS650 Enthusiast


    This is a great thread. I’m currently in the process of the same Motolanna/ Bembo upgrade, except with a MikesXS / XS650 Direct 19” front wheel.

    My disc of choice was an aftermarket Arashi for a SRX 400.


    Did you have to file the back of the caliper for spoke clearance (I did)?

    The following rebuild write up on the Brembo 40mm units was also helpful.

  17. Bushyeyed1

    Bushyeyed1 Cafe Racer XS650.com Supporter Top Contributor

    @SEd27 I did not have to file the caliper because I installed a washer between the fork leg and dust cap. You can see it in a picture I took in the first thread. I do have a 18" spoked rim in the front so maybe the spokes have a little more clearance; not sure. Oh and that is a nice looking disc.
    Mailman and gggGary like this.
  18. SEd27

    SEd27 XS650 Enthusiast

    Thanks. I will look at adding a spacer as well
    gggGary and Bushyeyed1 like this.
  19. jetmechmarty

    jetmechmarty XS650 Guru Top Contributor

    So, the Motolanna kit is for 40 mm caliper mount spacing and the Pandemonium kit is for 65 mm caliper mount spacing?
    Bushyeyed1 and Team Junk like this.
  20. timbeck

    timbeck XS650 Junkie XS650.com Supporter


    jetmechmarty and Bushyeyed1 like this.

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