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    Bleeding the brakes.

    The brakes feel spongy , sticky or just not as strong? It's time to bleed the brakes.

    Yes it's possible that you need to bleed them after the first ride!


    The following was written by Mark Kitaoka (a Luna Cycle customer, Sur-Ron owner, photographer and blogger) and he accepted that we use his article on our forum Knowledge base.

    You can checkout his fantastic blog and work here: http://www.markkitaoka.com/latest-ne...by-luna-cycle/
    He has plenty of ideas, tips and tricks for the Sur-Ron and some nice stories to tell.


    I belong to a small Sur-Ron Light Bee group and wrote up how to bleed the brake system on the bike. I debated over posting it here, but decided that some may want to know. So here you go!

    Bleeding Sur-Ron Brakes
    • Mark's GF: “Babe I made you some lunch…wait what are you doing? I thought you JUST worked on your brakes!”
    • Mark: “Yeah I did but that guy Matt wanted to know how to do it so I told him I’d post a how to.”
    • Mark's GF: “You must really like this guy!”
    • Mark: “He’s the one with that adorable little daughter.”
    • Mark's GF: “Ah no wonder you’re doing this. OK lunch is ready.”

    First and foremost I HATE when people try to tell me how to do something. Or worse they feel THEIR WAY is the BEST WAY. So I’m posting this to tell you how I do it. How you do it is up to you.

    If you don’t want to do a full bleed, a simple way I maintain my brakes is to just remove the top mushroom screw, insert the plastic syringe into the hole, fill it about halfway with oil and pump the lever. As time goes on the bubbles move upward toward the brake lever and they’re easy to remove with this method. Up to you. Just be sure to adjust your brake lever so that it’s level to the ground and you’ve turned your handlebars so that the respective lever is higher than the lowest part of the brake line.

    Here is the kit I purchased to work on my MTB and Sur Ron brakes:
    Support notes: If the link is no longer available, just search for "universal mineral oil brake bleeding kit".


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    The Locktite isn’t included nor are the brake olives in the upper right hand corner of the shot.

    I always remove the brake pads from the calipers no matter what I’m working on. Dirt bikes, MTB bikes, on road race bikes. I never want any contamination of the fluids to hit the pads or rotors.
    • Step one is to remove calipers from the fork leg and the rear swing arm. I think it’s a 5mm hex but I can’t remember. Easy.
    • Remove the pads from the calipers. Just use a number 15 Torx and unscrew the pin that holds the pads in the caliper. You’ll need to remove the small retaining safety clip on the end of that threaded pin. BE SURE TO INSERT A BRAKE PAD BLOCK INTO THE CALIPER!

    Unlike motorcycle master cylinders the Sur Ron’s are tiny. Hence they use tiny screws too. On motorcycles I would draw the fluid from the top down. With the Sur Ron I push fluid from the bottom up. I like it better since it moves air bubbles up rather than down.

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    Here I have installed the bleeding nipple before attaching the hose on the front caliper. Where the bleed nipple is is where the tiny Torx 15 bolt normally resides on both calipers. Besides the pin that holds in the brake pads, it’s the only other Torx head bolt.

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    The threaded syringe and hose as I push fluid up to the brake lever. You can see the location of the teeny Torx 15 screw in the calipers here. It’s where I’ve inserted a bleed nipple, directly opposite of the brake line. You can also see that I’ve inserted a brake pad block into the caliper. It’s the red plastic thing.
    • Pick which brake you want to bleed first. Loosen the brake handlebar 5mm bolt and adjust the lever so that it is level with the ground. You should turn the handlebar to the right all the way if you’re working on the left brake. This will allow the brake line to be as high as possible.
    • In this case go to the back caliper and remove the teeny tiny 15 Torx screw which is the ‘bleed’ screw. Don’t worry if mineral oil starts to leak out. Place one of the threaded hose fittings (the one that fits from the kit I use) into the bleed port on the caliper. Attach the hose. Fill the syringe ¾ of the way with mineral oil and attach it to the fitting.
    • Undo the very small mushroom screw and place an empty syringe into the opening. Be careful to notice if the rubber washer is on the screw or left in the threaded hole. Place the non-threaded syringe into the hole.


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    The larger mushroom head screw is the one you remove to add or remove the oil.
    • Go back to the caliper and start compressing the syringe with the ¾ amount of oil. You will see the syringe on the brake handle start to fill and you will see bubbles too. That’s what causes the mushy feeling when you brake. Stop when you have about ¼ inch of mineral oil left in the caliper syringe.


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    The brake lever filling with oil as I push it from the caliper. This is the non threaded syringe from the kit I use.
    • Then pull the oil back through the line by drawing the caliper syringe back until the one on the brake handle is about 4mm from the bottom. Reverse the procedure and again push the mineral oil back into the line.
    • Doing this removes more bubbles than just doing it once. Once that’s done place the pushing rod slightly into the top of the brake lever syringe. Not too much, it’s just to keep the fluid from flowing out of the caliper fitting once you remove that syringe.
    • Remove the syringe, nipple and replace the bleed bolt.
    • Use the caliper syringe to suck out the majority of fluid out of the brake handle syringe after removing its plunger.
    • Replace the mushroom bolt, do NOT over tighten.
    • Wipe down everything with a rag and alcohol. (Not the kind you drink) The caliper, the brake handle, anything that has oil on it.
    • Remove the brake pad block and reinstall the brake pads and be sure to align the spreading spring properly as to NOT be in front of the brake pads.
    • Reinstall the caliper. I use Blue Loctite on the threads.
    • Remove the mushroom screw and reinsert the plastic syringe without its plunger.
    • Fill it halfway with mineral oil.
    • Pump the handle. This is to remove any remaining bubbles. If some remain, you will see them rise up from the brake handle. Do this for about three minutes.
    • Reinstall the mushroom screw and adjust your brake lever to where you like the angle.


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    This is the distance from the handlebar grip where I want my brakes to start having hard resistance. I want NO mushy feeling when I get to this point. Bleeding the air out of the lines resolves this for me. In case you’re wondering I safety wire my grips. Old habits die hard. And I’ve switched to Scott grips, I loved them on my motocross bikes.


    The brake levers are also adjustable for reach, although it may not be readily apparent. Using a hex wrench you can adjust the reach to be further or closer to the handlebar with this small screw:Click image for larger version  Name:	8.jpg Views:	1 Size:	123.4 KB ID:	71608

    Mark, thank you so much for your contribution - The Luna CS crew
    Last edited by Sebz; 12-11-2018, 04:47 PM.
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