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Sur-Ron mechanical troubleshooting, repairs, adjustments, tips & tricks

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  • Jasdidit
    commented on 's reply
    The brake sensor bolt is an M7 1.0 pitch, if you want to install a bolt to seal it.

  • paxtana
    Aftermarket cranks for the Sur-Ron pedal system

    These cranks are lightweight aluminum with a good offset.
    These will fit but they are about half an inch longer than stock, and you may need to move the kickstand a bit back to clear the cranks.

    Click image for larger version  Name:	image.png Views:	1 Size:	2.12 MB ID:	79095

    The alternative is the Monty crank arm

    (update: both these sources are sold out, this crank may also work)

    Support notes: these links come from our customers, we have no affiliation with these vendors or tested the products.
    Last edited by Sebz; 09-28-2020, 11:45 AM.

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  • paxtana
    Sur-Ron pedal system

    Please read the following if you consider to use the pedal kit.
    Sur-Ron made the pedal kit (unbelievable but yes) and it is only a compliance kit, it is not made by any means to be ridden off-road or made to actually pedal the bike on leg power alone for a long distance (or even short distance). It's only goal is to be able to use your Sur-ron on the street (check with you local DMV and such for compliance), and the other purpose is have something to put your feet on them! Let's face it, they are not high quality, bearings are rough, cranks arms are soft, pedal are basic, it may need to be adjusted after a few rides. If definitely needs to be grease and adjusted and will require some modifications to be used off-road. But you can make them A LOT better with simple modifications (things that Sur-Ron should have done from the start).

    Yes the freewheel can wobble if you pedal along.. but remember you can't really pedal along if you ride past 5mph anyways... If you do not pedal along the freewheel does not wobble at all. If the wobble bothers you, you may fine tune it to get rid of the wobble and it only takes a few minutes to do. Possibly, you will have to fine tune it again every couple rides if you want it to stay perfect. We have a video on how to adjust it. But warning, we will not replace your bike because the freewheel wobbles or because it's a little rough or not on part with the high quality of the bike. IF you wants to have a real pedal bike were you can go 20mph using your leg I highly recommend you to check the Luna X1! But again that being said, the Sur-Ron is a blast and the pedal kit can be very VERY useful and they can be tuned to work a lot better.

    The structure (bottom bracket, mount and spindle) is solid so all you need is better pedals and crank arms to replace these weak links. To make them smoother you can replace the bearing and outside cups and add grease and block the hole in the middle (they use bearings for 3/Piece older style bottom bracket 1.37x24tpi)

    For install video see this video

    How to fix the freewheel/sprocket wobble :

    Also another video on how to adjust the bearing cup to get less spindle wobble :

    This covers full rebuild, reassembly and typical pitfalls / solutions.

    Last edited by Sebz; 01-13-2021, 02:58 PM.

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  • paxtana
    How to change or adjust Sur-Ron primary belt

    The following video explains how to replace the main belt. In the video you see a 4 pin socket to remove the mid axle nut, while it's a good idea to get that tool (hint AliExpress ) you can still remove that nut without. I use a long nose plier and fit the tips into 2 notches not turning but just holding that nut while I turn the axle on the left side of the bike!

    Now if you want to just adjust the tension, you will have to loosen up the motor (no need to remove the bash guard). Watch the same video at the 37 sec mark, up to 1:01 mark. Skip to the 4:44 mark to adjust the tension on the belt and you're done! The belt should be tight, like if you pinch in right down in the middle (between the 2 pulley) you should not get more than1/8" deflection on each side... Too loose and you will strip the teeth eventually, there is a lot of misinformation out there about riding with a loose belt.

    This is another video found on Youtube that you might find helpful, we have no relation to this YT channel, we just though it would be helpful.

    Last edited by Sebz; 01-25-2021, 02:26 PM.

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  • Jasdidit
    How to remove the seat from a Sur-Ron

    These are the tools you will need.
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    Here is my method for popping off the plastic button-head "rivets".
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    Here is a picture of the expanding bit, once the button-head is removed.
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    Here are both parts of the plastic "rivets", only slightly worse for wear.
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    Here is the whole "rivet". You can see how pushing in the pin, expands the inside to hold it in place.
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    There are three on each side and two in the front, see below.

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    Once you get all of those out, the plastic cover just drops down. Then you need to unplug or unbolt the brake light, see above. There are only 4 bolts holding the seat on, but the rear fender bit needs to pushed towards the front of the bike to release it, so the seat can be removed. See below.
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    Don't forget the fender bit when you put it back on! It actually goes on after the seat, but before the installation nuts.

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  • Sebz
    Picking the right front fender for your Sur-ron

    The surRon comes with the RST fork or the DNM/fastace inverted forks.

    For the RST you can use any mountain bike fender you like, under the cross brace or under the front crown

    But if you go for a "under the front crown type" you will need to check if that the cross brace clears the fender when it's fully compressed or you will break it right away,

    Picture below is a Topeak Defender FX fender kit, it clears the cross brace fine and installs in minutes.

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    If you dont like that style you can go for the "under the cross brace type"

    like this one from Mark K, he used a
    Mudhugger Long Front Fender

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    Here is an installation video on modding mx fender for rst

    If you have the inverted type you cannot use a over the tire fender because you don't have a cross -brace, so you will need a fender that is fixed under the lower crown like the Topeak shown. Since you don't have to worry about the cross brace hitting the fender you can use any mini-motocross fender you like but you will likely have to fabricate a mounting plate.

    Picture is a Topeak defender on the RST fork, but can be fitted on the inverted forks.

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    Another option: topeak defender xc1
    DNM Fork users ONLY:

    We have stocked this fender which will work and is a more ideal solution than the topeak defender fork:

    Distributors and builders of high power electric bikes and trail bikes plus parts

    Last edited by paxtana; 07-05-2021, 05:35 PM.

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  • Sebz
    Setting up the rear shock

    The shock (either the DNM or the Fastace) like the front fork has a rebound adjustment and a compression adjustment. these work the same way as the front fork and need proper setup, please read the fork setup guide.

    FYI: DNM takes a Fox sized coil 36mm inner diameter, the FastAce takes a RockShox sized coil 38mm inner diameter.

    What differs from the fork is the spring pre-load adjustment and this is what we will cover here:

    Your Sur-Ron light bee is probably set at the loosest setting possible so it's important to check the rear spring.

    By this I don't mean to say to tighten down the spring a lot, too much pre-load will make the ride harsh and will require too much force to move the shock. If you are too heavy for the spring (just by sitting on it you get over 35% sag) or that you jumps cliffs for a living and bottom out on the stock spring then best would be to change the spring rate to get the proper sag and proper pre-load.

    Lift the rear wheel up and sit the bike on a stool or a box. Grab the spring if you can move it or if you can turn the lock nut over the spring with your bare hand then it's too loose, But If you can rotate the spring and not the lock ring with your hand it's likely OK.

    If you only need to tighten the lock-ring 1/2 turn or a full turn you can do the caveman technique and use a big flat-head screwdriver and hammer, be gentle you don't want to dent the lock ring. I personally used this technique as I only needed about 3/4 of a turn. Proper sag should be around 20% of the full travel, I weight about 170lbs with gear and I get good enough sag without much pre-load.

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    If you need to apply more than just a turn then maybe it's best to remove the rear shock and use a locking ring spanner wrench.

    Click on the pic to enlarge.

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    Thanks Jonathan B for detailed instructions.
    Last edited by Sebz; 11-16-2020, 01:37 PM.

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  • Sebz
    Need to make a key copy?

    Click on the pic to enlarge.

    Ilco X121 DC3 for the Sur-Ron that came before mid 2019, after you would need a locksmith to make a copy or replace the whole ignition.

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  • Sebz
    Adjusting the front fork

    The Sur-Ron uses a basic downhill mountain biking type of fork

    One of the fork leg has the spring (can be a real metal coil or can be an air spring) Depending on the model: FastAce, RST Killah, DNM USD-8S.

    If your fork is a an Air type you will have to buy a fork pump to add some air to it for you weight and to get proper sag, search on Youtube for setup sag on a air fork. If it's a spring type you will either have to deal with the stock spring rate or try to find a springs from another fork manufacturer (like Fox, Manitou and etc). Spring or Air both have their own pro and cons but both are effective!

    The other fork leg is the damper, on any basic fork you will find a compression adjuster and a rebound adjuster.

    Compression (Low speed): regulates the force that moves a fork or shock through its travel. Compression damping is achieved with fluid, usually oil. This oil circulates through a compression circuit, and by restricting its flow, the suspension can be made firmer and can even be almost locked out.

    So basically the more you turn the knob the harder it will be to compress the fork. Ultimately you can use the compression knob to firm up the spring (ie: to prevent bottom out) You can dial it down when you need a super plush ride for comfort.

    Rebound: Rebound damping regulates the speed at which your fork or shock recovers, or bounces back, from an impact and returns to its full travel.

    So rebound is the opposite of the compression, Too slow and the fork wont have time to recover for the next hit and will start to pack up and eventually you will have no more travel :) Too fast and the fork will bounce you back and you will loose traction.

    What is my ideal setting? well you will have to find out yourself, rider weight, speed, riding style and the terrain will all play a role. It’s important to remember that suspension is intended to maximize traction; it does this by keeping your rubber in contact with the ground.

    Some say start in the middle or the adjustments while others will tell you to start from 0, either ways are good just need to take the time to setup your fork properly.

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  • Sebz
    Replacing/locking the grips

    Stock grips are 7/8 inch grips (or 22.2mm) from the factory. Mine were already slipping after a wet ride so I had to do something.

    Our friend Mark K told me about using safety wire to make sure they don't come out so I can say now that I tried it, Iwill never ride without them.

    Here is a great video on how to replace your grips and how to lock them in place.

    Oh and while you are at it get some grip donuts and say bye bye to thumb blister

    Click image for larger version  Name:	image.jpg Views:	1 Size:	80.8 KB ID:	75006

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  • Sebz
    Replacing the throttle

    2017 to early 2020 models:

    The stock throttle is a cable throttle like any little dirt bike or pit bike, it is compatible with Honda CF50 throttle and etc...

    If you do not wish to use the stock Sur-Ron throttle, you can get one for cheap from Ebay or else (See link for an example)

    To remove it
    1. You will need to pull out the grip or cut it off from the tube.
    2. Turn the cable adjuster clockwise all the way in.
    3. Unscrew the 3 bolts holding the throttle, remove the tube and cable guide
    4. fully remove the cable adjuster from the the throttle body.
    5. Install the new throttle
    6. adjust the throttle properly.
    7. Install a new grip or the old one
    8. If the new grip is loose you can use rubber glue and safety wire to lock it in place (see pic below)

    Once done it should look like this:

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    Video of the throw with this throttle

    For the newer 2020 models you can convert back to the old mechanical type which is likely superior, more robust and better throttle feel (with the metal throttle handle upgrade which reduced the throw to about 1/5 turn )

    You will need a aftermarket pit bike throttle like the blue one up there, you can use the cable that is included with the throttle it's long enough. If you are getting you're throttle handle elsewhere make sure it's a 900-950mm cable.

    You will need also a cable anchor because the throttle cable does not come with one, the barrel diameter is 6mm (1/4") so I bought a kit similar to this : Click here

    And you will need the throttle box : You can get one from Luna but we are often out of stock on them

    Click image for larger version

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    Or maybe try Aliexpress here , or other Sur-Ron dealers across the globe

    Last edited by Sebz; 01-11-2021, 07:02 PM.

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  • Sebz
    Adjusting the rear wheel and chain tension

    You will need proper tools to get the job done properly:

    1) 17mm socket and wrench
    2) 2x 10mm open end wrench.
    3) Measuring tape, ruler, micrometer or else.

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    First step is to put the bike on a stool or a work bench, loosen up the rear axle, it's pretty tight so have someone holding the bike!

    Next step is to loosen up the 2 axle adjusters (on on each sides)
    To do so you just have to turn the locknut counterclockwise (lefty loosy) that should free up the bolt and the locknut

    locknut is the one with the chrome 10mm wrench
    The tensioner bolt is the one with the black wrench

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    Now the important part is that you need to adjust the axle to get proper tension on the chain while keeping it straight.

    There are notches on the frame near the axle so use them to get the wheel straight.
    Work slowly by adjusting each side little by little till you get proper tension, what is proper tension.. about 1/2 ich to 3/4 inch slack
    When you have proper chain tension check the alignment of the wheel,You can use a ruler to measure the distance between the rim to the frame or use your hawkeye like I do :)

    Here you can see I pull on the chain to get to the zero mark and then pull the chain up to see if I'm between the safe slack range.
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    How I center the wheel to the bike
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    Once you have proper alignment and chain slack you must lock the tensioner in place, if you don't it will likely be all loose after your next ride.

    Hold the bolt in place with the black wrench then turn the lock-nut clockwise with the chrome wrench till the nut to set to the frame and tight.

    Recheck the chain tension again, pull hard on the chain to be sure if the axle is sitting on the tensioner. If you got more slack you will have to redo it again.

    Click image for larger version  Name:	IMG_2683.JPG Views:	2 Size:	1.34 MB ID:	74788

    Once it's locked on place it,s time to get that 17mm socket an wrench and firmly secure the axle, it's a large diameter axle so you can put a lot of force on it.

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  • Sebz

    Upgrading to riser bars

    Default stem clamp will hold 31.8mm bars
    If you need a riser handlebar we got you covered:
    To use a different diameter bar you would need to change the stem or use shims.

    What ever you do don't use adjustable stems to raise the bars, it's a serious safety risk for such an heavy bike... If this riser bar is not enough, use a downhill rated fixed riser stem or find a direct mounted stem with a all metal riser block under it.

    Click image for larger version

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    Last edited by Sebz; 03-11-2022, 10:18 AM.

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  • Sebz
    Ebrakes: More Detail

    The ebrakes are a sensor that is installed by the brake lever via a screwset.

    When installing it is VERY easy to rip out the ebrakes, which is the cause of most 'DOA' issues or intermittent working issues. Try fully unplugging to troubleshoot.

    Here is a video showing how they work and how to adjust them

    Below shows the sensor itself where it plugs into the lever, and the other side of it where it plugs into the white connector on the bike (these are from a Sur-Ron).
    The hex bolt that the sensor enters sets the depth, and the set screw keeps it fixed in position.

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    Here we can see a closeup of how the sensor actually goes through the bolt.

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    Side angle and a view of one of the sensors fully removed.

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    How to unplug the brake cut off sensor connector

    Open battery lid slide the breaker across to OFF and remove the battery.

    Remove the 2 screws that hold in the ignition and usb.

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    Gently remove ignition to access the wiring harness for the brake cut offs.
    Trace the wires from the front and rear brakes. These are the 2 wires marked with red arrows. Unplug them.

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    Gently remove the required brake cut off wiring and you are done.
    (Black arrow is pointing to the head light plug)
    Last edited by Sebz; 08-16-2023, 06:12 PM.

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  • Sebz

    Sur-Ron replacement connectors:

    Charger connector

    You would like to use your charger (at your own risks), the charger connector is a CNLINKO LP-20 series

    Male charger Plug: LP-20-C03PE-01-001
    Female battery Socket: LP-20-J03SX-01-001

    You can purchase them at NLINKO through Amazon.

    Discharge connector

    They are RCproplus dc-6.
    Last edited by Sebz; 09-28-2022, 02:34 PM.

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