125cc Motorcycle Owners Club

Honda CBF125, CBR125 and Yamaha YBR125


< Servicing

Rear Brake

See Owner's Manual.
If you need to replace the brake shoes / pads I recommend the EBC brand,
since they are well known for their performance and quality.

Front Brake

Check brake is not Binding

If you're in any doubt after doing the following, ask a mechanic to check for binding, they should not charge you,
if they try to, find another shop / mechanic.

If you do not have a centre stand, it's very hard to work out if brake is binding,
unless it's so bad it's hard to push the bike
or you find the brake disc is warm or hot after a ride when the brake has never been used.

Put the bike on its centre stand;
make sure the front wheel is off the ground by pulling up on the handlebars if necessary.
Then spin the wheel forwards and backwards with your foot (while standing by the petrol tank).
Binding in the forwards direction is a real problem.
In the backwards direction it only makes it hard to reverse the bike,
this can hurt your back and unless you are strong,
it can make the bike seem very hard and heavy to reverse out of the garage.

To work out if brake is binding too much.
Rotate wheel until its air valve is easy to see.
Then spin the wheel forwards with a single kick as quickly and as hard as you can.
If the wheel stops as soon as you let go or after a very short distance, it's desperate to be fixed.
If the wheel rotates a 1/4 of a turn it's debatable.
If it's good it will rotate a whole turn or more (a whole turn is when the air valve ends up in the same place as when you started).
For example my brake will rotate 1.5 turns in the forwards direction but only 1/4 turn in the backwards direction.

Brake binding could decrease or increase as soon as the brake is used.
Spin the wheel forwards,
while it's spinning put the brake on as quickly as possible and just hard enough to stop the wheel instantly,
then let go of the brake as quickly as possible. Then check for binding again.
You may need to repeat using the brake a few times.

You may also want to see how much binding there is after a ride,
try to brake hard at least a few times during the ride, especially at the end.

Another test for a binding brake is to take the bike for a long run without using the brake at all,
then put your hand on the brake disc and see if it's cool, warm or hot (the hotter it is the worse the binding).

If the binding is bad in the forwards direction, it's an MOT failure (in the UK) and it can cause brake failure, warp the disc,
or at least slow the bike down and bad braking performance (due to overheating).

The reason brakes start binding is due to corrosion, over time it will increase (depends on amount of water / winter salt),
if it's ignored (not stripped down and cleaned by a mechanic before it gets to bad),
it can become so corroded it's impossible to repair and so has to be replaced (costs around £150 just for the part!).
When it's that bad, I bet it's also an MOT failure (in the UK),
so you will have no choice but to fix it if you want to use the bike on the road.

There is a chance the brake is binding due to brake dust, dirt or corrosion between the brake pads and the brake disc.
Simply spay some brake cleaner on to a piece of standard disposable white kitchen towel (it's paper based = slightly abrasive).
Rub both sides of the brake disc with it, when the towel becomes to black,
repeat the process with another towel with brake cleaner on etc.
Only use brake cleaner, it's available at car or motorcycle accessory shops.
Look for any white bits that have come off the kitchen towel and on to the disc,
wipe them off with the towel (downwards, not sideways).
For the first few times when using the brake (while riding), expect the brake performance to be bad.
Then retest for brake binding, cleaning like this may reduce or hide a more serious problem, but it is worth trying

Otherwise fixing a binding brake does require skill and so I advise letting a mechanic work on it.
If you want to make sure you're not overcharged by a mechanic, agree an hourly labour rate and watch them work.
If they will not agree to let you watch them work or charge per 30mins, find another mechanic / shop.

When to change the Brake Pads

The pads should have a worn out indicator, but if you cannot see it,
the pads are worn out when there is very little brake pad material left (1mm).
You may wish to change the pads at 2mm,
since braking performance maybe reducing (pad manufactures often recommend replace when half worn).
You can use a feeler gauge (thickness gauge, thin pieces of metal) to help measure,
available from most car shops (used for many other jobs as well).
Use a torch to see both brake pads (one pad on each side of the disc),
often the hard to see pad can wear down faster than the other one.
If you ever hear or feel what seems like metal grinding against metal,
your pads are worn out and must be changed immediately or you will damage the disc.

Front Brake Pads

I highly recommend you change the original brake pads to EBC Organic brake pads
(EBC make them for your bike model and year).
I bet you will find them much, much; much better in every way (improves your enjoyment and your safety).
Of course using a really good brake,
also needs a good quality tyre to use it fully (see Tyre Makes and Models in Tyres page).

CBR125 has sintered pads fitted at the factory (see below about why I do not like Sintered).
CBF125 has organic pads fitted at the factory (I bet they are much lower performance than the EBC Organic).
YBR125 not sure which type of pads are fitted but I bet the EBC Organic will be massively better.

My motorcycle had Nissin Sintered pads fitted as standard (at the factory) and they were absolutely terrible,
the performance was more like a Front Drum brake (no friction and brake fade).

I put EBC Organics in and got completely the opposite result
(more friction than I can use even in an emergency stop, no brake fade).
As well as being smooth, progressive and needing far less pressure from my fingers to use it (can stop quickly with 2 fingers).

EBC Organics have a reputation for being the best organic pads on the market and I believe it after my results.
They even brake very well on soaking wet roads when it's raining
(organics are supposed to be bad, sintered are designed to be good).

I tried EBC Sintered pads but my braking system did not have enough power to use them (more details later on in this section),
I got much more braking power from EBC Organics (I expect your bike will be like mine).

If your old pads had a shim fitted, I recommend you do not transfer the shim to the EBC pads.

To improve braking performance even more,
I recommend you replace the original rubber brake hose with a stainless steel braided hose.
Rubber hoses only have a life of around 4 years, a stainless steel braided hose last a lifetime.
Stainless steel braided hoses give you more pressure and more feel of the brake,
they are a very common aftermarket accessory.

After trying 2 makes of Sintered pads and speaking to some mechanics, I am getting very suspicious about Sintered pads.
The main reason motorcycle manufactures switched from organic
to sintered on road motorcycles was to improve wet performance.
Many organic pads are bad in the wet, but EBC Organic are very good.

Sintered are meant to have more friction and less brake fade.
EBC Organics are GG rated, the best Sintered are HH (including EBC Sintered), that means there is not much between them.

So why have I had such bad results with Sintered,
one explanation could be Sintered needing to be warmed up before substantial friction is created.
In order to warm them up you may need to brake a lot before you need them and before they cool down again.
A 125cc bike is light and is at slow speeds compared to a big bike at 100 mph (weight and speed affects brake temperature).
A big bike will also have a much more powerful braking system since it's designed for much higher speeds.

One mechanic told me on a big bike at 100mph, trying to stop with sintered,
friction was not brilliant, but as the heat builds up (as bike was slowing down) it gets better and better,
around 70 to 80mph the pads have fully warmed up and the friction is massive and the bike stops very quickly.

So it could well be a 125cc bike is so light and is at such slow speeds (60mph), that sintered will never get up to heat.
Resulting in much less friction than with organics pads.
I cannot confirm this idea, since I have not tried EBC Organics and EBC Sintered on a race track on a big bike.

The next question is, on a big bike at 60mph, which stops the quickest, EBC Sintered or EBC Organic.
If I had to bet, I would guess the EBC Organic.

Sintered are supposed to last much longer than Organic,
that still seems to be true but EBC Organics claim to last much longer than normal Organics.

Sintered are meant to have little feel, are harsh and hard, ether they are off or substantially on
(EBC Sintered have reduced this problem).
Organics do not have this problem.

So whatever motorcycle you have, big or small, remember to change the brake pads to EBC.
And do not go straight to EBC Sintered thinking they will be better than EBC Organics.
If possible try them both, if you cannot afford to do so, I would guess EBC Organics for 70mph and below.

Red Grease

General advice about greases (working with brakes needs some skill and experience).
Many types of grease are not designed to be used with rubber, so unless they say they are, avoid them.
They should say can be used on rubber or they may say can be used on seals.
You also need the grease to be suitable for high temperatures (brakes get very hot)
and water repellent (they get a lot of road spray).

If a grease is red coloured, this should mean it is suitable to be used on rubber and can be used for the brakes.
That's what the red colour is meant to mean, but I cannot guarantee every manufacturer will stick to that.

Silkolene PRO RG2 is suitable, if not in stock ask your dealer to order it or buy it on the internet.
The grease can also be used on many other items, including the bikes rear swing arm.
But it's not designed to be soaking in brake fluid,
Silkolene UK said it's ok on the brake piston seals, but not on the brake master cylinder on the handlebars.

Fuchs lubrications uk, Renolit red rubber grease G51,
your Silkolene dealer may be able to order it or you can buy it on the internet.
It's designed to be used with brake fluid.
It can be used for many other jobs; I use it on the bikes rear swing arm and brake piston seals with very good results.
But when I put it on the Honda CG125 Brakes Floating Calliper pins, it made it to slippery (excessive floating),
there is a chance it was my fault since I did not change the O ring at the time,
but for now I am using Silkolene PRO RG2 on the pins.
On a different model, make or design of brake you probably will find no excessive floating and find the grease is really good.

Front Disc Brake fluid changing

I advise you to change the fluid if it's a new bike before the 2 year schedule,
I changed it 2 months early and noticed a substantial improvement in power and feel.
There are several different ways to change the fluid,
you can buy a one way valve brake bleeding system for less than £10 and instructions are included.
It's pretty easy and I recommend you try it, just remember brake fluid eats paint so cover it up.

The smallest bottle (250ml) of DOT 3 or 4 brake fluid is needed.
Brake fluid goes stale over time once the bottle has been opened so do not buy a larger bottle than required.
A 250ml bottle has far more brake fluid than you need anyway.

Any brake bleeding device will come with plastic tubing to connect to the brake, if you do not buy anything,
you will need transparent clear plastic tubing with an internal diameter of 5mm,
available from car shops and maybe DIY and fish tank shops.

The instructions below are how I replaced the brake fluid;
it's a combination of the one way valve system and the non one way valve system.
The instructions might make it look hard and complicated, but it really is very easy, lots of the instructions are not needed,
there just in case something goes wrong (unlikely).

I used the metal one way valve (look for the arrow on it, for the direction of flow)
with transparent clear plastic tubing on each end (small tube = brake end).
The plastic tubing was very determined to stay in its coiled up state, you need someone to help you keep it straight,
or you could trap it (I put it through a large funnel which I trapped in the handle of a large bucket).

1. Remove the small black rubber cap (see picture above)
on the brake bleed nipple (disc end of brake) and attach the small tube.

2. Unscrew and remove the brake fluid reservoir lid (on the handlebars), there's a second lid inside that you need to pull out.

3. Pull the brake lever in slowly (as far as you can without excessive force) and slowly release,
repeat this 3 or 4 times to get the pressure up,
then pull it in again slowly and hold while very slowly opening the brake bleed nipple nut
(the pressure on the brake lever will reduce, keep pressure on lever, when lever hits handle bars, keep it there),
as soon as fluid flows easily in to the transparent pipe, stop opening the nut.
When the fluid stops moving, close the nut and only then release the brake lever slowly.

4. Repeat step 3 until brake fluid has gone through the one way valve.

5. You can now leave the nut open and slowly pull the brake lever in and slowly release over and over
until nearly all the fluid is out of the reservoir,
do not let air get in to the small pipes in the bottom of the reservoir or you will get air in to the system.

6. Make sure you have covered everything around the reservoir since you may spill the brake fluid,
which eats paint, even a single drop.
Pour new brake fluid in to the reservoir (must be an unopened bottle, it goes off as soon as it's opened).
Keep repeating step 5 and put new brake fluid in when needed, when the colour of the fluid in the transparent tube changes,
you have replaced all the old fluid in the brake system, if you do not notice the colour change,
you must have changed all the fluid when most of the small bottle is used.

7. If the brake lever loses all or some of its pressure, you have let air in to the system, repeat step 3 to get it out.

8. The fluid in the transparent tubing before the one way valve should not have any bubbles or foaming in it,
if it does you need to get them out, you can try step 3 again,
you may also need to experiment with the bleed nut (try opening it less or more),
you may also have to try closing the brake bleed nut before the brake lever touches the handle bars.

9. When finished, make sure brake bleed nut is closed tight and top up the reservoir (never let it drop below the Lower mark).

10. Put reservoir lid back on and then the outside lid, you do not need to tighten screws very hard since it's all rubber,
remember how easy it was to unscrew.

11. Any brake fluid that has been spilt needs to be diluted with loads of water to stop it eating things,
it's normal for some brake fluid to have escaped around the brake bleed nut.

12. If you have trapped air in the brake system (unlikely), the brake will have a lack of pressure and feel spongy.
If step 8 does not fix this problem, the air is trapped higher up the system,
you need to make sure the brake bleed nut is closed tight,
then slowly pull the brake lever in until it touches the handle bar, then tie the lever to the handle bar while it's still touching,
leave it like that overnight.
Then open the bleed nut slowly and hopefully the air will come out.
If this still does not totally work, try again, the reservoir lid might need to stay off overnight.

< Servicing