125cc Motorcycle Owners Club

Honda CBF125, CBR125 and Yamaha YBR125


How to Clean a Motorcycle

Never use a pressure washer to clean any motorcycle, water can get in to wheel bearings and in to the electrical system.
I have never needed to use any detergent or shampoo on a motorcycle (I just use water).
At least one motorcycle manufacturer advises you not to use washing up liquid since it contains salt that will scratch paintwork.
I use on paintwork, chrome and glass
General Microfiber Cleaning Cloth (often sold for normal house cleaning),
very good at removing grease, dirt and insects, not the best finish.
Genuine Chamois Wash Leather (available from car shops, do not get the artificial type),
not good at removing grease, dirt or insects but leaves a smear free finish.
Spectacle / Camera Microfiber Cleaning Cloth (used to clean mirrors, instruments and helmet visor), good at everything.

I also use Mer Car polish
(every 6 months to 2 years on the paintwork to make it really shine and make it slippery so insects do not stick like glue).
Mer Car polish is expensive but you use hardly any on a motorcycle so the smallest bottle will last almost forever.
It can also be used on chrome and even on hot exhausts (if it's chrome or smooth paint).
See Silencer / Exhaust section only in Bike part of Riding In Winter page to see how to remove rust and stop rust coming back.

If I need a strong degreaser to remove for instants months of chain oil from the back wheel,
I use WD40 (only because I having it around anyway) and an old cloth.
WD40 is a very powerful degreaser and flows like water in to all the very small places,
this is very bad if it gets in to the wheel bearings and other places
since it will get past the rubber seals and dissolve the bearing grease.
So spray only a small amount on to the back wheel and rub with a cloth,
it often leaves a WD40 film of oil afterwards, do not let it get on the silencer or it will stain.
I normally do not bother to remove the chain oil from the back wheel since it protects the wheel and prevents rust.

Gear Change Lever

You can adjust the Gear Change Lever height to the size of your boots or shoes.

The motorcycle dealers often set it pointing down,
which is totally wrong since your bike has an upright riding position (CBR125 is different).

The gear change lever probably wants to be at the same height as the foot rest (level with the foot rest).
I found this to be correct for my boots and expect it to be the same for most people.

See Owner's manual.

Rear Suspension

Adjust the Suspension to the weight you are carrying.

The correct suspension setting for you will depend on your weight and how old / worn the suspension is;
all springs age / wear and drop in stiffness.
It's simply a matter of trial and error, it will affect how well the bike handles round bends and handles bumps in the road.

See Owner's Manual.

How to stop your engine from clogging up

It's a good idea with any engine, if it's only been on short trips, like 5 miles to work,
to take the bike for a long fast ride to clean it out.

Any engine that does not get up to full temperature (low engine revs or short trips)
will get condensation inside and burning deposits will build up excessively,
that's why you have to change the oil more often in these cases,
but you still need to take the bike out for a long fast ride from time to time, it can also help the chain.

Lots of people think a 125cc engine is so small it will get up to full temperature very quickly
and its engine speeds are much higher in normal operation than larger engines.

Well the temperature takes a lot longer than many think, 5 miles just does not get it up to full heat.
In my 125cc bike, I have noticed that if I do loads of 5 mile trips at 40mph in 5th gear the bike suffers.

But when you take it out for a 50mph or faster run,
of at least 15 miles it cleans itself out (you still need to change the oil more frequently).

You may notice the bike starts better; idling is faster and healthier, less vibration, smoother and more power.

If you do a lot of short, slow trips try to have a long fast one now and again.

You can also buy better quality petrol that has extra cleaners in to reduce the problem (see Petrol below).


It is easy to blame yourself for a poor quality clutch,
thinking it's you not being sensitive enough on the clutch or you not getting the throttle to clutch right.

If you wear out a clutch on any make or model of bike,
I highly recommend fitting EBC clutch plates and clutch springs,
instead of the bike manufacturer's genuine parts (which might not even be the same as originally fitted).

EBC have a reputation for making high quality and performance parts including their clutches.
My clutch tests also back this up and as a result,
I would expect EBC to outperform your original clutch or at worst equal it.

Of course I cannot test every make and model of motorcycle, but I do know the quality of EBC.
They even make their clutch springs 10 to 15% stiffer,
which only makes the clutch lever very slightly heavier (the muscles in your hand very quickly adapt),
but also results in much better clutch performance and less slipping (even on a 125cc bike).

EBC make 3 types of Clutch plates for road motorcycles.
Standard CK series (that's what I have tried and are available for a very large amount of motorcycles).
and 2 Race / Sports Clutch plates (only available for some bikes).

I was able to compare the EBC clutch to my 125cc bikes original clutch (even when both were brand new),
the EBC Clutch is so much smoother and makes off the line starts perfect every time (no juddering),
even when you make a mistake.
I did not realise it at the time, but the original plates were always slipping slightly
(nothing to do with the oil myth, even happened on semi synthetic).
The EBC plates do not appear to be slipping,
resulting in a better connection between gearbox and rear wheel (more power and smoother power delivery).

EBC make Clutches and Springs for the
YBR125 (no spring kit available when writing this article, that might have changed by the time you read this).


What often seems like gearbox problems to a novice is often a bad quality (or worn out or bad designed) clutch.
A mechanic will be able to advise / work out more after hearing your complaints about it.

The faults below are due to the clutch or gearbox overheating due to bad design in my motorcycle
(other motorcycles may suffer the same or similar).
You can improve the overheating by using better quality oil.
Silkolene Comp 4 (real semi synthetic) engine oil was not able to stop the faults.
Silkolene Pro 4 Plus 5W-40 engine oil has substantially reduced the problem (see Silkolene Pro 4 Plus for more information).
I then tried an EBC Clutch (see Clutch above), which improved things even more.

When you are in 5th gear and want to change down to 3rd or below,
you must let the clutch out in 4th gear.
If you do not, the gearbox will refuse to change down to 3rd or below,
until you let the clutch out (in 4th gear) and then pull it in again.
If you are stuck with this problem at a standstill,
with the throttle closed, let the clutch out just enough so the engine starts to connect to the back wheel,
then pull the clutch back in before the engine stalls.
When the fault is fixed you will hear a mechanical click from the gearbox.
Sometimes rocking the bike forwards and backwards while blipping the throttle also works.

The gearbox / clutch will overheat if for instance,
you race from one set of stopped traffic lights to another a short distance away on a hot day.
You will not have any problems if you let the clutch out in every gear when changing down,
but the gearbox will refuse to change down if you do not.
When it refuses to change down and you're stuck at a standstill,
with the throttle closed, let the clutch out just enough so the engine starts to connect to the back wheel,
then pull the clutch back in before the engine stalls.
When the fault is fixed you will hear a mechanical click from the gearbox.
You can also just wait for things to cool down.


This section was last updated in March 2014
(petrol is constantly changing and ethanol increasing so it may be out of date after a while).

Also see Ethanol in Petrol Warning

In the UK I very highly recommend you never use supermarket petrol in any engine including motorcycles and cars.
The only branded petrol that I would dare to put in any of my petrol engines are Shell, BP, Esso, Texaco, Jet, Gulf.
I am not alone in making the above statements,
many car and motorcycle mechanics and shops have been going on for years about never use supermarket petrol.
Supermarket fuel has been causing so much trouble over the last few years;
some shops have been telling their customers when they pick up their new car / motorcycle,
that if they put supermarket petrol in it their warrantee will be invalid.

Supermarket fuel may often be cheaper,
but you may well find your fuel economy reduces making it more expensive than branded petrol.
Your throttle may also become sluggish.
But the most worrying problems may include the purity of the petrol (contamination),
stale petrol (gone off) and not enough cleaners.
If the cleaners are not strong enough,
burning deposits will build up reducing the performance of the engine and may well increase engine wear.

If it was an emergency and I had no choice but to use supermarket fuel.
I would only use Tesco and only if they sell 2 types of petrol, the most expensive one is the only thing I would dare to use.

All but the smallest petrol stations that sell Shell, BP, Esso, Texaco, Jet or Gulf have two types of petrol.
The cheapest petrol is the standard unleaded.
The expensive petrol is their quality unleaded,
it is not only higher octane but often has more / better cleaners
and performance enhancing things in it (maybe even better fuel economy).

The expensive petrol should really be called super unleaded, but every company has come up with their own name for it.
Super unleaded often has less or no Ethanol in it compared with standard unleaded.
Super unleaded of different brands will perform differently and will depend on your engine,
so the only way to find what's best is to try them all in your engine.

Please note petrol does go off with age,
super unleaded does not sell in large quantities so a remote / small petrol station may have old stock.
Many BMW, Mercedes, Subaru cars can only run on super unleaded,
they are often found at branded petrol stations on busy roads.
So the places they go to will often have fresher stock.

From time to time any petrol station of any brand or supermarket can have a faulty batch of petrol or a contaminated tank.
If your engine suddenly shows symptoms of bad fuel, try to avoid that petrol station for a while.

Below are the results I had experimenting with petrol in my engine a few years ago.
Please note petrol has and still is changing a lot due to the UK government forcing more ethanol in to petrol.
The amount of ethanol in petrol often depends on the brand and where the petrol station is in the UK.

Super unleaded is much better than normal unleaded in at least the Front Disc Brake Honda CG125 engine.
The effects of super unleaded and the different makes will depend on the engine design,
the following results are from the Front Disc brake model Honda CG125,
another make or model of bike / car engine (or even the Front Drum Brake model Honda CG125),
might have less improvement or no noticeable improvement or improve even more.

I started off with Sainsbury's super unleaded which is only 2p a litre more than unleaded,
the bike increased in power, torque (pulling power) and the engine ran smoother.
The improvement was largest in the lower and mid rev range of the engine.

I then tried Shell Super (it's called V Power, the old version was called Optimax)
that costs 7p a litre more than normal unleaded.
The Shell Super improved my petrol consumption by more than 7p a litre,
the bike increased in power, torque (pulling power) and the engine ran smoother.
The improvement was largest in the lower and mid rev range of the engine.
That was all compared to the Sainsbury's super unleaded.
I would say the jump from normal unleaded to Sainsbury's super was small compared to the jump to Shell super.
The Shell super also kept improving all of the above the more I used it,
it took a tank or two before it slowed the improving down to a crawl.
It does claim to have extra cleaning powers to clean out your engine and improve all of the above.
It also significantly reduced the amount of time the choke is on for.

You can mix any super unleaded brand with another brand of super unleaded or normal unleaded,
but expect the improvement to only be 50% if you only have 50% super with 50% normal unleaded.

Which brand of super unleaded petrol is best for your engine I cannot say.
The best way is for you to test them yourself. You may or may not find a large difference between them.
Watch out for fuel consumption, cleaning and performance differences.
I went back to Sainsbury's super (put nearly a whole tank of it in),
immediately the bike lost most of the Shell V Power differences.
But as I used more and more of the Sainsbury's super in the tank,
the bike got slower and slower (no Shell V Power to keep it clean).
When I was down to half a tank, I filled up with Shell V Power and got half the benefits back.
This proves the engine was being cleaned by Shell V Power and Sainsbury's Super was making the engine dirtier,
like normal unleaded.
Also see Ethanol in Petrol Warning