125cc Motorcycle Owners Club

Honda CBF125, CBR125 and Yamaha YBR125

Improving Performance

It is possible to increase the top speed against a head wind and much better cornering etc.
All this can be done without doing anything major like increasing the engine size,
exhaust change or messing around inside the air filter etc.

Wind Resistance

By far the largest thing slowing down the motorcycle is the wind resistance of your body against a head wind.
The wind resistance is massive on this bike,
due to a lack of aerodynamic screen/fairing and upright riding position;
any small changes can have a substantial effect on speed.

See Screen in Accessories page.
Over time the screen will increase in resistance (gradually when washing you will notice more resistance to the cloth),
this also increases the wind resistance substantially,
I removed the resistance with two coats of Mer Car Polish on the outside and one on the inside of the screen.
It may be a good idea to use Mer Car Polish even on a new screen to protect it and may reduce the resistance a bit.
Mer Car Polish is available from most car shops
and is normally used on car paint but can be used on many other polished surfaces.
If you look through the screen when riding, do not use Mer Car Polish or any other type of polish,
it leaves a white haze which makes it hard to see through (especially when the sun hits it or car headlights hit it at night).

I advise against fitting new handlebars that lower you in to more of a racing position,
it does reduce your wind resistance, but not by as much as other ways.

The screen will substantially improve the wind resistance,
you can slightly improve it even more by using the best coat (see paragraph below).

Without a good screen, you can still improve the wind resistance (not by as much as a screen) by wearing the best coat,
see Coat in Clothing page.
You can also put your chin on the petrol tank,
use a lorry to shelter behind (stay within your braking distance!) or only travel when there's no wind or back wind.

Other Things

See Spark Plug in the Servicing page, read all of it even if you think you do not need to.

See Petrol in the General page.

See Tyre Makes and Models in the Tyres page.

See Which Oil quality to use in the Engine Oil page.

If you have a Front Disc brake, it may be binding, substantially below maximum power or the fluid may need changing,
see Check brake is not Binding and Front Disc Brake fluid changing sections in the Brakes page.

See Luggage in the Accessories page.
Look at the 2nd and 3rd paragraphs.

See Rear Suspension in the General page.
And Suspension in Servicing page.

See Anti Vibration Handlebar Devices page and Seat in Accessories page.

Things you should have already done.
See Tyre Pressure in Tyres page.
See Chain Tension, Chain Oiling, Clutch Cable, Valve Clearance, in the Servicing page.
Also check Throttle cable and Air Filter (See Owner's Manual)