Honda CG125 Improving Performance
It is possible to increase the Honda CG125 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 carb or air filter.
For the real mechanical enthusiasts who want to increase engine size, see Increasing Engine Size page,
but I still advise you to also read my non engine size advice below since engine size is only part of what makes a bike go fast.
Disabling the Air Suction Valve if you have one, probably will not improve performance, see Air Suction Valve in Basic Fault Finding page.
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 Givi A601 Review Givi A660 Review and Motorcycle Universal Screen Review pages.
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.
Without a screen, you can still improve the wind resistance by wearing the best coat, see Coat in Motorcycle 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.
Look at the Important Spark Plug Information section, find the paragraph that starts with,
You need a NGK DPR8EA-9 spark plug for normal riding and a NGK DPR9EA-9 for extended high speed riding,
Make sure you also have a look at Which Spark Plug Model to find out if you can use the spark plug in your engine.
Also make sure you do not have an old worn out spark plug in.
See Petrol in the General page.
See Tyre Makes and Models in the Tyres page.
See Which Oil quality to use in the Servicing page.
See MPH to RPM page.
If you have a Front Disc brake, it may not have ever run in and be substantially below maximum power or the fluid may need changing,
see How to run in the Front Disc Brake and Front Disc Brake fluid changing sections in Front Disc Brake in the Servicing page.
See Idle Mixture Screw in the Servicing page.
See Luggage Rack in the Accessories page.
Look at the 2nd and 3rd paragraphs.
See Rear Suspension in the General page.
Things you should have already done.
See Tyre Pressure in Tyres page.
See Chain Tension, Chain Oiling, Clutch cable, Throttle cable, Valve Clearance, Air Filter ?, Ignition Timing(not if you have electronic ignition) in the Servicing page.