Derestrict your bike to unleash its full 33bhp!

The Aprilia RS125 restricted to 14bhp for learners or derestricted to 33bhp for those who hold a full license. This guide will tell you where to find restrictions and how to remove them.

How can you tell if your RS125 is restricted?

• Ride it and look for a significant increase in power at 800rpm
• Lift up the tank and check the right hand side of the battery compartment to see if a powervalve solenoid has been installed (the solenoid is tubular and mounts via two bolts).
• If you don’t get an increase in power but the powervalve has been installed then the system is not working correctly.
• If it has been fitted ensure that the cable is correctly connected to the blade and the system moves freely (check out this guide for loosening a seized powervalve).
• Test the solenoid by disconnecting the 2 pin multiplug that connects the solenoid to the wiring harness.
• Earth one of these pins and connect the other to the positive terminal on your battery (it will move if it is working)
• If it has seized then it will need to be replaced.

Removing the exhaust restriction

• Bikes produced since 2003 have a catalytic convertor in the exhaust expansion chamber. You can either
• Purchase a new expansion chamber and end can (you MUST rejet your carb)
• Take the expansion chamber from an older bike
• Cut open your pipe to remove it and weld it back together.

Installing a powervalve and solenoid

• Installed the blade with the flat side facing up and the tapered side facing down (when retracted, the slope on the end of the blade lines up with the exhaust wall).
• Install the solenoid on the right hand side of the battery box.
• Connect the cable to the blade
• Adjust the solenoid once it is in place.
• The more the powervalve protrudes into the exhaust port, the more low end power you will have and the less top end power you will have.
• The less it protrudes, the less low end power you have but the more top end power you will have.
• You must now install the RAVE unit.
• Remove the tail fairing to get to this area.
• The RAVE unit is a similar size to the CDI unit (also underneath the pillion seat) and you will find a multiplug in this vicinity that connects to it.
• Change your spark plug or you will destroy your piston.
• A restricted bike should run a BR8EG
• A derestricted bike should run a BR10EG.

Removing the CDI restriction

• The stock setup retards the ignition at around 6000rpm so the bike can pass emissions tests.
• This causes very poor running at this engine speed and you will notice a drop in acceleration.
• Derestricting the CDI will invalidate your warranty, so buy another from ebay if you bike is still in warranty and derestrict that.
• The CDI is located under the pillion seat. Remove the tail fairing to get to it.
• The back of the CDI is filled with rubber and the bridge is underneath it.
• Remove an area of about 10mm from the bottom of the CDI and about 15mm either side of the centre line of the unit.
• You will eventually reach a bridge between two terminals.
• Snap this and then refill the hole with silicon.

Carburettor

• Newer bikes have a 28mm carburettor whilst the original bikes had a 34mm carburettor.
• Fitting the 34mm carb gives better mid-range performance and better top end power without affecting your pertrol consumption significantly.
• Get hold of a Dellorto VHSB 34MM and a new inlet manifold (the original will be too small).
• The original airbox should be fine with the bigger carb.