Friday, 20 April 2012

Aprilia RS 125 derestricting Derestriction RS125

APRILIA RS 125 CDI Derestriction

The Aprilia RS125 comes with a CDI restriction. It retards ignition around 6000rpm so the bike can pass EU emission tests . This makes your bike perform poor at around 6000rpm

Derestricting this will invalidate your warranty.

If you bike is in warranty the best thing to do is buy another CDI and derestrict this and use it on your bike.

Derestricting the CDI,

The CDI will have a serial number on it? if the serial number is in the following format 071000-XXXX-XXXXX then this derestriction will work if done correctly (may still work on others).

You will need to cut out a hole in the CDI to reach the bridge. Cut out a rectangle 30mm by 10mm and 5-10mm deep.
You will see a part of a circuit board, snap this. This is known as the bridge. (If you reach glass it means you have dug too far!)
Once you have snapped the bridge, fill your hole back in with silicone, make sure its waterproof! Now there will be no environmental dip between 5000-6000rpm.

Aprilia RS 125 derestricting Derestriction RS125
Try here on Ebay UK for already derestricted CDI units 

Full Power Derestriction

The Aprilia RS125 can be restricted so its learner legal, and then derestricted to full power (claimed 33bhp). To do this you will need the following items:

If your RS125 is restricted then it will not get a significant power increase around 6000-8000rpm. If you know the Powervalve is installed but you are still not getting this increase ensure all parts are working correctly, connected, and the solenoid is set correctly and cleaned as per maintenance schedule.

What does the Powervalve do?
The blade of Powervalve goes in the barrel of the engine. This then moves up and down to increase and decrease the exhaust outlet size to give you different performances at different rev ranges. The more revs you give the bike the more the Powervalve blade is pulled by the solenoid and opens the exhaust outlet.

All a solenoid is, is an electromagnetic component. Basically all you need to know is the solenoid  pulls  a cable which is connected to the Powervalve blade which pulls it out to increase the gap in the exhaust outlet.

You must check your bike for the components listed above.
a blanking plate will be fitted in place of Powervalve blade if restricted. You can see this by removing your right side fairing and looking above the exhaust. It will be a small plate and have 3 bolts along it (one either side and one in the middle). If you see a blanking plate then you will need to purchase the Powervalve blade, mount, and other parts see photo above .

Once you have acquired the parts remove your blanking plate and fit the powervalve into the bike.

Note, the powervalve goes in one way!

It has a tapered end on one side, this should face downwards, and the flat side of the powervalve blade should face upwards! Ensure you do this!

If you can see the powervalve mount sticking out the exhaust then you will not need to purchase it of course and you will see something like this above the exhaust...

Remove your tank...
To the right of the battery there should be a solenoid which should have a cable connected on the end of it. The cable connects to the powervalve blade that goes into the engine that we looked at before.
It should look something like this altogether...

If you do not see the solenoid and/or cable then you will need to purchase these.
Once you have purchase these parts mount them to the right of the battery, there is a place for it to be fitted, it goes on the part of the radiator frame that goes right next to the battery.

If you see the solenoid and cable, and you see the powervalve mounted in the engine but your bike is not performing as it should... then it may be a case that the solenoid is not connected! If you look on the picture above there is a connector block on the end of the solenoid, see if this is connected, it connects to the main loom which runs along the right hand side of the bike from the front all the way to the back of the bike.
If you connect it up and it does nothing then keep reading....

Remove the passenger seat and check for the RAVE unit. (just remove the two back side fairings and tail)

If you cannot see this, then you will need to buy one of these and fit it to your bike. There will be a spare connector block coming out of the main loom were it should be connected to. Once you have fitted all these parts your bike should be derestricted!!!

All you need to do now is to set your solenoid up correctly... It has adjuster nuts on it, so the cable can be adjusted. This is because the solenoid starts acting around 3000rpm (you can see the solenoid opening when you rev the bike to this with the tank off). The more the powervalve blade sits in the exhaust the better low range power you will have, but poor top end. This works vise versa. See how to adjust your solenoid below...

WARNING: WHEN YOU DERESTRICT YOUR BIKE YOU WILL NEED TO CHANGE YOUR SPARK PLUG OTHERWISE YOU WILL BLOW A HOLE IN YOUR PISTON. Despite what the manual says, the spark plug to use when your bike is full power (powervalve installed) is a BR10EG. This is because the plug is colder. When your bike is restricted you should run a BR8EG. You can change these plugs for other versions e.g. Denso plugs, Iridium plugs for smoother running.

Aprilia rs125 blog


Derestrict your Aprilia rs125

The Aprilia RS125 restricted to 14bhp for learners or de-restricted to 33 bhp 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? hard to do on a bike without tools or riding it .

  • significant increase in power at around 8000rpm

  • power valve solenoid fitted under tank requires removal of tank fastener and lifting tank
  • another thing to look for is either a blanking plate or powervalve blade assembly in the barrel but again hard to check without removing fairings

  • If it has been fitted ensure that the cable is correctly connected to the blade and the system moves freely blades can stick in barrel and need regular cleaning another problem can be frayed cables preventing movement or even a seized solenoid .

  • Test the solenoid by disconnecting the 2 pin multiplug that connects the solenoid to the wiring harness this is an easy test and confirms the solenoid functions correctly.

  • 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 quite expensive new but easily found used 

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 or sports exhaust  (you MUST rejet your carb after fitting)

  • Take the expansion chamber from an older bike pre 2003 but beware exhausts are swapped and changed between bikes a lot especially on the older bikes where original exhausts have been replaced so you could end up with a cat model exhaust anyway .

  • Cut open your pipe to remove it and weld it back together.
or buy your self a sports exhaust  and rejet carb to suit would be easier option 

Installing a powervalve and solenoid

  • Installed the blade with the flat side facing up and the tapered side facing down 

  • 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 see manuals for settings 

  • 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 6000-8000 rpm so the bike can pass emissions tests.

  • This causes poor running at this engine speed and you will notice a drop in acceleration.

  • De-restricting the CDI will invalidate your warranty, so buy another from ebay if you bike is still in warranty and de-restrict that fitting you old one back on for any servicing or warranty based work.

  • 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.


original airfilter is fine but other aftermarket versions are available ,but may require jetting to be checked further .

BUY the ultimate Aprilia RS 125 workshop manual bundle 

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