CDI Derestriction
The Aprilia RS125 comes with a CDI restriction. It retards ignition around 6000rpm so the bike can pass EU emission tests so they can be manufactured. This makes your bike perform very poor at 6000rpm and does not let the engine pull. 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 is a black box under the passenger seat. Therefore to get to it you will need to remove the tail of the bike. The easiest way to do this is to remove the rear side fairings with the tail. See the manual for more details.
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.
https://flexiweb.atspace.com/rs125/1.jpg
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.
Here is a detailed diagram...
https://www.angelfire...di-instruct.jpg
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:
o RAVE controller
o Powervalve blade
o Solenoid
o Cable
If your RS125 is restricted then it will not get a significant power increase around 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.
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 componet. Bbasically all you need to know is it pulls a cable which is connected to the powervalve blade to pull it out to increase the gap in the exhaust outlet.
You must check your bike for the componets listed above.
Your bike may be restricted via a blanking plate. 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 parts diagram below... Your probably best getting a gasket for it too even though there is one on the blanking plate... you can reuse them but to ensure the bike performs well and you dont get any problems get a new one...
https://flexiweb.atspace.com/rs125/2.jpg
Once you have aquired these 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!
https://flexiweb.atspace.com/rs125/3.jpg
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...
https://flexiweb.atspace.com/rs125/4.jpg
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...
https://flexiweb.atspace.com/rs125/5.jpg
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)
https://flexiweb.atspace.com/rs125/6.jpg
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 exhuast the better low range power you will have, but poor top end. This works vise versa. See how to adjust your solenoid below...
https://www.125ccsportsbikes.com/forums/uploads//post-9-1093176496.jpg
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.
Exhuast Derestriction
The later bikes 2003 onwards have a CAT in the expansion chamber. In the expansion chamber not the end can. To get rid of this CAT which makes your bike perform differently, get an after market expansion chamber (best buying the end can with it) or buy an earlier expasion chamber from an RS125 or take the expansion chamber off and be prepared to cut it open, remove the CAT and weld it back together.
If you are going to buy a different expasion chamber then you will have to rejet your carb. The bikes with a CAT in them are set to run rich (more oil) because the CAT requires the bike to run like this. Therefore you will need to buy a standard main jet for your carb. If you have a 28mm carb (finally got it right I normally say 26mm) then your standard main jet size is a 120. If your carb is a 34mm your main jet is more likely to be a 158(i think) You can get these for a couple of quid. This means taking your carb off and removing the old main jet, and replacing it with a new one.
The racers tend to use the standard expasion chamber because it is thicker then aftermarket ones therefore contains the heat more, and these work better with more heat. They normally just change the end can.
Removing your CAT (if your being a big man)
You will need to take your expasion chamber off the bike (see manual if you dont know how)
You need to cut your expansion chamber open where this fella is cutting it and where the white line is indicated...https://flexiweb.atspace.com/rs125/7.jpg
Once you have done this you will be able to remove the CAT
https://flexiweb.atspace.com/rs125/8.jpg
Thats it really, dont know too much about it because I havent done it... Just weld your expasion chamber back up with the CAT removed, give it a respay (heat resistant of course) because they tend to rust like hell even if you dont ride your bike in the wet.
https://flexiweb.atspace.com/rs125/10.jpg
The expasion chamber doesnt really have anything in it anyway if your thinking this was too simple. Literally just cut it open, remove the CAT and weld it back together.
Some exhausts also have a recirculation tube that goes to the air box. You just have to cut this off and weld it up and seal up the air box.
The snorkel in the air box can be taken out too, this will let some more air in slightly and make your bike sound a lot better. Just pull the rubber out the top, or you can cut the part that sticks out. This shouldnt affect your jetting since the bike is not jetted correctly from standard anyways. If you want to be sure stick a bigger main jet in (121 on a 28mm carb). Do a plug chop to confirm. To do a plug chop see the pinned topics... under useful RS125 information.
Carbouretter
The older bikes had a 34mm carb on. The new ones have a 28mm carb. I think it was the 98's that had the 34mm carb on then after that unless modified it was a 28mm carb. If you want better mid range power, and a better top end without affecting your petrol consumption too much get a 34mm carb. The petrol consumption is suprisingly good, it does guzzle more but you get that back in power!
All you have to do is get hold of a Deloroto VHSB 34MM and a new inlet manifold because the original will be to small and then fit it onto your bike. The standard air filter will still fit this new carb.
Well thats basically it. Your bike is derestricted...
Mods to follow to make your bike faster and all round better performance...
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