Different bikes restrict by different means, sometimes smaller carbs are put on other times the jets are just changed to a lower width, the exhaust shape can restrict airflow from the engine. sometimes the airbox restricts flow into the engine. so first stop is check how high a jet you can get for carb, maybe get a jet air filter racing kit.may need to change exhaust for a power pipe. you can put a bigger sprocket on front end for less accelleration but higher top end or smaller for higher accelleration. you can put a bigger sprocket on back for greater accelleration loosing top end. you could change the piston for a higher compression piston and/ or have the head skimmed. the list goes on and if its a 2stroke there's reed valve to play with.
SOURCE: de-restrict an aprilia rs 125
Hate to disagree with tina783, but you may have restrictions in place, there is two on the aprilia rs 125. if your on a L plate then the bike should be restricted to 11.5w of power, which is about 15 bhp, when it's de-restricted should be around 34bhp. First is the power valve or a RAVE Valve as some people call it, have you got one? located on the front of the cylinder body, above the exhaust. some times the body of the power valve is there, but there is a blanking plate is underneath it. If the body of the power valve is missing, then its a blanking plate. need to get a power valve and the control unit and the solenoid, fitting is easy look around the net and you'll find one. The next one is the emissions restriction, which is in place due to italy have a real hard on about thier air. The CDI at the back of the back of the bike needs to removed and then if you look at one side you will see a rubber sealant has been used to fill in one side. You need to dig that out and snap a little piece of the circuit board and then refill the hole with a rubber sealant. try to search the net for a how to do on this you need to look at the pics and see what part of the board needs snapping, don't go blindly into this other wise you will kill the CDI. the bike then will act alot more smoothly in the lower end revs.
SOURCE: I have a Aprilia rs 125 2008,done 4000ks. It blows too much smoke
maybe rings are you losing coolant check the spark plug if it comes out with oil or too wet this means your oil pump is pulling to much in get back to me budd
SOURCE: de-restricting aprilia rs 125 (jetting)
hi not putting you off but when i fitted a arrow exhaust system and power valve. i had great power. but i had to rebuild the engine every 800 - 1000 mls. regards
SOURCE: how do you de-restrict
It is similar to the Yamaha and Aprillia 125S.
If it has not got one fitted already, at the upper most front point of the cylinder head, there needs to be a valve fitted. This valve keeps a constant pressure on the exhaust gasses leaving the engine, two stroke engines require "back pressure" to enable the reed valves and the whole sytem to run as smooth as possible. The valve is controlled by the CPU or Engine Management Unit of your bike, which also has a built in restrictor between 2500 and 5500 revs. Depending upon the CPU used there may be a way of removing the European Restriction at those revs.
Cgheck online for that reference. Try joining a blog on your bike, there are a few about.
Hope this helped you.
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