Question about Derbi GPR 125 Racing Motorcycles

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Try this

will show you how to do it


Posted on Mar 14, 2011


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How do I de-restrict a 2008 axon 50

Spend more than a new (better) bike will cost, to replace the restrictive parts, Exhaust, ECU, Camshaft and cylinder head. Then put it all on your bike. In other words -It isn't worth it. It will cost more to do than exchanging your bike for a better one.

Sep 14, 2013 | 2008 Qlink Axon 50


How to tune / de-restrict a 2 stroke

2 strokes in lower ccs are usualy slow, so heres a list of things you can do to de-restrict and tune your 2 stroke.

1) Get a racing exhaust, Key part too most 2 strokes is a good exhaust, this will remove some restrictions. Gianelli, Big One, fmf and many others are available on ebay or your local bike shop.

2) Big Bore kit, adding a big bore kit can give up to 30% more performance, and will usualy de-restrict the bike. search ebay for (Bike Model) (year) Big Bore kit. it will come usualy with everything you need for the upgrade.

3) Carbon Reed Valves, are a key part too your acceleration, also removing the little cages that stop them opening all the way and replacing with big washers is another good step, make sure theres nothing for your reeds to nock on when removing the cage.

4) Boost Bottle, a boost bottle will help 2 strokes with no reed valves more then reeded bikes but will give alot more low and high end performace. search ebay for (bikes cc) boost bottle.

5) Jets, are a key thing when getting a bore kit or race exhaust. you MUST change the jets if you change exhaust, get bigger ones if you get an exhaust go a few sizes over and check the spark plug if its a brown tan/ grey collor you got it all right, if its black it means you have to much fuel so go smaller, and if its white it usualy means not enough fuel. you can buy jets from any motorcycle shop usualy around $1 a peice. you onyl need to change the Main jet.

6) Air Filter, you dont need it on most bikes but it could add extra acceleration, measure your carbeurator intake and search it on ebay for a K&N style filter, Power filter.

7) Restrictors in the intake, some 2 strokes have restrictors between the carb and the cylinder, it is key to remove these or drill them out to the size of the carb/ cylinder hole size.

8) Sprockets, if your lucky enough to have a chain and sprockets, its a nice trick to change sprockets on your bike.
For Top Speed - Bigger front sprocket & smaller rear sprocket
For Acceleration - Smaller front sprocket & bigger rear sprocket
by bigger or smaller i mean more or less teeth on the sprocket. if you go for speed your acceleration will lack and vice versa if you go for acceleration you will loose top speed.

9) Electical Restriction, Some bikes are restricted in the CDI, if yours does not want to reach a good RPM search up CDI, de-restriction. usualy it involves cutting a wire between the CDI and engine. and will unlock that slow engine into a screaming 2 stroke.

If you follow all these steps your 2 stroke will no longer be restricted and slow and will be the fastest arround.

on Feb 16, 2010 | Motorcycles

1 Answer

Increasing top end 125 4 stroke

de-restrict the exhaust , leave the engine alone, may cause more problems.

Mar 20, 2013 | Motorcycles

1 Answer

Why do none of your so called experts know how to de restrict an a.j.s.125 dde, or even answer if it can be done

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.

Mar 18, 2013 | Motorcycles

2 Answers

My qlink axon 50, 2007 i believe, is a little slow for me. How can i make it faster without boring it over?

if u can take some hardware off bike-cud help-its only a 50--research racing modifications-library sec629 or online--changing jets on carb or injector helps but u need a pro tech or u cud fry engine

Nov 16, 2011 | 2008 Qlink Axon 50

1 Answer

I would like a method to de-restrict the mufflers for 'some' more exhaust noise. any re-jetting advice would be appreciated. thanx

Removing the baffles will do that but the engine will require retiming. I would purchase some Screaming Eagles or some such slash cut pipes.
Check out ebay for ideas.

Feb 26, 2011 | 2006 kawasaki W 400

1 Answer

Wanting to de-restrict my bike, it has something to do with or around the inlet manifold, but where`s it at and how?

put a racing exhaust and a racing air filter it shoud go faster but tell your insurance because if you have a crash they will not cover you for the changes

Oct 18, 2010 | Hyosung GT 650 R Motorcycles

2 Answers

How do i de restrict my kmx125

i am led to beleev that restricting a kmx is simply taking off the earth wire for the power valve if you could find a diagram of the pow val system or if you have the haynes manual then earth the pow val if the pow val is working then i cnt help gd luck m8

Apr 08, 2010 | 2000 kawasaki KMX 125

2 Answers


if it seems to be running fine, its probably about as good as its gonna get. the 125 just isn't a power house. you might be able to gain a little bit of extra power through add ons like exhaust, rejetting the carb, etc.

Apr 03, 2010 | 2005 Yamaha DT 125 X

1 Answer


It`s ALREADY de-restricted!!! Restriction is only for keeping the 50cc models in the Moped category so some people whould not need an endorsement and not exceed 30mph,

Nov 10, 2008 | 2005 Kymco People S 200

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