nsr deristriction

[whelleyman]

HI ALL i have a 2002 nsr 125r1 I HAVE JUST HAD IT DERISTRICTED air intake restrictor and exhaust restrictor removed
THE BIKE SEEMS TO HAVE A IMPROVED POWER BAND AND QUICKER ACCELERATION THE WHEN RESTRICTED BUT THE TOP SPEED HASNT IMPROVED IT DOES ABOUT 75 MPH ANY IDEAS HOW TO INCREAS TOP SPEED

[knockout_bar]

You'll need to fit a smaller rear sprocket, but you'll loose acceleration by doing this.
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125 trail bike, custom bars, handguards etc. - ?500.

"egg flied lice" - R6jonny (inspired by McGee)

[Biker-Kev]

There is a restrictor in the carb!
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Zhongyu ZY50, Aprilia SR50, Motorhispania RX50, Aprilia RS125, Honda VFR400 nc24 and my corsa
https://www.bikepics.com/members/bikerkev/
Theory: Passed 8/11/2005 Practical: Passed 13/12/2005 Proud holder of A2 license

[alains]

the restrictor is in your brain , mate . the carb is a bit underjet that's all .
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the worst day fishing is better than the best day working

[Biker-Kev]

https://www.nsr125.com/derestrict.htm

alians- i cannot find the website which told of the restrictor in the carb, which was in the form of a small metal plate, but if i come across it again i will be sure to post it!

If you know there is not a restrictor here, you oubviously know where they are so help the guy out!

Kev
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Zhongyu ZY50, Aprilia SR50, Motorhispania RX50, Aprilia RS125, Honda VFR400 nc24 and my corsa
https://www.bikepics.com/members/bikerkev/
Theory: Passed 8/11/2005 Practical: Passed 13/12/2005 Proud holder of A2 license

[alains]

the restrictor is a plate in the intake between the carb and the engine where the reeds are . nothing in the carb !
https://125nsr.free.fr/accueil_debridagemecanique_admission.htm
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the worst day fishing is better than the best day working

[knockout_bar]

Taking the restricter out of the carb will not increase your top speed!!!!!!!!!!! You NEED to fit a smaller rear sprockt (or a bigger front sprocket).
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125 trail bike, custom bars, handguards etc. - ?500.

"egg flied lice" - R6jonny (inspired by McGee)

[OreoXX]

Do not fit a smaller rear sprocket! If you want, you can fit a front sprocket with an extra tooth, this will give you some extra top speed in the expense of some acceleration. If your bike is French, German etc. import, you will need to change the CDI unit from CI639 to CI626 and the RC Valves Control Box from TV124 to TV78. You can find these at ebay or breakers for a total cost of about £60.

[trafficdodger]

I had my nsr derestricted and all i had to do was have it rejetted sorry every one i have to agree with alains. my top speed went from 75mph to 98 from rejjetting only.

Cheers

Nige

[OreoXX]

Me too, I haven't bothered to fit a new sprocket or anything, but I bought a new CDI and RC unit on ebay, since my bike is a French import and requires this if you want it fully derestricted.

trafficdodger, I assume your bike is a UK spec?

[trafficdodger]

Yeah its uk. It goes ok fast enough for what i want it for until i pass the full test.

Nige

[ayfy]

is a rejet a simple DIY job or do you have to take it to a garage, if so how much would it cost? also any instructions around on how to do it?

[alains]

order your jets first at https://www.dellorto.co.uk (about £3 each)
then you need to take the carb off :
- take off tank (1 bolt + fuel pipe) mind the rubbers on each side
- take off air box (2 screws , 1 collar between carb & air box and a pipe in front underneath)
- undo all pipes coming out of the carb , lift up the oil feedind pipe and let it up (avoiding oil leak)
- undo the screw on top of the choke et take it out
- undo the 2 screws on top of the throttle and take it out
- untighten the collar screw and now the carb is your's
to dismantle the carb :
- under the float chamber , in the middle , undo the bolt , the float chamber will separate
- the main jet is in the middle of this bolt
- the slow jet has same dimensions as the main jet
- the powerjet is much smaller than the others
- by the way clean the fuel strainer
- pay attention at the float valve
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the worst day fishing is better than the best day working

[OreoXX]

Isn't the slow jet a size between the main jet and the power jet? When I replaced my jets from 132-38-55 to 138-42-65, the main jet was the biggest, then the slow jet a little bit smaller, then the power jet was way smaller and had the size number on the side instead of on the top! My carb is a standard Dellorto PHBH 28mm

[alains]

you've got everything right , do not worry . now you will feel the difference , providing you had clean the foam in the air box and re-set your pilot screw (about undoing 1/4 to 1/2 round more than previously)
after the next 100 miles , check your plug colour here
https://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html
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the worst day fishing is better than the best day working

[OreoXX]

I fitted the 10EIX spark plug, and I have ridden for a while and checked it occasionally, it seems fine! the pilot screw also seems to be set fine, and the idle RPM is at 1400 +- 150 (appr.) My sprockets are standard sizes and I'm not considering replacing them either, the bike is fast enough!

[alains]

which size of sprockets ? when it will time to change them you will think about (for me ,the best is 14x36 , if you are lightweight you can run 14x35)
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the worst day fishing is better than the best day working

[OreoXX]

I have 36 on the rear, and I'm pretty sure the front is 13, I don't know if it is a 13 or a 14. If mine is 13, and I fit a 14, will I lose a lot of acceleration? Im not an expert on the topic

[alains]

i think if you have 36 at rear your front is 14 . it's simple adding a tooth in front will increase your top speed by 71/2 mph , taking off a tooth in the rear will increase by 3 mph . obviously if do the contrary you will decrease top speed . as it is easy and not expensive (less than £8) if you have a 13 in front , buy a 14 and fit it . if you are satisfied about your top speed & acceleration keep it otherwise back to your 13 . when you will buy a new kit you will know what you want
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the worst day fishing is better than the best day working

[OreoXX]

Sorry, I was wrong, my rear sprocket is a 35. And now I have no idea what my front is. How do I check this? And What do you recommend changing if the front is 13? Or 14?

[alains]

ok now , i think you have a nsr before 1993 . so the genuine sprockets are 13x35 . if you are not near the end with your sprockets , just buy a 14 and change it (see JT they are UK made) and when your chain will be worn (or your rear) buy a 14x36
here is the link (all sprockets are the same) :
https://www.jtsprockets.com/52.0.html?&L=0&sel_uid=151&p=
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the worst day fishing is better than the best day working

[OreoXX]

No my NSR is a 2001 model, but it had an owner before I bought it, maybe he changed the sprockets, I'm not sure. Anyways, I will buy a 14x36 set, since my sprockets are badly worn already and the chain is at the replacement mark

Will this make any difference if my sprockets are 13x35 now?

[alains]

probably an increase of 4 mph and not a big difference in acceleration 13x35=2.69 and 14x36=2.57 (about 4.5% more top speed)
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the worst day fishing is better than the best day working

[kenny]

you have got the same problem i have on mine v had mine deristrcted on the carb and exhuast then had a arrow race system put on then jetted up and it still only does 80mph top end but gears out so easy coz of the size of the sprocket

im getting a bigger front sproket and a smaller rear gear which should give me an extra 10mph
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KeNNy 100cc peugot speedfight 125cc Honda NSR125R 650cc suzuki SV650R 125cc suzuki GZ125 600cc yamaha YZF-R6

[alains]

hey , kenny can you reach 12000 RPM in 4th gear , if not , you have some other restriction . "the best animal on earth is the hen , because she only cackle when she has lay her egg"
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the worst day fishing is better than the best day working