NSR125 lost its grunt!

[neon]

not that it had much to begin with

no, but seriously, it seems to have lost what it had, takes a while to build up rpm. would it be the spark plug is old and needs changing, would that make a difference, or could it be summin else?

[alains]

start by changing your plug , but it appears to me that it is more a power valve problem than anything else . check that at the servo pulley(under the right side of the tank) . key on valves open fully , start engine valves close , throttle up to 6500 rpm valves starts to open and go fully open .
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the worst day fishing is better than the best day working

[JakeyC]

same problem here mate, mine was left standing for 2 weeks and is gettings it grunt back now, but there is still some more noise left behind, and to narrow thnigs down for you, my sprakplug, and my valve was fine, my next step is redex lol

[alains]

what do you mean by redex ?
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the worst day fishing is better than the best day working

[Rs-Sean]

Wo redex lol if you have changed your spark plug to a new 1 and its still powerless and your powervalve servo is working fine take your spark plug out stick your thumb over the hole where the spark plug went into and hit the starter hold your thumb on there as hard as you can and if its not blowing your thumb off your losing your compression slightly take it to a honda dealer and get them to presser check it for you god luck

[alains]

thanks !
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the worst day fishing is better than the best day working

[tokarev]

[DisabledRider]

my nsr is also dieing, Im going to put my jolly on soon and fully de-restrict it, but need to set it up properly.

I want to have it fully serviced and de-carbonised but I reackon a dealer will charge me an arm and a leg.

Anyone want to guide me though it, or link me to a guide on servicing the whole bike?

I can do most things so hopefully it wont be too bad, and I dont mind taking the bike off the road for a week cause I want to have it re-sprayed etc.

Thanks

[alains]

the works (as says honda) is 3 hours to de-carbonize . do not forget to change (at least) the rings and that you need cyl head gasket , base cylinder seal , valves axel seal , piston pin , small end bearing , clips (2) . remember also that the valves axel nut is a left-hand thread (if you DIY).
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the worst day fishing is better than the best day working

[DisabledRider]

ok sounds good, is their anything else I can do? Im gonna replace brake pads, all the oils and everything at the same time, just wanna get it mint again.

cheers

[alains]

if your bike has around or more than 15000 miles , i recommand piston change , the only problem is for ordering it you need to know the size (it's shown underneath the barrel with a letter A to E) see the workshop manual for the diameter of letters . you cannot put a C piston in a B barrel , need the same letter . if you approach 22000 miles it's better to change cylinder-piston kit (£85 ex VAT) and you need all seals & the rings .
https://www.davidsilverspares.co.uk
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the worst day fishing is better than the best day working

[hproduction]

Been reading some replies from you and I need help. I need to know where the powervalves is/are so I can clean them. Also my Servo, i'm not sure how it works but it's always on Low. When I "Key-on" it twitches but remains on Low. Rev up to 6500 and over it still remains on Low. Is this right?? I need your help.

I believe it could be something to do with the CDI maybe?

Thanks
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[alains]

it's a red/white wire coming from the cdi which transmit the engine speed to the rc valves unit . if the info doesnot get through , your valves will not move . check for a loose contact . look the joined picture and tell me
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the worst day fishing is better than the best day working