nsr 125 probs helppp

jimmycc · L Plate Warrior Joined: 22 Nov 2013 Karma :

hi my nsr 125 square headlight classic model isnt revvin out, it get to 7-8 000 revs and bogs out,it smokes like hell as well any ideas on whats up with it,suspecting crank seals as ive changed air filter, rubber between engine and carb, cleaned tank filter ect ect ,it also isnt brill at ticking over, Embarassed

bought it like this so dont know too much of history cheers jim Mad

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rjchapman

WD Forte · World Chat Champion Joined: 17 Jun 2010 Karma :

I know sfa about the NSR and usually avoid 2 strokes nowdays but
dont bad crankcase seals usually lean out the mixture ?
your sounds like its too rich( flooded crankcase?) or getting excess oil.

We used to give the exhausts a dose of caustic soda to clean out
the pipes from time to time as well to help em 'breathe'.
Mind you, it was on pretty agriculteral stuff using pre mix.
I expect the NSRs much more sophisticated than the things we used to hack about on.

Is the plug/ignition system up to par?
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jimmycc · L Plate Warrior Joined: 22 Nov 2013 Karma :

dont know much about them but it wouldnt run off choke/or tick over, and it smoked like hell,changed what i mentioned and also i noticed a groove where needle sits so i changed needle mechanism and now it just about ticks over,but it wont rev out and bogs,it seems to smoke less when warm but just wont run right,put new plug in and was black,god know lollll fookin bikes yeeeehhhhaaaaa Middle Finger

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rjchapman

DMCpro · Traffic Copper Joined: 16 Jul 2012 Karma :

Drain the gearbox oil if it smells like petrol your crank seals are gone
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jimmycc · L Plate Warrior Joined: 22 Nov 2013 Karma :

cheers ill try that regards jim Twisted Evil

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rjchapman

skatefreak · World Chat Champion Joined: 06 Feb 2010 Karma :

Evening there.
Right, if it is anything like the later NSR's and if it has a power valve then this is what you want to be looking at.
These engines essentially have a flap over the exhaust port, when the engine gets to 7,500 rpm a servo opens up this flap and you get the surge of the power band.

I know that with the JC22 (fox eye) the power valve is open from 0-2,000 rpm, closed from 2,000-7,500 and open from 7,500 +.

Because the power valve compliments the tuning of the engine, without it operating the engine will now run well. Once with electrical problems I had the power valve stuck closed and indeed idle became poor/lumpy and anything over 7,500 was uneventful.

Shamelessly plagiarized from another website as its late and i'm off to bed but good advice Thumbs Up

Bomberman · World Chat Champion Joined: 17 Aug 2004 Karma :

My TZR had similar issues, turned out the oil pump was shot.
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Vincent · Banned Joined: 16 Oct 2006 Karma :

When was the exhaust last cleaned through?
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jimmycc · L Plate Warrior Joined: 22 Nov 2013 Karma :

thanx for all replys,im at mi wits end so im takin engine out and changing bottom end,im sure piston and rings are ok and carb ect , can anyone tell me the combination ie allspeed exhaust ,main jet size? is there special reed valves to match, k+n ect ect, im really keen to get this bike ruunning sweet then i can put pics on and everything cheers jim Embarassed

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rjchapman