nsr 125 urgent !!!

[jay123]

hi all i was woundering if anyone could help out at all im looking at an olld nsr 125 for a friend it gets to about 55 mph and thats it
doesnt have much of a band either its fited with a delorto carb withch i think is standard but has a k&n filter on it its all he has for it and was told because of the filter needs re jetting one of the jets is a 45 if that helps just woundered if anyone know the right jet size he should use and if the problem could be anything else many thanks all

[Jamie S]

Is it de restricted ? If not follow this guide and the bike should go a lot faster. https://nsr125.com/derestrict.htm

[jay123]

Nah dont think its been dersticted how would i know as usally deal in mx bkes lol

[alains]

normal jetting on JC20 (1989-1992) is 145,45,70 . normaly these bikes are not restricted apart the exhaust (easy to de-restrict) and the intake plate (between the intake pipe and the reed block) which i dont beleived it's still on . a poor power like this ,comes certainly from a worn piston,barrel , rings .......
you should have a pressure test
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the worst day fishing is better than the best day working

[john-125]

you dont want to buy it if its only reaching 55 mate
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honda nsr125 (h)reg

[ncrn]

It's possible that its not reaching speed cause the power valve is faulty, maybe the engine is slightly siezed up, it could be that the gearing is insanely bad. But I doubt that one.

I'd check that the servo motor (just below the fuel tank on the right there is some cables round a servo) this should open slightly at around 5500rpm, then fully at around 7000rpm, if it doesn't move then odds are it aint working.
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Past: 55 Sym Jet, 91 ZZR250, 03 NSR125R. Present: 97 ER-5.
https://www.nsr125.co.uk - NSR Owners forum.

[alains]

i agree
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the worst day fishing is better than the best day working