NSR 125 problem 8000rpm

[RSD00]

Hi, i recently buy an NSR 125 (ZDCJC22B) - i think french
I changed oil,air filter but it works perfect untill 8000rpm at 8000rpm it stucks and doesn't go up to 9-10-11k rpm.
Goes max 80km/h.

What should i do ? Can you give me some advice or some steps to follow to solve my problem.. ?

[-]

Strip and clean the carb and jets. Check fuel flow. Check compression.
____________________
TZR250 2MA road, TZR250 1KT road, TZR250 2MA race, TDR250, YZF-750R Boost colours.
Jaguar S Type 3.0 V6 Sport R, VW Transporter T5 GP LWB Shuttle 140ps DSG.

[RSD00]

i will check that, but alains in the last topics said something about an "red shunt" under seat

i think there is an german limiter at 80km/h

[Easy-X]

French bike? German limiter?! Roll on Brexit
____________________
Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[RSD00]

I saw in one post the french bikes got limiter like german bikes ..

[Easy-X]

[RSD00]

1998 year

[-]

[-]

[MarJay]

When you say changed the air filter what exactly do you mean? Ripped off the airbox and replaced it with a pod? Or replaced the standard filter with another OEM standard air filter?
____________________
British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[stevo as b4]

I'm no NSR expert, but firstly the OP needs to decide if the bike is speed limited by a fault/wear, or if its by a restriction.

I remember Alains posting up about all kinds of different NSR specs, and particularly different CDI boxes too.

If the bike is limited to 12/15bhp it should still accelerate past 50mph with ease. If the bike has a fault or wear that's reducing power very significantly then it might be down on power enough to only reach 50mph. It'd have to be pretty knackered andow on compression to do this I would have thought?

I don't think Honda used speedo restrictions like a Reed switch for example, and the NSR250's are more advanced in that the ignition system is linked to a gear position sensor. This allows them to really only restrict the bike in mph, by messing with the ignition timing or rev limiting in say the top three gears.

I don't know if the 125 NSR is as advanced as that, but it'd be worth checking.

If I was OP however, I'd be giving the bike a full detailed service and possibly an engine rebuild depending on the compression reading etc. Then I'd want it on a dyno to see if it's fueling correctly and if the power output is in the right ball park which should be 20 something bhp at the wheel.

If I had any doubts then about the CDI being either faulty or having a restriction built in, then I'd go for an aftermarket CDI and get it set up correctly. OK dyno time and programmable ignitions aren't cheap, but if I wanted a pride and joy 125 to run as well as possible it'd be worth it IMO.

[RSD00]

I changed air filter with a new one standard, it not revs after 8000rpm doesn t matter if is in 1-2–3-4-5-6 .. in 8000rpm he locks there and misfire between 7500-8000


Idk when was the last time when was changed top end

[Tankie]

Is the exhaust clear of coke? restriction of revs is a sign of carbon build up, check the exhaust port in the cylinder and then check the rest of the system
____________________
Always learning, everyday is a school day

[Ice Burger]

Check the RC valve, it's a device that's supposed to kick in at higher revs and change the mixture to achieve a taller rev range. Maybe yours istnt working properly or not doing anything.

https://en.wikipedia.org/wiki/Two-stroke_power_valve_system#Honda_RC-Valve

[-]

[alains]

for everybody and especially for you
french bikes are not limited at 50 mph
some swiss bikes have a limiter with a red shunt on the valves controler
german bikes have a CDI CI626A in order to limit at 50 mph for youth
but as french bikes have CI639 a special wiring must be fit to obtain the same result as above
as i dont like DIY for the wiring , i suggest to change the harness
PS i think our young fellow is a bit hard to convince
____________________
the worst day fishing is better than the best day working

[Ice Burger]

This might sound really obvious but check the choke isn't left on.

[alains]

that's a comment from a guy who knows nothing !
____________________
the worst day fishing is better than the best day working