ns125r questions and oppinions

[fanatic88]

Heya evryone , im new here , im boban from Serbia and i ride ns125r from 1989 year... Finaly after 2 years of riding i decided to fix and refresh my bike as much as my budget alows me to . Got few questions to ask , if u got time id appriciate your answers and suggestions.

1st- Would K&N filter give my bike bit more speed/acceleration ? Would he "eat" machine?

2nd- Ive read aloth about 2stroke exaust , learned i cant change the exaust pipe , could i just change the exaust at the end? If i put bigger exaust , from a bigger bike , etc from 600ccm , would it be better or worse?

3rd- As u can see @ the image bellow , there is aluminium part between arrows. Is that intake restrictor? Should i take it off? If i do would it hurt to the engine?
https://upload3.postimage.org/384171/a56e867d1.jpg

4th- Is there any chance installing electrical starter to my ns? If it does what parts do i need?

Id be really thankfull if you could help me ... Cheers!

p.s Bike dont look this bad right now , its being repaired , repainted , im going to paint each part and try to bring it old retro style shine...

[biker_king]

hi, a k&n is not suitable for two strokes and will actually slow downe the acceliration its best to keep the original air box and filter for healthy running.
also the exhaust of a two stroke engine is verry inportant to the way it runs/preforms ect so would be best to leave it standard.

these bikes are pretty nippy when de restricted so would be worth de restricting it i think their is also a exhaust restrictor but not shure so would be best to get help from someone else.
hope this helps.

[ncrn]

Well just wanna say the K&N filter won't help a 2 stroke engine at all.

Also a larger exhaust will not help the 2 stroke engine run, its shape is very important to how the engine runs, if anything a bigger exhaust will make the bike slower.

There may be restrictors but I don't know anything about the ns125 I'm afraid.
____________________
Past: 55 Sym Jet, 91 ZZR250, 03 NSR125R. Present: 97 ER-5.
https://www.nsr125.co.uk - NSR Owners forum.

[fanatic88]

Thanks for answers. I was thinking also that K&N wouldn't give me any performance. Im thinking to drill holles on airfilter so it can suck more air ... About exaust , i was thinking to change just the part where is that shiny pipe , the end - eiher modify it or put different one , does whole exaust affects to the bike or just the part where pipe is huge ?

[ncrn]

The full system effects the exhaust emissions. You want to keep the whole thing the same so that the bike can pull enough waste gas out of the cylinder.

There may be some plates that you can remove from the inside of the exhaust that will improve the bike, I know there is in the nsr, but then it may be different between the two.
____________________
Past: 55 Sym Jet, 91 ZZR250, 03 NSR125R. Present: 97 ER-5.
https://www.nsr125.co.uk - NSR Owners forum.

[Evo]

Just where pipe is huge = Expansion Chamber. Thats most important part of it. I don't think the silencer has a great effect other than it's obvious job. But wait for someone who knows better to reply.
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Bikes owned
1989 VFR 400 RR NC30

[hmmmnz]

there are plenty of aftermarket exhausts for thensr that will actually give you better performance, the expansion chamber on any 2 stroke is very important, that is where most of the tuning is done,
bear in mind you will have to change your jets in your carb to benifit and exhaust changes usually you get these when you buy a bike specific 2stroke pipe, the silancer on the end does nothing except quieten the bike, you could run without it with minimal ill effects.
you could give the ports a bit of a polish to help things moving more freely,
don't drill your airbox!!! this will only make your bike run like shit,
if you want more performance buy a new pipe!!

edit.... its a ns not an nsr

good luck
____________________
the humans are dead
I kick arse for the lord
Wiring Diagrams BIDNIP it bitches

[Kickstart]

Hi

NS airbox was a poor design. A K&N / S&B type air filter might well help, although be prepared to play around getting the jetting right. Also have a feeling there was a spacer tube around when the NS was popular to help it work with a single filter.

The bit the arrows points to is the reed block. Not a restrictor (engine would stuggle to run at all without it).

Changing the silencer won't do much. Fitting one from a larger bike will just add a load of weight.

As to an electric starter. Anything is possible (you can get electric start conversions for 60 year old Vincents), but not at a realistic cost.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Welshd1k]

oh its a ns125rk1

with twin front disks wanna sell me the complete front end??


and restrictors i found where:

just the one in front expansion chamber in exhaust poet drill it out.

and add a 14 tooth front sprocket and it was ace

and who ever put up all the links this bike is a ns not a nsr
____________________
Current >Cb600fx hornet, ns125rk90 21.7bhp@wheel<
Sold >,zxr400 h2 (33bhp kit) rd350 n1 rd350 lc2<

[fanatic88]

Thanks for answers.
@ns125rk90
Can u paint on picture where is that exaust restrictor?

So should i put K&N or not? its NS not NSR

Im planing just to modify silencer , planing to make small slipon silencer for my bike.

@Kickstart
Thanks didnt knew whats that part , tought its intake restrictor... Did u had K&N on ur ns? Thanks.

[alains]

NO K & N ! mixture will be unstable . all the exhaust listed ARE NOT SUITABLE for your bike ! the NS125 is totaly different than the NSR125 . here are the types :
1987-1988 TC01
1989-1992 JC20
1993-2001 JC22
a lot of spares are the same for JC20 & JC22 but none for TC01
____________________
the worst day fishing is better than the best day working

[fanatic88]

@alains
Thanks . Could u give me some info about my bike , it seems ur bike fanatic as i am ... Restrictors , what could i do to get better performance or just help my bike to run better?

Best regards , fanatic

[alains]

i am a NSR fanatic , not a NS and i am sorry but i cant help you
____________________
the worst day fishing is better than the best day working

[fanatic88]

Damn ... Thanks anyway

[Kickstart]

[Welshd1k]

your exhaust looks derestricted also looks like it has a larger bore pipe between expansion chamber and the end can. more power try a kandn they make hell of a difference if your willing to lay around with the carb setting.
____________________
Current >Cb600fx hornet, ns125rk90 21.7bhp@wheel<
Sold >,zxr400 h2 (33bhp kit) rd350 n1 rd350 lc2<

[fanatic88]

omg i cant decide now ... K&N or Standard ?
Half ppl said no , half said yes ...

[fanatic88]

Im going to order K&N , its around 30 euros here , so aint much , if it runs better ill leave it , if doesnt just going to send it back to seller wich can be done here. Now he asked me what "FI" , the size of filter i need? I guess i need 26mm one cause charb is 26mm as it says on this link

https://www.motorcyclespecs.co.za/model/Honda/honda_ns125r%2087.htm

Or im wrong? Thanks

[Kickstart]

Hi

You are wrong. the size refers to the outer diameter of the inlet to the carb (ie, the filter clamps onto the outside of the carb inlet).

The problem people say with K&Ns is that the metal plate at the ends causes pressure waves through the carb at some revs, giving a very rich mixture (and why the Ledar kits came with extension tubes to move the filter further from the carb). The foam Ramair type filters apparently do not suffer this problem.

Order a few spare main jets and be prepared to spend some some playing with the jetting to get it acceptable.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[fanatic88]

Well there is a problem ... Only filter i can get here is K&N ... Tho i could make expansion from a plastic pipe ? When u said jet u ment air filter or someting else? Im pretty bad with english part names . Thanks for answers , if i ever come to UK ill buy ya a beer

Cheers!

p.s anyone knows that "FI" size of ns125r charb?

[edit] Ive googled and ive found what u ment - thats main jet right?

https://www.harley-performance.com/images/main_jet.jpg

also found this

[Kickstart]

[Welshd1k]

kick start one of these kits ??
https://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=170155288030


____________________
Current >Cb600fx hornet, ns125rk90 21.7bhp@wheel<
Sold >,zxr400 h2 (33bhp kit) rd350 n1 rd350 lc2<

[Kickstart]

Hi

That is the replacement nozzle, there is also a tube kit (none of them are common these days).

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Welshd1k]

he has more by the looks of it

https://cgi.ebay.co.uk/honda-ns-125-fh-fg-rk-L-E-D-a-R-2stroke-nozzle-kit_W0QQitemZ170156181854QQihZ007QQcategoryZ10460QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

and kickstart says