honda nsr 1125 jc20

[Burnzy1989]

Hi all does any one know if I can get aftermarket parts for my nsr im in need of a exhaust, carbon reeds, and a 32mm carb and manifold to bolt the carb on. I am also splitting the cases to match up the transfer ports to the barrel as manufacturing costs to match things up cost too much so it will be interesting to see if it makes any difference.

[stirlinggaz]

hi,
just out of curiosity, why a 32mm carb?
most ppl ask about the more common 34mm, due to there being an abundance of dellorto vhsb 34mm carbs about, often fitted to carts (rotax max) aprilia rs125's (LD version) & sometimes the cagiva mito (ES version - this is the model I have).
if you specifically want a 32mm, look for a dellorto vhsb 32 that came off a certain version of tzr125 ( I cant remember which 1, sorry) but these are a bit harder to find (I also have 1of these )
the carb manifold off a cr125 will fit as its intended for a 37mm carb.
LATE EDIT : you could just stretch the original manifold in boiling water.
problem with the bigger carb is, it won't fit onto the air-box, so you'll need to find a bit of hose to join the carb to the airbox, this wont stretch im afraid.

reeds : plenty of carbon reeds available. including v-force but I went for the ones Alain (BCF's resident nsr guru) recommends...i cant remember the brand but im sure Alains will point you in the right direction, or you could look in his nsr tips document which can be found on-line (its more for the jc22 but well worth downloading) the reeds are, iirc, intended for jc22 versions of the nsr but seeing as they share the same engine, im sure they will work just as well on a jc20 as they do on my foxeye.

exhausts : theres a guy called Romeu in portugal making very nice expansion chambers/exhausts for the jc20 (& plenty other 2t bikes)
he advertises on ebay & is active on fb. his prices are very good, especially when compared to jolly-moto, giannelli etc & ppl have many good things to say about his pipes.
im considering having him make me an expansion chamber for a project nsr (jc22) that will have a mallossi 180cc cylinder....when I get around to buying the rest of the parts I need.

cheers,
GAZ

[Burnzy1989]

thanks for the reply , a 32mm carb will give better low speed throttle response instead of it bogging as iv learnt with trials bikes and motocross bikes they use smaller carbs for sharper response and larger for higher rpms , just also comes down to the crank case volume as it can only hold and deliver x amount of fuel and air as the port timing is so fast you only probably get 100cc of fuel and air into the cylinder , but it will a experiment to use both sizes of carbs , yha iv sen the exhaust on ebay but wasn't sure about it as you have to know what you are doing you can ends up melting your piston . but a 180cc block will pull it up to 110mph easly lol . I guess im trying to make the best out of the little 125 as possible refine barrel to crank case ports polish the exhaust port to a mirror finish,

[stirlinggaz]

hi,
like I said, I can recommend both the dellorto vhsa/b 32 or 34mm carbs,
but you will need to fabricate a joining pipe for carb to air-box (dont be tempted to ditch the airbox, just open it up a bit)
the 34mm is the more popular upgrade (probably cos there's very few 32mm's about) so theres definitely info out there
remember the same engine (near enough) is fitted to the cr125 with a 37mm carb, so its capable of making the most of a 32/34mm carb...imho..
I'd suggest speaking to Romeu direct, he seems to know his stuff & theres plenty people out there using his pipes.
if you explain your intentions, he can probably make a pipe to suit,

cheers,
GAZ

[stevo as b4]

Unless you've seen the insides of a stripped NSR engine, and know for a fact that port/cylinder/crankcase matching is really poor, and can be noticeably improved over factory spec by yourself at home, then I really think your clutching at straws there IMO.

Your posts come across almost like your trying to give us all a tutorial in how to tune and set up 2stroke engines, yet you were originally the one asking questions. I think you will also be surprised just how well matched up the parts are on a Honda two stroke engine that has high performance as std. If there were large gains to be had from better parts matching, I really think Honda would have taken the trouble to get at it.

A slight carb size upgrade, Vforce reed block and a custom pipe and ignition would probably be the best value gains to be had from a 125cc motor, with some professional dyno set up time after.

Anything else will be lots of work for small gains, even porting and careful setting up/optimising the squish and compression ratio.

[Burnzy1989]

I was responding to why I wanted a certain size carb and not giving any lecture I was also asking initially what parts are available for the nsr, as Honda have ditched the 2 stroke development.

I just want to improve on it , the bikes a winter project I have neglected the old girl in the shed and feel a good spruce up is in order , I will only know when I split the cases and bolt the barrel to the one case and see if it needs doing.

I also made the fatale mistake a few years ago of not checking the ring gaps when replacing the piston rings (I have learnt a lot since then and not saying I know it all and still ask when im not sure and not blowing my own trumpet) and its what caused the scoring marks where the ring end gaps are and need to scrap them and was wondering if any one uses foged piston like wossner and wiseco on the nsr .

I gues your right I will get in touch and see what he can do for me and I will keep a eye out on ebay for a manifold but is there any particular year of cr that I need to get it off ,

Thanks you both for the replies Ian

[stirlinggaz]

[Burnzy1989]

[Burnzy1989]

ok iv got the barrel off and found a mess my barrel exhaust bridge is cracked , the rings were too tight and the piston has been polished on the bottom skirt , but bear in mind this barrel is only 300 miles old roughly I hardly used the old girl after the barrel was done. never rode it too hard ether. here are the pics iv had to use photobucket https://s700.photobucket.com/user/burnzy1989/library/?sort=3&page=1