issue with my bike help please

[shuffy1989]

Hi all i have gone and brought my self an 2004 honda nsr 125rr full power,

just one thing i am struggling with i think it may be the carb so here i go,

The other day i managed get it started and seemed a bit hard start, i kept the choke on for a bit and was running sweat, i then took the choke off and the revs went so low that it cut out, so i started it again would only start with choke and i kept the revs on manually for about 5mins so it was warm, as soon as i let go it cut again, so this time i tried a few more revs and when i rev to about 5k it just goes syco and starts picking up revs on its own also the revs take a while to drop down, I have checked there is no air leak what i can tell, does anybody have any idea about these. Thanks in advance

[Efes123]

Inb4 sell it and buy something more sensible

Serious answer. When you say "full power" what do you mean? It does sound carb related, and sounds like the idle speed is set too low, needs a small turn on the screw. Have you tried spraying some quick start, or something similarly combustible around the air box intake? If it revs higher when you do this, then you have a loose connection.
____________________
Honda Goldwing GL 1000 Current love
Honda VT500 ED - SOLD
Projects Suzuki GS125 Done, then stolen - Kawasaki GPX750R SOLD - Honda VF750S SOLD

[UnknownStuntm...]

[Efes123]

[shuffy1989]

hey thanks for your replies, this bike is somewhere near 33bhp, from what the guy told me it has been jetted in stuff with a power valve, tbh i don't really know much about these, And no i haven't tried spraying quick start in, i would have a tinker with the idle screw but all i can see is a big gold one it is a lot bigger than a usual one so im a bit baffled, I can tell tho it has not got the original airbox tho would this be an issue ??

[UnknownStuntm...]

These three things:

* it has been jetted in stuff with a power valve
* a big gold one it is a lot bigger than a usual one
* it has not got the original airbox

...lend me to think it's still an intake issue. When you 'jet' something, generally you put a bigger needle in the carb. This allows the carb to suck more fuel in. To keep the engine working right, it needs to take more air in too. So the airbox can be played with too - normally just a higher flow filter will do the job. Removing an airbox altogether is a bad idea as it restricts the air to somewhere near the capacity the carb can deal with.

I'd suggest looking at the air box, maybe get hold of an original one, and see if it works better with that.

[Efes123]

That's the problem with these bikes, too many people f**k about with them trying to get more power and end up screwing the bike up .

I do hope you have a license to ride it

Anything done to de-restrict it by it's nature will have an affect on the fuel mix, including idling settings. Check the rubber collars where the air box and the carb meet. Are they in good condition, and are they tight? I presume the "jetted in stuff with a power valve" means that the jet sizes have been modified, but not quite sure what the power valve bit is.

EDIT: Damn, need to type faster, although you answer is more eloquent
____________________
Honda Goldwing GL 1000 Current love
Honda VT500 ED - SOLD
Projects Suzuki GS125 Done, then stolen - Kawasaki GPX750R SOLD - Honda VF750S SOLD

[shuffy1989]

Thanks i will get an airbox sorted, How hard is it to setup a carb, i herd you do something with a needle and that will be the correct measurement any ideas thanks

[shuffy1989]

this one has been messed with im just trying to get it running sweat, From what i know power valves work as when the engine hits a high rpm it will release pressure out of the exhaust it has an expansion chamber, sorry if i got it wrong surely somebody will know no it works

[UnknownStuntm...]

Look at this, compare images etc:

https://www.nsr125.com/derestrict.htm

If I were you, I'd half trust the jetting to be 'working' so don't fiddle with that. As Efes123 said, check the rubbers and small pipes all around the place, make sure there's nothing 'missing'.

[Efes123]

It's unlikely you'll be able to get it back to 'normal'. I seem to remember reading somewhere that de-restricting requires drilling into the exhaust and doing 'something', sorry, memory is a bit vague.

Just start with checking the connections. Too much or too little air will have an effect. If you try putting the original; box back on, you'll then have to change the jets back, as US says, try not to change too much at any one time. And try the simple things first.
____________________
Honda Goldwing GL 1000 Current love
Honda VT500 ED - SOLD
Projects Suzuki GS125 Done, then stolen - Kawasaki GPX750R SOLD - Honda VF750S SOLD

[shuffy1989]

Am i right in saying this carb have x2 breather pipes ??

[Efes123]

One will be a drain pipe (should be fairly small diameter) at the bottom of the carb (it to drain excess fuel from floats), the other, more normal size, is the breather. There should be an oil and a fuel pipe in.
____________________
Honda Goldwing GL 1000 Current love
Honda VT500 ED - SOLD
Projects Suzuki GS125 Done, then stolen - Kawasaki GPX750R SOLD - Honda VF750S SOLD

[shuffy1989]

Ohhhhhh i have 2 tubes at the top coming out but i only have one pipe in take it as that is fuel so i am missing oil !!

[Clutchy]

Some of these bikes are modded to run pre-mix (pretty pointless, usually when the pump fails) and they do away with the 2t reservoir, does yours have one? Have you topped it up?


Does sound more like a low idle? Can you rev through the whole rev range?
____________________
Malaguti F12 Phantom-Dead, Suzuki AY50- Dead, NRG power DD LQ, CBR125.
*33 BHP restriction up on 10/12/14* Current bikes/car: SV 650 S/ MKIV GOLF
Guide to pass your test with no lessons!

[Efes123]

Don't get too excited, it may not be a standard carb. Does it look like this:
https://www.ooracing.com/store/images/uploads/Carbs/carb-2367908712346-09781234.jpg

or this;

https://i.ebayimg.com/t/carburettor-carb-honda-nsr-125-2003-20263-y-/00/s/MTIwMFgxNjAw/z/fpIAAMXQw8hRaDsm/$T2eC16J,!)sE9swm(vm4BR,DsmfGmQ~~60_58.JPG

The top one seems to be a racing carb, the other I think is the standard. Are both of the pipes coming out if the top connected? One should go to your fuel tap.
____________________
Honda Goldwing GL 1000 Current love
Honda VT500 ED - SOLD
Projects Suzuki GS125 Done, then stolen - Kawasaki GPX750R SOLD - Honda VF750S SOLD

[Efes123]

[shuffy1989]

Hi its the bottom carb, but the gold nipple what you see is connected to fuel and the other 2 aint connected to nothing, and for revving thru the range tes it does only did it once i took the revs high and they just carried on going on there own until it reached max so i pressed the kill switch nothing carried on so turned the key off and it still carried on, so i turned the throttle back and it cut out, I am confused

[Efes123]

TBH, this is a bit difficult as have no idea of what's been modified I found this which might be useful to you:

https://www.nsr125.com/derestrict.htm

It sounds like you have two problems: 1) the idle is too low, and 2) the high revving.

1 should be a simple adjustment by turning the idle screw in slight increments, should be done when engine is warm.

2 could be several things. It might be worth while whipping the carb off and opening it up to see if there's any gunk inside, and the floats are working as they should. A fairly simple job, just make sure you don't damage the gasket, or you'll have to buy a repair kit. They don't cost a fortune, but it'll mean the bike's off the road till you fit it. You'll also need to go over the air box with a fine tooth comb to check for cracks, and the state of the air filters.
____________________
Honda Goldwing GL 1000 Current love
Honda VT500 ED - SOLD
Projects Suzuki GS125 Done, then stolen - Kawasaki GPX750R SOLD - Honda VF750S SOLD

[UnknownStuntm...]

[Efes123]

[TheSmiler]

Meh I'm no help with bikes but to me something sounds like sticking throttle or air leak.

[raesewell]

Shuffy please learn to spell, bikes dont sweat
I think you meant sweet
____________________
Yamaha FJR 1300 Normanton West Yorkshire