tuning tips !!

[FLASH]

has any 1 got any tips how to make my nsr125 rk go faster it is an import and it is on a g plate would a racing pipe and can help ? ive been told k+n filterwould make alot of difference plz help

[G]

how fast does it go now?

[James]

I did the full tuning works to mine. Fitting a K&N makes biggest difference of all bar a bore kit. Take alot of trial and error to get jetting perfect though.
Dont even think about fitting a K&N without altering jetting. Youll make it leaner than an ethiopian marathon runner and score/seize the fuck out of ya barrell.
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[Dylan]

More differance than a sports exhaust???
Dyl

[James]

Yep, quite a bit more difference than a sports exhaust when jetted properly. Youll be disappointed with just a sports exhaust on its own. Youll get more revs, but not much more power.
With the K&N and jetting sorted you get low down, mid-range AND top end power extra. If you use a sports exhaust, have you're had skimmed, advance the ignition timing very slightly, AND fit a K&N and again replace all you're jets to perfect sizes, which is what ive done to a few strokers in my time, you're looking at a very fast 2 squeeker indeed.

I wouldn't bother having your barrel ported and pollished. Usually people have the ports altered so the bike will rev higher but hit powerband later. Wouldn't advise this. Seen too many go bang.

My best advise would be, dont start messing around unless you know what you're doing. ESPECIALLY dont start messing round with stator coil to advace your timing unless you know very much what you're doing.

Happy stroker tweaking
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[Danny]

What jet sizes did u change upto & needle grooves moved to.

Ive got a micron system & carbon reeds & have raised the needle up 1 groove (2nd from bottom & it seems ok)

Did u remove all the airbox etc as ive got a K&N & a RAMAIR Filter already
just waiting to order some jets.

[James]

Yeah youll need to remove all the airbox and pipes. Bolt your K&N directly to the Carb inlet.
I went up exactly 20 sizes on the main jet and didn't touch the pilot jet for a while.
By the way Danny mate, if i was you when ive fitted all stuff i wouldn't put any plastics back on your bike cos youll only be taking them off every five minutes as itll take a ew attempts to get your jetting right. Engines love cold air, sadly when you fit your K&N, in summer it gets loads of air but the induction temperature is slightly higher. Id like to explain in more detail but im ina bit of a rush fella.

I had a web-site with some tuning stuff on there, but ive took it off to redo it. I writ a jetting article but never got round to finishing it.
The following should help you a little, the only way to really know how the bike is jetted is how it feels with different jets. Trial and error kind of thing. Anyway heres my jetting milarky:

Jetting: The jetting of a carburettor is the most important aspect of any engines performance. You can have your jetting in three different variants:

Lean Jetting: This is where the mixture of fuel to oxygen contains too much oxygen in relation to petrol. When jetting is like this it can make the engine run either very well, clean and crisp. Or it makes the engine gasp at full throttle and pull badly when under load. I prefer having an engine jetted the leaner side of perfect. The bike revs extremely cleanly without any bogging down and more importantly doesn’t have any flat spots at mid-rpm’s. Be very careful not to jet too lean as this will eat the engine and can cause a top-end seizure on any two-stroke. Its also worth noting that a leaner engine will run hotter.

Perfect Jetting: This is how most bikes come out of show room. However with 2-strokes manufacturers predominantly jet their bikes slightly rich, this slims the chance of a seizure and prolongs engine life and reliability. To determine how your bike is jetted you need to examine the spark plug. Most 2-stroke tuners will tell you to go flat out in top gear up a slight hill, pull clutch in and let engine stop. Then pull over and look at spark plug. This method is good, but it only tells you how the bike is running when flat out and will only tell you how the Main Jet is working. Instead of that procedure just ride the bike as usual and look at the plug occasionally. If the plug is black this is caused by soot fouling, and this is caused by having a mixture that is too rich. Eventually this mixture will lead to a weak spark and a misfire. A plug that is a light tan or brown colour is pretty much perfect. A plug that is a grey colour or has a blistered electrode usually indicates too lean carb jetting.

Rich jetting: If your engine doesn’t pull very well and makes an engine like a machine gun firing at mid-rpm’s then its very likely the carb jetting is too rich on the main jet.

I never got round to finishing the articel in greater detail. I really wanted to go about the feel of the bike etc but my many years of tuning since an early age have made me slightly tired of the subject. I prefer messing with my Rover 200

Good luck,
be careful though, cos its so easy to bash barrels with lean jetting.
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[Danny]

Thanx 4 the reply it was extreamly helpful m8,

When you say u went up 20sizes do u mean 20% bigger jets or 20 added on to the orriginal etc?

Does your NS125F(i think thats right) pull to the red line, what speed do you get, power & MODS have u done to it & what sprocket sizes did u use (find best). Mine does not pull 2 the redline in 6th & struggles to do 85mph, any ideas

cheers m8

[Arne]

Anser for fuck sake!

[tanner18]

chill out arne
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[James]

I meant 20 jet sizes
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