Jetting

[BrakesR4pussi...]

Have been riding my bike approx 1 year now, got it for my 30 mile round trip to work....only in the last 6 months have i got into learning a thing or two......but am completley lost when it comes to jetting.....after deresticting everyone is going on about rejetting...i take this to be the amount of air / fuel allowed to go through the carb (is it?) compensating for the extra power......

I got a de-restricted exhaust but if i dont do the above is it just a waste of time???

Any explanations will be much appreciated as i feel a bit of a tit! 25yrs old and still dont know about engines.......

oh yeah just wondering when your riding does anyone acknowledge peds/scooters??

[Gazdaman]

I acknowledge peds/scooters.

When you open the throttle a slide lifts in the carb, letting more air through. At the bottom of the slider there is a needle, this needle goes into your main jet. So when the slide is closed, the main jet is sealed.

As the tapered needle comes out of the jet, the air rushing past sucks petrol out from the float bowls in your carbs.

A bigger jet lets more petrol through. If you've derestricted the bike needs more air/petrol mixture.

But if the amount of petrol is restricted it'll just get more air, which will mean it'll run lean, which is very very bad.

Hope that helped.

Gaz

[John C]

So may NSR 125 with the restrictors taken out won't last five minutes unless I get it re jetted??

[Gazdaman]

It's advisable you/get someone to look at the jetting after derestriction, depending on the method.

Gaz

[swampy]

If you derestrict an NSR by removing the exhaust and intake restrictors, then you shouldnt need to fiddle with the jetting (lots of people here have done it, and I think that most have just left the jetting as stock). However if you swap the exhaust for a non standard unit, then you may well need to upjet. The reason that running a bike lean (too much air, not enough petrol) is a bad thing is because a lean mixture will burn hotter thus buggering up things like cylinder and piston.

HTH
____________________
"I hate to advocate drugs, alcohol, violence or insanity to anyone, but they've always worked for me." Hunter S Thompson
"Faster, faster, faster, until the thrill of speed overcomes the fear of death..." Hunter S Thompson