To do my best to inform and to hopefully lay this mess to rest I've decided to compile what I know into a (not very) short post and try and clear up some of this jetting mess.

First and foremost; A healthy ruck is a happy ruck. Before you go buying jets from bss or bowls because you think your ruck isn't running right; Clean the thing up. Check and change the oil, the gear oil, the plug. You've all heard it before. A simple touch of my idle-mixture had my bike running terribly. A touch in the other direction and it ran like a champ. There is a LOT of things that CAN and WILL go sour on the ruck that CAN and WILL affect performance. Just because it's running bad does NOT mean you need to re-jet.

With that out of the way, let's try and figure out what it is we're actually talking about with jetting. If you're confident you know how an engine works, then skip past this; otherwise, keep reading.

Your engine makes fire. It's as simple as that, fire makes you go. You need a handful of things to start a fire. You need oxygen. You need a fuel of some sort. And you need to ignite the fire. The more powerful the fire/explosion, the more power you make. You can't just throw fuel and air at an engine and expect to get a powerful explosion (although I'd like to see a video of this.) Your engine (unless your a euro) is carburated. This means that there is no complex fuel injection system to counter and readjust when you add or take away the amount of air you put into the engine. It is up to you to add or subtract fuel as needed.

Well how do I know when I need more fuel? Simple, darling. You need more fuel when you've added more air. So what is our goal? What is the proper mix?

Ideally, you want your engine burning stoich. Stoichiometric. The stoichiometric air-fuel ratio for gasoline is 14.7:1. This means that it takes 14.7 parts air per one part gasoline to make the ideal explosion. There ar exceptions to this in the automotive tuning industry but I'm trying to keep this as simple as possible. So what if I'm not stoich? Well then you're either lean or rich.

Lean is a condition found when not enough fuel is present for the amount of air. If you remove your stock airbox and the restriction it applies to the air intake track, you allow the engine to take in much more air. If fuel is not added to counter this, you will run lean, and in the rucks case, very poorly.

Rich is the opposite of lean. Rich means you've got more fuel than you need for the amount of air you have. Say for instance you leave the bike stock and move up from the stock jet to a much larger jet, you will run very rich and will end up drowning in a sea of gas and despair.

The common lingering thought I see floating around is the fact that jetting is a way to add power. Well without any sort of supporting change in airflow, a change in fuel will not help you at all.

To summarize,more horsepower comes from bigger more intense explosions. Explosions require a proper mix of fuel and air. If this mix is not found, power is lost, period.

Lastly, SEARCH THE INTERNET. It's full of information that I ASSURE you is better than what you're reading right now. Do not be afraid to dig in and actually learn something, and do NOT expect everyone to want to teach you.

fin.

So how do i know when to rejet and when not to?

And will a 100 main make me go faster?

anyone can do jetting by trial and error, and seeing which goes better.

once you get used to it, you can just plop a jet in there, and feel the carburetor circuits whiile it is on the centerstand.

lean is a little tough!
it will fade, and you will have to ride to know for sure,

rich is easy!
start high, keep going down untill it is crazzy fast!!!!

You should rejet about everytime you change your oil. Make sure and re-oil the new jets before installing them.

Yes, but you'll want to make sure and recalibrate the speedometer to take advantage of the new found power.

I am not trying to be a jerk, and i even posted my findings on the stock carb, but finding a jet by trial and error can be super time consuming, i know so far, that most mods, do not require a bigger slow jet, but setting on a main jet and spring lenght, have being (at least for me) quite a challenge, i was hoping you guys know an easy way

I definitely don't think you're being a jerk at all. I agree that jetting by trial and error wouldn't be the easiest way to do it, but for some of us it might be the only way. I've read your threads on the carb and they were very informative. When I finally move to a pod filter set-up, I'll just order a multi jet pack and play around until I get it right. I'm not worried too much about it as I've broken the stock carb down before and it wasn't nearly as difficult as I thought it would be. My original post wasn't really meant to be technical or anything along those lines, and while I understand the more technical workings of the system, I just wanted to provide a brief answer to the "I have no air intake system at all, do I need to rejet" type of questions.

This is the BEST!!!!
http://www.factorypro.com/tech/carbtun.html

when i did it for my first time, i used a combination of links from this website: http://www3.telus.net/dougsimpson/CVcarb.html

the jetting effectiveness chart on Battlescooter would also help you out!
http://www.geocities.com/MotorCity/Speedway/2476/basics.htm
not the best, but it gives you a general idea!

EDIT:
more links
http://www.factorypro.com/tech/carbtun.html

less useful(but still carb related) links
http://www.nightrider.com/biketech/hd_cv_mods.htm
https://www.johnsmotorcycleparts.com/Ke ... g_tips.htm

I Bought the big carb kit from bowls and did the whole trial and error for the jets. I pretty much figured it out after some time. I also install the posh c.d.i. When running full throttle it seams that it is actually killing my power. Any help or recommendations would be a big help.
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for real break it down m-town style u cant eat like superman and shit like bambi its all the balance try to find it if u add this and that work the brain and get it back to the happy its the see-saw efect to the air-fuel thang ive made 34pic3 vw carb work on 4 diffrent motors made by 4 diffrent flags ive learned this either you lose or the motor do dont over think it

SPEAK ENGLISH OR DIE MOTHER FUCKER

are you another phuck's alias?

This is my new most favorite saying of all time.
It can apply to almost anything in a real poetic, kinda existential way...

This thread is useless!! It provides no useful information about jetting the carb and installing aftermarket exhaust and intake will more than likely make you run rich not lean. Go read how the stock ruckus carb works it sucks gas up from the float bowl and the amount of suction depends on velocity and quantity of air therefore if you install aftermarket intake and exhaust try going to a 72 or 70MJ first. Popping close to top end(Not at the rev limiter) is excess gas that isn't burning and flooding your engine when suction pressure is high enough.