So I have the Jardine exhaust and KN lunchbox I want to install. I also have the dynojet kit. I feel comertableish putting on the exhaust and air filter but in no way want to attempt the jets.

My question is what kind of damage can be done if i install exhaust and airbox without the jetting but I have limited driving for another month or so as season is coming to an end?

Is resetting something a regular mechanic should be able to do?

I should add that if I myself am unable to do it and my mechanic can't not I will be having it done in spring for sure.

I highly recommend doing the jets first. Forget the filter and exhaust - because even if you jet the carbs and don't get around to the intake / exhaust, you'll be running rich (better than running lean).

If for whatever reason you can't get the carbs done, don't make your mixture leaner than what it already is.

Will adding exhaust and intake make it run leaner? What will this do to engine?

.......sigh...........

Engines require an ideal mixture of gas and air to run effectively. Believe it or not, the gasoline is used to cool the motor down (even though it flammable). So if you add more air thru the carbs (with the lunchbox filter) or allow more air to be sucked out of the exhaust (therefore sucking more in thru the filter), you are disrupting that ideal mixture of gas / air. Since there will be more air and less gasoline (which cools the motor), the engine will run hotter than before. When a motor runs hotter than what it was designed for, that's when all sorts of very bad things happen.

In your case, the engine would be trying to run on too much air and not enough gas, which runs like crap. Seriously - you'll either not want to ride it anymore, or ignore it long enough for the motor to damage itself.

Quote from: Big Rich on September 30, 2012, 10:15:49 PM
.... or allow more air to be sucked out of the exhaust (therefore sucking more in thru the filter), you are disrupting that ideal mixture of gas / air.......

I would like to question the validity of that statement. On a 4 stroke engine, intake is closed as exhaust goes out. The piston going down sucks in the air/fuel mixture. What goes out of the exhaust is separated from the intake due to the valves and that exhaust is on an upward stroke while intake is on the next downward stroke of the piston.

What you say would seem perfectly valid for a 2 stroke engine. Exhaust sucks in the new air/fuel mixture.

With that, changing the exhaust on a 2 stroke would greatly affect the intake. Exhaust and intake are controlled by the same downward stroke of the piston.

On a 4 stroke, it seems that anything done to the exhaust would have minimal effect (if any) on the air/fuel mixture going into the cylinder.

You're right Addy - it's a 2 stroke thing. But when a 4 stroke motor is revving at 10k rpm, I would like to believe everything is moving so mind bogglingly fast that a more free flowing exhaust does help the intake pull more air. Sure there are the mechanical restrictions you pointed out, but it's been proven before that an exhaust does change the air/fuel ratio in the motor. Not nearly as much as a K&N lunchbox, but that's beside the point..........

Makes sense. I can see exhaust having a little effect on a 4 stroke.
Definitely jetting and air filter go hand in hand.

A little back pressure at high RPM's might leave a little exhaust in the cylinder so it won't pull in quite as much air/fuel.

I changed Junior's from stock to V&H with no change in performance other than more noise. Trey went to a Sito. Phenix went to a Motad. No change noticed in any of them (other than change in sound).

One had K&N filter. With/without restrictor makes a slight difference. Always stayed with stock jetting except for pilots on older carbs going from 37 to 40.

So if I understand correctly? I could attached the exhaust only and as long as I'm not driving the piss out of it (with limited driving too) I should be ok?

This might come out the wrong way, so I'll apologize in advance.

If you are changing out the exhaust without any interest of jetting the carbs to match, then I'm assuming you're doing it for looks. Which is fine of course, but everybody looks cool already on a motorcycle. That's just a lot of money to spend on "looking cool".

Without working on the carbs in conjunction with the intake / exhaust, there is always a possibility of changing the fuel / air ratio to dangerous levels. Chances are that won't happen with just the exhaust but I do want to point it out.

Changing out the exhaust is pretty easy, and the intake is even more so. Try doing the carbs first, since they should be done anyway. If for whatever reason you're not able to change out the jets, then you can always mount the carbs back up and run the bike with a completely stock drivetrain.

I fully intend to do the carbs, I even have an unopened kit beside me (along w exhaust, intake and chain/sprockets) my problem is the guy who was willing to install it free for me is no longer available until spring.

This is why in curious about potential damage as I'm considering doing the exhaust and possibly intake to help him. The jetting is something I do not wish to attempt until he is there to show me. I hope this was clear.

It's extremely easy once you do it, i thought it was going to be really hard, but when i realized i couldnt afford a mechanic i did it myself and actually had alot of fun with it

with the exhaust, as long as you have the proper tools it should be no problem

as far as the intake, as far as i know they are pretty much "plug n play"

Changing the Air Filter and rejetting the carbs is pretty easy, especially if you're using Buddha's kit instead of the dynojet, since you don't have to drill the carbs.  Spend the $20-30 on the service manual, it has step-by-step instructions for assembling/disassembling everything on the bike.

Even without the exhaust, it's usually recommended to rejet the carbs, as they are lean from the factory.