What is the problems that could occur when not jetting a bike when it has a exhaust and air filter upgrades?

Question

So, in saying that what stage should I choose?

Answer 1

Ya. Randy C is pretty close. Think of your M/C's engine as a big air pump. The more air you move through it, the better it performs. Now if you replace parts with the intent of increasing this airflow, you must also increase the fuel flow. Otherwise your engine will run lean. "Lean", by the way means that the ratio of atmosphere to fuel is too high. "Rich", is another word used to commonly describe the opposite condition. This is where the ratio of atmosphere to fuel is too low.

Adding a freer breathing exhaust and intake will cause the air/fuel mixture in the combustion chamber to contain too much atmosphere. With this increased presence of atmosphere, there is an inherent condition resulting in higher amounts of oxygen being present at the time of combustion. Oxygen burns at a very high temperature. Much higher than vaporized gasoline, for instance. The most common result of running your machine too lean, is having a hole, quite literally, burned through the top of the piston. This is an extreme example.

Jetting is not the only thing you need to look at here. You re-jet with the idea in mind that you are adding fuel to a situation that you just added more air to, right? But wait. Look at how many times I just used the word, "more". As you might guess, there is a time factor at work here as well. Your ignition timing is based upon the principle of having the spark plug arc at just the right moment. That moment is relative to certain conditions in the combustion chamber being met. One of which is, of course, the length of time involved in delivering all these burnable goodies to the CC for combustion. More air and fuel, more time it takes to get it all in there. Bam, now your timing is off just a fraction. So some ignition timing, "retardation", needs to occur, so that you are not burning the air/fuel mix prematurely.

Add after-market intake, or exhaust individually, and you will likely get away with a re-jet. Add them both, and you are going to have to either re-map the existing ECM, or replace it with something more performance oriented. Which is illegal in all 50 states. Which gets me to my point. High performance parts on street motorcycles will yield very little more than a giant headache. If you change your ECM after writing your insurance policy, for instance, you just voided your policy, as you are no longer on the M/C they agreed to insure. You can do all of this, ride around, do your thing. But if lightening should strike, you could really get screwed.

Save the performance gains for the track.

Answer 2

I added an aftermarket air filter to my bike many years ago and had to rejet the carb. Not a big deal. Without rejetting the carb, the engine runs lean. Some bikes are more sensitive than others, but at the very least, it won't run as well as it could. At the worst it can ping or knock and damage the piston. Since when does oxygen "burn at a higher temperature"? All oxygen does is speed up the combustion process. If you can pack more oxygen in the cylinder, you can put more fuel in there and get more power.

Answer 3

Seems like a pretty big jump in jet sizing (54-88) just to handle a different filter, a 65 maybe.

Answer 4

Vance is right except that nobody is gonna know you upgraded the performance on your bike unless you tell them, Hey Vance if your scared go to church!!! And as for you its gonna make the bike run lean untill and unless you richen up your fuel supply. easily done and no big deal. Ive been building 200 plus horsepower bikes for years.

Answer 5

Burn a Valve and or ring on the piston, run hot and over heat, plus you even take a chance on burning a hole right through the top of your pistons.

Answer 6

it will run too lean. this makes the motor run much hotter, this results in a shorter life for the motor. It can cause the motor to "ping and knock" with pre ignition, it can cause a surging or hesitation when under throttle etc etc etc. And yes, you can even toast the motor.

Answer 7

More than likely, you won't hurt anything, you just won't get the most out of the upgrades you have already made. I would check with Factory Pro Tuning Components. They offer the best jet kit I have found.