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View Full Version : can i run exhaust without the silencer?????



cjmadison9
08-18-2010, 10:53 AM
i got a lexx exhaust for my kfx400, it runs ok but when i take the silencer out of the pipe it seems to have more power exp on the bottom end, i was woundering if i can run it without the silencer in it? i just woundering i dont wanna do it if its gonna hurt the motor or anything...thanks

Scro
08-18-2010, 11:36 AM
I'm guessing it's all in your head. Without the silencer, it's going to be annoyingly loud, and make you feel like it has more power. I say this because if you were to do it (and rejet accordingly), you wouldn't see an increase on the bottom end. You would see an increase on top, and probably loose on bottom.

armstrong88
08-18-2010, 09:29 PM
Originally posted by cjmadison9
i got a lexx exhaust for my kfx400, it runs ok but when i take the silencer out of the pipe it seems to have more power exp on the bottom end, i was woundering if i can run it without the silencer in it? i just woundering i dont wanna do it if its gonna hurt the motor or anything...thanks Won't hurt a thing other than your & your friends' ears! lol. It will allow your engine to deliver more power.

audioworks04
08-28-2010, 11:02 PM
i highly doubt that it will/does make anymore power. You need back pressure to make low end power. All you are going to do is make alot of people very mad. Loud pipes does not make more power or make you faster. Tuning makes it run right and strong. Yes you can tune to an open pipe, but you most likely will not gain anything worth making that much noise.

JOHNDOE83
08-29-2010, 08:23 AM
4 strokes dont work with back pressure like everyone thinks, thats how 2 strokes are, if 4 strokes worked with back pressure, there would be a expansion chamber on the exhaust.

a 4 stroke works best with more air flow in and out of the motor, the more you can let in and the more you can let out, creates more HP, thats why drag bikes have open headers, drag cars have straight pipes...etc.

4 strokes dont have pipes for low end, mid, or top end like 2 strokes have, the performance pipes for 4 strokes are just more free flowing, the more free flowing they are, the more power they give.

trxPOWER
08-30-2010, 10:29 AM
why do you lose bottem end when you put a bigger diameter head pipe with a stock moter then? if you theory is correct all that the head pipe should do is gain power.

RobRacing
09-08-2010, 12:01 PM
Originally posted by JOHNDOE83
4 strokes dont work with back pressure like everyone thinks, thats how 2 strokes are, if 4 strokes worked with back pressure, there would be a expansion chamber on the exhaust.

a 4 stroke works best with more air flow in and out of the motor, the more you can let in and the more you can let out, creates more HP, thats why drag bikes have open headers, drag cars have straight pipes...etc.

4 strokes dont have pipes for low end, mid, or top end like 2 strokes have, the performance pipes for 4 strokes are just more free flowing, the more free flowing they are, the more power they give.

Actually four storkes do have pipes for low/mid and top end. A longer head pipe will produce more low/mid power thats why they kinda loop down and then back up. A header that just bends right out of the head and back to the silencer will produce more top end. It is true if you just run your engine wide open all the time that straight pipes will give you more top end power thats why the only time you see this set up is in a drag race. Any other type of motorsports uses some type of muffler.

BakerRacing40
09-08-2010, 03:45 PM
Originally posted by cjmadison9
i got a lexx exhaust for my kfx400, it runs ok but when i take the silencer out of the pipe it seems to have more power exp on the bottom end, i was woundering if i can run it without the silencer in it? i just woundering i dont wanna do it if its gonna hurt the motor or anything...thanks

your making the engine run more lean with it removed. you do risk running cyl temps to high and start burning stuff up.. your probably ok but there is always the risks associated with runnin them lean and mean..

BlaineKaiser450
09-08-2010, 04:57 PM
I would put it on. It just seems faster because it's louder haha

deathman53
09-08-2010, 07:53 PM
put it back on, you are hurting your motor, yours and others ears, all of our riding and making that much more people hate quads/off-roading. I seriously doubt it makes more power, it just sounds like it. I had a Cobra system on my trike, it was really loud and very free flowing. I put a S/A tip on the end and it made it faster, more responsive and much more pleasing to the ear. You need back pressure on 4 stroke, ever see how the supertrapp system works? Fmf, CT and others have a similar system. It works by altering back pressure to move the power to where you want it. I myself use ~8 discs on my shorty supertrapp, its below 96 db's and makes great low end power. I couldn't care about top end power for most of the riding I do, most of everybody's riding is 1/4-3/4 throttle, yes, even you pit racers who think you go WFO the whole time. For the average state of tuning and motor specs, your motor is actually making less power and torque when you increase the rpm limit and move the power up there by altering the pipe. This is not a blanket statement for all, a pro's motor is nowhere close to what our motors are, they have specially made cams, special valves, very specific pipes and other things they don't want us to know. This is why pro's motors will go strong from 1/4 to WOT and not lose power, like most of our motors will. Very very very few of us have motors that can withstand and benefit from higher revs and still made power.