How come no power from a slip-on?

[CasiUSA]

OK, the general consensus seems to be that a slip on canister will not add power to the bike. It seems to me, however a bit confusing. The stock muffler has an opening roughly 1" in Diameter. The inlet pipe from the headers to the muffler is larger than that (Maybe 1.5-2.25"?)
If you look at an aftermarket (Or even oem from another bike) canister, the outlet is larger.
Now why would this not increase the airflow? It seems like the exhaust path. originally having to travel from a larger path to a smaller path, would improve with an after market can that would allow more exhaust to come out of the canister.
It looks like the OEM Can is restrictive.  :dunno:

[sanityfree]

that makes a lot of sense(sp?), but i don't know anything. i'm going to have an adventure soon: i've got to take my wheels off, and i have no freakin clue what i'm doing.

i have a friend who's a technician at Owen Motor Sports, i'll ask him about the can thing.

[GRU]

all depends on the type of a engine...harleys and big stroke (american) cars and bikes use straight pipes for best performance but japanese bikes and cars with short strokes need some backpressure

many engines lose power when they don't have any backpressure so then you need a restrictive canister....

i don't know where you got the idea that a slip-on want give you any HP but i belive it will give you a max of 2 or 3 hp on a GS500

the only way to test it is to put on a stock gs exhaust and run it on a dyno or a 1/4 mile track...then put on a slip-on canister and see if it runs faster

one more thing.....if you have a stock GS500 and put on a aftermarket cansiter, you will not gain any power...if you take a stock GS500 and rejett with biger jets and leave the stock exhaust on, you will not make any more power....you have to get the mix just right....puting on a huge exhaust doesn't work right, puting in huge jets will not work right and so on

[The Buddha]

OK, the general consensus seems to be that a slip on canister will not add power to the bike. It seems to me, however a bit confusing. The stock muffler has an opening roughly 1" in Diameter. The inlet pipe from the headers to the muffler is larger than that (Maybe 1.5-2.25"?)
If you look at an aftermarket (Or even oem from another bike) canister, the outlet is larger.
Now why would this not increase the airflow? It seems like the exhaust path. originally having to travel from a larger path to a smaller path, would improve with an after market can that would allow more exhaust to come out of the canister.
It looks like the OEM Can is restrictive.  :dunno:

Whose consensus is that... I swear by slip on's. They are on un modded engines ( not decked head, higher compression pistons etc) just as effective as full systems. The jetting need to be right of course... but that's true even of the full systems. Back Pressure... we dont need no steeenkin back pressure. Just kidding... small quanitiies of back pressure are needed, too much is bad  and those full systems or slipon's do let you have about the right back pressure... and I think that's mostly the headers that are causing it.... That near right angled bend right by the port, and the secong right angle at the bottom on the pipe is about what you need... that is my theory, cos any slip on I have tried has some advantages over the others... So I guess the headers are 80%, the other 20% is can... one that is WFO makes the bike run better up high, one that is pretty tight makes it run better down low etc etc. The reason they are all so close is that the headers make it so... Cant get too far away from that aspect. So slip on's work just fine if jetted right. With or without air filter changes.
Cool.
Srinath.

[octane]

A slip on should give you some power improvement if the bike is running well, but it's not going to be a huge difference. It takes a series of modifications working together to make significant gains on any combustion engine. And the old saying, "There's no replacement for displacement" still holds true. A slip on will allow the bike to move exhaust a little more efficiently, but our little 500 cc motors can only move so much air. Not to mention the fact that a slip on doesn't allow any more air INTO the motor, just makes it a little more efficient getting it out. Do the same mods to a 1000cc engine making 100hp and a 500cc engine making 40hp and the gains will be significantly larger on the bigger motor.