wondering...????

[Major Voltron]

I have a 99 kat 600. It came with a yoshi Rs-3 on it ... But there is a hole about the size of yor thumb on the back side of the can ... First off can that do any damage to the engine running with that hole. Number 2 , the hole in towards the center i was thinking I could cut out that center 3 inches and weld it back together so that there is no hole . Now the next question is will shortening the can do anything different . Will the sound change , fuel mileage, run better or worse that way ........

[arsenic]

It's a slip-on. It doesn't effect how you're bikes runs at all. It only gives you a different sounds, that's it. As far as how it will change the sound, I've never tried it. It sure won't have any effect on how your bike runs.

[superbike]

Unless it was put there by the manufacturer (for perhaps drainage of condensation) you might want to buy a small "freeze plug" to fill in the hole, they come in many sizes. A picture would be helpful.

[tone]

It's a slip-on. It doesn't effect how you're bikes runs at all. It only gives you a different sounds, that's it. As far as how it will change the sound, I've never tried it. It sure won't have any effect on how your bike runs.

Very very wrong, although "race" cans wont always have an effect you can feel in the seat of the pants, any change to intake or exhaust will effect how the bike runs, typically (but not always) a more open (or shorter) exhaust will make a bike run slightly lean at the top end, it's to do with ...
A. the scavenge effect
B. tuned length
C. outlet size (compared to stock)

An exhaust gas analizer & preferably a dyno run will help to tell the truth of the above statement.

[Wild-Bill]

...and worn/missing packing will also cause the bike to run lean. Re-packing the can will fix that provided the jetting was right to begin with.
Sorry Arsenic, you're wrong here.

[arsenic]

I'm not gonna argue with you Bill. You win, I have no clue what I'm talking about with jetting. Unless all of the packing came out that hole. I imagine it will make a huge difference.

[Wild-Bill]

The packing comes out that big hole at the back of the can. You know, the one that points at the car behind you?

You know carbs. I know that my bike stopped popping on decel after I re-packed the can.