Hey, i visited my Dad last weekend, and he brought up sumin'. He drilled Holes in his exhaust Bafflle ends, (72' Honda 350 4cyl.) back in the day. He said it made his Bike Louder, more noticable! He pointed out, that if i did the Same, maybe it would work on my Ninja 250?
No camera, so i cant give a Pic. The area im thinking of drilling 5-6 Holes are on that BLACK Baffle Plate that Circles around the Exhaust Hole! In between the Allen wrench screws! If i did this, would it Void the Exhaust Warranty, Or Increase HP (+1HP?), or Decrease my MPG (-1mpg?), or Damage the Exhaust system in some way... long term down the road?

I dont have $400-$800 for a Slip-on, or Full Exhaust mod, so im just Curious as to If anyone has done this to their 250R, and what was your results?

Ill try and get my GF to find her old Digital Camera, so i can take some Damn PICs to better Help with Info for you guys and myself! lol :D

http://www.newninja.com/modifications/my-$36-dollar-muffler-(video)/

This dude cut his can in half and made some mods. Kinda crazy to me, but it's an idea.

yea i came across this weeks ago when i was looking at ninja 250r stuff.

Better off punching thru the existing hole, than drilling a bunch of little ones.
^ You know, if you just had to do it :)

update?

i havent drilled those holes i was thinking about. after looking over some videos and stuff online, i dont think my original plans if i did these holes would do Anything of sort in making it alil louder. if i do thou, ill post a update and a DIY.

Heres a few pics, so you can see what your drilling into :)

Exhaust goes into the outter chamber, back into the middle chamber, then out.

I'm intreged. I'd like to add just a little more volume to my stock exhaust without having to change anything else (no rejetting). Is it possible to drill into the baffle without affecting the back pressure? Can I simply drill the the outer plate?

Any attempt to make the exhaust louder by drilling will reduce exhaust back pressure, thereby leaning out your overall mixture. From what i understand, the bikes leave the factory lean to comply with emissions. I would not recommend anyone drill the exhaust, or change it out for a totally new one, unless they richen up their mixture, otherwise it is possible they might burn up their exhaust valve(s).

In the automotive world we use whats called an "Innovate LM-1" which is a tailpipe sniffer with an oxygen sensor that gives you the air fuel ratio coming out your exhaust pipe from the motor. In the automotive world the magic number is 14.7/1, im pretty sure it would carry over to bikes, since the bikes use the same fuel as the cars do, and the nature of combustion does not change just because your riding on two wheels instead of 4.

Maybe i'm new to bikes but im surprised so many guys here swap out exhausts and then blindly "jet" or "shim" based on recommendations without knowing what the actual af numbers are coming out the tailpipe of THEIR OWN bike. I guess i need to do more reading, but i just hope my 2cents prevents someone from wrecking their bike if it applies to bikes. If anyone is inclined to school me, please do, i want to learn as much as i can about my bike, right now all i know is cars, and that is what i've carried over.

Scorpion, instead of modding your exhaust, please pick up a new one, and place the original aside, so when it comes time to sell the bike, the next owner has the option of purchasing an unmolested bike. Your bike will hold it's value much better if all the mods are reversible with included hardware. If you don't have the money for a new exhaust, then look in the forums for someone selling a used oem and mod that.

But remember, even modding a stock exhaust you still need to "rejet", and doing it without proper hardware to measure your exhaust gasses will only get you in the ballpark by following online suggestions, and not optimal for YOUR bike, thereby defeating the purpose of trying to squeeze more power from your bike, possibly loosing power as the end result. And if you think that every bike is the same and so the same amount of jetting will produce the same results, just take a look in the "do you always have to use the choke when you start your bike, because i dont" threads. You will see how different the mixture is set up on everyone's stock bike as it left the factory.

That's what I had figured. Thanks for the definitive advice. I will leave well enough alone for now, knowing that I will get a bug in my ear to change the exhaust as a whole and get it re-jetted.

Please note, for anyone considering measuring tailpipe gases, if a catalytic converter is present anywhere in the exhaust, it will give false readings at the tailpipe.

drill, drill, drill, drill...

DIY A/F meter:
http://www.redline.lt/magazine/spec-features/article/article/17/1/