Exhaust end cap on 250ex

I want to hollow out my end cap and make it so it flows freely instead of havin to run thru the perforated pipe.
Now my question is... Will this cause problems other than being louder?
From what I understand this is basically the noise reduction part of the exhaust system.
I will not mod the inner part of the muffler just make the end cap free flowing.
Any comments or suggestions are appreciated.
I live out in the woods so noise pollution is not a problem.
Thanks everyone!

[moto93]

Isn't the end cap the spark arrestor? I always thought that it's the chambers inside the muffler that deaden the sound.

Anyway, I took the end caps out of my 400EX and my Son's 250EX and made my own out of a piece of aluminum. They look identical to the stock cap but they sound/flow so much better!

[4punksdad]

Originally posted by moto93
Isn't the end cap the spark arrestor? I always thought that it's the chambers inside the muffler that deaden the sound.

Anyway, I took the end caps out of my 400EX and my Son's 250EX and made my own out of a piece of aluminum. They look identical to the stock cap but they sound/flow so much better!

are the end caps on the 2 bikes identical?

moto93 you may be right about the noise reduction, Im not sure. How did you make your end caps? I just got done hollowing out my end cap.
All that is left is the stainless cap. I took everything out.
Let me know exactly how you did yours.

[moto93]

Originally posted by 3punksdad


are the end caps on the 2 bikes identical?

No, the spark arrestor set-up is a little different but the bolt pattern is the same. The 400 has a straight through exhaust pipe after the spark arrestor screen while the 250 has a larger diameter pipe the inside end is capped off and the exhaust has to exit through holes in the OD of the pipe. Also the 400's is chrome while the 250's is bare metal (stainless?).

[moto93]

Originally posted by 250exguy
How did you make your end caps?
Let me know exactly how you did yours.

At work we make engine dampers for Toyota. The hubs are aluminum so I took a couple of scrap hubs, machined off the OD, finished up the rest, and then drilled the holes in it. It was pretty easy for me because I had something close to start with.

Here's a picture to give you an idea of what I'm talking about.

[250rampage]

. The 400 has a straight through exhaust pipe after the spark arrestor screen while the 250 has a larger diameter pipe the inside end is capped off and the exhaust has to exit through holes in the OD of the pipe.

Not Really, the 400 has 3 chambers, and the exhaust gasses have 2 changes in directions.

That looks like a sweet conversion moto. You gotta have the right equipment to do stuff like that. Looks kool!
But again gettin to my question, Will hollowing it out hurt anything?

[moto93]

Originally posted by 250rampage


Not Really, the 400 has 3 chambers, and the exhaust gasses have 2 changes in directions.

If you would have read all the posts I'm sure you would have figured out that we were talking about just the end cap.

[moto93]

Originally posted by 250exguy
But again gettin to my question, Will hollowing it out hurt anything?

No, it won't hurt anything but you'll probably want to check your jetting... I'm sure it leaned out a little.

[250rampage]

Oh, sorry, I thought that since you said "after the spark arrestor screen" you were talking about the entire silencer. My bad.