Cutting Spark Arrestor Off

[Florida400EX]

I am in need for power for my 400EX, for an upcoming race. I already removed the air box lid, and it feels a little bit better. I was wondering what would happen if I cut the spark arrestor/ baffle off the the stock exhaust. The part that unscrews out of the muffler with the 3 screws, and has the screen. I was thinking of what would happen without the screen. Anything at all?

thanks!

[Florida400EX]

Also, what else could I do to squeeze a little more power out of my EX?!?!?!?! I was think about going to the carb, and lowering the needle maybe? I honestly don't know, and any opinions/ ideas are greatly appreciated.

Thanks!

i dont think cutting out oyur spark arrestor will give you any power, (correct me if i am wrong), but it'll just make it alot louder. a good cheap mod would be a k&n powerlid. it's a lot safer running a powerlid rather than no lid at all

[trx440]

Do a search on "modded factory exhaust"

86atc250r has posted info on this in the past.

It will give you the how to on the exhaust, airbox mods/filter applications and carb jetting.

Also make sure you are using the optimal tire size vs. gearing combo for the type of racing you are doing.

[powerslider]

The screen is not the restriction, it's the small pipe inside the screen in the endcap that is. I carefully drilled the spotwelds on the screen to remove it from the endcap then cut the inner pipe around the weld and removed it from the endcap. Now you have a very large opening, I rivited the screen back on the endcap so I still have the spark arrestor.

The muffler is a 3 chamber can, the exhaust first enters the middle chamber then flows to the front then the rear and out. I drilled the rear plate full of 1/2" holes. now you have a straight through exhaust flow. It will be louder, similar in sound to an E-series. The power gain is very noticable.

[yamaha250f]

if you cut ur spark arrestor you will pick p some low end and some throttle responce but u will have a louder souund i did it and its worth it.