A Caution on Performance Mods (My Experience)

[Easy Rider]

Set up:
2006 GZ 250 with 16T front sprocket, US/Canada model (non-California)

There is a lot of information already on here about intake/exhaust/carb mods. Most of it is good but some is just plain misleading (dare I say WRONG). :roll:

So here's my take:

Don't undertake ANY air box mods or any drastic exhaust mods unless and until you are also ready to do the necessary carb mods too.

If you want to see what a less restrictive intake will do for you, just take the stock air filter OUT and ride the bike for a half mile or so. (This will NOT hurt anything unless you do it on a day there is a dust storm or you ride on a dirt road!). It makes a big difference alright; it runs like crap! Do NOT do this in traffic; you are likely to get rear-ended!

So, after that little test, I put my air box back to stock; runs good again. I even put the diverter back on in the stock position 'cause I could tell no difference with it off, on or turned around. In the stock (facing to the rear) position it offers protection from sucking in rain and large particles.

On to the exhaust. I drilled 4 each, 1/4 inch holes around the outlet INSIDE of the ridge that forms a ring on the back plate. Others have done it outside of the ring and I wanted to try something different. That plate is HARD; drilling where I did goes through 2 layers of metal. I'm assuming the inside layer is the end of the baffle "can".

The result was generally good. The sound is a tiny bit louder but I doubt anybody but the rider would know the difference. The note is a little bit deeper at low speed. Wind and engine noise still pretty much masks the exhaust at higher speeds so I can't tell if it is louder or not. I did notice (I think) a slightly different sound from the top end of the engine after the new holes. Not necessarily louder than before, just different. I am not concerned with this as it was (somewhat) expected.

Is there any difference in performance? Not much if any. I think I've got slightly better acceleration and a tiny bit more at the top end but the difference is so small that it might be all in my head. I plan to leave it this way. Riding more than my initial short test may give me a better perspective on this.

NOTES: Since non-US/Canada models are jetted differently when stock, the results on those bikes would probably be different.

I did notice in my short test that under some conditions (head wind, up a long hill, etc) I am now able to go faster in 4th than 5th gear (with 16T front sprocket). I shifted at ~ 63 mph in 4th but I think there was some left. In 5th, it strained to maintain 65. On the return trip (with the wind), I approached 75 with no problem before it flat-spotted.

More later but I think I'm done........at least until I see the write up on the latest carb. mods.

Feel free to add your experiences with "simple" mods but discussion of the carb/jetting part probably should be put in threads specific to that.