still confused about jetting....

i've read and re-read post on pipes and jetting. the way i read all these posts are once you put a aftermarket pipe on and do the air box mod the engine has more power and needs more fuel. which from reading these post's means i would need to richen the mixture accross the board.

based on what i'm reading as stock i have a for my 92 kdx 200:
1172n
150
48

these post and sites are recommending that i would use the following:
1173n
152 or 155
48

after looking at the sizes for these they seem smaller except for the change from the 150 to the 155.

so my ? is does this really indeed richen the mixture or is it leaning it do to the larger id of the needle?

here is a cut / past from just kdx.

Stock -Run the stock R1172N jet needle in the second from the top clip position, 48 pilot jet, 155 main jet and fine-tune the pilot circuit using the air screw.

With a performance pipe/expansion chamber, the air box lid removed and the stock or a performance silencer run a 45/48 pilot, R1173N jet needle in the mid clip position, a 152/155 main jet fine tune the pilot circuit using the air screw.

thanks for any help in clearing this up. i really don't want to blow an engine up. i'm just missing the point on how this richens the mixture.

thanks
doug

well, i for one rather have it a bit richer and slightly sluggish then burn up. i've had my 92kdx 200 stock ever since day one. i usually ride at 3k-4k feet except once a year at 6k-8k feet. i have never had any reason to change it and its still on the same plug for the last 4 years. of course i finally just put the first rear tire on it since new so i don't ride much as you can see.

i thought i read though that when putting on a new pipe i would need to go richer on the mixture because of the extra power it now has, but it seems every one is still leaning them mixture out. thats where i'm getting this confusion from. i will do the plug tests in the mean time though. unfortantly buying needles get expensive<G>. oh well