RMs 'n' plugs

[crazyxr250rider]

Her is a good Q for you, my local mechanic said I don't need to change teh jetting if I change teh pipe, another said I do.

What is the real story???

Its better to rejet with a new pipe or new piston with higher or lower compression.If you dont on 4 strokes all the bike will do is fart and bang

[laRIKin]

Her is a good Q for you, my local mechanic said I don't need to change teh jetting if I change teh pipe, another said I do.

What is the real story???

I forgot to answer this one.
Some times you do and some time you don't.
More often you do have to re jet.
But it all depends on how your bike was jetted before, as you can get a bit of over lap in jetting.
For example you may have been running a bit rich before and then a bit lean on your new pipe. Or the other way around.