do I have to

I want to put a fmf powercore pipe and a uni filter on my xr100 if I did would I absalutely have to rejet my bike :confused:if so what sizes should I use 102 main 100 maybe?

Probably. But maybe just the main. higher flowing exhaust and intake means more air through the engine. More air requires more fuel, i.e. richer jetting.

i did K&n pod filter and a FMF powercore exhaust.

i did a 40 pilot and a 110 mail. it runs well

i live at 4500 ft

You don't have to rejet it, but it will run a lot better if you do. When I did airbox and full exhaust on my bike, it ran better and was faster so at first I decided not to re-jet. But like a week later I said what the hell and got the jets dialed in correctly. It was much faster after that, definetly worth it!

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