Wanted 18" wheel, muffler

[J&J]

I would like to get an 18" wheel & spark arrestors for Jacob's 250

Anybody have an 18' rear wheel that would fit a 07 crf?
Also how about an old FMF that I can perhaps modify to fit a 1 1/2" head pipe. I'm not really wanting to spend $250 on dual spark arrestor caps or $300 for a new FMF. I want the approved spark arrestor stamp, not home made from a sink strainer.