What exactly qualifies as a spark arrestor?

[tri again]

We've got some major fire danger in the NW.
No chainsaws or lawnmowers allowed between 10am and 8pm.

Our sx's have stock mufflers, but what exactly are the rangers gonna look for?

We want to try a sanctioned BLM trail atv off road area and they do check sound levels
stickers and prob for spark arrestors.

Maybe some sort of aftermarket slip on window screen looking thing?
Maybe they already have something in the stock muffs?

[nd4speed]

I bought a Pro Circuit spark screen at a local bike shop and made it fit in my 2 stroke silencer.

They look for US Forestry approved stamped on the muffler.

[brd812]

I think all stock systems are forestry approved and stamped on them. What they are looking for is the free flowers like the DG and other that have no screen to stop sparks. Thats why the supertrapp styles were so popular for the off road racers not close course guys. The rangers are looking for the 2 stroke w/ stinger w/out a arrestors and 4 strokes with open ends w/out a core insert and screen. My e-series has a core that goes in before the disks and E2 has insert screen that goes on the cap. Hope that helps, i think your stockers will fall into the 96db and spark arrestor catagory without any problem, Id call and ask to make sure, but thats how Michigan is.