I have heard that a GYTR spark arrestor fits into the stock 250F pipe - but there are 2 different ones. One has a screw hole to mount it inside the pipe. I'm hoping that one fits because the other one looks like it would be hard to mount.

DOES ANYONE KNOW WHICH ONE FITS?

So I finally got a response from FMF, who make the GYTR spark arrestor screen. It is in fact 1.5" in diameter and should fit into the stock pipe. Just have to drill a small hole in the pipe and screw in a sheet metal-type screw. This is good news as it goes for around $30. It seems like such waste to spend $100 - $400 on an end-cap or slip-on when the stock pipe is fine 90% of the time.

 Hectoralis, on 27 April 2012 - 08:31 AM, said:

What year YZ pipe does the arrestor fit ? THANKS.

Great research and info man.

I think 2006 to 2012. Has to have a 1.5" opening. I ordered one so I'll let you know how it fits on my 2009.

It's a bust. The GYTR spark arrestor is too big and doesn't fit in the 250 pipe. The FMF tech. guy told me it was 1.5" in diameter but he was wrong. Love it when folks don't even know their own products...

So, I just ordered DirtWerkz dB Dawg spark arrestor screen #8001. It's 1 3/8" OD and should work even if I have to fab a shim. We'll se!

or you can get a pro moto billet end cap.  most likely will set you back a bit more though

Ya, trying to go on the cheap...