Deceleration Knock--Normal?

Stan,

3 options come to mind or 4.

1) change pilot to 1 size richer or turn in the air screw
2) raise the needle one position.
3) Race gas
4) live with it or don't decelerate

I presume you have the owners manual and in the back there is a nice section on jetting for altitude and temp. The main jet rcommendations might be a bit conservative.

I think I'll try to work mine out using the air screw if that doesn't work I'll go larger on the pilot. It doesn't happen very often but can't be good on the bike.

When I got my 02 250EXC, using the needle out of a 2000 yz250 was the ticket. I don't remember who came up with it. It was a straight taper needle. I think it was referred to as a N3EJ. That may be a Yam #. It solved my fouling problems and made the power delivery very smooth. If anyone wants details on it I'll find the info again.

Thanks for the help guys.