Possible Jetting Problems

[quadmxracer]

Yesterday I started my EX and I was running kinda funny. So I pulled the plug and it appeared that it was running rich, but when I had it started it would back fire like it was lean. The plug was new as of last friday. So I cleaned up my old one, and put the old one back it and it ran just fine. So I checked that plug and it shows that my jetting is fine. As far as I could tell the other plug wasn't fouled. I have a K&N and a FMF Mega Max 2 slip on silencer. Any ideas would be welcome. Thanks in advance.

-Quadmxracer (Clayton)

[Chanman420q]

are they the same plug?

[quadmxracer]

yes they are the same plug both NGK DPR8Z.

[ewalker302]

I've read a lot that it's tough with today's gas to read rich/lean conditions by the plug colour.

Are you running the stock main jet?
Air box lid?

I have a megamaxII slip on, & a uni filter w/ the lid on.
It had the pipe & stock main in it when I got it.
It backfired a little on decel.

After I swapped in a Dynojet 146 (1 size up from stock),
it cured the backfire & gave me a little more power.

Hope this helps since we both got the same pipe & all.

:bandit: