i just put the fmf 4.1 titanium full exhuast on my 07 z400. then i rode it for a while and it bogged and died. then it didnt want to stay running. so i bought the fmf jet kit hoping it would help with the problem becuase i think i was running way to lean and burned out the plug.

would the bike start if the plug was burned and would it want to die if i hit the gas?

another question is the main jet is a 130 and the fmf kit says to put in a 130, is thats even gunna help at all with to even out the exhaust change? should i go a size or 2 bigger?

 

Were you running with the airbox lid off? If you had it on without rejetting your probaly going to be ok.
Your jet kit and the OEM jet size are not sized the same, In other words a dynojet 130 is bigger than the OEM jet. I'm running my Z with the airbox lid off and a Whitebrothers E2 exhaust and It took the OEM jet from a 120 to a 160 and runs perfect. I also bumped up the pilot jet from the stock 22.5 to a 25. It makes all the difference if you run with or with out the lid on. With it off it will suck in more air so it will need more fuel. I'd send the jet kit back and just go to your local dealer and at the parts counter ask for a main jet around 160-170. It will save you about $40 if you just buy the jets from the dealer.