350x engine cuts off on decel at high speed?

[3wheely]

So when hitting fifth gear wide open (haven't tried 6th) and pulling in the clutch and hitting the brakes the engine cuts off. A little hard to start afterwards. Doesn't seem to do this in lower gears. Where should I start looking for a diagnosis? The exhaust pops on decel which may be a leak. Also when revving after idle there is a little smoke (greyish color). Uni filter/supertrapp pipe. Here's a pic of the plug. Any suggestions would be appreciated. Thanks guys. Attachment 0

[3wheely]

Guess nobodies ever had this problem or has any ideas. Guess I'll get to work and try and figure this thing out.

[350xx]

Mine did that before.
It was just a plug for me, i put a new one in and it worked great. Try a new plug first.

[whyzee]

Sounds like and looks like you are running way too lean. Try going up 2 sizes on the main jet. Test her out. See if it eets better. If not, go up 2 more sizes. Keep going up until she bogs and then go back to the largest jet you had in before she stumbled. Should do the trick.

[Dirtcrasher]

Your lean, even more so if the air box lid is off...........

[3wheely]

That's what I was thinking. Airbox lid was on. No mods other than the supertrapp and uni filter. I haven't counted the disks but I was going to take a few off to see if it richens it up enough but the bolts are seized. I think I'll put the stock pipe back on for now and see if that helps any. If not, on to jetting. Thanks for the help guys.

[350xx]

Oh yeah...thats probably why i burned up a plug or 2, because i didnt rejet after getting a new pipe.
Now im running stock pilot, needle clip, but a 148 main.
We will see how she goes!
I havent got a chance to really open her up yet. Need to go riding!

[3wheely]

Let me know how that 148 works for you. I've got to order a few this week. My 200x didn't need jetting after adding a pipe. But then again every bike is different.