jetting starting point??? kinda dont know where to go

[400exmxrider15]

Okay guys, tearing my gas tank and plastics off tomorrow, to fix my valve cover gasket, while i was at it, I was gonna adjust my f/a screw...What has been happening is on deceleration, its been backfiring. I thought adjusting that screw would help that. I've got a full Yoshimura RS-3 exhaust (older style), Twin air air filter, 42 pilot and a 170 main, needle is set to stock. I have no idea of what to set it to. or a base starting point, it also idles really funny, it will idle a little, then miss, then go back to idling as if its not getting fuel? had carb rebuilt back in march and it still did this.

[CJM]

Needle 3rd clip from the top (flat end), 170 is probably too rich. Id try a 165 or 162 first.

This chart and info will help: Carb jetting (http://www.exriders.com/vbb/showthread.php?s=&threadid=445695&highlight=jetting+placement)

Make sure you check the plug, you want the electrode insulator (white part) to be a chocolate to tannish brown. Blacks rich and whites lean.

[400exmxrider15]

After one WOT run, i brought the quad back, and plug is just a tad black, its not an oily black though, i thought it was rich too cause 170 is really big, there arent air leaks either. There is 6-7/16 holes drilled in airbox lid....I can always cut part of it off if i need too...

[CJM]

Then Id try a 168 and go down from there.

Probably gonna end up a 165 :D

[400exmxrider15]

Thats what I had in it before the 170 man, mechanic said it was running a little lean on top, so he went and put that 42 pilot, and 170 main. I plan on doing the choke mod, cause i dont want it in the way anymore.

[CJM]

I still say thats a tad rich for what ya got.

Check the needle and make sure its set to the 3rd clip, put a 168 in and see how it runs.

Im running a 170 main/42 pilot and I have an open airbox, filter, my homemade full exhaust, 416 and 11:1 on 93 pump.

[400exmxrider15]

I think i would rather remove my airbox lid cover....that way, I dont have to mess with buying a new 168, cause i dropped it in my dang drainhole in my garage..natch/.... I also live at an elevation of 1100....
Yeah, I'll beck that too. It may be set on 2nd clip....if so, thats prolly my problem, i'll set f/a screw at 2.5 turns, see what it does for me. thanks man,

[CJM]

Sounds, good, GL.

[JOHNDOE83]

It is only to rich when the engine stutters at WOT, until that happens the fuel is being burnt properly.

It would only be excessivly lean on the main jet if you get a slight backfire/hesitation on acceleration.

I would say leave your 170 and dont worry about it to much.

if your gonna do a plug chop you cant just pull the plug out and look at the color of it, you have to actually cut it open to see main jet on the plug, and that only counts if you do the plug chop run right.

you may be better off just taking the lid off?