Mixture screw question

[carlj75]

I have a 426 with stage 2 cam, running 11:1 comp. I removed the choke and installed a #42 pilot jet. I am running a 175 main and the needle clip is down one notch from stock. K&N with no lid. The spark plug looks perfect.
My bike was running really crappy at idle. Once it warmed up, it would idle fast for a few seconds and then almost die, then it would speed up again. Sometimes when I was going down a hill with the clutch pulled in, the bike would stall.
Well, I played with the mixture screw and ended up finding out that it runs the best when I have the screw all the way in. The idle is consistent now, but it occasionaly still dies.
Do you think my pilot jet is too large? Or is something else wrong?

[carlj75]

bump

[cals400ex]

did you just get done building your motor? i just got done with my 406 with stage 2 and my idle is weird too. it seems to fluctuate a little bit. you definately won't be too big on the pilot. i am running a 45 pilot about 3 turns out. i am a little rich on the pilot but this way my stainless steel headers don't glow. i would think you would need to be 3 turns out or so with the 42. i would not leave it in as that would make it run lean and too hot. i assume your plug is in good condition. also, with the higher compression they recommend running a ngk drp9z plug. the factory is the drp8z. the 9z is a colder running plug. this will make it a little harder to start and won't want to idle sometimes, but overtime it seems as if the bike get use to it. that is how mine felt anyways.

[carlj75]

Yes, I got done building my motor about a month ago. I am still using the stock type plug and it looks fine. I was having the idle problems when my fuel screw was about 2-1/2 turns out. Once I turned it all the way in it somewhat solved it.

[ewalker302]

Just my 2

But it sounds like u should drop 1 size on your main then start w/ your fuel screw at least 2 turns out & start testing from there.

:bandit:

[cals400ex]

it looks like i am running a similar set as you and this is what i have for jetting: i am running a 160 main, stock needle and clip position, 45 pilot, 3 turns out on the fuel skrew. i have a 11 compression 406, stage 2, uni filter with modded lid, and sparks x-6 pipe.

[zephead400ex]

Originally posted by ewalker302
Just my 2

But it sounds like u should drop 1 size on your main then start w/ your fuel screw at least 2 turns out & start testing from there.
:bandit:

True. You do not want you idel screw all the way in. No matter how big of pilot jet you have, this can still make it run too lean.

Does not make much sense with the plug looking ok? By looking ok, it is not white is it? haha jp!

good luck

[cals400ex]

your plug may look just fine because you are not only getting a reading from your pilot jet, but you are also getting readings from your needle and mainjet. with the pilot all the way in, i bet you would have a whitish color plug if you drove around at less than 1/4 throttle for a period of time.