Are the pilot screws and the mixture screws the same thing or are they two seperate components? Reason I ask is because when I let off the throttle at higher RPMs, my muffler begins to make audible "pops" around 7000 RPMs down till about 4500 RPMs. I know that these are probably lean pops because if I move the choke lever out about 3/4 of the way they disappear. My guess is the pilots need to be turned out about 1/4 of a turn or so. Right now I'm running the needle clips at the Stage 2 clip position with Kehin 117.5 mainjets. If these pops disappear when the choke is moved out, would this be a lean condition with the pilots? The bike runs awesome and pulls strong throughout the powerband so there's no drivability issues.

 

"Pilot" screws and "Mixture" screws are referring to the same thing. Remember, this adjustment only deals with your "Pilot Jet" mixture, which (generally) covers the RPM range from idle to somewhere between 6000-8000 RPM.

As far as your issue goes, turing the screw out a little bit -probably- won't change your issue. IT MIGHT, so try it, you're not going to hurt anything.

As I understand it, you're probably getting a little bit of leanness at when the slide is in a mid-kind of position, which has always been a trouble spot for 600s. Remember, you're usually in your pilot jet until about 6000 RPM when you're going wide-open ON THE WAY UP, but not necessarily on the way DOWN. Slide position and RPM aren't really a linear relationship.

My first suggestion (if the mixture screw thing doesn't help any) is to go up a jet size to 120 or something.

BUT IF you don't want to try that, you could TRY to move the main jet needle clips DOWN a notch, (move the clip more towards the center of the needle.) This should make the mixture a little bit RICHER at the beginning of that main jet curve, without changing much at the wide-open position. The needle is FURTHER out of the way early on, more gas comes in. At the top of the curve it's out of the way completely anyway, so your "wide open" mixture doesn't change.

 

Gogar, thanks for the fast response. When I mean "letting off the throttle" the throttle is completely closed. i always thought when your throttle is closed only your pilots are fueling the engine when it's still at higher RPMs?

 

(SET YOUR IDOL TO 1150 ) ONE AT A TIME TAKE YOUR MIXTURE SCREWS OUT SLOWLY TILL THE RPM DROPS , THEN GO BACK IN A HALF A TURN THEN RESET YOUR IDOL AND REPEAT ALL THE OTHERS THE SAME WAY.

 

Well, I guess all I mean it that:

Just because you let off the throttle,

Doesn't mean that the slides slam closed and you're back to the idle jet. The vacuum in the system still pulls gas and air through and it gradually closes the slides. So, even though you've let off the slide position still could conceivably be somewhere in the middle and you could be pulling some gas through the main jet still.

 

AND YOU ARE RIGHT WHEN IN DECEL THE PILOT CIRCUIT IS THE ONLY ONE BUT THE VACUUM IN THE MOTOR IS SUCKING THE FUEL AS MUCH AS POSSIBLE.

 

I see, so like you said, move main jet up or move the needle clips to the 5th notch. Like I said it only starts popping around 7500 but if I move the choke out about 3/4 is stops popping. I even made a few redline runs with the choke out and nothing changed performance wise.

 

If your engine is WARM and you can do a full throttle redline run with the choke on and it DOESN'T bog down, I'd say you can DEFINITELY go up a jet size.

Messing with the clips is only for fine tuning if you have the jet size nailed.

Leave the clips alone for a minute if you can.

Is the 5th notch the last one?

Factory Pro or Dynojet?

 

They are Dynojet needles and yes 5th clip is the last position. I'll see what I can do with the mains.

 

Today, I messed around with the pilot screws. I found that 2/4 carbs were 2-1/4 turns out, 1 was 2-1/2 turns and the other 1 was about 2-3/4 turns out. I set them all at 2-3/4 out. This is about a 1/4 more of a turn outthen the manual and the dynojet instructions say. So far I think the throttle became a little more snappy but the popping is still there. I live next to road where today I heard alot of street bikes fly by and when they backed off the throttle, their bikes made the same pops so I've come to the conclusion that since my exhaust is pretty much baffleless, it's more prone to audible pops? How far out is it safe to have the pilot screws before upgrading to the next size pilot jets?