I agree about slowly rolling out of the throttle. Mine doesn't pop at all if I do that. It just kind of burbbles which is just the normal tone of the FMF. I take the F/Ascrew into account and try adjusting it while idling.

 

[sm=funnypostabove.gif]

 

So the first thing I did last night was to start the bike and check for exhaust leaks. I found none but I did notice that head pipe got extremely hot after only 3-5 seconds of idle. Maybe that's normal? I thenpulled the plug expecting to see indications of a lean condition. The insulator was white to light tan so I think it was a little lean. I then moved the clip from the second to the third position and tested it out. The popping definitely decreased.

I probably should have clarified eariler that the popping with the clip in the second position was happening when closing from WOT and at high rpm (7-10K) and would continue as the rpms dropped down as low as 2-3K. So we're talking popping from 10K -> 2K. With the clip now in the third position there is no popping at all when closing from WOT at high rpm (7-10K). However, as therpms comeback down through the6.5K rangeit startspopping until I pull in the clutch although not nearly as bad as before. So now we're talking not popping in the 10K -> 7K range and popping starting somewhere below 7K.

So it seems that moving the clip to the third position is a step in the right direction. If I am correct, the N1TC needle basically controls the vacuum pressure that is drawing fuel from the bowl, through the main jet and into the venturi. Thus raising it up one slot created a stronger vacuum which draws inmorefuel (aka richens the mixture). I think but I'm not sure, that this is pretty much the same thing as increasing the main jet size?

Next I'll try moving the clip to the forth position. If the popping decreases further, it would seem that I have the choice of leaving it there or moving to say a 125 main and putting the clip back in the second position?

Other than that, I pasted a excerpt from an article that I found regarding the CVK40 below.

You're blasting down the trail and you see a
hairpin coming up, so you close the throttle.
This closes the butterfly valve. You and your
400lb baby (the bike, not the other love of
your life), are still rolling with inertia, keeping
the engine revs high. Now it can't get the
mixture it's trying to suck in because the
butterfly valve is closed, blocking the air flow.

To compensate for this there's an air jet in the lower
diaphragm chamber that transfers ambient pressure to
one side of the coasting enricher's spring loaded cut off
valve. The excess vacuum in front of the butterfly valve
is transferred to a drilling that leads to the other side of
the cut off valve. This sucks it open, allowing the pilot
jet to feed more fuel to the engine preventing an overly
lean condition. (Pop. Pop. Pop.)

What air jet is being referred to in the hightlighted text above? Is this only on the CVK40 and not the CVK34?

 

It's not that I don't want to open up the airbox.Only after exhausting all other options do I want to open the airbox.The way I see it opening now would only add yet another variable into the mix (figuratively and literally). Baby steps...

 

I would also suggest the link that Nobrakes posted. I use and recommend that procedure. It usually will get you very close with just a little fine tuning ofthe screw required. The popping on decel is usually a lean condition in the pilot circuit and a slight amount of pop on decel is OK. From my experience with KLX 250's and 300's with the CVK carb you are probably going to be on the3rd or2nd clip on the needle.I think it is also easier to get the needle and main fine tuned after you have the pilot adjusted correctly. If the pilot is off you tend to just jump all over the place on all three circuits. I would also open up the air box, throw the lid away, you don't need it and if you haven't done so, do the crank case vent mod.

 

You really need a 125 main.

 

Think about what you typed...if the threads were finer do you really think it would even screw in the taped port?

 

Iowaguy ...there..its mentioned...lol

Seriously though...I agree with you about the airbox, drilling the vent to 3/8or doing the nobrakes crankcase vent mod...removing the smog stuff...adding the #40 pilot etc. He is changing things like the clip location that are correct and not changing the items that need to be done.