Yes, but now we know that your rev range for the main jet circuit is not running optimally, as with the mains dialed in, you should be pulling hard from about 7,500 all the way to redine, with no flat spots in that range - bear in mind, when I say redline, I'm meaning 13,000! I was thinking 12,500 for some reason before, but I do belive it should be 13K.

The thing that must be done, in order to get your carbs fully tuned, correctly, is to start with a good baseline setting for all circuits, and then go out and work on only the main jets first... resisting making changes to more than one circuit at a time can be difficult, but the only time you want to do this, is when you're setting your baseline.
See the 1st point in the link below.

CV Carb Tuning Procedures

The overlap folks are alluding to here, is the overlap between the main jet circuit and the needle jet circuit, though it is true that each lower circuit has an affect on those above it, to some extent.
That said, with your setup, a size 40 pilot shouldn't be necessary.

I'm assuming you meant "putting 38 pilots back", but anwyay, wise choice.
With your setup, this is what I would recommend - meaning, if this was my bike, this is what I would do.

1. Even with a very free-flowing exhaust, with an OEM air filter, I would start with 138 mains, here's why: let's say you start with 138, which no doubt, might be lean, and you go to 140 and it's much better, then you've still got your 142 and 145 sizes to try, and you'll know when you've nailed it, when it stops getting better with each up, and actually gets worse, telling you exactly where you should park it.
In this scenario, if 140 was an improvement, but 142 starts to get doggy again, then you know 140 is your main.
The more you go in any direction, the more you'll know which direction is correct!

2. Put your needles at the middle position, with the original shim in place. You might end up later raising or lowering this, but once you have your mains dialed in, that's the time to do that... try to ignore the mid-range until you know you've got your mains right.

3. Restore the 38 pilot, and set your fuel screws to 2 1/4 turns out - once again, try to ignore the idle/low RPM cruise issues, and popping on decel, until you get the above circuits set right.

None, unless you need more fuel for good idle and low RPM cruise, then what can be afforded by turning out your pilot screws... I usually don't think about upping a pilot jet, until I've had to exceed 3 turns out, to get that circuit set properly.


Check this link, which you might have seen before... if you follow it, you will do well, especially if you have the time and money to use a dyno to check your work, but if you're like most of us, that's out of your price range!

CV Carb Tuning Procedures

Bear in mind, on both of these links I posted, you can ignore the section about the float height, as the float tang on our Keihins is non-adjustable - as long as your floats aren't damaged, they height should be fine.
Good luck!

 

yes it can but it will also cause turbulence.. put it back in before you change anything because this may very well be your issue..

 

Thanks very much you guys have been real helpful. I don't have a heat shield but I'll try and find one.

One more question, can the difference between 38 and 40 pilots be completely canceled out by pilot screw adjustment? Because right now my idle/midrange is perfect. Will putting 38s in and screwing out the idle screws affect the 7-9k WOT operation?

 

Another question, the instructions for the dynojet needles say that one of the carb slide holes should be filled. Mine aren't, why would dynojet require this?

 

Concentrate on getting your main jets correct first, then see how the rest goes - there is a chance that you'll have to make adjustments to the lower circuits after you get your mains right - your idle and mid-range might be ok now, but when you get your mains changed, they might not be, but get your mains sorted, then work on the others, so your not "working in circles".

 

with dynojets stage 1 set they want you to fill in one of the slide holes and they give you springs as well and this adds up to changing the slide speed..

 

Why do they want that to change, you guys think I should glue the hole shut on each slide?

 

so they open slower.. if you have the springs then you may as well try running the dj needles..