First off thanks to all who have helped me thus far, without your help I wouldn't be as close as I am. Anyway, here's whats up. The bike has a 4-1 'race' header and shortened pipe with almost no packing or baffling in it (sounds almost like a straight pipe), and a stock air filter. It has a dynojet stage 1 jet kit in it; glued one of the slide holes shut on each slide (per dynojet instructions), has 126 mains, and the needle clips on the second spot from the top.

It runs perfectly from idle to 8k then hits a flat spot where if i play with the throttle (alternating from like half to full) I can get it to like 9.5-10k where from there to redline it pulls real hard. From all my experiences thus far, the 8-10k prob seemed like a rich problem, so I put on a k&n filter to try it out.

Idle-8k stayed perfect but from 8-redline it sputtered and barely ran (guessing way to lean?). My next move I think is to put in 124 mains with the stock air filter and try that. What do you guys think?

BTW idle-8k is real perfect, I just rode this sucker 630 miles in 2 days averaging 70-80mph getting 46mpg. Not bad

 

Those who have seen my previous posts know I've pulled these carbs 7-10 times. I've tried stock needles, mains as big as 145, all different combos. Turned out one of my main problems was my absence of a heat shield. I made one up modeled after the stock one and it changed everything. They're real important to prevent turbulence under the air box

 

I can't remember where we left off in any other threads, but 124 will be too lean on top with a paper air filter, and of course, even more so with a K&N.

The top-end (main jets) have to be dialed in before perfecting the other ranges, though if your real darn close with mid-range and low speed/idle, then once you get your mains right, you might not have to make much adjustment of those (jet needle and pilot settings).

With 126 mains, race header, and essentially a straight-through exhaust, I would expect 126 to be too lean as well, especially bearing in mind that the stock jets are 135.
Personally, with the K&N installed, I would leave your jet needles alone for now, set your fuel screws to 2 1/4 out, and start working from 138 mains... if 138 gives you a nice hard pull from about 7500 to 13,000, then try a 140, if it then gets worse, then you know you're going in the wrong direction, if it gets even better, then repeat with 142 mains (both of my bikes are on 142 mains, with race headers and shortened cans, and they run like mad).

I cannot stress enough, that you need to focus on the mains first, completely ignoring other ranges, so long as it idles and runs decently in the lower ranges, THEN start working on the circuits below, i.e. needles and pilot screw settings... I'm sure I mentioned this before, but it is crucial to dial things in "from the top, down", or your're going to work in circles.

Another thing worth mentioning, is that if you're still doing all this testing on the same plugs, you need to at least pull and inspect them, in case they've been fouled-out during previous running... clean or replace them, so you KNOW you've got good plugs when you test the bike on the road.

Just out of curiosity, do you know that this motor has good compression in all four cylinders, and with good plugs in, have you ever done spark tests on all four, to verify you're getting a good blue/white spark? With any other issue at play, this will just get totally confusing.

 

Maybe I didn't emphasize this in my first post but the 126's and the 124's I intend to use are in terms of dynojet numbers. The DJ 126's are the same size as keihin 135's and DJ 124's are keihin 132's. Also, I've found that the dynojet needles significantly change the 7-13k operating range when compared to stock needles. As an example, when I didn't have the heat shield in, keihin 140 mains and DJ needles gave me a perfect 7-13k pull. When I tried stock needles, it was so lean it would barely run past 10k.

Correct me if I'm wrong, but if I recall from your threads, you're using factory pro needles right? How do those differ?

I've had the bike pulling real hard in all of its rpm ranges so I know the motor is good. With one of my setups it would barely run up to 7k but lift the front wheel off the ground past 9k. My problem has been I can't find the combo that gets all the rpm ranges correct at the same time. Also, I recently changed the plugs, they're good.

Thanks for the help man you always have good advice. If worse comes to worse, I'm putting in stock slide springs, stock needles, 135 mains, and a stock header and starting from there.

 

Now that is just annoying!! Why in the world would they do something so confusing?!?
Anyway, I did not know that about DJ mains, and no surprise, because I've always used Factory Pro stuff, and I only use Keihin main jets, for consistency, though Factory Pro does claim that their jet size designations are to be used for direct replacement of Keihin jets of the same size.

OK, now this is what we need to be focusing on, getting your mains correct first. Now that we got the cross-referencing of jet sizes out of the way, what you're saying above is close to what I was suggesting, which is working in the range of 138 to 142 (Keihin sizes ).
If 140's were giving you a perfect pull, then get back to those - did you by chance also run 138 and 142, and found 140 to be "the sweet spot"? Anyway, mains first, so if 140 gives you a rocketing from 7,000 to 13,000, then put 'em back in, and forget 'em... now, work on your needle jet circuit.

Bear in mind, and I know I'm being repetitive here, but putting the 140s back in, to get your top end stout, might very well cause what was working at some point with low-end and mid-range, to need adjustment - personally I would start with the clip position in the middle, with the shim, and focus now only on hard pulls from 5,000 to 7,000. By the way, how many positions are on the DJ needles?
So, ride the bike, and see how the needle position feels, and take your best guess at whether you're rich or lean, from 5K to 7K. This is not easy, and if you're not well versed in "feeling this out", you might guess wrong, but if your change makes it worse, just go the other way until you stop improving with each change.

It's true that the stock needles could be more of a challenge, and could take a lot of shims to get things right, that's why the aftermarket needles have the variable clip positions, and you can still use/lose a shim, in conjuntion with a raising or lowering of clip position, to make smaller changes.
I can't make any comparison to the DJ needles, but I hear they are slimmer, with regards to the diameter/taper, which allows a bigger "hit" of fuel when the slide first starts opening. Some have complained about the "driveability" of the bike, due to this slimmer taper, and most of those that I've read about, that went from the DJ to Factory Pro Needles, were pleased with the change... in short, I've heard a lot of complaints about DJ needles, and I don't think I've heard any about the Factor Pros.

Yes, I use Factory Pro needles, and they don't seem that far removed from stock, with regards to the overall diameter and taper, but they seem to have a smoother tip, which would allow a smoother flow of fuel perhaps - the main advantage to me is the ease of adjustability.


Carb tuning can be a royal pain, but if you only make one change at a time, start with the main circuit and work your way down, and stay consistent with other aspects of setup (same header/can, same air filter, good plugs at all times), it will work out eventually!

 

It bothers me to lol, I wish they'd go by keihin numbering

You unfortunately omitted the most important part of my quote, the "when I didn't have the heat shield in" part. After putting in the heat shield the bike ran completely different. As squale147 pointed out in one of my earlier threads, the absence of a heat shield creates turbulence and strange jetting confusion. After installing the heat shield, 140s were wayyyy too rich, the 135s (DJ 126s) are still even too rich. I haven't yet found which mains create the best 7-redline pull with the heat shield installed. I'm hoping 132s (DJ 124s) will be my answer.

135s are too rich for the stock filter but too lean for the K&N. It stands to reason that 132s with the stock filter then should be right.

6. They recommend starting on the second position from the top for f2s.

I've heard the same thing. I would not have purchased a DJ kit, its just what my bike came with

Yep you're right, I'll go down to 132s (DJ 124s) next. If those are still too rich I'll try 130s (DJ 122s). Thanks again for all the help, I should have time to pull the carbs by mid next week. I'll try the 132s and report how it goes.

 

With the DJ 126s it pulls hard from 9000 and up, but you have a flat spot around 8000. This is the needle transition point. It sounds like a lean spot rather than a rich spot. Try raising your needle by moving the clip down one or even two slots. If it gets worse then you need to raise your clip up to lean it out. I lean (no pun) towards the lean condition, as it runs crisp and clean up to 8000. Tuning is fun without an AF meter. Old school

 

You really think its lean? I think its rich because I had the same problem with 140 mains but intensified. Like instead of having the flatspot from 8-10k it was more like 8-11.5k then it ripped hard to 15k (I know I shouldn't take it that high). Also, right now it doesn't pull hard from 9000 up its more like from 10,000 up. I'll try raising the needle clips and see if that helps. Thanks for the advice, thats a good idea to try toying with the needle clips first, I didn't think of that because of how on point my 5-7.5k is

 

Well juggling in my head whether its rich or lean from 8-10k a lightbulb went off. Why don't I run it with the choke on and see what happens? Am I right? If with the choke on it pulls from 8-10k I will have discovered it's lean right?

 

Pulled a lot better with the choke on, gonna lower by 2 positions and try it