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Discussion Starter #1
Okay so here's what I got. I bought the bike it already had the 4 degree ignition advancer and the Ivan's jet kit with needles shimmed one each, also a yoshimura slip on with block off plates and a flo-commander. I've now got 170's for main jets after dropping in a K&N. Questions are:
Anybody with the same setup that can suggest where mixture screws should be at as well as flo-commander setting? Also pilot jets, should they be left stock. The Ivan's jet kit, is there anything special about it or is it just a set of 160 jets (I believe). I'm running a high rich down low (loading up and sounding like a ninja 250 kinday sputtering) but once I get above about 3K RPM it clears itself. I found out my mixture screws were at 1.5 turns out and one of my floats had a hole in it and filled itself which I'm sure caused it to fail.
Here's what I'm gonna try: leave needles shimmed one each, leave the pilot jets stock, leave mains at 170 (I'm at 600ft altitude), replace the bad float and turn the mixture screws to 2 turns.

I just pulled the plugs and they were just barely on the black side instead of brown. I'm hoping the new float and mixture screws will solve it all.

Any advice or suggestions? Much appreciated.
 

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Here is how I see it.

Good job at identifying the float issue. That will probably straighten out the low RPM sputtering without your having to mess with the pilot air screw.

The plugs are black on the insulator tip? That's a clear indication that your mixture is too rich. What you're describing is called dry fouling. You don't want any carbon, brown or otherwise, to coat the white insulator tip. According to NGK, that part of the insulator, through the plug's heat range, is suppose to self-clean and remain new-in-box pristine white. The reason being, that carbon provides a path for the electrical current (spark) to bypass the spark plug gap, causing the engine to miss. I know this goes against WWW conventional wisdom, but I'm in agreement with NGK. That's how my plugs run and they don't miss. What NGK recommends for determining AFR plug color reading, at least as far as the jet needle and main jet are concerned, is to read the white insulator base color, deep inside the plug. That is where it should be black and only at the base. Spark plug residual coloring there is indicative of a proper heat range and mixture.

The other thing I'd like to pass on is that the "mixture screws" as you call them are not mixture screws at all. They are a part of the idle fuel circuit and should be used to establish high idle speed. This is determined by setting them at about 1 turn out, then turning them out incrementally and equally to raise idle RPM. Once idle RPM no longer increases, there's no point in turning them out any more. I know, I know. This goes against WWW conventional wisdom too. Yes, you can turn them out and they will help deliver more fuel at higher RPMs as well, like what you had hoped from mixture screws, but your idle fueling might end up too rich. And since the pilot circuit delivers its fuel downstream from the jet needle, fuel is not as efficiently atomized, i.e. wasted in the process. Tuning fuel with the pilot air screw is what I call the lazy man's way of tuning your carbs. You can verify your pilot fuel circuit's AFR by reading the spark plug's last thread ring, where it surrounds the white insulator tip. Here it is okay for the ring to be black, since the carbon here will not cause spark plug fouling and engine miss.

On to the Ivan's kit and your other mods. I have not heard of anyone putting a jet kit and a flo-commander on the same bike. That sounds like having two fuel injectors per cylinder. :headscratch Your jetting doesn't sound too crazy for your elevation, but getting back to plug color, the two are putting in too much fuel IMO.

Having a +4 probably adds something and should work together with the modified fueling, but it will also require higher octane fuel. Keep an ear out for detonation problems. You certainly don't want that.

I just think that the AFR needs to be sorted out so your engine can reach peak power output. I don't see that as being the case here. It looks more like the PO threw on a bunch of mods, then told himself how much more powerful the bike was, when it really wasn't. And when that reality finally set in, it was time for the bike to go. :tard
 

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Discussion Starter #3
I appreciate the fast reply. I'll have to read it all a couple times to let it all sink in. I just went out of state for a few days but I'll post pictures of each plug if that will help you understand how my engine is doing. Hopefully by Sunday I can get those pictures uploaded to here.
The idle circuit screws, you seem pretty religious with that tuning process as opposed to setting them per the book. Also, there were probably 4 threads up from the bottom of the plugs that were wet. Are there any tests to perform to see how the main circuit is performing?
 

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...The idle circuit screws, you seem pretty religious with that tuning process as opposed to setting them per the book. Also, there were probably 4 threads up from the bottom of the plugs that were wet. Are there any tests to perform to see how the main circuit is performing?
2000/2001 ZX9R tuning advice
Let me answer these in reverse order
A3) Yes, there are several tuning guides linked from many many ZXF threads, starting with the main jet. Factory Pro’s CV Carb Tuning Procedure is an excellent source.
A2) I wouldn’t worry about the plug’s outer threads being wet. Mine always come out that way too.
A1) The book should say1 5/8 turns and no, there’s nothing wrong with just setting them by the book. But since you asked for advise and were hinting at going to 2.0 turns, I thought I’d give you mine.
 

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Discussion Starter #5
So where exactly do you reccomend those idle screws go? I'm not sure I understand your process mentioned above. I'll search for that carb tuning forum, thanks for that.
 

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Oh! :lol Nobody actually sets their PAS this way, like with the engine running and turning screws. That would be correct, but very difficult. Instead carry the theory forward. Yours are set at 1 1/2 and let's say your idle speed is 1,200 RPM. If you set them to 2.0 and idle speed remains at 1,200 RPM, then you know that 1 1/2 or something lower is where they should be at. Trial and error.
 

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Discussion Starter #7
So basically our symptom of optimum air/fuel ratio (14.7:1) is gonna be the engine trying to idle itself a little higher, which shows us optimum performance at idle?
 

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Pretty much; idle to 1/4 throttle, the low speed/pilot fuel circuit.

It's acceptable for closed throttle idle AFR to actually hover at around 16.0:1, just like it does in our cars. There's no load, no detonation danger and no need for dumping in plug fouling loads of fuel on an engine that's basically air deprived. When the throttle opens, AFR will drop back into more respectable territory.
 

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Discussion Starter #9
After thinking about it for a few minutes, basically for the Idle Air screws, turn them till the engine slows down, then then them the other way I'll it slows down again, and set them finally halfway in between to two points. Does that sound about right?
 

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That would be another way of looking at it, yes.

If you Google how to set them, there are several well written write-ups on how to do this on multi-carb engines. That's a level to which I have not gone, since I feel I have found a successful setting after just adjusting them and riding the bike up and down in elevation to record the affects less and more atmospheric pressure had on how they were set. I didn't like when they were at stock or at 2.0 turns; stock meaning screwball OEM settings hovering around 1 1/4 turns. They were a mess and the bike broadcast that fact. 1 5/8 was great, but caused RPMs to go up too much when I rode to lower altitudes. Whereas, 1 1/2 worked best at everything from sea-level to 10,000' AMSL.
 

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Discussion Starter #11
I see. Just experiment somewhat. What im gonna do Saturday when I get back home is:
Drop back down to 165 mains, and remove the shims on the needles, and set the flo-commander to stock setting. Should float height be left at 4mm? I had a guy at the dealer tell me set the floats at flush, basically 0mm. I'll also try 1-5/8 on the IA screws. Then I'll proceed with the tuning guide you referred me to. Does that sound like a good thing to do?
 

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Sure does. Float height is 4mm +/- 2mm. Maybe flush means 4mm. Mine are at 5mm, 1 mm leaner than 4mm.
 

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Driveability, no. When preventing fuel seepage while parked on hot days, FOR SURE!
 

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Discussion Starter #15
Haha I suppose I'll favor the "+2" and set 5-6 then. Hey buddy I really appreciate everything. I'll post again Saturday night here and let you know how thing worked out, will you be available this weekend for advice?
 

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Trust me, you won't need me. There are plenty of others on here that can help you, if I'm away from my computer.

Weather's suppose to hit 81 here on Sunday (gonna ride) and I have to work Saturday as it turns out.
 

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+2, i.e. 6mm may result in throttle lag. I know on my 2002 F1, I cannot run + 1mm. They have to be at 'flush' at 13mm.
 

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Discussion Starter #18
I see. So shoot for 4-5? Take the carbs off, flip them over so the bowls are on top and measure just like that correct?
 

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Discussion Starter #19
Also E1,I've been reading alot of forums on here and I see a lot of people are shimming needles just like us, is there a certain amount that seems to work best for everybody? Also,it seems most people are going to #40 pilot jet, should all 9r's do that? And lastly when experimenting with different shim thicknesses, is that gonna create a domino effect? For example, I change shim thickness, so I need to change mixture screws AND main jet AND float height?
 

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Jet fine tuning

Subtle changes make for big results. Your jet kit needles are technically superior in adjust-ability. Shimming is more for us folks who want to change our mid-range AFR without buying a jet kit. In this case, 0.5mm - 1.3mm seems to be the sweet spot for stock E/F needles. Again, it doesn't seem like a lot, but you have to consider the needles were engineered to be at a specific height. You don't want to go messing with that height too much, like by adjusting several millimeters up or down at a time.

Fine tuning jet kit needles comes down to potentially stacking a washer shim under the clip, if you find it has some advantage for you.

And yes, the jet needle's fueling will carry over slightly into the low and high speed fuel circuits, but would only have detrimental affects on those if it wasn't tuned correctly for mid-range, i.e. set too rich/lean. Try to follow the Factory Pro CV Carb Tuning Procedure. For a novice jet tuner, just stick to what they recommend and you'll end up with superior results. Violate or ignore their tuning rules at your own peril.


On my bikes, I like the 0.78mm shim. I have a healthy mid-range boost and mid-range surge elimination, without the gas guzzling side affect I found from running higher settings. A win-win. Superior range to anything I'm riding with, including touring bikes, while at the same time having the awesome grunt to took keep pace with the liter bikes. :headscratch "How many gallons does that thing hold?" -- "What Power Commander are you running?" :lol

Strange coincidence possibly, but since tuning my SuperTrapp and fueling, every single one of my riding buddies has upped their bike mods too, all have opted for more HP. One went as far as adding an engine management system with traction control and clutchless shifting. So from my perspective there's the appearance I'm doing something right. :lol
 
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