[d3ad1ysp0rk]

I'm talking a carb'd engine; the katana.

Did Ivan list what his jet kit was originally designed with? I mean.. if it was designed with a certain exhaust in mind, wouldn't having a worse/better flowing one negatively effect the bike in the fact that it wasn't "already tested with components in place"?

Isn't the point of the A/F screws to allow some play in what a certain jet size can accomedate in terms of fuel?

[steves]

To "dial the bike in" requires the use of dyno equipment and usually an exhaust gas analyzer to determine if you are combusting everything you are putting in.

From Ivan's site:

This kit needs to be used with a stock airbox and filter.....

Aftermarket filters were tested and there was no performance increase at any rpm -

Dale's kit does use a K&N Filter on the kat, but doesn't change the needles... which as I recall effects the mid-range power.

Here are Dale's Dyno results

And here are Ivan's

[fsand03]

I pu t a K&n on my Kat and had some problems. I ended up putting a dynjet on (stage 1) and it runs like a champ. I also wantede to note that I knocked a vacume hose off when I first pu the K&N in and Imade it about three miles and the bike started acting really sluggish. Slipping the hose on solved that, however, my bike still stuttered at 55 MPH to 65 MPH. Once I jetted the bike, it ran great.
Agree with the others, changing the air filter changes the mix.

[d3ad1ysp0rk]

According to those, Dale's actually makes more peak power.. (2.6whp increase vs 2.4 with Ivan's). They're using different Dyno's so the difference in power is all you can use to compare with.

Either way, I looked at Ivan's site, and I guess if that's how it is, that's how it is. I just can't wrap my head around it fully.

Thanks

[steves]

According to those, Dale's actually makes more peak power.. (2.6whp increase vs 2.4 with Ivan's). They're using different Dyno's so the difference in power is all you can use to compare with.

Either way, I looked at Ivan's site, and I guess if that's how it is, that's how it is. I just can't wrap my head around it fully.

Thanks

I don't really think I helped answer the question... try reading here

http://www.dansmc.com/carbs2.htm

[The CyberPoet]

According to those, Dale's actually makes more peak power.. (2.6whp increase vs 2.4 with Ivan's). They're using different Dyno's so the difference in power is all you can use to compare with.

You need to look as power differences as a percentage (esp of torque peak) and not as a hard number -- that will help remove biases based on the dynometer and environmental factors.

Either way, I looked at Ivan's site, and I guess if that's how it is, that's how it is. I just can't wrap my head around it fully.

Perhaps I can explain it better.

(A) As you basically said, any gasoline-powered engine is basically an air pump system -- how well it breathes is what limits it's performance, as long as you can keep the fuel mixture in the right ratio. It needs to breathe out as well as breath in -- with the limit to performance being whichever of the two is most constrictive.

(B) On injected cars (and most turbocharged and/or injected vehicles of any type) there is a lambda circuit that compares values from O2 sensor(s) in the exhaust to decide how much fuel is needed for the air to get a perfect "burn" (to make sure the amount of oxygen in the air is matched perfectly to the amount of fuel dispensed as vapor). Changing the air filters, air boxes, exhausts on these vehicles usually presents zero problems because the circuit will compensate by increasing the fuel to balance. If the changes are too extreme, the stock oxygen sensor may not be up to the job, so you use a wide-band sensor instead.
Modern versions of those systems also check for other factors (such as pinging, whether the engine is cold or hot, etc) and factor that into the fueling and spark timing to acheive optimum results.

(C) On virtually all vehicles with carbs have no way of automatically adjusting the fuel ratio in response to an O2 sensor or lambda calculation. The only exceptions are a few GM vehicles sold at the end of the 70's using Fischer's patented controllers that he designed for GM to do specifically that (Cadillac was the primary beneficiary here).

(D) Thus, changes in the breathing rates on carb'd engines needs to be matched to appropriate jetting to compensate and that traditionally means aftermarket kits (or alternative parts from the original carb manufacturer), plus time on an external exhaust analyzer and dynometer (where the dynometer's real job is to provide a resistance to the engine output in order to give you valid readings across the running RPM range -- simply testing the bike in neutral won't produce the same values out the exhaust pipe). The exhaust analyzer tells you what's happening to the fueling in each RPM range based on the readings of the gases (usually CO2 and O2 content).

(E) On the Kats, the primary choke point to breathing is at the OEM collector -- where the four header pipes merge into one and mate to the midpipe (at least on the 98+ units; I suspect it's generally true of the pre-98's as well, but I'm not absolutely sure). Thus, changing the air filter to a less restrictive filter without changing the constriction point at exhaust headers doesn't let the engine breath any easier (because it still can't exhale any faster, meaning that becomes a barrier to inhaling better). And as a result, all that happens is that the vacuum pressure at the carbs drops because there isn't as much restriction to the air coming inbound (to keep the vacuum levels up). So to compensate, K&N users install the smaller-opening donut in the airbox opening to restrict the inhaling AGAIN to approximately what it was with the OEM air filter, plus often still have to increase their fueling circuit sizes (opening the pilot screws further, installing larger jets, raising the needles) simply to permit the same fuel-air ratio at the same volume to get into the cylinder -- which results in no net performance gain, but a bunch of money spent on filtration and jetting to compensate. They're looking at the wrong end of the equation!

(F) Now let's reverse the equation, saying that Johnny Katana leaves the stock air filter and airbox and gets a larger header system instead (such as what I did when I installed the 750 headers & exhaust on my Kat 600 -- and increase of 24% cross-sectional area). What happens now? Well, we've addressed the primary constiction point at the exhaust, so the system can now breathe better. Well, unless the header & collector system is really oversized, the stock airbox and air filter will still flow enough air to let the system work correctly, while continuing to maintain the same vacuum levels at the carbs that permit the stock jetting to function. And you got a power increase because the engine can breathe better! But not a big increase (not really worth the cost of the replacement header, unless you can get it really cheap -- but I didn't know that when I set-out to figure it out).

(G) The problem on the extreme end (such as V&H's Katana headers, with something in the neighborhood of a 76% increase in cross-sectional area) is that the exhaust opening goes so large that the primary constriction point can become the air filter opening to the outside world -- and it's in cases like this where a higher-flowing air filter starts to pay dividends (and also, noteably, the point where you stop using the smaller-opening donut with the K&N and move to the larger opening donut or to pod-style filters). But the higher-flowing, less restrictive air filter still reduces the vacuum levels going through the carbs, so rejetting to avoid being excessively lean again becomes mandatory. But here's where we hit the trouble-point: it can be extremely difficult or even impossible to ideally fine-tune all the different fueling circuits individually with this set-up. Pressure waves bouncing around can induce problems fueling correctly in specific RPM ranges, and it's common for this kind of set-up to have a narrow (usually 600 to 1200 RPM wide) band where it simply doesn't fuel well and the engine either goes way to rich or leans way out. And after throwing money at an exhaust header, aftermarket can, K&N filters, jet kits and a bunch of dyno-tuning time, many people get really frustrated by this fact. Some manage to move that problem band out to an RPM range they regularly never use (so it's not significant), or learn to avoid a specific RPM range (simply power through it and then keep the RPM's up to avoid hitting it again). But many give up in frustration and start asking for solutions, depending on how bad it is and how much money they've been willing to toss that the upgrade...

(H) Which leads us to the most common answer when things simply can't be tuned well and people are bashing their heads against the wall: return to a known-good combination. And the best defined known-good combination is bone-stock, as the bike came from the factory. Which oddly enough, is the configuration that virtually every manufacturer tests their aftermarket equipment with. V&H didn't sit down with a Kat that already had an ignition advancer, K&N pod filters, a DynoJet or FactoryPro jet kit and design their exhaust -- they sat down with a bone-stock Kat and built an exhaust system that would work. And DynoJet didn't grab a Kat with a V&H exhaust to design their initial jetkit for the bike -- they started with a Kat that was bone stock again. Etc.
Some of the firms with larger research arms (or just more dedicated product developers) may have come up with solutions for a wider variety of circumstances (such as K&N including two different donut sizes with their airbox filter), while others learned the hard way by getting reports from the field on what worked (DynoJet is a perfect example here -- their tech database has information on what configurations work with *some* particular combinations of equipment, but these answers were gotten from dyno-tuner operators in the field after the initial jetkit was designed).

(I) Which leads us full circle to the johnny-come-lately in the Katana fueling game: Ivan. By the time Ivan started building his katana jetkit in late 2005 or so, every breathing accessory on the market for the Kats was already out. So he sat down with a bone-stock Kat (well, a Kat that was returned to bone stock) and designed a jetkit to maximize the performance (trying to hit that perfect 13.2:1 fuel-air ratio that maximizes the torque out of any gasoline engine). And after cutting needles and swapping jets, running the dyno & exhaust, taking readings, then milling fresh needles & changing settings (in a loop that was approximately 7 weeks long of doing this every day of the week his shop was open), he had a highly optimized kit for the stock 98+ Kat 600 that was head-and-shoulders above everyone else's kit (I know because I field tested his kit that week back to back with both the stock jetting and the dynojet kit). But he also had the other accessories on hand, so he slapped in the K&N airbox filter, and started testing again. And then an aftermarket muffler, nd started testing again. And both together. And an advancer, and the aftermarket header from some company that I forget.. And after three weeks of this, he emerged from his workshops and declared definitively:
1. The stock airbox & filter will let you produce more power with my kit than any aftermarket filter. That there was no power-benefit and sometimes there was a loss of power compared to the stock airfilter if you were using the K&N airbox or Uni-Fam filters, -- but that if you insisted on running the K&N anyway, he would send you the correct jets to run the K&N (instead of the right ones for the stock filter) to make you happy. Which, oddly enough, was exactly the same answer Marc over at FactoryPro had seaid many years ago in regards to his Katana kits (both pre- and post-98 kits).

2. Ivan continued, saying the constriction point in the system was in the collector/midpipe area, and that all the aftermarket headers for the 98+ kats actually used the stock midpipe gasket, so they all retained at least some of that same constriction point. And again, that he would send you the right jets if you insisted on going that route, but to be very wary of going to an excessively large header, because you would end up with potential problems in being able to tune correctly for them (which matched what everyone at KR, and prior to that, KP, knew from reports from people who had tried it).

3. And finally he said, they're ready. Come n' get 'em. And they came... and many people were very happy, because unlike DynoJet's kit, Ivan's came with exactly the right jets and needles to install (no guessing which of the 5 different sized jets you should use, as is the case with DynoJet's solution, or which needle clip position).

Now, hopefully all that makes more sense to you
Oh, and Ivan then turned around and made the Kat 750 jetkit, although it took a lot less time because many of the same design elements (such air filter/airbox sizes) are shared between the two engines, so he had a much easier/faster time of it. And the results of 1-2-3 remain the same for that engine as well.

Cheers,
=-= The CyberPoet

[The CyberPoet]

I just went through this. I had a UNI brand oil soaked air filter. I was ready to start messing with the jetting, but decided to spend $50 on the stock filter, first. I solved all of my problems!

Next time, order it from me -- I only get $33 plus shipping for the OEM air filters and have them here on the shelf ready to ship at any time

Cheers,
=-= The CyberPoet

[d3ad1ysp0rk]

Hmm, thanks CyberPoet.

Just so I don't need to start a new thread for one simple question; has there been any jet kit decided on as the "best" for a Pre 98 with a Full V&H exhaust?

[The CyberPoet]

Hmm, thanks CyberPoet.

Just so I don't need to start a new thread for one simple question; has there been any jet kit decided on as the "best" for a Pre 98 with a Full V&H exhaust?

From what I understand the best (most reliable) solution for it appears to be the FactoryPro kit combined with the OEM airbox & filter. But since I haven't owned a pre-98, it's just me repeating what I've heard.

Cheers,
=-= The CyberPoet

[md86]

Pre-98's seem to respond maybe a little better with pods . I've heard of a few people that got them running fairly well that way . Hell , Keith built a few that way , so ....
I HAD pods on mine , I could get it running ok , but seems to be CONSTANTLY tinkering with needles and pilots , and never could get it "perfect" . I MAY try again sometime when I'm SURE there ain't no more gremlins in there messing with my shit ....

[Oly03kat]

Jets

CyberPoet, EXCELLENT, I have done about all the above and so have the factory engineers. If you change one thing you may have to change other things. Very good explanation.
BTW Kat 600 with K&N, Dale Walker, 5 degree and Yosh. Around town and normal freeway - great. Race track at 160 mph, don't know not where I ride.

[bswasey]

Mine seems to run fine. 06 600, K&N w/ large donut, Factory Pro Kit with jetting one size up and A/F screws at 2.5X, scorpion can, and factory headers with the excess welds at the manifolds ground out. It runs better with the larger donut over the smaller one. That ran good too, but I noticed in 6 gear at low RPMs (2.5-3K) if you went 3/4 to full throttle it would make a chugging sound until it about 4000 RMPs them accelerate really good. The larger donut smooted that right out.

[JohnbliYayzzy]

Is the performance gain significant for grounding down the excess welds at the manifolds on a 99 kat 600?

[bswasey]

Honestly, I didn't notice much of a difference. I didn't think the welds took up that much space until I pulled the header off and yeah, they rise up about a 1/8 of an inch so they take up about 1/4 from the diameter. It was time consuming to grind them down and I went through a lot of grinding heads. You also need to get them close to each other to prevent pressure differences between cylinders.

[The CyberPoet]

One note about grinding header seam welds (how to listed here: http://www.motorcycleanchor.com/katana/header.html ) -- you will need to sync the carbs afterwards because it changes the vacuum levels at the carbs.

As for the power-improvement, most of the benefit will be at and above 7k RPM, where the engine is really pumping a lot of exhaust gases out, and will only make a marginal difference. But it will change the sound of the bike a bit (I started hearing intake roar instead of exhaust rush on heavy throttle application after I did it).

Cheers,
=-= The CyberPoet