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View Full Version : Jet kit VS Poor mans jet


BlackburnD
02-08-2007, 08:08 PM
Spring is on it's way (slowly but surely) and I have every intention on putting a Scorpoin slip-on on the Kat in the next month or so. I want to get the carbs jetted and I brought this up to the guys at my dealer. I know these guys they are pretty good guys. Anyhow they asked me why I wanted to buy a jet kit when they could easily just install larger jets, and save me a good bit of money. So I am a little torn for more than one reason.
Is there going to be a big difference from the jet kit and them just taking care of it for me with no kit?
Secondly how hard are jet kits to install? I am a bit nervous of doing it myself because I have very little motorcycle mechanical experience, but was a Jeep and Chrysler tech for four years. Things like Carbs have always made me nervous. But if it will be cost effective and not too hard I would almost rather install the kit myself because I don't know that I trust them to actually do what Iwant them to do. I'm not a very trusting person. I have read a few old threads but none really answered my questions or made me feel at ease.
I'm also curious who makes and where I can get one of these ignition time advancers like Cyber has on his bike.
THanks all

The CyberPoet
02-08-2007, 08:56 PM
For the ignition timing advancer, you can order one from me -- I stock them (Q: have you seen this thread of what I stock for the kats? CyberPoet's "Kat Riders Members Special Offers: Maintenance and Upgrade Supplies" (http://www.katriders.com/forums/viewtopic.php?t=17251) ). Or, if you are a machinist, you could take your existing one and mill it exactly 5 degrees (to change the stock timing from 4 degrees BTDC to 9 degrees BTDC). Personally, I'm no machinist, so I just bought the pre-fab'd one and used it (not to mention the potential for things going wrong if your not a good machinist -- one of our guys had his whole sensor set-up & cover get chewed to bits by a home-made jobber a couple years ago).

Now, as for the jetkit:

You can do a poorman's jetkit. Half-shims under the existing needles, and a half turn out on the pilot jets, double check with an exhaust analyzer at various RPM's and you should be set. It'll richen the whole mix up a bit, and take it from borderline too lean (say 14.8:1) to slightly rich (say down to 14:1 is probably the best you can hope for) across most of the RPM range. More than good enough to match an aftermarket exhaust's increase in flow (if there is any), and it'll get better performance out of most of the fuels currently on the market (because alcohol, TANE, MTBE all drop the stoichiometric rate -- you're a mechanic, you should know what I'm talking about).

Or you can step up and buy one of the pre-engineered solutions from one of the outside companies which includes different jets (may or may not be larger -- Ivan's are actually smaller), new needles (with different tip-grinds) and instructions.
My own experience has taught me that I'd rather use the poor-man's kit than DynoJets -- and I'd rather use Ivan's over either of the others, based specifically on performance and throttle response. If your goal is mileage and absolute top-end speed, stick to the poor man's kit or to stock; if you want 0-100 to improve significantly, go with the Ivan's.
With the Ivan's, you're going to be ending up with a mix rate of about 13:1 for most of everything off-idle, which maximizes torque and throttle response & helps run the engine cooler (at the expense of pollution and fuel-mileage, obviously; you're sucking in more fuel). In the case of Ivan's, you'll end up with much sharper, finer needles, smaller mains (110's for the 600 typically), and much richer pilot screw settings (4 full turns out). These aren't ball-parked solutions, but instead Ivan spent a good 4 weeks cutting the needles, tweaking the jets, testing on the dyno with the sniffer attached, retesting, running another batch of needles, back-and-forth to get the results he did. If you compare the stock ones or dynojet's to Ivan's, the stock & Dynojet brands needles look like they were formed by a blunt hammer out of a fat blank -- Ivan's looks like exactly what it is -- a thin needle with five different taper grinds on a super fine tip. It's literally precision work.

As for the hassle/trouble/skill set involved in installing them: getting to the carbs and getting them off the bike (then reassembling everything after install) is 90% of the trouble. The install of the jet kit is really a virtually no-brainer, somewhere around a 2.5 on a scale of 1 to 10.

Cheers,
=-= The CyberPoet

BlackburnD
02-08-2007, 09:32 PM
Ya I have seen that post before, but never noticed the link in your sig. I will def keep a btter on that in the future. Thanks for the info CP. I have the service manual for my bike so I think that should make the whole job a bit easier. I think I will probably go with the Ivans.
One more question before I make my final decision. Are there any special tools I need for any part of this job? I imagine not but thought I would ask anyway.
Thanks again.

The CyberPoet
02-08-2007, 09:42 PM
As a mechanic, I suspect you already have access to a set of vacuum gauges or manometer to do a carb sync procedure to the bike after the install -- so that, plus a fuel source aside from the existing gas tank (or 6' of fuel line hose and a platform to put the existing tank above the height of the bike, so you can use it as the fuel source during the carb sync procedure). In strictest terms, it doesn't absolutely need to be sync'd, but general rule is to do it any time you change the valve clearances or open up the carbs, especially anything that richens the carbs up (which causes differences in vacuum levels to be more noticable as vibration if not sync'd).

For the install of the jetkit, you'll need a #2 phillips, a 1/8th drill bit (or some other small sized bit -- need to make a pilot hole to get a self-tapping sheet metal screw into a piece of sheet metal) & drill to drive it, a can of carb cleaner, a towel or rag, and possibly an impact driver (depending on how tight the float bowl retaining screws are). Many of us replace the float bowl screws with allen-keyed replacements when we disassemble the carbs because the factory tends to really do a number on tightening certain ones (making it a bear to get them off).

Cheers,
=-= The CyberPoet

The CyberPoet
02-08-2007, 09:43 PM
Oh, and there's a walk-through for both procedures (jetkit install and for the carb sync) on my website.

Cheers,
=-= The CyberPoet

md86
02-09-2007, 02:33 AM
It's the needles that make the kits cost so much . Supposedly the R&D that goes into getting their needles "just right" . I'd LOVE to see some dyno/EGA graphs comparing JUST the needles :thinking .... And different mains don't play well with odd needles , either . Can't use Mikuni jets with DJ needles , for instance . Go on , ask me how many jets I went through to find out THIS one :roll: .

BlackburnD
02-09-2007, 06:23 PM
Hmm. I'm sure I can get my hands on all of those things. Unfortuantely I used to be a mechaninc. So I don't have all the stuff I used to. (I know you should never sell your tools, but times were tough). Thanks for the info

The CyberPoet
02-09-2007, 06:41 PM
Hmm. I'm sure I can get my hands on all of those things. Unfortuantely I used to be a mechaninc. So I don't have all the stuff I used to. (I know you should never sell your tools, but times were tough). Thanks for the info

If you can't borrow the carb sync tool from a former co-worker/friend, ask around on the board who is in your area that might be able to help you in person with theirs -- then buy 'em dinner ;)

Cheers,
=-= The CyberPoet

Jhonyquest97
02-09-2007, 09:28 PM
Cyber, do you have to use the sync tool or can you just ball park it?

The CyberPoet
02-09-2007, 11:21 PM
IMHO: you either use the sync tool (or vacuum gauges or some other viable alternative), or you don't. There is no good way to ball-park it (based on those I've seen try and then I've gone back with the actual sync tool to measure it) -- there's simply too many other variables outside of the butterfly positions at play involved, such as valve clearances.

If you've gone and for some reason messed with the sync screws that control the butterflies, by all means, ball-park it back to miniscule openings (all even), but if you didn't touch the butterflies (which you don't to do a jetkit install), leave them alone unless you have a good way to measure the vacuum and balance it.

Somewhere there's a list of parts to build a manometer out of about 30 feet of clear tube and water (or any heavier liquid that won't kill your engine if ingested), but it requires a lot of ceiling height to be able to use -- something like 12 to 15' foot ceiling height if I recall correctly (because water is much less dense than mercury). Still, total cost is under $15 if you shop well.

Personally, I just opted for the Morgan CarbTune II right off the bat, because I knew that I would have a bike for as long as I can physically ride, and even injected bikes need to have their vacuum measured/butterflies balanced. One time purchase (was about $110 delivered last I looked) and you have a tool for life.

But like I said -- see if you can find someone else in the area that already has one that you can borrow if you're tight. Odds are someone within 50 miles has one -- and it doesn't take much time to do it (for example, if you roll up to my place, I can have the tank off and the carbs sync'd in about 8 minutes if I can avoid burning myself on a hot engine when I put the tubes on).

Cheers,
=-= The CyberPoet

md86
02-10-2007, 02:23 AM
Dayton's not TOO far away , and I know someone with a synch tool . I actually have it in my shed . :lol:

Steveb
02-10-2007, 07:55 AM
Somewhere there's a list of parts to build a manometer out of about 30 feet of clear tube and water (or any heavier liquid that won't kill your engine if ingested), but it requires a lot of ceiling height to be able to use -- something like 12 to 15' foot ceiling height if I recall correctly (because water is much less dense than mercury). Still, total cost is under $15 if you shop well.

Not sure where you figured about all this ceiling height VS fluid density, but it's just a comparative meter, so ideally, the fluid doesn't move.

Normal ceilings will work fine.
http://www.powerchutes.com/manometer.asp

The CyberPoet
02-10-2007, 09:19 AM
Not sure where you figured about all this ceiling height VS fluid density, but it's just a comparative meter, so ideally, the fluid doesn't move.

Normal ceilings will work fine.
http://www.powerchutes.com/manometer.asp

The plans I saw were tall enough that even if you had zero vacuum in one cylinder and max vac in the other three, it couldn't pull the liquid all the way through to the engine. Same basic concept though.

Cheers,
=-= The CyberPoet

flyguyeddy
02-12-2007, 12:55 AM
just bumping this to the top with a question: what exactly is a half shim? and where would one go to get such a thing?

The CyberPoet
02-12-2007, 01:44 AM
A shim is a common term for a washer specifically intended to raise the needle up. Item #8 in this fiche:
RonAyers: 98+ Kat 600 Carb (http://www.ronayers.com/fiche/300_0298/carburetor/carburetor.cfm?man=su&groupid=4880&parent=4850) is a typical full-thickness shim.

Since the stock needle (item #9) only has one slot cut in it for the E-clip (item #7) to clip onto, the only way to raise it up is to place something additional under the existing washer that is already under the e-clip. Raising it too high would make the fueling too rich, so a half-shim is recommended instead of a duplicate of item #8.

A half-shim would be one that is half as thick as the standard one, and you'd add it under the existing one.

Cheers,
=-= The CyberPoet

flyguyeddy
02-12-2007, 07:31 AM
any idea how thick they are?

when i had my ninja 250, i could buy a bag of washers from radio shack that would have an appropriate sized washer in it for a shim.

has anyone found a good source for half shims?

The CyberPoet
02-12-2007, 04:51 PM
I've never bought 'em (always went with packaged jetkits), but someone else around here has gotten them out of radio shack and might be able to post up a radio shack part number.

Cheers,
=-= The CyberPoet

md86
02-13-2007, 09:34 PM
Just get some thin washers and experiment :dunno: . Every bike will be a lil different anyway .

katanasport600
02-14-2007, 08:42 PM
Dang, yall gettin pretty specific. i guess i need to learn to do this stuff. i can restore a car( built a top 25 at pigeon forge) but for some reason i am terrified of bike motors(maybe cause there so small!) are there books or something i can pick up and start readin about all this(with blowout schematics)?

The CyberPoet
02-14-2007, 08:50 PM
...but for some reason i am terrified of bike motors(maybe cause there so small!) are there books or something i can pick up and start readin about all this(with blowout schematics)?

Start with the 98+ factory service manual, which is available here on the site in PDF format -- it will have 99% of what you need to know.

The only real screw-up that many people make is to not use a torque wrench (or not use small enough of a torque wrench to get accurate readings at very small values, like 7 or 8 lb-ft). Failure to do so is a good recipe for stripping out important threads, like spark plug & drain bolt receiver threads. Aside from that, unless you tear the engine all the way down, it's very hard to hurt a Kat in general. They're considered fairly bullet-proof engines for a reason ;)

Cheers,
=-= The CyberPoet

katanasport600
02-14-2007, 09:25 PM
hey thanks for the direction on the service manual. i will check it out over the weekend! small engines just scare me. i can make a 351 windser breath fire at 586horse, naturaly aspirated, but 600 CC's? yipes!

The CyberPoet
02-14-2007, 09:28 PM
Instead of thinking motorcycle, think a military jeep engine turned sideways -- that should see you through ;)

Cheers,
=-= The CyberPoet

pritchett29
03-11-2007, 11:04 AM
would a Dynajet kit stage 1 be a good jet kit with my full D&D exhaust sytem on my 2004 katana 600

The CyberPoet
03-11-2007, 10:03 PM
would a Dynajet kit stage 1 be a good jet kit with my full D&D exhaust sytem on my 2004 katana 600

Out of the three aftermarket jetkit choices you have available for your bike, I think that would be the worst possible one. Having tested DynoJet's back-to-back with Ivan's, Ivan's comes out way ahead. And knowing Marc over at FactoryPro, I'm pretty sure his will come out way ahead of the DynoJet brand as well, although I haven't tried his jetkit yet.

Cheers,
=-= The CyberPoet