750 Headers on a 600

[slanteeeyes]

I was wondering if anyone has tried grinding down 750 headers and placed them on a 600? I found a set that came off of 2000 and I'm thinking about putting them on my 06' 600 Kat. I read this great article article written by CyberPoet http://www.motorcycleanchor.com/katana/header.html in regards to modification procedures but I wanted to make sure the 2000 750 headers will fit on my '06 600.
I'm hoping I won't have to rejet the carbs but I will if I have to heh

[steves]

3mm difference in size.

http://www.katriders.com/forums/viewtopic.php?t=9303&highlight=

[slanteeeyes]

will they bolt right up to the 600s without any major issues?

[steves]

[Thus, the 750 header flows 27.7% more than the 600 header. That's a substancial difference, enough to warrant serious jetting changes under most circumstances. A jump to an 1100 exhaust may induce an even bigger change, one that will take a lot of experimentation to come up with the right jetting for...

BP, this is what i thought. when i bolted the 750 header onto my 600 i installed dynojet 120's - which his recommended for an AFTERMARKET header. when i had my bike dyno'd it was running too rich. i talked to the owner - engine builder ( EDR performance ) he told me that it is still a stock header and the collection tubes are not OPTIMAL like a true aftermarket header would be. he also stated that a bigger header doesn't always mean you need more fuel - it can just make the present tuning setup more efficient.

i'm currently running 118's and think it's a bit rich still.


if you have a jetkit w/ an aftermarket filter - you probably wouldn't need and jetting changes if you put the 750 header on.

tim

Probably.

[slanteeeyes]

Shweettt Thanks!

[The CyberPoet]

I am running the 750 headers on my 98+ 600, with the headers dremelled out and then ceramic-coated (jetcoated) on the outside. With the Ivan's jetkit, the exhaust dyno's out around 13:1 for most of the RPM range, which is clost-to-ideal for fast/hard acceleration through around 100 mph (but not for absolute top speed, which is better done with something around 14.2:1 mixture rate).

With the stock jetting, going to the 750 header dremelled out may run a stock US bike a bit lean (they are lean to start with); an extra 1/4 turn on the pilot jets and a 1/2 shim washer under the needles will correct for it more than adequately and keep you around the 14.2-14.5:1 range.

Cheers,
=-= The CyberPoet

[slanteeeyes]

Thanks for all the info Cyber.
It looks like my tinkering will have to be put on hold. I was warned the other night by an HOA member that working on auto/motocycles in the garage is a violation of the CC&R's . I wish I knew someone around here with a garage.

Anyways...if anyone is looking for a carbon D&D slip-on for $230 checkout this link http://www.hyperformanceparts.com/ca...ducts_id=17276

[brooder]

See if you can find a place that rents out garage space for working on vehicles. I'm lucky that I have an auto hobby shop on the base where I work that also has a motorcycle lift. $4/hour is what I have to pay for the lift. $10 flat fee for unlimited tool rental. It's not bad for periodic work.

[The CyberPoet]

I was warned the other night by an HOA member that working on auto/motocycles in the garage is a violation of the CC&R's

Yes, but working on it in your living room isn't. Time to get an oil-proof throw rug.

Cheers,
=-= The CyberPoet

[Drastion]

With the stock jetting, going to the 750 header dremelled out may run a stock US bike a bit lean (they are lean to start with); an extra 1/4 turn on the pilot jets and a 1/2 shim washer under the needles will correct for it more than adequately and keep you around the 14.2-14.5:1 range.

Cheers,
=-= The CyberPoet

This addresses a question I have been wondering about and trying to understand for a while now. I have read my Katana factory service manual and I'm trying to get a good understanding of how carbs work.

I understand that when you jet a carb, you install thinner needles and a larger main jet to increase the amount of fuel delivered into the venturi while the "main system" is in operation. I keep reading threads, such as this one, that talks about turning the pilot screw, or in this case the pilot jet wich in the book says only meters the fuel for the slow sytem, a 1/4 turn or so to richen up the mixture and allow the bike to run better throughout the entire rpm range. But doesn't the pilot screw only affect the mixture when the throttle valve is closed and the "slow system" is in operation. If this is so, then what affect would turning the pilot screw have other then allowing the bike to idle properly at stand still?

[The CyberPoet]

I understand that when you jet a carb, you install thinner needles and a larger main jet to increase the amount of fuel delivered into the venturi while the "main system" is in operation.

Actually, that is somewhat incorrect. The needle itself may be thinner or thicker; the most critical factor is the grind of the flutes at the end and how it mates to the corresponding jet underneath. Once the needle lifts completely clear, the needle isn't really part of the equation any more -- it's how it interacts when it is only partially blocking the jet passage underneath it that is critical.

I keep reading threads, such as this one, that talks about turning the pilot screw, or in this case the pilot jet which in the book says only meters the fuel for the slow system, a 1/4 turn or so to richen up the mixture and allow the bike to run better throughout the entire rpm range. But doesn't the pilot screw only affect the mixture when the throttle valve is closed and the "slow system" is in operation. If this is so, then what affect would turning the pilot screw have other then allowing the bike to idle properly at stand still?

As each step of the carbs open up (pilot jets, then needle-interaction, and the main-jets), each one contributes to the total fuel entering the air-fuel mixture. Thus, while it can be said that the pilot jets are solely responsible for idle, they are still a part of the equation even at high RPM's (albeit only a small part of it).

The mixture rate on the Kat is by EPA regulation quite lean as shipped in most countries, targeting an approximate 14.7:1 mixture rate, which (given idealized fuel made of only octane and heptane) would burn as cleanly as the fuel can (this full-burn ratio is known as the stoichiometric rate). In most of the USA, fuel is not idealized but contains both other compounds, as well as additional additives (such as alcohol, TANE, MTBE, etc) for pollution control reasons, and these all affect what the idealized stoichiometric ratio is -- usually driving it downwards into the 14.1 - 14.4:1 range. The leaner the mix, the hotter the combustion, and mixtures above the stoichiometric ratio can easily run an engine hot enough to damage metal parts and/or start a temperature-related knocking effect. In any vehicle with an oxygen sensor [and usually knock-sensor], this is automatically compensated for, but our Kats (and most carb'd motorcycles) don't have this ability to self-regulate fueling to compensate.

A stock kat's exhaust will usually register 14.5-14.9:1 mix ratios across the board (varies with RPM which controls vacuum levels). When you put a larger header on the engine, the exhaust gases will normally go slightly leaner (14.6-15.0:1); obviously age-related passage clogging can also affect how much fuel is being delivered (esp. in the idle circuit). Opening the pilot jet a bit more permits a small amount more fuel to be added everywhere across the RPM range and (most critically for our purposes) at idle, dropping the mix ratio some. Even with stock headers, given our modern fuels generally available in the USA, doing this should make the bike slightly more responsive and slightly less prone to running excessively lean (should also lower the running temp of the engine, as rich mixtures don't burn as hot). In countries which don't require testing at idle (or as strict a testing at idle), the pilot jets come from the factory already opened by a 1/4 to 5/8ths more turns than the stock US models (depending on the target market).

Shimming the needle raises it by 0.5mm in the jet it blocks and engages the needle's interaction earlier, also adding more fuel and again richening the mixture up a bit more.

Hope that all makes sense, and that I explained clearly enough.

Aftermarket jetkits (esp stage 1 kits), with their different jets and different needles (both in terms of fluting and in terms of height-adjustability), target a far richer mixture to give you better throttle response & more useable power up to about the torque-peak of the engine, generally sacrificing the powerband above torque-peak some as a result. Since max speed of the bike relates to power above torque-peak in top gear, most jetkits actually lower absolute top-end speed of the bike, but cause it to accelerate far faster to the torque-peak. These kits also have specific instructions for different sized headers and/or air filters, designed to compensate for the leaning out of the mixture due to higher through-put and lower vacuum levels at the carbs.

PS - personally I'd recommend the jetkit purchase & install before you bother installing a 750 header, unless it's a case of you desperately need a header because yours is damaged in some way -- the performance increase from the jetkit alone will be significantly higher than the performance increase from the larger headers, esp. on the 98+ kats.

Cheers,
=-= The CyberPoet

[Range]

you could even put the headers from a Bandit 1200 on the Kat...with a little work.

[Drastion]

As each step of the carbs open up (pilot jets, then needle-interaction, and the main-jets), each one contributes to the total fuel entering the air-fuel mixture. Thus, while it can be said that the pilot jets are solely responsible for idle, they are still a part of the equation even at high RPM's (albeit only a small part of it).

I believe I see my flaw now. The pilot jet still contributes a small amount of fuel even after the throttle valve is opened and begins to pull fuel through the main jet. And the pilot screw regulates how much air/fuel mixture from the pilot jet actually makes it into the venturi.

One thing I want to clarify though is that you say you should turn the pilot jet, as opposed to turning the pilot screw. Are you able to turn the pilot jet inside the float chamber to alter the amount of fuel that passes through the jet, or are you only able to turn the pilot screw to alter the amount of air/fuel mixture that makes it into the venturi?

Hope that all makes sense, and that I explained clearly enough.

Definately. I didn't know that it was the relationship between the tip of the needle and the jets that made the difference. I thought it was the actual diameter of the needle that controlled the flow of fuel.

PS - personally I'd recommend the jetkit purchase & install before you bother installing a 750 header, unless it's a case of you desperately need a header because yours is damaged in some way -- the performance increase from the jetkit alone will be significantly higher than the performance increase from the larger headers, esp. on the 98+ kats.

I just installed one a week ago. Ivan's. Then it developed a stupid tick that got me worried so i'm going to pull the valve cover this weekend and check the valves just for piece of mind.

I really appreciate the write up. Definately helped me make sense of things.

[The CyberPoet]

One thing I want to clarify though is that you say you should turn the pilot jet, as opposed to turning the pilot screw. Are you able to turn the pilot jet inside the float chamber to alter the amount of fuel that passes through the jet, or are you only able to turn the pilot screw to alter the amount of air/fuel mixture that makes it into the venturi?

I mis-stated what I meant to say. The pilot screw gets turned, not the jet itself. The proper way to count turns is to screw it inwards until it softly bottoms out against the rubber o-ring, then start counting turns backwards (outwards). You should already have done this when you installed the Ivan's kit and not need to make any further adjustments.

Definately. I didn't know that it was the relationship between the tip of the needle and the jets that made the difference. I thought it was the actual diameter of the needle that controlled the flow of fuel.

Part of the difference in the qualities of various 3rd party jetkits is the degree of engineering that went into determining the angle and length of the milling operations on the fluting -- the Ivan's kit for example uses 4 different millings to create the particular shape it has (while dynojet's is simply cast with a specific shape that is far courser and far more likely to be "sloppy" in it's fueling).

-------

Since you posted that you already installed the Ivan's, you can just slap the 750 header on there with zero additional issues. You may need to replace the midpipe gasket [between the midpipe and the collector on the header) at the time of install, because they often deform/get mangled when you disassemble/reassemble the collector. Smearing it with high temp antiseize will make mating easier and less likely to deform it if you ever take it off again, but it will also smoke hard for about 15-20 minutes when the engine first runs up afterwards.

Cheers,
=-= The CyberPoet

[slanteeeyes]

Does Ivan's rejet kit come with decent instructions? I always thought factoring in weather temp, altitude, etc, is necessary when rejetting or is that just dealing w/ 2-stoke engines?
I was also wondering if you can buy the same size needle and jets that come Ivan's kit individually??