Stage 3 jet kit questions and tuning

[kat astrophe]

Im hoping some one can tell me what size jets come in the Factory Pro jet kit for a 92 600. id like to know both stage 1 and 3 if anyone knows.

I bought there jet kit and installed it but my bike is running super lean accross the entire rpm band, so im not sure what stage the kit was.
(I bought and installed it last summer)
I have a KOSO air/fuel gauge to confirm the bike is running so lean the gaue couldnt even read it and the bike is stumbling like crazy.

Ive got my carbs all disassembled again and the main jets are 137.5 and pilots are 32.5.

[Kreylyn]

Im hoping some one can tell me what size jets come in the Factory Pro jet kit for a 92 600. id like to know both stage 1 and 3 if anyone knows.

I bought there jet kit and installed it but my bike is running super lean accross the entire rpm band, so im not sure what stage the kit was.
(I bought and installed it last summer)
I have a KOSO air/fuel gauge to confirm the bike is running so lean the gaue couldnt even read it and the bike is stumbling like crazy.

Ive got my carbs all disassembled again and the main jets are 137.5 and pilots are 32.5.

OEM... main jets are 112.5. 137.5 are WAY bigger.

Stage of the kits is based upon over all setup... a combination of exhaust, engine, and intake. Not just the jets used. You use the jet size that works for your setup.

Stage 1 = basically factory setup with maybe a slip on exhaust.

stage 2 = race exhaust (not an aftermarket street exhaust, but a real honest to goodness race system.)

stage 3 = High flow intake setup + Race exhaust + (for a kat, nessasary) some minor engine modifications like swapping cams...

Then... you choose the jet size that works best at WOT, then tune the rest of the carbs from top RPMs down... So you adjust the needles, then the floats, then the a/f settings.

FYI... if your using K&N pods or other high flow air filters on your bike, especially if no air box installed... then your problem is there. Too much air, and not enough pressure to pull the fuel out... even with the way over sized main jets.

Oh, and answer the specific question about what jets... Factory Pro should list the kits contents on their website, but generally they have jets that start 1 size up from OEM (which in most cases is the one to use for Kats) and then have 4 additional sizes up to the max size... which is probably what is installed on your kat.

Krey

[kat astrophe]

Thanks for your reply, i currently have velocity stacks and vince and hines full exhaust. And to be more clear the bike pulles pretty hard but stumbles when i get to about 7k rpm and more then 3/4 throttle. but like i said it is lean accross the board.
And i have searched factory pro's web site but its confusing to navigate and so far i havent found anywhere were they say what size jets are in there kits.

[91_gsx600F katana]

My stage 1 kit came with 115 and 117.5 main jets. That's it. Stock is 112.5. How have u verified that its a lean condition? 7/8k or 3/4 throttle or more is When the main jets are fully in so those issues are main jet related.

My experience with hesitation at 7/8k was an overly rich condition which I was able to see on my wide band. But that was with a turbo and 112.5 main jets and 3psi base fuel pressure.

[Kreylyn]

Thanks for your reply, i currently have velocity stacks and vince and hines full exhaust. And to be more clear the bike pulles pretty hard but stumbles when i get to about 7k rpm and more then 3/4 throttle. but like i said it is lean accross the board.
And i have searched factory pro's web site but its confusing to navigate and so far i havent found anywhere were they say what size jets are in there kits.

Velocity stacks with no filter at all?

If yes, that would definitely be a problem.

Put the velocity stack filters on. (buy/make some if you don't have any). The thicker you make the filters, the more backpressure you make, the richer the carbs will work for you...

Too much air is most likely the issue.

Krey

[kat astrophe]

The lean condition was found via KOSO wide band A/F gauge. and when i say hesitation i mean a bit past half to 3/4 throttle it goes dead, just completely flat fall on its face.

Krey, As much as I hate to say it yes its velocity stacks with no filters, i know bad on me. The velocity stacks were in attempts to speed up air flow which everyone says is the main issue if not running the stock air box, correct?

[Kreylyn]

The lean condition was found via KOSO wide band A/F gauge. and when i say hesitation i mean a bit past half to 3/4 throttle it goes dead, just completely flat fall on its face.

Krey, As much as I hate to say it yes its velocity stacks with no filters, i know bad on me. The velocity stacks were in attempts to speed up air flow which everyone says is the main issue if not running the stock air box, correct?

Well, your fighting an up hill battle with that setup... like... straight up.

That said...

It's not just that you have too much air... it is that the air source is calm (the box), the air box boots work as velocity stacks (which you have replaced with actual stacks...) and the filter provided back pressure so fuel is pulled from the carbs.

No back pressure = too much air flowing through the carbs and not pulling enough fuel. So your seeing the top end just drop right out on you.

Here is a simple test... Make a wire mesh cover so that nothing can be sucked into the carbs. Then, use some cloth, cut out some circles that you can fit over top of the velocity stack intake points and use a simple clamp/strong rubber bands, what ever that you can... to make a home made filter. Just make sure they are not going to come off and the wire mesh under will prevent the cloth from being sucked into the carbs. You can layer the cloth with more circles to adjust how much air flows through...

You will probably see that creating a back pressure through the use of them will increase the a/f mix at WOT for you by doing so. You can adjust how much by increasing/decreasing the cloth circles to adjust the air flow/pressure.

Simple to make, cheap to make, probably have materials around your house to do so. Once souce for the mesh btw... gutter guard material that is used for the mesh mod. It's bendable to make simple caps out of.

Krey

[kat astrophe]

Dang thats a awesome idea, im doing that when i get off work. the only issue still being are my jets i currently have to big then(137.5 M & 32.5 P)? because i just ordered 142.5 mains and 42.5 pilots thinking that would fix it, so i can return them and order smaller then i currently have if need be? im just not sure because im fighting so many issues at once here.

[Kreylyn]

I wouldn't go larger... but you can probably adjust some what for what you have installed with the air flow/back pressure with using the cloth covers.

I think what you have is the largest size you can reasonably use with out some major engine work/carb replacement.

Krey

[steves]

What's the float height set too? Might need to make it a little higher... could be fuel starvation

[MEngineer]

Here is a simple test... Make a wire mesh cover so that nothing can be sucked into the carbs. Then, use some cloth, cut out some circles that you can fit over top of the velocity stack intake points and use a simple clamp/strong rubber bands, what ever that you can... to make a home made filter. Just make sure they are not going to come off and the wire mesh under will prevent the cloth from being sucked into the carbs. You can layer the cloth with more circles to adjust how much air flows through...

Krey

Using this rational would it be possible to "build" or somehow make pods filters a viable option for a Katana? There are so many variable and different ways adding back pressure could be done, but that doesn't mean they will work. I'm curious, trying to think outside the box.

[Kreylyn]

Using this rational would it be possible to "build" or somehow make pods filters a viable option for a Katana? There are so many variable and different ways adding back pressure could be done, but that doesn't mean they will work. I'm curious, trying to think outside the box.

Well, it doesn't resolve all the problems with pods...

One of the issues with the K&N pod filters is they fit in a way that blocks the main/pilot air jets at the front of the carbs.

Another issue is the air turbulence. The air box works to provide a calm air source equally for all 4 carbs... pods you don't get that equalization, nor do you have a calm air source. So when moving down the road you will see variances in external air pressure depending on location. Outside pods get more air than the insides. Air flowing around the bike being turbulent will also make massive fluctuations to that.

Having different air flow and turbulence to each carbs = variable a/f mixes for every cylinder... and that means not optimal performance.

There are lots of creative ways to try and counter the effects, but it's a lot of work and modifications/testing/changing/testing again... and so on... and on... and on...

Krey

[MEngineer]

Well, it doesn't resolve all the problems with pods...

One of the issues with the K&N pod filters is they fit in a way that blocks the main/pilot air jets at the front of the carbs.

Another issue is the air turbulence. The air box works to provide a calm air source equally for all 4 carbs... pods you don't get that equalization, nor do you have a calm air source. So when moving down the road you will see variances in external air pressure depending on location. Outside pods get more air than the insides. Air flowing around the bike being turbulent will also make massive fluctuations to that.

Having different air flow and turbulence to each carbs = variable a/f mixes for every cylinder... and that means not optimal performance.

There are lots of creative ways to try and counter the effects, but it's a lot of work and modifications/testing/changing/testing again... and so on... and on... and on...

Krey

Gotcha. I didn't think about the outside variables. There's a lot more to think about than just between the filter and the carb. Thanks!

[steves]

Mikini flat side carbs

[MEngineer]

Mikini flat side carbs

I've read that. Easiest way to run pod filters: put on different carbs.

Sorry for the hijack. Please continue.