new air filter set up

[Jvacustoms]

I have installed a 4 inch k&n style conical universal air filter with a pvc adapter straight off the carburetor. and I am unsure of where to adjust the carburetor to make the bike run right. It takes of smooth until you hit 1/4-3/4 throttle which I think is needle jet settings but I am not sure if i need a new needle jet or just to set that one properly i have already moved the needle jet washer to under the eclip but that doesn't seem enough. can i just add another shim washer below the eclip or do i need to buy an jet kit so that I get the adjustable needle and some other jets to try. also i read that in "Jaime" gz250 power increase that there might be need for a larger than 130 main jet with the air filter and exhaust modifications. It does good in top and bottom throttle points but revs like hell in the middle.
I have tried just adjusting the mixture and that seems to be moot, until i get the needle fixed.

[Gz Rider]

...

[Jvacustoms]

I have installed a 4 inch k&n style conical universal air filter with a pvc adapter straight off the carburetor. and I am unsure of where to adjust the carburetor to make the bike run right. It takes of smooth until you hit 1/4-3/4 throttle which I think is needle jet settings but I am not sure if i need a new needle jet or just to set that one properly i have already moved the needle jet washer to under the eclip but that doesn't seem enough. can i just add another shim washer below the eclip or do i need to buy an jet kit so that I get the adjustable needle and some other jets to try. also i read that in "Jaime" gz250 power increase that there might be need for a larger than 130 main jet with the air filter and exhaust modifications. It does good in top and bottom throttle points but revs like hell in the middle.
I have tried just adjusting the mixture and that seems to be moot, until i get the needle fixed.

Since you removed the box that holds the old air cleaner and the oil drip tube that removes oil from that box how will your system handle that oil. Will that oil simply soak your air filter or have you set up somethinge else to handle it.

A pretty standard universal crank case vent on a three way one once side it has the crank case vent and on the other it will have the original hose that holds the oil at the bottom of the airbox. I cant ride her right now until i figure out these carb settings. But that is my plan I will hopefully get some good carb setting answers and then when she runs again i will go get the crankcase vent filter and 3way from napa.

[jonathan180iq]

You are correct in your assumption that the mid range is most affected by the needle. But the main jet also effects all areas to an extent.

I'm not sure of the washer number, but there is one that can be stacked to raise the needle. You may just have to go to Home Depot and play around with different sizes. Try #4, 6, 8 & 10.

I know that once you get down into the guide hole, it gets kind of narrow. You need a washer that will both raise the needle and fit down into the guide hole. (There are two needle designs and I'm assuming you have the kind that allows you to move the clip down, based on your description.)

The biggest jet I've ever heard of anyone using on one of these bikes was a 135. Anything bigger than that has always resulted in the bike running too rich.

What main jet are you running now? 130? Richen it up just a tad, with maybe a 135 and your needle adjustments won't need to be so drastic.
You'll then have to alter the pilot a smidge. But sounds like you know what you are doing enough that it would be better to get it dialed in 100%.

[Jvacustoms]

You are correct in your assumption that the mid range is most affected by the needle. But the main jet also effects all areas to an extent.

I'm not sure of the washer number, but there is one that can be stacked to raise the needle. You may just have to go to Home Depot and play around with different sizes. Try #4, 6, 8 & 10.

I know that once you get down into the guide hole, it gets kind of narrow. You need a washer that will both raise the needle and fit down into the guide hole. (There are two needle designs and I'm assuming you have the kind that allows you to move the clip down, based on your description.)

The biggest jet I've ever heard of anyone using on one of these bikes was a 135. Anything bigger than that has always resulted in the bike running too rich.

What main jet are you running now? 130? Richen it up just a tad, with maybe a 135 and your needle adjustments won't need to be so drastic.
You'll then have to alter the pilot a smidge. But sounds like you know what you are doing enough that it would be better to get it dialed in 100%.

there are no settings on my needle just a washer and an eclip I am hoping to add a washer to adjust it so that I don't have to buy a needle that has the "slots" that you move the eclip from place to place. I have the brass washer that was above the eclip below it now But I am looking to add some more but m unsure of the extent that washers can be added before it will cause malfunction of the needle jet system that is there, i.e. if i add too many washers is it gonna damage the diaphragm or the needle jet guide system ?

[jonathan180iq]

As long as the washers allow the needle to fall down into it's guide all the way, you would have to REALLY stack the crap out of them before they start pushing up against the diaphragm. I mean, it drops down in there a good ways. I think we're talking inches. If you have to adjust that much, might as well buy a new carb ;)

There is no way to know until you experiment. But it shouldn't take too many washers to get a good lift. Even with extreme adjustments to the Ninja 250 carb, 2-3 washers is considered a lot.

[Jvacustoms]

As long as the washers allow the needle to fall down into it's guide all the way, you would have to REALLY stack the crap out of them before they start pushing up against the diaphragm. I mean, it drops down in there a good ways. I think we're talking inches. If you have to adjust that much, might as well buy a new carb ;)

There is no way to know until you experiment. But it shouldn't take too many washers to get a good lift. Even with extreme adjustments to the Ninja 250 carb, 2-3 washers is considered a lot.

Thanks, i happened across the thread where u were talking about mods to your bike and Jaime jumped in. It looks like we think a lot alike, but I am always looking for something to tinker. And ways to save money in the long run. I think that with the washable filter it will save me a little and with the custom made baffling that I made I saved a bit, maybe I will be able to just get what i want outta the bike and that is just to know that i have tried everything that I can think of to increase the overall performance of the bike. for the way I like to ride it. which just might be the opposite of almost every other rider on this forum. but it is the way I am, Stubborn and always looking to learn and try things just to see how they work.

[jonathan180iq]

Yeah, I gave up on the project because after I had all my stuff dialed in, it just wasn't worth the effort to push on the group as a whole.
(If there's one thing I've learned throughout years of tinkering with all of my vehicles, it's that unless there is a readily available and affordable aftermarket bolt-on part, I'm not worried about changing factory performance.) That may make me a little more boring than I was in my younger years, but it is what it is. ;)

If my original quest had made the bike run tons better, you would see me telling everyone who owns one to do all of this stuff first. But it's just a tight work space, a lot of extra trial and error and not as large of a benefit as I wanted to see. Unless you fall in a certain category of tinkerer, as I think you do, then it's not something that everyone should take on. (I really got enthralled when I saw how much throttle was left @ 60mph with the 16T sprocket.)

It's certainly not impossible and you are already about 80% of the way done. Now the dialing-in will just take some piddling. Once you get it set, you never have to worry about it again. But I know that last little bit can be a bit of a drag.

[Jvacustoms]

Yeah, I gave up on the project because after I had all my stuff dialed in, it just wasn't worth the effort to push on the group as a whole.
(If there's one thing I've learned throughout years of tinkering with all of my vehicles, it's that unless there is a readily available and affordable aftermarket bolt-on part, I'm not worried about changing factory performance.) That may make me a little more boring than I was in my younger years, but it is what it is. ;)

If my original quest had made the bike run tons better, you would see me telling everyone who owns one to do all of this stuff first. But it's just a tight work space, a lot of extra trial and error and not as large of a benefit as I wanted to see. Unless you fall in a certain category of tinkerer, as I think you do, then it's not something that everyone should take on. (I really got enthralled when I saw how much throttle was left @ 60mph with the 16T sprocket.)

It's certainly not impossible and you are already about 80% of the way done. Now the dialing-in will just take some piddling. Once you get it set, you never have to worry about it again. But I know that last little bit can be a bit of a drag.


I thought about making it too rich on purpose and throwing a hotter plug in there probably iridium they foul less easy. and just see if i can push a little more power from the bike that way.

I am also very captivated by the remaining throttle but I am going to try to make the motor use that bit even if it hurts my gas mileage to a good degree it will still always be cheaper than my car to drive around...

[jonathan180iq]

Word!

Post back with final results. Expand the body of knowledge.

[Gz Rider]

...

[Jvacustoms]

I changed my needle shim a little. I have excessive carbon on the end of the exhaust which made me think it might be slightly rich. I moved the washer back to the stock position, went to lowes and bought some #4 stainless steel washers. They are almost exactly the same size as the carb's washer, but approx 1/2 as thick. I used one of these as a needle shim. It ran about the same. We'll see how it affects my mileage. Now on to my point... When I put things back together I forgot to tighten the boots between the airbox and engine. It ran fine at low speeds. I got on the freeway and it must have been sucking air around the boots. I could barely hit 60mph. I tried your choke trick and it sped up to 65-68ish. I guess with the boots tight my bike was already running rich enuff that the choke made no difference.


just thought i would share this as i found it after a good bit of searching.

[alantf]

A pretty standard universal crank case vent on a three way one once side it has the crank case vent and on the other it will have the original hose that holds the oil at the bottom of the airbox.

My European model has a +ve crank case ventilator fitted as standard. It's connected by a tube & tee piece to the petcock vacuum line.[attachment=3:3vfxfwbp]b19.JPG[/attachment:3vfxfwbp][attachment=2:3vfxfwbp]b22.JPG[/attachment:3vfxfwbp][attachment=1:3vfxfwbp]b24.JPG[/attachment:3vfxfwbp][attachment=0:3vfxfwbp]b17.JPG[/attachment:3vfxfwbp]

[Jvacustoms]

A pretty standard universal crank case vent on a three way one once side it has the crank case vent and on the other it will have the original hose that holds the oil at the bottom of the airbox.

My European model has a +ve crank case ventilator fitted as standard. It's connected by a tube & tee piece to the petcock vacuum line.[attachment=3:2vsqbjhg]b19.JPG[/attachment:2vsqbjhg][attachment=2:2vsqbjhg]b22.JPG[/attachment:2vsqbjhg][attachment=1:2vsqbjhg]b24.JPG[/attachment:2vsqbjhg][attachment=0:2vsqbjhg]b17.JPG[/attachment:2vsqbjhg]

I dont believe that can be done to the american model I dont remember seeing that area to add that feature i could be wrong, i wil check that out when i get home but I am almost positive that the way I am thinking about doing it is alot cheaper

[Jvacustoms]

ok new problems that I have come up with.

I have added 2 nylon #4 washers to the needle jet and put the original washer back on top of the eclip. and this morning i rode to work with some finagling and my result is that I can ride the bike and get here normally until it reaches top of the throttle around 3/4 then it starts struggling. I turned the mix out and it seems to be better but i am wondering if i pull one of those nylon washers back off and turn it a pit richer if that would cover for the lower needle jet and make the richness enough for the top end. I found that when at top of the throttle in 5th gear i could pull the enricher all the way back and increase speed by 15mph and almost level the fuel out. maybe that is enough for some input but maybe not i am just trying to use all the brain power that there is to resource this thing.

[jonathan180iq]

Sounds to me like you're just using a main jet that is a tad too small.
Go up one size, make no other changes, and report back.

Only test one thing at a time, to eliminate variables.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Just for some companion reading, I've got a recent story similar to yours.
I put a CN250 custom exhaust on the Qlink and had great low end and mid-range power. The top was a little weak, but passable... I thought. After a test run, I stopped at the light in front of my house and started smelling smoke. Thinking it was the new muffler just breaking in, which is not at all uncommon, I kept on going. Got to the house, and noticed that my shiny new muffler straps had melted. UH OH! Someone is too lean in the top end ;)

http://i44.tinypic.com/23jh69z.jpg

I then rejetted, (very rich, just because it's a cheap bike and I prefer to run rich and cool than lean and hot) and started getting fuel delivery problems in the top end. It was actually working too good and using all the fuel in the float bowl if I tried to maintain 65mph for more than a minute or two. I had to open the intake even further, to create a stronger vacuum and gas flow, and then had to increase the mid range even more in order to keep the bike from dying out at speed. It took two disassemble sessions of the carb before I finally got it dialed in.

The bike now cranks and stars easier and faster than it ever did before, runs cooler and feels more stable through all speed ranges. I've actually lost some top speed, but I don't care. Rejetting and changing the flow characteristics of bikes, especially when you do it on your own, doesn't necessarily make the bike faster. It just makes the bike run better for your current intake/exhaust settings and leaves you with a bike that run better... not necessarily faster.

[Jvacustoms]

Sounds to me like you're just using a main jet that is a tad too small.
Go up one size, make no other changes, and report back.

Only test one thing at a time, to eliminate variables.

will report back in like a week while i wait on the jet to come in

[jonathan180iq]

I have some spares. Have you already ordered them?

[Jvacustoms]

I have some spares. Have you already ordered them?
nope I haven't I really hate the bike parts store here it is like they have their heads up their butts 24/7/365 and cant get the part that i order... I can give them the part number and they will still mess it up.

[jonathan180iq]

I'll see what I have in the drawer when I get home this evening.
What size do you have in the bike now?

[Jvacustoms]

I'll see what I have in the drawer when I get home this evening.
What size do you have in the bike now?

130

[Jvacustoms]

also is it me or is it just easier to work on this bike by pulling the tank when u need to work on it ?

[jonathan180iq]

Well, I was gonna help you out, but I don't have anything bigger than a 125. I know that without even looking.

I always pull the tank. If for nothing else, it gives you more space to work. I hate trying to cram my finger tips around corners just to grab the end of a bolt or something. Plus, it only takes maybe 15-30 seconds of extra time.

If your shop is weird about it, I would just go down a generic bike shop and have them open their box of main jets... (they have to have one or else they don't know what they are doing.)

If it looks like this, and has a number stamped on it, it will work.

http://www.provoscooter.com/magento/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/3/6/36.19718.1.265.jpg

Keihin Round Main Jet

[Jvacustoms]

Well, I was gonna help you out, but I don't have anything bigger than a 125. I know that without even looking.

I always pull the tank. If for nothing else, it gives you more space to work. I hate trying to cram my finger tips around corners just to grab the end of a bolt or something. Plus, it only takes maybe 15-30 seconds of extra time.

If your shop is weird about it, I would just go down a generic bike shop and have them open their box of main jets... (they have to have one or else they don't know what they are doing.)

If it looks like this, and has a number stamped on it, it will work.

http://www.provoscooter.com/magento/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/3/6/36.19718.1.265.jpg

Keihin Round Main Jet


i just bought a 130 but they normally dont have them in stock around here they always have to special order them it takes a week and they charge me for a set of 4 most of the time, which can get extremely expensive really quick.

[jonathan180iq]

What are they charging you a set? I mean, jets are like $3 a pop, retail.
What a load of crap. Find a new place, man.

[Jvacustoms]

What are they charging you a set? I mean, jets are like $3 a pop, retail.
What a load of crap. Find a new place, man.

there is only two bike shops in the area and cycleworld is one and the other si a local and they both have the same policy

[blaine]

I had #130 in mine and they cost me $2.75 a piece. :cool: :)

[Jvacustoms]

Johnathan didn't you attempt a similar set up on your bike what did you have in there ?

[Water Warrior 2]

In all likelyhood a $3 sale costs the shop money. Any profit would be used up in paperwork. But I do agree with the sale of only one item to satisfy the customer. Try getting 3 spokes for the rear wheel of a GZ. You have to buy the entire spoke kit which is 36 spokes. You don't want to know what that costs in the GWN.

[jonathan180iq]

Johnathan didn't you attempt a similar set up on your bike what did you have in there ?

I had stock exhaust and a pod air filter. I was good with a 122.5 or a 125, I don't recall 100%.
One shim on the needle and just a slight turn on idle screw. I was lucky to get it locked in so quick, but just didn't notice an improvement that would allow me to push the mod on the masses.

[Jvacustoms]

Johnathan didn't you attempt a similar set up on your bike what did you have in there ?

I had stock exhaust and a pod air filter. I was good with a 122.5 or a 125, I don't recall 100%.
One shim on the needle and just a slight turn on idle screw. I was lucky to get it locked in so quick, but just didn't notice an improvement that would allow me to push the mod on the masses.

so the pod filter only took a gain of 5 in the main jet?

because i had 130 running perfect on my pipe and now not so much.

I will look for a 135 that should do the trick, I do think that the k&n style might bet more air flow than the pod type i saw in the other post. So i will go 5..

I don't know though I am thinking that I might just need 1 shim under the needle because right now the mix is at somewhere around 4. I had to make it rich to get it home and to work to see where it was really lacking. and i am convinced that it is the main jet and maybe an over-shimmed needle.

[jonathan180iq]

When you're jetting on your own, you have to start with the main and then work your way down. It's because the main most controls 3/4 to full throttle, but also has a minor impact at all levels.

So, ideally, you want to dial in the full throttle part of the ride, then work down to mid-range and finally end with the pilot/idle.

You've done it in reverse, I think. It's not that big of a deal, except that you're seeing why getting the main jet is the most important part.
You're lower and mid-range were spot on. But if it turns out that you have to up the main jet (which is where you're headed) then you have to do the mid-range and low stuff all over again. If not, you'll get a perfect high flow and then be rich in the mid and bottom.

Sure it's just a couple of steps. But why do something three or four times when 2 times is good enough? ;)

[Jvacustoms]

Sure it's just a couple of steps. But why do something three or four times when 2 times is good enough? ;)

Because I learn more about how it works and I wont make those mistakes again, and also I will be able to finer tune the carburetor now that I know how each part effects the bike first hand. And the most important part, I get to tinker with something. I like tinkering it keeps me thinking about new inventions!!

[jonathan180iq]

viewtopic.php?f=9&t=513&hilit=jetting%3A+part+I&start=25 (http://gz250bike.com/forum/viewtopic.php?f=9&t=513&hilit=jetting%3A+part+I&start=25)

I just read back through this.
It was a 125 that I was good with.

You'll also see me respond to someone else in there about how jetting varies from bike to bike and location to location.
Lots of different variables.

[Jvacustoms]

http://gz250bike.com/forum/viewtopic.php?f=9&t=513&hilit=jetting%3A+part+I&start=25

I just read back through this.
It was a 125 that I was good with.

You'll also see me respond to someone else in there about how jetting varies from bike to bike and location to location.
Lots of different variables.


well i believe that I am finally getting close i have went full spectrum from 130-140 (130,132.5,135,137.5,140) and at 140 i finally started to get a nice responsive throttle and not so much pop so i installed a new plug and I am gonna ride her and let the plug tell me what to do because of the newer exhaust it is a bit harder for me to differentiate the sounds of lean pops and rich backfires unless it occurs in the carb, so I am letting the plug do it for me. let it be my ears. and i have 3 spare new ones in case i need them, and a tool kit. i have the needle shimmed using the factory washer from above the e clip and i installed a thin nylon washer on top of the eclip to ensure proper spring pressure. I have the mixture set to about 2.625 turns out and the idle set a little on the high side cause she's not smooth yet.... skips every once in a while so i figure i am not perfect on the mixture yet.

I am learning alot about the way the carb works and i get to learn at my own speed so, i am not at all unhappy that I have had the carb off so many times. :2tup:

[jonathan180iq]

Cool, man.

140 would make you the richest jetted GZ on the planet, as far as I know.
Do you have a huge exhaust pipe diameter or something?

[Jvacustoms]

Cool, man.

140 would make you the richest jetted GZ on the planet, as far as I know.
Do you have a huge exhaust pipe diameter or something?

I have taken it from a 1.25" o.d. to a 1.5" o.d. outlet but the middle is a 2-2.5" dia.with removable baffle, that I have blown the baffling out of a few times. It had fiberglass wrap it lasted 2-3 days, so it was straight pipe after that. Then i added steel wool from the local hardware store and wrapped that to the baffle with bailing wire. that seems to have lasted thus far but it is steadily getting deeper and louder so i have a feeling that is slowly blowing out too. I am gonna get some baffling when it is convenient for me as far as shipping goes from rocky mountain ATV and wrap the baffle in a thin sheet of fiber glass then a nice layer of steel wool and then some more fiber glass to protect the pipe exterior from the steel wool turning my chrome as it has tried to started doing already when it touched it while i was working on the carb settings and it was so lean.

[jonathan180iq]

Your local bike shop should have this stuff:

http://discount-cabin.com/shop/images/4/9/4/494cc7beac2256245fba118af9e1a643.jpg

Although, based on your tales of your local bike shop.... I guess we'll just have to see.

It will last longer than any of the homebrew stuff.
And I am partial to picture wire. ;)

Use steel wool under the packing material.

check this out:
http://faq.ninja250.org/wiki/Repacking_a_Muzzy

[Jvacustoms]

that is the stuff i was gonna get from rocky mountain atv when i order next time!