***carb Jetting Guide***

[NormalZ]

Start a topic in the Mainenance, Repairs and Tuning Section - you'll get a better, faster response like that.

[XCRacer93]

QUOTE (Blastermaster58 @ Jun 17 2004, 11:25 PM)

If there are any mistakes, please PM me, or e-mail me about it.

Here we go!

I created this while cleaning out my carburetor, and it is not necessary to completely take the carb off of the quad if you don't want to.

After each explanation is a picture. Sorry if some of the pictures are blurry, the next time I have my carb apart I will take better pictures. Enjoy

First off, clean your quad! You don't want any dirt or any type of anything besides gas getting into your carb. That will be bad news.



Next, remove your seat, gas tank side plastics, and gas tank cover plastic.



Next, make sure that the petcock valve is in the "On" position, so that only a minor amount of gas will leak out. Pull the gas tube from the carb, and let the gas leak onto a towel. Then, pull the other tube coming from the petcock to the carb. Then, remove the two bolts that are holding on the gas tank, and remove the gas tank.



Next, go up to the throttle body on the handlebars, and remove the cover. Then release the cable from the jig thats in there. Then just unhook the cable from the body. I suggest putting the throttle body cover back on so that nothing gets in there.



Then, unscrew the choke cable from the side of the carb (For those of you with a carb mounted pullout choke, you do NOT have to do this). Then, you may loosen the boot clamp screws on both the airbox and engine sides. Remove the carb.

Now it is easier to work with (Again, you do not have to completely remove the carb to rejet! I find it easier to work with this way though). You should have something like this:



Now, I recommend getting some type of pan to put the carb in, because in this next step, gas will pour all over the place.

Turn the carb upside-down. Remove the Idle mount screw. Remove the four screws holding the bowl on. Remove the bowl



Now, from here you can do many things. I will list 3 things, because I do not have pictures for the rest.

Changing Your Main Jet

*For the "Changing Your Main Jet", and the "Changing Your Starter Jet" sections, pictures will be posted before explanations...*



To change your main jet, it is very simple. Take a flathead screwdriver and remove the Main Jet. Replace it with a larger/smaller main jet (Stock size is 130 Mikuni Small round). That's it, you're done.

Changing Your Starter Jet

*Refer to above image*

To change your starter jet, do the same thing as you did with the main jet. unscrew it with a flathead screwdriver, and replace it with a larger/smaller starter jet (Stock size is 60).

As you can see, jetting is very simple, its just getting it spot on that takes time. Let's continue...

Adjusting The Needle Jet Clip Position

*Explanations posted before pictures*
**Note: If you have a stock needle, you will not be able to adjust your needle jet due to the fact that the stock needle only has 1 position!

First, you start off with this...



Second, remove the 2 screws holding the big black cap on (Carburetor diaphragm cover), so that you get something like this (Watch out! HUGE spring under the cap!):



Then, remove the slide (diaphragm) by slowly pulling the rubber boot upward.



Next, take a pair of needlenose pliers, and reach down into the slide with them, grab a hold of the gray needle holder, and pull (WATCH OUT! There's a tiny little spring that will shoot across the room, and will never be found because it makes no noise).

Next, if you want it to be leaner, move the little clip up a position on the needle. If you want it to be richer, move the needle clip down a position. This may take a little patience, because sometimes the clip does not want to move.





When you are done with rejetting your quad, reassemble everything back together, it is fairly easy.

You're done. Now all you have to do is check your spark plug after riding it for a while. Black plug = rich... White/Gray plug = lean... Tan/Brown plug = Perfect (this is very hard to obtain though... Just make sure that your not lean, or too rich)

I will update this thread with how to change your pilot jet, and adjust the Fuel mixture screw as soon as my carb is apart to take pictures again.

Hope this helps anyone with jetting questions. Have fun![/b]

i have a z400 with a full yoshimura pipe and i ride in indiana with a 150 main jet and 2 1/2 turns out on the fuel screw. sometimes i have bogging on the low end, do i need a bigger or smaller jet

[Robhuffman]

If anyone could post a pic of the dj needle with all the washers and stuff on them that would be great. Mines running kinda weird and im thinking something could be wrong. The carb was into before I owned it so I just wanted to make sure I had the correct washers etc.. Thanks

[jonbsbb]

I have a question. I was reading the directions in my dynojet kit, and it says to remove the vacuum slide what does it look like?

[Zquad1]

here is some really cool jetting tips also Four-Stroke Carburetor Jetting Tricks on 4Strokes.com