Z400 carb guide

First off, the list of part's you'll need:

1.) Z400 carb (obviously) these can be found on ebay for really cheap, I got mine for $45+ shipping
2.) Choke knob for BSR carbs, I was sent this link, but they can be found on ebay too.http://www.advantagecyclelc.com/showproduct.php?id=122&prodnext=0&searchvalue=&nbrProds=15&catId=16#prod
3.) Raptor 350 intake boot+ clamp: find them at your local dealer or any OEM parts catalogue.
5YT-13586-00-00 JOINT, CARBURETOR 1
90450-52003-00 HOSE CLAMP ASSY
4.) Assorted jets

The first thing you should do is remove the throttle cable, to do this, remove the cover from this block:

Then pull the throttle open all the way, grab the little metal piece with a pair of pliers, twist it 90 degrees counter-clockwise and pull up, it should come out with the throttle cable attached.

Now get rid of the stock cable-style choke. Just unscrew it and pull up, mine was really stuck so I sprayed a little WD-40 and just pulled really hard. Then just screw in the knob-style choke.
Here you can see it installed with the TPS block off plate:

You should get rid of the TPS, it's useless on the warrior anyway. Just unscrew it. To cover the hole I first cut the wires off the stock one, but it was ugly and got in the way of the choke, so I just cut up a piece of sheet metal and made a cover.

You'll have to block the vacuum hose, it's the one that connects to the carb beside the choke plunger, using a connector similar to the fuel line connector. You can leave the other hose because it's just a vent hose.

Now on to jetting, you'll need to rejet it because the Z400 is a completely different motor.

Since this carb is pretty much the same as the Raptor 350 carb, you'll have a starting point. Your main jet should be about 1 size smaller than what you're currently using with your stock warrior carb, and the pilot jet should be 22.5, which is what came on mine. You'll have to tune the pilot screw for this motor though, mine's about 3.5 turns out. If you have just a pipe/filter combo, go up 1 size on the pilot if you feel it's too lean. Now about that starter jet, The Z400 manual calls it a starter jet, while the raptor 350 fiche calls it a pilot air jet, either way, don't mind what it's called, all that matters is that it's a 70 according to the raptor 350 fiche. It's the same size as a main jet, just ask for a 70 mikuni screw style main jet. Annoyingly, the pilot screw is behind a metal cover, so you're going to have to drill it out if you want to tune that. Here's a picture I found on Z400central explaining how to do that:

Mine came out pretty easily, stock position is about 1 turn out. The plug is really soft metal, so I drilled with low speed and light pressure and just stopped once it broke through, scratched up the screw a tiny bit but that's OK.

Now to mount it and connect the throttle and gas lines. First you have to come up with a way to attach the airbox or a filter, what I did was heat up the carb end or the airbox boot with a heat gun and stretch it over a funnel. It progressively got wider, eventually it was stretched enough to fit over the carb. Then I heated it up and let if cool a few times while it was on the carb to make it keep that shape better.

Then you take off the stock carb and all it's lines, plus the rubber boot that goes to the motor. You'll have to route the throttle cable to the right side of the frame because that's where the cable connects in this carb. I just pulled it out a bit, then routed it through some hanger with a bundle of wires that was already there. Before you connect the throttle cable, be aware that the threaded part of the stock cable is much further away from the end than the Z400 cable, so you're either going to have to hook up a Z400 cable and throttle control, or come up with a fix for that. What I did was cut a piece of tubing just long enough to act as a spacer, it's far from perfect, but it works. There is some play in the thumb throttle because of it, but i wouldn't be noticeable unless you looked for it. Then screw the cover back on.

Install the raptor boot, and slip the carb into it. Then install the airbox boot and slip in the fuel line. The fuel line joint on the carb is thicker than stock, so I had to sue some really stretchy silicone tubing I had, but even that barely fit.
This is what it looks like with everything installed:

Funny how the fuel tubing looks transparent in the picture when it's pink in reality. (It was the only colour the store had :-[)

But wow, what a difference. I can nail the throttle from any RPM and it'll just take off instantly, no hesitation like the stocker. I can also hold it wide open and it won't bog down when the revs drop. It also seems to start much more easily in the cold with the choke on, but the knob's hard to reach when wearing gloves. Sorry about not having pictures of mounting it, it was really cold and I wanted to just finish with it to go riding.

Not sure if you mentioned it, but that black choke knob has to be bought, they dont come on any stock z400 carbs.

Yea I did, it's on the parts list and I wrote how to replace it.

EDIT: Just realized that I wrote Pillot instead of Pilot in the picture, don't mind that, I'm too lazy to edit it again.

Oh ok, good job lol ;D

How are you going to mount it to the airbox? The z400 carb is MUCH larger than the warrior carb. Also, watch the right side of the carb- it comes real clost to the frame- I had to twist mine to get the clearance needed to miss the reverse lever ground and frame. I have not mounted mine to the airbox yet- I may just toss the airbox and install an open K&N mounted directly to the cover with an outerwears cover. I will just keep a spare cover with me if I run into any mud- just swap it out and keep going.

Cool, I still haven't tried mounting it yet because I don't have the boot yet. Once I get that I'll figure something out. Thanks for the advice too.

After comparing the carb and airbox boot, I think I have an idea. I'm thinking of sticking a piece of PVC pipe or something similar into the boot to reinforce it and then get a really wide hose clamp and attach it that way. The boot and carb opening have pretty much the same outer diameter.

Cool, I still haven't tried mounting it yet because I don't have the boot yet. Once I get that I'll figure something out. Thanks for the advice too.

After comparing the carb and airbox boot, I think I have an idea. I'm thinking of sticking a piece of PVC pipe or something similar into the boot to reinforce it and then get a really wide hose clamp and attach it that way. The boot and carb opening have pretty much the same outer diameter.

Click to expand...

Think that wide clamp can withstand a hard days riding?

Well the airbox is in the frame pretty well. I've noticed that with the stock carb you don't even need a clamp, it stays on because there's nowhere for it to move really. And the extra length means it puts more pressure on the carb, so it'll move even less.

I installed a z400 carb last year on my warrior and I used a heat gun and different size metal cans pipes to stretch the rubber filter boot to to make it fit to the air box

So how exactly did you stretch the tube? I can't really understand from what you wrote.

use a heat gun to soften the rubber and something bigger round to stretch the tube, like a glass, metal can, pipe,

Ohhh, that's genius! Much better than my idea. I'll probably do that.

EDIT: That worked, after some hard work and swearing it's finally on, I'm afraid to take it off though because I have a feeling I won't be so lucky next time.

great work you guys and info!!
This will for sure make it into the tutorials section

Cool, I ordered the carb boot earlier today, hopefully I'll have everything ready and running this weekend.

I hope the site I hosted the pictures on goes back online because I deleted them off my camera.

EDIT: Stupid me, I found them on another memory card. :-[

if your heat gun doesn't get hot enough and your careful use a propane torch, I stretch mine and it goes on and off pretty easy

My heat gun's fine, the problem is that when it gets to a certain point it becomes hard to handle because the opening gets too hot.

I think that you can also use the rubber tube from the airbox to the carb off a Raptor 350. It is much larger on the carb side and appears that it will work. It is only like $8 from Seattle Powersports Plaza. I am thinking about ordering it from them.

Oh and another stupid question- really more wondering than anything. If you left the stock z400 carb alone and installed it, what would it hurt. It is jetted for a larger motor- the 400.. Would it be possible if you have a filter modification, exhaust, and higher compression on a Warrior. Sounds kind of strange but a friend and I were discussing this the other night and I really did not have a straight forward answer for him.

Mine had a main jet in the 130-s, which would be way too lean for a warrior. You have to use a main jet 1 size down from what you use on the stock carb according to the raptor 350 jetting. You would also need a different pilot and possibly a different starter jet. Read the jetting section of the first post.

Now I have a question, since nobody seemed to notice it in the first post. What is the stock size starter jet on the rappy?

Just got the intake boot, but forgot to get a pilot jet when I was at the dealership. I'm gonna go there again soon and hopefully have everything mounted and working well before it gets too dark to ride.

How much power gain do you think you could get from this mod?