Z400 carb guide

[madcow]

I would say the power gain would be negligible, maybe 1 hp at most, but the difference would be in the throttle response, it'll be much better because of the CV design. The main reason I went through with this is because my stock carb is acting up and this will cost about the same as a stocker, but it'll be better.

Just a little update, I had to drive all over the damn place to get the jets, went to the yamaha/suzuki dealer and they didn't have anything, went to the kawasaki dealer and bought the pilot jet, and went to the honda dealer and got the starter jet, which is actually an air jet according to the parts catalogue.

 

[madcow]

Just a little update: IT'S ALIVE! Turns out the stock pilot jet is a 22.5, but the pilot screw is set too lean, I had to richen it 2 turns to get it to stop popping when the revs come down with no load. Everything seems fine though, I took it out for a really short, slow ride but I still have to hook up the airbox. Hopefully my main jet is good because I really want to ride it right now.

 

[madcow]

Wow, night and day difference. It revs from any point almost instantly, and pulls harder until the valves float. I wasn't expecting this much of a difference. I was almost floating the valves doing donuts in the snow in 2nd gear, with the stock carb I was barely getting halfway to floating in 2nd.

Now a jetting question, since I haven't done this in a while and forgot. Missing at high RPMs means too lean right? Mine sounds almost like like I'm bouncing it off a rev limiter, it goes up, misses, goes down, and repeats. It's not like when it was rich with the stock carb, where it would get to a point where it would just stop making power and missing constantly, it just misses once really high up under load, falls down and misses again when it hits the same point.

 

[jasonp]

Wow, night and day difference. It revs from any point almost instantly, and pulls harder until the valves float. I wasn't expecting this much of a difference. I was almost floating the valves doing donuts in the snow in 2nd gear, with the stock carb I was barely getting halfway to floating in 2nd.

Now a jetting question, since I haven't done this in a while and forgot. Missing at high RPMs means too lean right? Mine sounds almost like like I'm bouncing it off a rev limiter, it goes up, misses, goes down, and repeats. It's not like when it was rich with the stock carb, where it would get to a point where it would just stop making power and missing constantly, it just misses once really high up under load, falls down and misses again when it hits the same point.

I didn't even see this post until today.. SWEET **** MAN!
Pretty awesome carb.
Ok, first off how many turns out on the fuel screw are you? More then 3 1/2 then you'll have to jet up on the pilot or down on the air jet.
I think you're very close to the correct mixture, as you get close like that the "rev limiter" effect (miss) gets longer and longer. I does sound rich yet to me, not by much. Which I've found works a little better for the warrior engine as it's air cooled and likes a little more fuel. I think the difference here are the fact that it's a vaccum operated slide so as the slide is coming up in the bore the mixture is getting richer until the engine misses because of the mixture then the slide closes and regains the mixture.
If it's a little lean you'll be able to tell also as the bike would sound more crisp and have more of a tinny sound to it, like it's being choked off. Usally you'll find that if the mixture is rich on the top end the engine will fall off when you get to that WOT throttle postion. I would just try going down a jet and see what happens. If it gets worst then go up two.

 

[madcow]

Hmm, I went up one and it felt a bit better, but I didn't have time to do some WOT runs down the road because the carb refused to work right. It's as is the float bowl doesn't fill completely, so when I give it throttle it can't deliver enough gas and it stumbles. Gives a really hollow, sort of "whump" sound and the revs drop. If I sit there revving it for a few minutes it would be alot better, but it would still stumble every once in a while. Maybe it need a rebuild, it was in pretty ****** condition when I bought it.

 

[jasonp]

yeah check the float height..

 

[madcow]

Well I'm done the guide, can I get this moved to the tutorial section now?

 

[jasonp]

everybody should thank Mad for this one and putting up the great pic's and info. Awesome job man, glad it turned out for you as well.

 

[frack77]

Dumb question coming.
Are the LTZ400 and Z400 the same bike/carb?

 

[madcow]

Yea, LTZ is the full name, Z400 is essentially a nickname for it. Also, the Kawasaki KFX 400 and Arctic Cat DRZ 400 have the same carb, they're essentially the same bike.

 

[courchaine]

Arctic cat DVX 400 a DRZ 400 is a suzuki dirtbike from wich is derived the LTZ400 engine

 

[madcow]

DVX, that's the one! :-[ I thought I had something mixed up. But as far as I know, the DRZ has the same carb too.

 

[frack77]

Ok, thanks guys,
I am thinking about buying a z400 carb to put in the warrior. Thats why i asked, just wanted to make sure!

 

[madcow]

Ok, thanks guys,
I am thinking about buying a z400 carb to put in the warrior. Thats why i asked, just wanted to make sure!

I would say go for it!

Another thing I noticed is the exhaust note sounds a bit more crisp now, especially when I rev it quickly. Even if that jetting's off it still sounds better than the stock carb.

 

[frack77]

So you still have not got the jetting right? Right now my main jet is a 148 on the stocker warrior carb. Thats the only one that i changed after drilling the airbox and putting the k & n in. Would that work/fit in the z carb? Im really looking forward to doing this. Hopefully this gets the damn bike running!

 

[madcow]

Just read the section about jetting, it's all explained there. The only reason I don't have the jetting right was because I didn't have the time. You sure it's a 148 though? Because mikuni jets don't come in 148, the closes is 147.5

 

[frack77]

Hey MadCow,
What is the TPS? Would there be a problem if i left it on?

 

[frack77]

Just read the section about jetting, it's all explained there. The only reason I don't have the jetting right was because I didn't have the time. You sure it's a 148 though? Because mikuni jets don't come in 148, the closes is 147.5

Its stamped 148 and i believe its a dynojet (from the kit)

On a side note, i now have the z400 carb/thumb throttle and cable(with the carb mounted plunger style choke)! The kid said that it had a 180 jet in it.. Heres my second question(second of MANY im sure i will have for you) will the jets that i have in the stocker fit in the z's? Im gonna take a crack at putting it in this weekend..

 

[madcow]

Yep, they're both mikuni carbs, both using screw-style jets. But please don't use dynojet jets, that'll only cause problems and frustration when you realize that the mixture changes based on where the needle's sitting. I had a mikuni jet with a dynojet needle and it was horrible, it richened like hell at half throttle.

A TPS is a throttle position sensor. All it does is read where the throttle is. It hooks up to the CDI to change the timing based on throttle position. Since the warrior CDI doesn't support one it does nothing. You can keep it on but then there will be a random wire just hanging there, and it'll be a bit harder to reach the choke knob, that's why I made a block off plate.

 

[frack77]

You are the man Mad Cow!