z400 help!!

[USMC 350]

I just got my Z400 carb in today. Jetting is not my problem as I can do some research and figure it out myself ( I think :loco.....

Problem 1 that I encountered is the air screw.....fortunatly the cap that the EPA requires is not there and I have access to the screw....bad news is that years of riding has the air screw jammed up with crud and I am close to destroying it while I attemt to turn it....right now I have some PB Blaster sitting on the air screw to see if it frees up. If not Im open to suggestions......The needle is a fixed position with no options to raise or lower it.....is this ok for the warrior or do I need a needle with the clip positions?

Next is more of a question rather than a problem.....on the stock carb when you pull on the throttle cable both the butterfly and the slide rise.....On the Z400 carb only the butterfly opens......How does the slide rise? Does something pressurize that diaphram and causes the slide to open? Educate me people....:tup:

 

[lbjamm]

Airflow opens the slide.

 

[duneracerweston]

The slide is vacuum operated

 

[warriorgirl09]

the slide is a vacuum slide. you can mod the hell out of them to make em work better... i love vacuum carbs. as for the needle. the only way to adjust them is to take the need out of the slide and put real thin washers under them but you shouldn't need to adjust it up if your running it on a warrior. as for the air needle... what your doing is about your only option. the z400 i had had problems with the air screw... the threads stripped out so i got it where it ran good and filled the hole with JB weld and sold the quad lol

 

[Gen1Pat]

I love vaccuum carbs, too. On quads, not cars. And they get better with engine mods. More engine vac the better they perform.

Only other thing you can do with that mixture screw is to drill it out.

 

[warriorgirl09]

So you don't like quadrajets anymore? Asshole.... Lol

 

[88WarriorBoy]

lol he's bipolar about his carbs

 

[Gen1Pat]

So you don't like quadrajets anymore? Asshole.... Lol

I like the early q-jets with mechanical 2ndarys.

 

[warriorgirl09]

"Quadrajet carburetors have mechanical secondary throttle plates operated by a progressive linkage (primaries open before secondaries) but use "on-demand" air valve plates above the secondary throttle plates." The air valve plates are the vacuum butterflies... Aka ALL QUADRAJETS ARE VACUUM ONTROLED SECONDARYS so

 

[USMC 350]

I tried penetrating oil.....heat with a torch.....cold......heat.....nothing!!! Air screw is there to stay....I started to drill it out but the deeper I went the more I got nervous....I chickened out....I am gonna run it as is and hope that its close. If not how should I go by drilling it out and being able to pull out the whole assembly and then fix it so that I can install a new air screw?
:???:

 

[warriorgirl09]

I'd find a drill bit small enough to drill the center out as close to the threads as possible but leave the threads and then take a small pick or something and fish the threads of the screw out of the threads in the carb body

 

[Gen1Pat]

"Quadrajet carburetors have mechanical secondary throttle plates operated by a progressive linkage (primaries open before secondaries) but use "on-demand" air valve plates above the secondary throttle plates." The air valve plates are the vacuum butterflies... Aka ALL QUADRAJETS ARE VACUUM ONTROLED SECONDARYS so

Damn... I completely forgot that. I have to stop workin on fords&dodge, they are corrupting my database. Oh! But wait! If I did then I'd never make money!

 

[Gen1Pat]

I'd find a drill bit small enough to drill the center out as close to the threads as possible but leave the threads and then take a small pick or something and fish the threads of the screw out of the threads in the carb body

Ditto^^^ I have to do that too often. Sometimes you can even run a tap down it if you know the pitch.

 

[warriorgirl09]

Ditto^^^ I have to do that too often. Sometimes you can even run a tap down it if you know the pitch.

I think a lot of Japanese carbs use a special thread on the air screws

 

[Gen1Pat]

Hmm... I'm going to have to look now. You have me curious, but, I think you are right.

 

[USMC 350]

I think I made a wise choice.....just bought another "parts" carb off ebay, fleabay, sleezbay.....whatever you wanna call it...it looks great and I paid 40 bucks for the carb body and misc jets, parts, and theres even a pilot jet in the pile....hahahha. Once I have everything installed I'll post the results....I'm installing an open element high flow air filter, z400 carb, ceramic coating the header, FMF slip on, 14 tooth front sprocket, YZ 426 shifter for direct shift, and the oil cooler mod (clutch cover mod).......yes all at the same time......cant wait to go :atv:!!!!!!!

 

[warriorgirl09]

Sounds good dood

 

[USMC 350]

:???: we have a sucessful failure!!

Open airbox with filter adapter.......check
Z400 carb..................................check
Valves adjusted..........................check
FMF slip on.................................check
Start up.....................................NEGATIVE!!

I started with a 150 main, 70 starter, and 25 pilot.....
Checked float height and I'm pretty sure its good ......

Went to fire her up and nothing but popping stumbling and lots of rich smelling smoke out the pipe. Would not run or fire up.....

Pulled the carb off and found the intake boot very wet.

installed the stock jets of 130 main, 60 starter, and 22.5 pilot.....

went to fire her up and she started up with lots of difficulty but it would not keep running unless I really worked the throttle......lots of heavy blubbery popping and rich smelling smoke but at least it was running (bad) with the stock jets.

Pulled the carb and found the intake boot wet again. Before I drive myself crazy with the float height is there anything else on this carb that I should check out????? All attempts to start were with the choke off......

Choke on and the engine would not even pop or fire.

 

[duneracerweston]

Sounds rich to me. Make sure your jets are all in the correct locations.

 

[USMC 350]

Sounds rich to me. Make sure your jets are all in the correct locations.

Jets are all in the correct spot.......Just looked at a diagram of the jet layout for that carb and they are all correct. With these mods and the stock jetting on that particular carb it should be running lean as hell......not the case here.:argh:......hahahahah.