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MtnEX
10-27-2010, 07:29 PM
OK, so when this Z400 came my way it would not run at all.

I got it running later, but then it would not idle.

I finally got it to idle but then had to wait like a month on parts to get here to get it rolling again.


Well now it cranks right up... but the idle hunts... and it smokes like it's rich... etc... no question at all it is fuel smoke...

I took the air box lid off and it's the same... except it breaks up like crazy when you get on the throttle.


Best I remember it had stock jets in it?
Pilot screw is set to stock specs...

Mods are a ReadyFilter foam filter and someone gutted the stock muffler.
ridehonda400ex
10-28-2010, 03:04 PM
im not quite for sure but maybe your pilot/idle jet is to big
MtnEX
10-28-2010, 05:34 PM
That is what it acts like... but I think the jet is stock...



I took the air boot off and watched... and the slide moves up and down a little during idle.
MtnEX
10-29-2010, 12:44 AM
I took it back apart and everything looks good.

Jets are stock and everything seems good.


Hummmmm.....
ridehonda400ex
10-30-2010, 08:05 AM
is there different adjustments on the float level?
RATPACK Z400
12-02-2010, 09:18 AM
You probably cant run stock jets with gutted pipe,it needs to be jetted when you put highflo filter with gutted pipe. IMO
ridehonda400ex
12-02-2010, 05:47 PM
ohhpp i didnt catch that about the gutted pipe
witech
12-02-2010, 06:53 PM
We had a z400 carb have one of the needle clips fall off and let the needle float around in the slide. It would only run at idle or wide open and nowhere in between. just something to check.
MtnEX
12-02-2010, 08:43 PM
The jetting is OK I think because the pipe is not totally gutted... just the outer end of the muffler... it still has that small outlet inside.

Taking the lid of sure will lean it out in spots upon hard acceleration.


As it turns out, the tank valve leaks and so does the needle valve apparently.

It was hiding from me because the overflow was clogged.
ridehonda400ex
12-03-2010, 04:02 PM
cool. so did you get it running then? and you should post a picture of the quad
MtnEX
12-18-2010, 02:48 PM
OK, so I changed out the needle valve and it seems to not be leaking anymore when sitting.

And it does idle better, but...

It is still way rich at idle it seems with stock jets.


Will a bad tank valve on these things cause this? Never messed with this type of petcock.
2001400exrida
01-02-2011, 05:56 PM
my buddy has one of these and it won't start unless you pull start it. he can get it to start rarely if it is warm but usually it takes a bump start.

i think it's something to do with his fuel petcock because his jetting is fine because the quad used to run perfect.

what do you guys think?
MtnEX
01-02-2011, 10:10 PM
Originally posted by 2001400exrida
my buddy has one of these and it won't start unless you pull start it. he can get it to start rarely if it is warm but usually it takes a bump start.

i think it's something to do with his fuel petcock because his jetting is fine because the quad used to run perfect.

what do you guys think?

Check battery voltage... seriously... only bike I ever saw that would spin and spin the starter without enough juice to run the bike.

Try and see if it will start with the petcock on "prime".

Check the vacuum lines between the carb and petcock.

Then check compression and valve lash.