air fuel mix problems

[Xs400_4_life]

i have a 81 xs400 that i have owned for 7 years, she has alway ran like a champ. i just put pod filters, mac 2 into 1 exhuast and a 6sigma jet kit on. it is running a 45 pilot and a 150 main with 2 spacers on the needle. when the choke is at mid it will idle fine but if i pull it all the way out it dies right away. with the choke in it with idl but when i try to start moving it will die unless i rev up to like 6000 rpm and then when i come to a stop it will die most of the time. I have tryed everything i can think of but i just cant get the mix right. i will be greatfull for any help that can be givin.

 

[DARKMIDKNIGHTWARRIOR]

Welcome to the forum! Sorry I'm not able to answer your question.

 

[Edgee2004]

Pods and exhaust mods take time to sort. just take time and be patience.
then try this.
pull the plugs, clean, re-install.
start the engine with no choke (if you can). let it idle, then pull and inspect plugs.
Rich, lean?
repeat with half choke. (rich, lean?)
repeat with full choke. (rich, lean?)
if you have an issue adjust the idle jet.

if no issue in idle circuit pull plugs clean and re-install. then start the engine and start giving it gas. the throttle should be quick to react, engine should increase and decrease RPM smoothly with throttle. adjust the fuel mixture accordingly. inspect pulgs (rich, lean?)

p.s. a rich plug is black and a lean plug is white-ish.

if you notice a lean condition increase the jet, rich condition decrease your needle hight first, then jet.

keep us posted.

 

[xschris]

Drop the main jets to 142.5 and get rid of the two spacers under the needles. Your too rich!! The sigma 6 kits are crap.

 

[Edgee2004]

arent these carbs CV type? no need to space the needle.

 

[xschris]

The pre-80 bikes had adjustable needles. The later 80-82 did not (emissions control). Most of the time they don't need to be changed, even with pods. That part of the throttle is the mid-range where your cruising and don't need much fuel.

 

[Xs400_4_life]

ya kinda thought the kit was crap. waiting on gaskets for the exhaust to come in. ill take out the spacers, I have a 135, 145, and 150 main really don't want to buy a new main ill try it with the gaskets and see how she does.

 

[Xs400_4_life]

just swaped in the 145 mains and removed all spacers on the needle> the exhuat gaskets should be in in a few day, will try to start her up then. will keep you guys posted thanks for the help

 

[devdg]

I don't know why but I find the pods to hinder more then help the performance of my bike. wishing to go back to stock.

 

[Xs400_4_life]

well got the new exhaust gaskets on, no luck still dies eveytime i start to move and will die if the choke is all the way out> i think this means i am still running to rich and need to order the 142.5 main jets. hope someone can give some advice dont realy want to order any more parts for her ( spent to much already

 

[16VGTIDave]

The Main jets are only in operation above about 3/4 throttle and high RPM. You need to be looking at the Pilot jets and Screws if the bike is dying at low RPM.

 

[xschris]

What are your floats set at. Did you do any other "mods" to the carbs from the sigma 6 kit?

 

[Xs400_4_life]

the floats are set to stock and have not been altered. i have swaped out the 35 polit for the 45, i haved swaped the 135 main for the 145, and turned the screw out to 3 turns.

 

[xschris]

You say you turned the screw do you mean the screws. There are two idle mix screws. Have you synced the carbs yet? What knid of "pods" are you using? We need some pics of your bike. This will help also.

 

[Xs400_4_life]

I have an 81 so I beleave there is only one screw, but if im wrong I would like to know where the other one is. I did the paper test on the butterfly valves and they felt the same. I don't have the money for a vacuum gadge. I think they are emgo.

 

[HoughMade]

On an '81, there are mixture screws under a plug on the engine side of both carbs. They were factory set and the plug put on to prevent tampering. You need to tamper. The plugs need to be drilled out carefully to access the screws underneath.

There is one idle speed screw and one balance screw, but neither of those adjust mixture. Here's a pic for reference.

In this pic, it's a '79 so the idle mixture screws are out there and proud. On an '81, the screws are in the same place, but hidden under the aforementioned plug down in the carb body.

...and then just for reference, not necessarily for you, OP, but for anyone who may reference this thread, the faint red circle in the below pic is the idle speed adjustment (extra credit and warm fuzzies to anyone who can tell us why this pic is "famous"):

The balance adjustment screw on the filty example carbs (can't have people thinking they are mine) is circled:

You can also see the tall and proud mixture screws with plastic caps in that pic.

Good luck!

 

[iamunique127]

Very helpful, HoughMade, thanks.

 

[Xs400_4_life]

when i said "I have an 81 so I beleave there is only one screw" i did mean each side. Is there more then one mix screw per side?

 

[HoughMade]

Nope- 1 per side.

 

[JARichmond]

extra credit and warm fuzzies to anyone who can tell us why this pic is "famous"

It's on our shirts!