some one please help me with these carbs

bennett834725

Military xs400
Messages
220
Reaction score
0
Points
16
Location
Ephrata, Washington
so i have done cleaned these carbs 2 times boiled them once and also had them professionally hot tanked at napa so i know they are clean as hell inside, no the air fuel screw is 2.5 turns out and it will run but at a idle it dies out, also i looked up the carbs and they look like the bs34cv carbs but have many differences is there something i am missing, i have brand new jets in it and new rubber diaghram also just wont idle and im getting frustrated as all hell:banghead:
 
heres some pics of the carbs
 

Attachments

  • IMG_1615.jpg
    IMG_1615.jpg
    184.6 KB · Views: 329
  • IMG_1616.jpg
    IMG_1616.jpg
    183.5 KB · Views: 330
  • IMG_1617.jpg
    IMG_1617.jpg
    197.8 KB · Views: 328
  • IMG_1618.jpg
    IMG_1618.jpg
    149.6 KB · Views: 297
  • IMG_1619.jpg
    IMG_1619.jpg
    135.2 KB · Views: 289
When you boiled them did you remove all the rubber bits?( butterfly shaft seals, idle mix screws o-rings). What size pilot jets are you running? Is this from the same bike you are selling? These carbs are off a 80-82 sohc xs400. Did you try to swap any parts from the 79 bikes carbs into them?
 
yes i stripped the carbs all the way to bare nothing removed all seals and components and no i didnt know they were from a 80-82 these were the carbs that came with it what carbs am i supposed to be running on it
 
The 80-82 sohc carbs will work on any sohc xs400. But when you order carb parts you must get the ones for these year carbs. If the bike will start but not idle it sounds like the pilot circuit is lean, still has a tiny hole plugged of out of adjustment. So if all is cleaned and all the tiny holes are clear and all the o-rings and seals have been replaced with new ones then it's a lean mix or out of adjustment issue. Make sure the floats are set to the proper settings. If you have aftermarket pod filters go up a size on the pilot jets. Make sure to sync the carbs with a manometer once you get it running.
 
pilot jet is the oem factory one, and i cleared all the small channels with high pressured air and also choek and carb cleaner and all have fluid coming out i spent roughly 4 hours on them cleaning them and i did a bench tune on them as per the factory specs on it and when i open them up and flip them over the pilot jet has a small black rubber plug over it and i read up on it, and the main jet provides fuel to the pilot
 
As a suggestion.

If your look in the first pic of my post #6 here

The whole thread is pretty good and may help you

http://www.xs400.com/forum/showthread.php?p=111641#post111641

The float needles (may be the wrong term) in the middle of the pic. There are little spring's in them that can get seized. I soaked them in carb cleaner then made sure they inner part moved freely. If there bad, replace.
 
Are you talking about the needle that is mounted to the upper diagram with 2 Philip screws if so then yes I checked that also and that small hole is cleared out also I used 120 psi of air to blow them out :thumbsup:

Posted via Mobile
 
I would go to a 45 pilot jet and make sure the rubber plugs over them are new and tight. The floats if they are brass should be set at 26mm.
 
Float is set at 27 and the rubber plug is new also cause the old ones were hard as rock loll but I tried to fire it up today and still nothing runs like shit :banghead:

Posted via Mobile
 
If they are wet than it's too rich. I would go back to a 42.5 pilot jet. What mains does it have and what jet needles are in it?
 
Something happened when you cleaned them or put them back together. Mains should be 135-142.5 If you have adjustable needles what are the numbers on them and what clip are they set at?
 
Last edited:
Did you assemble the mix screws correctly?
 

Attachments

  • user3160_pic5112_1395861195.jpg
    user3160_pic5112_1395861195.jpg
    127.6 KB · Views: 275
so im saying fuck these dual carbs and im doing a single carb setup on my bike, i got a single housing from a mikuni mkII off of a xs750 so i broke em down and cleaned one up nicely and re-jetted it to a 150, basically using a 180 bend pipe into the factory boots with a flange welded to the pipe, this way down the road i can re install the oem setup
 
here is a before and after of the jets and internal parts after a nice sonic clean :thumbsup:
 

Attachments

  • 10151428_611162828977661_5301388741347262713_n.jpg
    10151428_611162828977661_5301388741347262713_n.jpg
    50.3 KB · Views: 274
  • 10252073_611162832310994_2942234597521643840_n.jpg
    10252073_611162832310994_2942234597521643840_n.jpg
    45.9 KB · Views: 291
I found one problem. Your needle jet is wrong for you carb. They look like a X-8 off a dohc model. They should say 270 Y-O and look like this.
 

Attachments

  • DSC02477.jpg
    DSC02477.jpg
    179.3 KB · Views: 291
Back
Top