only running with full choke after cleanning

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drifter

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Hi, first post

Just purchased a 80 xs400, was running on one cylinder .. adjusted balance and got it running on both ... but was rich on one still adjustd idle mixture still was rich .. took carbs apart.. main jet had fallen out and was sitting in bowl ... and was missing air jet in carb throat .. hole was too over sized to replace air jet ... purchase replacement carbs from a 81

Bench ballanced and got running but was surging at idle... took them apart and cleaned all .. small hole in diaphragm ... changed slides and tops from older carb as diaphragm were good on them..
Adjust floats to 26mm.. set idle mixture to 3.5 turns... wouldn't run unless choked.. turn idle mixture in .. no improvement ..out no improvement. ..... I am stumped:banghead:
 
Only running while choked suggests the pilot circuit is still clogged. I hate to say it, but you'll learn it... re-clean the carbs. I think I had to do mine 3 or 4 times before it really started working properly...
 
How much of the. Carb guts are swapable ....
ie can I take the floats and emulsion tube etc
from the old carb and put into new?

Old carb have brass the new has black plastic floats
what should plastic floats be at?
 
usually measures 1-2mm below float bowl joint. there is a recess at the bottom of the float bowl where you can push in some clear tube.

It easier to do clamped on a bench so you can access the bowls for adjustment.
 
drewpy said:
usually measures 1-2mm below float bowl joint. there is a recess at the bottom of the float bowl where you can push in some clear tube.

It easier to do clamped on a bench so you can access the bowls for adjustment.
Click to expand...
Drewpy ... what is the purpose of the clear plastic tube? And would incorect float level cause the symptoms I described?
 
Sounds like you might have a leak somewhere[air] like a gasket missing or a loose bolt or screw.Something is causing a lean condition and the choke is giving it gas,so look for a leak.I use a propane torch[unlit]barely open and when the motor revs,you have founds the leak.It can be done with WD-40 as well,but I've found the propane better,and when you find the leak,you know. lha
 
ok ripped em down and blew out everthing even bakingsoda blasted the outside of the throttle body

the original diaphram have small holes so i am swapping the slides & diaphrams from the older carbs with the brass floats, is this compatible ? should i try to swap emulsifier too?



will post pics of my soda blaster settup and carbs later tonight
 
I hate to say this, but it sounds like the carbs are still dirty, particularly the idle circuit.

Heres how I clean this circuit...FWIW- and this is assuming the enrichener (choke) parts had already been removed, all passages cleaned, and reassembled:

1. With the carb off and the idle mixture screw in 3 to 3.5 turns and the enrichener (choke) in, use aerosol carb cleaner (I like Berrymans...and it will burn on your skin and mely any platic in the area) and with the straw on, spray cleaner through the air jet at the carb inlet. While doing this look through the engine side of the carb. You should be able to see s strong stream coming out where the idle mixture needle is. If you don't, keep spraying until you do.

2. Once that is clear, turn the screw in and seat it lightly. Now spray the carb cleaner in the air jet again. It should not come out the needle hole anymore, but there are 3 tiny holes right above the throttle butterfly. You should see 3 distinct streams coming out the holes. Not trickle, not dripping- thre strong distinct streams. You may have to hold the butterfly open a bit to get a good view. If you can't, spray until you do.

3. With that done, turn the carb over and if the float bowl is not off, remove it now. Remove the plug on the idle jet tube. It is a smaller tube built into the side of the main jet. Then, with a small flat screwdriver, remove the idle jet. Make sure it is clean. the hole through it as well as the holes on the side should be clean. Use carb cleaner if you have to, but do not stick anything harder than the brass it is made of in any of the holes.

4. With the idle jet out, repeat the same procedure that you did spraying through the air jet, but this time spraying up from the bottom where you just took the idle jet out. With the screw in at 3 to 3.5 turns, you should see the strong stream coming out. With the screw seated, again, you should see the 3 strong streams from the holes above the butterfly.

5. Re-install the idle jet and plug. Set the idle screws to 3 to 3.5 turns- reassemble everything else.

- if you do all this and actually see the streams of carb cleaner each time you should from each location, your idle circuit is guaranteed to be clean. If you do not actually see the streams where they should be when they should be, you can not be sure.
 
pictures

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DSCF0520.jpg

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DSCF0523.jpg

DSCF0536.jpg


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part of the choke "guide" ? broke used JB Weld to fix

DSCF0528.jpg


i think its my carb holders ... they are pretty cracked will try to repair or replace
also notice the new diaphrams also have pin holes :banghead:

i realize in the pictures i hav the brackets wrong ... i put them in the correct orientation now doh
 
Oh my,

I wish I could have saved you all that trouble.
If your carb boots are cracked your machine will only run on full choke. Take some permatex gasket sealant and completely coat your carb boots. Your machine will run like a charm.
 
Hehe that's exactly what the issue was, eventuallyy I gave up and took it to the shop, they ordered a set of boots and it runs like a top now:doh:

Posted via Mobile
 
drifter said:
Hehe that's exactly what the issue was, eventuallyy I gave up and took it to the shop, they ordered a set of boots and it runs like a top now:doh:

Posted via Mobile
Click to expand...
You can order the carb boots from mikesx and other sites for a lot less than a shop will charge you.I suggested looking for leaks,though I should have been more specific as to where to look. Worn carb intake boots,made of rubber,are a place to look whenever leaks are suspected. Good luck and glad you're closer to getting her going. lha
 

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