Wont hold idle (cuts out)

[Greasey Fingers]

I just cleaned out a set of carbs for a SOHC model and trying to tune them in. I seemed to have them synced on the manometer and they rev out no problems but WILL NOT hold idle not matter how much I turn up the main idle screw...it just runs out of ajustment and I can no longer screw it in and it still dies

This is a spare set of carbs, I have another set that tuned in perfectly so im pretty positive its to do with the carbs and not a factor on the motor or other things.

I noticed the left hand cylinder is noticeably hotter than the right after trying to tune these in.

I also noticed that the right hand carby idle mixture screw will not screw all the way in its as if it threaded at that point. But the tip is fine its not broken off, I can take it right out and check it and its fine. I just cant screw it right in like I can on the left hand carb. I sprayed carb cleaner through that hole and it comes out the other side so it doesn't seemed to be blocked.

I have cleaned these f&*cke#s RIGHT out and checked the float height and they still giving me grief!! AHHHHHHHHHHHHHHHHHhhhHHHHhhHHHHHHHHHHHHRRRRRHHHH

sorry just had to have a little tanty these carbs are really shitting me.

 

[16VGTIDave]

The idle screw should be barely holding the throttle open, otherwise the engine will be running on the pilot circuit rather than the pilot screws. When setting up carbs for the first time, I back out the idle screw until it isn't touching the throttle arm. Then turn it in until it touches and give it a full turn from there. That should be enough to get the engine running.

Check the pilot screw that isn't seating to see if it is bent. Also check to see if an old o-ring isn't stuck in there.

 

[Greasey Fingers]

Thanks dave ill have a look in there cheers!

 

[Greasey Fingers]

Just changed out the pilot screw with another one and it goes all the way in now, but still no joy. Still wont idle. But when I first started it up with the enrichener on, it did idle, it was low but it was idling. But yeah as soon as I turned off the enrichiner it cut out

 

[Pork Chop]

Hey Greasey,

What size pilot jets are you running in these carbs? Do you have a size larger that you can try? Also how do the plugs look?

Cheers,

PC

 

[Recreateme]

Did you properly set the butterfly valve gaps before putting the carbs on ?

If that isn't set properly you will be relying on the choke and idle mixture screws to dribble fuel in and will have issues idling.

 

[Greasey Fingers]

Hey pork chop, these are 250 carbs and don't run the changeable jets I believe. They do have the circlip on the needle so you can raise or lower it to lean it or make it richer.

I didn't set the butterfly gaps Recreateme! Whats the best way to do that?

Ok other factors involved here:
Its a 1979 SOHC xs250
Its revving up fine and runs ok
Running pods and straight through mufflers
I put the clips on the needles to the 3rd position, one below stock position to richen it up and compensate for the increased airflow which worked a treat on the other set I have.

Should I try put the circlip on the needle back to stock position?
Should I try run the h-pipe off the carbs so the pods are set back from the carbies?

Incidently I found a good video on ajusting the pilot screws in my searching for solutions, and hes doing it on an XS400 too:

 

[16VGTIDave]

...these are 250 carbs and don't run the changeable jets I believe...

Should I try put the circlip on the needle back to stock position?
Should I try run the h-pipe off the carbs so the pods are set back from the carbies?

I'd be surprised if the jets were not removable. But I've never seen an XS250, never mind their carbs...

Leave the circlips where you have it for now. Do run the H-pipe. In my opinion it is better than running a crankcase filter, and you will eliminate any problems with the pod filters possibly blocking the carb ports or disturbing the airflow.

 

[Greasey Fingers]

I'd be surprised if the jets were not removable. But I've never seen an XS250, never mind their carbs...

Heres a picture of another one I have with a broken float mount (obviously not what im using)

 

[Pork Chop]

I've got '81 xs250 bs32 carbs on my bike and they have removable pilot jets.

 

[xschris]

The pilot jets and the mains are in the bowls just like the bs34 xs360 carbs.

 

[xschris]

Some pics.

 

[Greasey Fingers]

Ahh thanks chris I never new that, and I didn't check them to see if they are clear. Is it possible that if they were a bit blocked they could cause the idling problem? I didn't even notice or think to look in the bowl. Underneath I thought that was just a drain plug for the bowls?

 

[Greasey Fingers]

Gonna clean out the jets in the bowl tomorrow, hopefully that's my problem

 

[Pork Chop]

That is the main jet exposed in the bottom pic. The pilot is in a smaller orifice as per pic 1. My right pilot jet was blocked and that explained why the right exhaust was cool at idle.

Ignore my half asleep ramblings...

 

[Greasey Fingers]

That is the main jet exposed in the bottom pic. The pilot is in a smaller orifice as per pic 1. My right pilot jet was blocked and that explained why the right exhaust was cool at idle.

Ignore my half asleep ramblings...

Its only 9.30 mate why are you asleep I think we may be onto something here though (hopefully). if the pilot jets are block that could explain the inability to idle no?

 

[xschris]

It will have a lot to do with it

 

[Scorpio1963]

Whatis the advantage of running the bs32`s insteadof the bs 34`s other than the adjustments are easier.Is there a power or torque increase and do they increase milege?Also are the hard the find and is there kits to rebuild them readily available?

 

[xschris]

The bs32's are for the xs250. The set I talk about are bs34's, just an earlier version.

 

[Scorpio1963]

So the bs 32`s wont work on our 400`s at all Is that what your saying?
So what about the older bs34s same questions as I asked above.
Thanks