emulsion tube

perkinja said:
with pods on the carbs and no baffles on the exhaust. I figured since the increase in air i would have to go up in jet sizes
Click to expand...
Your thinking was right. If there was so much loss of nozzle O.D. due to corrosion that you had to wrap it in teflon tape to get it to stay in the carb body, then the inside of the nozzle probably has equal loss due to corrosion, making the nozzle too rich as 5 twins suggested, which explains all of your symptoms and explains why you are running such lean jets and clip position. Replace your nozzles (aka emulsion tubes aka needle jets).

What I don't understand is how you could even read the Z-2 on the nozzle if there was that much loss of material.
 
DogBunny said:
What I don't understand is how you could even read the Z-2 on the nozzle if there was that much loss of material.
Click to expand...

It was clearly stated on there as z2, i've ordered new tubes and they're on the way. Once i get them and install them i'll find out if it was the tubes and not the seating that the emulsion tube sits in. I checked the float bowl gasket as the previous poster suggested and around the emulsion tube was wet but everywhere else it was good.
 
So I finally got around to testing everything out. I got the new emulsion tubes from mikesxs and put the o-rings on it and they barely held in there at all. I could turn the float bowl upside down and they would just plop right out of it. I took some yellow teflon tape wrapped it around and stuck them in so it sealed.

I put a 140 main and 30 pilot in and started scooting around. it responded great up 5-6k rpms but I couldnt get it any faster than that on my streets. at idle the plugs were good, quarter throttle the plugs were good, but when i took it past that ive ran into the same problem. it responds good but the plugs are just fouled out (i also tried all variations with my needle during this testing).

The only time i can get the plugs to stay brown is when i have a 30 pilot, 120 main, my left carbs needle clip is raised all the way to the top, and the right is 1 notch down from the top. good up to about 5k rpms but anything past that it just putters out from not having enough gas.
 
Check both diaphragms for pinholes. If one has a pinhole, it won't raise high enough at the higher rpms, and it would also account for you needing different clip positions.
 
Just got through checking them, they appear to be fine. turned the cup upside down and put a little water in there and it held without leaking.
 
I'm still not convinced. A diaphragm problem is consistent with your symptoms. Are the diaphragms soft and pliable, or hard or stiff? Have you done a diaphragm drop test: Best done with carbs off bike, raise diaphragm slide and put thumb over the oval hole at the top of the intake, and watch slide slowly fall. Compare rate of fall to other diaphragm slide. Switch bodies and compare drop again.

You do have springs in your diaphragm slides, right? Look at parts drawings, make sure everything is there and assembled correctly.
 
The diaphragms are soft and pliable, i did a drop test and to my naked eye they're the same. The springs are in there haha, all the parts for the carb are in it, that I'm 100% sure of.
 
For shits and giggles I'd slap a couple of mufflers on it for a trial run. I have tamed many a piss poor running engine (including XS) with a muffler. That may at least tell you the carbs aren't "wrong" just not tuned....
 
Sadly i dont have the stock mufflers for my exhaust. I put this thing together via bits and pieces and the exhaust i got was already cut in half.
 
You mentioned pod filters, What pod filters. Some of the cheap K&N style pods have a lip around the inside. This lip is to prevent the pods from going on too far. This lip can block off the vents in the carb bell.
The two small round vents, one leads to the pilot jet, the other to the main jet. These vents such in air to mix with fuel at the jets. If blocked the air is restricted. This richens the mix. Try taking the pods off and give it a test ride.
Also those K&N type pods can cause tuning issues. The pleated element of the pod causes excessive air turbulence through the carb. This cause a weak vacuum signal for the slides. Causing late slide lift. This gives you flat spots just off idle, up into the lower midrange. Just where you spend most of your time.
The shorter and more tapered the pod the stronger the effect. The long straight ones may be ok.
A lot of us have found the a straight foam filter works well, Uni-Filter by brand. The PK-82 for the BS38's.
Leo
 
I've got the pk-82 uni pods on my carbs hehe. I'll take them off and run it and see what happens. It's raining here so when i get that done ill post back with an update.
 
I was hoping the pods would be the problem, that was a good idea, but if you already have UNIs, then taking them off won't help anything.

If your exhausts are "cut in half," adding a baffle or some type of restriction will help a lot when you finally get things sorted out, you're probably going to need to do it eventually, so it wouldn't hurt to do it now, but I don't think it will completely solve things.

Your problem seems to be in the main metering, somewhere in the vertical assembly of parts from the main jet up to the diaphragm, and I think the only component not discussed yet is the 502 needle. Your needle assembly is held in with a snap ring, right? There should be a tiny spring and tiny washer under the needle clip, and a tiny nylon disc above it. You do have the tiny nylon disc above, and not below the clip, right?

What about the 502 needles? Do they look right? If the holes in the body that hold the emulsion tubes are as wallowed out as yours are, maybe the 502 needles are wallowed out to. Do they show signs of pitting, or excessive rubbing and wear, or modification, or do they look nice?
 
I just want to take the time right now and thank you all for the responses and help you guys have put into this. I find the problem and it was my error, the emulsion tube, I was sticking it in backwards. So the oring part I was putting in the float bowl and not the carb body. I'm gonna tear them apart when I get home from work and once it stops raining I'll do done tests.
 
Well, now we know what jetting to use with an upside-down emulsion tube...
Try the jetting I suggested in post #15, after first making some kind of mild baffle for your pipes.
 

Similar threads

B
My dead XS650
2
Replies
21
Views
1K
650Skull
650Skull
M
Float Height for Mike's/Aftermarket Floats
Replies
8
Views
876
5twins
5twins
V
A first time builders journey
Replies
11
Views
817
Kevin Werner
Kevin Werner
Cafe Murdock
Freshly rebuilt xs650 to face fireing squad
Replies
12
Views
1K
Cafe Murdock
Cafe Murdock
K
Right Carb Running Rich
Replies
18
Views
2K
5twins
5twins
Back
Top