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Discussion Starter #1
Hi folks. First of all please bear with me, I’m a bit of a novice when it comes to maintenance and repairs and I’m trying to build my knowledge base. When doing a carb sync. I set up a temporary fuel supply and the bike won’t idle without choke, and idles at 500rpms full choke. But as soon as the regular tank is hooked back up it idles perfectly. Here is the setup:

Bike: 06 ex500
Fuel setup: old peanut butter jar hanging upside down above the carb with a hole drilled in lid and tubing running into the existing fuel line. I don’t recall the exact dimensions, but the tubing fits snug into the existing fuel line. Tubing at peanut butter jar is sealed with hot glue and red rtv on the outside of the lid only. Vent holes in the bottom of the upside down jar to prevent fuel supply vacuum issue.

Things I’ve tried:
Fresh gas
Covering no 1 carb vacuum line with finger - helps a little but not much.
Unhooking both vacuum lines to vent to atmosphere - no change
Hooking up both vac lines to manometer - no change.

I’m at a loss here and would really like to get these carbs synced, any help would be much appreciated.
 

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The only way to hook up the manometer is to the vacuum ports ,1 on each carb. Are you doing it in some other way?
 

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sounds like you making a vacuum in the peanut butter jar, try a jelly container with an air vent. Take some photos of your setup so we can beter understand it.
 

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sounds like you making a vacuum in the peanut butter jar, try a jelly container with an air vent. Take some photos of your setup so we can beter understand it.
OK, jelly instead of peanut butter, that's what I missed. :grin2:

Things I’ve tried:
Fresh gas
Covering no 1 carb vacuum line with finger - helps a little but not much.
Unhooking both vacuum lines to vent to atmosphere - no change
Hooking up both vac lines to manometer - no change.
Here's what I need clarification on:

Covering no 1 carb vacuum line with finger - helps a little but not much.
That needs to be connected to the manometer.
Unhooking both vacuum lines to vent to atmosphere - no change
Both carb vacuum line need to be connected to the manometer.
Hooking up both vac lines to manometer - no change.
Was there, or is there something else besides 2 vacuum lines being hooked up to the manometer.

And I agree with @Kevinl7778 any pictures would help a lot.
 

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Discussion Starter #5
Sorry, let me clarify. I didn’t do all of those things at once, but they were steps I tried individually to narrow down the problem. So in order:

1)I set up the temporary fuel supply and before hooking up the manometer I wanted to get the bike warmed up for an accurate reading.

2) Tried to run bike with temp fuel supply and vac line 1 open to atmosphere and vac line 2 still hooked up to air switching valve.

3) Same setup but covered the end of vac line 1 with my finger - slight improvement

4) Unhooked vac line 2 from air switching valve with no improvement.

5) Hooked up manometer anyways to both vac ports even though bike wasn’t warm - still no improvement and wouldn’t idle.

Also to note - idle speed screw is fine because it idles fine with the normal fuel tank. I’ll try to post pictures in the next few days, I have bike put back together and will attempt it again in the next few days.

In the meantime, what is y’all’s setup for temporary fuel supply?
 

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I think you've got peanut butter in the fuel line.

OK, seriously now. How high are you hanging the jar? If it's too high then the extra pressure from the "head" (scientific term for the vertical drop of a liquid) can overpower the floats, letting in more gas than it can use at idle.
I made this mistake once and hydrolocked my Connie after I had to walk away from it for an hour. That's a LOT of fuel to leak past the floats in an hour. This was on freshly rebuilt carbs with new floats and once I lowered the tank down (and changed the oil) it was fine and those same floats have been sealing fine for four years now.

One other thing; If you were able to put vent holes in the bottom of the jar it must be plastic. Gasoline will not play well with it for long, especially the lid seal. If this setup has remained in place for a day or so you might end up with gasoline all over your bike. Plastic fuel containers are made from a different type of plastic that's designed not to break down in contact with gas.
 

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I 5h8nk your jist having issues getting the right amount of fuel out of the jar, or a vacuum leak at the carb/full supply.

On my 2 stroke helicopter a lean engine runs hot and fast and a rich engine runs cold and slow.
 

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I put a funnel in the business end and keep a constant watch, I don't do temporary for vary long.
That's what I do. I have since lost the picture to photobucket. I put something on top of the funnel to keep out any debris (I think I used a coffee filter ). And I had a length of clear tubing spliced into the fuel line at the bottom (directly into the one on the bike), So I could see in the line when the fuel was about to run out. The fuel in the funnel (only about 1/2 full) and the line it's self would let the bike idle for about 10 minutes.
 

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Discussion Starter #11
Here is my setup. I changed the container to a McDonald’s cup so I could pour in with lid off but it could vent through straw hole, but that didn’t solve the problem. What I ended up doing is I put my finger over the vac 1 line, then held the throttle at 2k rpms and opened the choke and held throttle there until it was warm and it idled fine. I just doesnt like to idle cold with the temporary fuel supply but after warmed up it idles. I got the carbs synced but if anyone has any other ideas I’d love to hear because I’m stumped.
 

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Assembled in 1974 and in service ever since......an open top, 2 lb metal coffee can with hose barb brazed to bottom, using 5/16" hose and inline shut off valve...hangs from hooks on ceiling or other device depending on specific height needed.

A vintage keeper....certainly not pretty but reliably does the job. I'll have to modernize with the Motion Pro rig one o' these days. :surprise:

I'd advise OP to raise the MickyD supply cup a bit to eliminate that low loop of the feed tube, possible carbs are being somewhat strangled of fuel... hence difficult in initial startup?
 

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Discussion Starter #14
I'd advise OP to raise the MickyD supply cup a bit to eliminate that low loop of the feed tube, possible carbs are being somewhat strangled of fuel... hence difficult in initial startup?
At first I thought that was the problem, so upon install I made sure to hang it nice and high to work out any air bubbles, but still the same issue.
 

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I can honestly say without fear of contradiction. I have no idea what your issue is.
it runs fine with the tank on. but not with a remote fuel source.
it runs even with a remote source when warm. but not when cold. there is something you are missing and the info is not being passed on.
it makes no sense otherwise.
 

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"I put my finger over the vac 1 line, then held the throttle at 2k rpms and opened the choke and held throttle there until it was warm and it idled fine. I just doesnt like to idle cold with the temporary fuel supply but after warmed up it idles."

Need to further dissect your cold starting setup within the synch procedure to understand:

"I put my finger over the vac 1 line"

? Not sure what you mean here...an open vac line? You actually mean the carb vacuum barb? In either case, why did it require your "finger"?
 

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Discussion Starter #17
Ducatiman,

Yeah so the vac line from carb 1 that would normally be hooked up to the petcock. I leave the line hooked up to the carb barb while warming it up. My thought for putting my finger over it was “well it ran when it was hooked up to something so maybe it being open to the atmosphere is the problem.” Again, covering keeps the idle at 500ish, but if I remove my finger then it stalls.
 

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Neither carb barb nor any attached vacuum hose(s) should be left open to atmosphere when running under any condition, cold or warm, either testing or "live" on the road, choke on or off, throttle open or closed....must be either capped or connected to Pair system (RH barb) petcock (LH barb) or to a manometer or vacuum guage of some sort (both L and R) NEVER open, instant vacuum leak, loss of vacuum at venturi.

So what you describe, running when capped with finger, and stalling when open....is to be expected.
 

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If RPM's just 500'ish....if this is warm, your idle is set too low. Bring it up to 1200. Book calls for 1150-1250 if memory serves.

Then synch either at the 1200 or the optional 4000. There exists some historical controversy at what RPM to synch at. Book calls for idle speed, Fog has suggested the higher. Your bike, your choice. Try one then the other, see which suits you best.
 

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Discussion Starter #20
So what you describe, running when capped with finger, and stalling when open....is to be expected.
That makes perfect sense and I don’t know why I hadn’t put that together.

If RPM's just 500'ish....if this is warm, your idle is set too low. Bring it up to 1200. Book calls for 1150-1250 if memory serves. .
No the 500 rpm is cold. After capping the vacuum port and holding throttle at 2k rpms to force it to warm iup, it idles fine at around 1150-1250. I guess that’s just what I’ll do now for carb syncs, it’s just my OCD is killing me wondering why it doesn’t want to idle cold on the temp fuel supply.
 
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