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Old 07-22-2014, 08:07 PM   #1
Ramanonos OP
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Carb sync weirdness. R100gs - bing

New to me bike with new to me bing carbs. I constructed a crude, but accurate device for a duel carb set up. A yard stick/tube meter. Oil in tubes, 1/4 tubing connected to vacuums. Here's a pic to get the idea

I basically copied this guy: http://wisconsin.airheads.org/techni...r-synchronizer

So here's my PROBLEM:

I can get the Bings equal on a good sounding idle. But when I twist the throttle, one side goes way up, suggesting I'm out of sync, or one carb is busted. Not sure which? Make matters worse, I'm unclear which screw is the idle and mixture (one screw is on top, the other one is underneath next to the vacuum nip). Been at this an hour and try not to overheat the air cooled r100.

Here's a video of the whole ordeal. https://www.dropbox.com/s/orwtb6hbr6...2018.23.38.mov






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Old 07-22-2014, 08:23 PM   #2
walkingbear
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having the same problem.
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Old 07-22-2014, 08:38 PM   #3
SculptD
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Well, first off, you should be spanked for asking openly on the airheads forum which screw is for idle and which for mixture. Seems like your vacuum rig is pretty useless if you don't know that! Okay, now what...

The mixture is adjusted below. The butterfly stop (idle speed) is adjusted above. Easy to tell, because it actually can be seen moving the butterfly. Okay, I've scolded you twice.

So, I adjust the mixture to best idle, and that will typically bring the idle above what you want, so you back off the butterfly stops. Got the idle nice-ish? Now rig up the vacuum system and balance the two sides using the butterfly stops. Then you should really redo the mixture, and balance again, probably.

Now, you can crack the throttle gently a tiny bit and see if there are differences in pickup. There will be. Adjust the throttle cable slack so both sides are vacuum balanced on pickup. Hopefully you then are in a good zone, but I find with these that balanced vacuum is not always the final optimum set point.

Others with more experience will possibly chime in with more and better detail, and add the crucial additions of valve adjustment, etc. and maybe they won't like my system either.
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Old 07-22-2014, 09:20 PM   #4
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Well, #1 can't be called an error. Legions of mechanics use vacuum to balance carburetors, and other multitudes not. Do it or not, it's a technique that is available.

And watching the vacuum on first throttle cable pickup is a very accurate gauge of determining if both sides are picking up at the same time. It just is. Many don't bother with that, as you are likely to adjust the cables based on higher rpm as you say, but it's also not an error. It gets you a very accurate starting point. A lot better than yanking on them and looking at the gap.
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Old 07-22-2014, 10:40 PM   #5
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I'm super frustrated by all of this. Too many things here. Almost had it, but now I'm all messed up and it runs like totally crap. Although it might sound it, I'm not that much of a dumb ass. Dual carbs are totally new to me. I do know which is the mixture vs throttle screws, but on a 357 Holley. The Bings are killing me. I had to sit down for a beer...

So how do I reset my mess and start over? Here's what I tried moments ago before swearing loudly, grabbing a beer, and typing this:

1. Turned BOTH carb mixture screws clockwise shut, then backing out 1/2 a turn per spec for an r100gs.

2. Turned BOTH carb idle screws clockwise until I could fit a paper card past the screw.

3. Tried starting (when warm) and turned BOTH carb idle screws counter-clock the same amount until I had what I guessed was about 1000-1100 rpms (no rpm gauge on the r100gs).

At this point I either get a solid rpm idle that farts, and randomly twisting the mix screws that gets something that doesn't fart. In either case my back forth tweaking (the 2 carb thing is messing me up) results in either:
A. stalling out on too low rpms
B. sounding ok, but high rpms
C. Thinking I got it right, plugging in my vacuum and oil shoots out one side-- not like my video where I almost had it right.

Regarding C. I clearly tried to follow too many things here and in the manual and now I'm all screwed up. Help?

Open to shots at me for being a dumb ass- only if you have a good explanation that will help me and others :-)




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Old 07-22-2014, 11:26 PM   #6
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Quote:
Originally Posted by Plaka View Post
You are not a dumbass---well---maybe the iphone thing. I can't imagine reading snowbum on one of those.


Mix in to closed, gently, then out 1/2 turn (if that is what the book says)

Butterfly stops or throttle stops so they just touch, then in one full turn.

Fire it up. Diddle the idle mix screws on both sides so it runs best, Go 1/4 turn at a time and let the idle settle down.

When that is done one side will be stronger then the other. Always weaken the strong side. I use shorting wires so I can see what one side is doing all by itself. Here you just short one side and the other should hit 3-4 times and die. Adjust the throttle stops to get this. Sometimes it won't die. Get both sides even.

Now adjust the throttle stops on both sides exactly the same amount to get the idle you want.

Let it cool, then balance the upper range. In short, you wind it up with one side shorted out and then quickly change so you are running on the other side. You are looking for no drop in RPM. Adjust the cable slack to get this.

Read snowbums write up. I'd link mine but I'm tired of the ripoffs and haven't protected the document against the jerks. (yes, they are from here). I'll get to it eventually.

Thanks. I'm with you right up until the "shorting wires". With 2 carbs it's difficult to tell which is misbehaving. I considered pulling a plug to hear one side, but I burnt my knuckle and then got a bit wimpy about getting shocked, which happened to me on a bad ground.

This is why i built that silly vacuum tube rig. Maybe it was not worth it, but it took 5 mins to build. I figured it would be more accurate as well when I twisted the throttle up. Unfortunately, it resulted in an oil fountain on one side - when I thought it sounded tuned.

I'll keep at it. Thanks again. Let me know of if you have anything to add to my ramblings.
Here's some leg.
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Old 07-23-2014, 02:24 AM   #7
a_bakla
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I believe it is really hard to fix the both side equal with this pipe type manometer , levels change even you turn the handlebar... I started to use vacuum gauges but they not sensitive as pipe types. I can do lots of mechanical works on bike by myself but this synchron job make sick.

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Old 07-23-2014, 02:41 AM   #8
ozmoses
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Ramanonos-

Have you ever read this:


http://ibmwr.org/r-tech/airheads/parklotbalance.shtml


Variation on a theme, but it does work.

I'd take Plakalaka's anecdotal input here with a large grain of salt, or not at all.
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Old 07-23-2014, 03:54 AM   #9
yankeeone
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Hi, also check the rubber intake manifolds for air leaks, imposable to get carbs right if you have a vacuum leak.
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Old 07-23-2014, 06:03 AM   #10
100RT
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I wouldnt use the shorting method with your electronic ignition. Bad things can happen.
I also use the "just off idle" for adjusting the cables.
Perhaps your manometer needs some restriction in each line to slow the action down. (small plug in each hose with a small hole drilled thru to reduce the air flow)
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Old 07-23-2014, 06:31 AM   #11
190e
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Only thing I'd add is before you do any carb adjustments make sure the fuel levels in both float bowls are the same.
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Old 07-23-2014, 08:59 AM   #12
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OK, here is the easier method, it seems that you aren't getting answers on how to get the best running condition.
  1. Get the bike to operating temp
  2. Adjust the mixture on each carb to the point you get the highest idle on each side
  3. Now is time to check the synch using your gauges
  4. With a slight amount of throttle one side may be pulling more vaccum. This is the side that is lifting after the other side (it has more slack in the cable)
  5. With the throttle held at that RPM, slowly remove slack on that sides throttle cable (using the adjuster) until the vaccum matches the other side
  6. Now use the idle screw to evenly set both carbs to the ide speed you want
Now, remove the gauges, plug the ports, revs the bike a few times and repeat that process again.
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Quote:
Originally Posted by Stagehand
your bike is suitably dirty. Well done.
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Old 07-23-2014, 09:30 AM   #13
yankeeone
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I made the same "vacuum" gauge , I set the oil level down lower so I have more time before the oil starts coming at me.
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Old 07-23-2014, 10:44 AM   #14
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Quote:
Originally Posted by Plaka View Post
But if you are stuck on vacuum it will be hard and the bike will never run as well as it could. I used to have one of the best vacuum gauges made (A Magnehelic Differential). But the bike didn't run so well so I sold the fancy gauge and went back to the old way that made it run well.
I've always had good results with vacuum gauges in the airheads I have owned. Sorry it hasn't worked for you Plaka
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Quote:
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your bike is suitably dirty. Well done.
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Old 07-23-2014, 11:14 AM   #15
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Plaka is way off base. So far off I don't know where to start. Maybe with plaka trying to sound smart. It's a bad joke. At least as long as some can't see through it. He makes me think of the title Professor Puka. Coughing up the worst of what we have all already chewed and presenting it as if it were fine cuisine.

(I usually stay away from the personal comments but PP and Bill have been dishing it out about SS so I thought I could do a bit of the same. Henry is so far tweaked out what's the use. Dr.T? Who cares?)

supershaft screwed with this post 07-23-2014 at 11:22 AM
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