'83 CARB Sync info

[jasonm.]

FYI- For those of you with 83's. The manual does not tell you to do this. BUT that rear hose from the rear carb that must be removed so you can connect your sync tool....Cap or plug that hose. It makes little difference at idle. But when you check the sync @3000 or so like you should. The sync tool will be slow to respond for the rear cylinder to throttle changes if you don't plug/cap this hose. I have 2 sets of '83 carbs.One set has very low miles the other with 30k. Both have proven this to be fact.  Trust me on this.

[Lucky]

Can't be true, disconnected, this system does nothing, hell, connected it does nothing.

this control valve's job is to prevent the accelerator pump from working while the bike is off (to prevent flooding).

trace the passages, they end up nowhere. actually they end up going to the pump gasket, but terminate under the sealed part of the pump cap.  it seriously looks like the designers were told to make it do a particular job, but were then told half way thru to abandon the idea....

actually they do one thing: create an internal vacuume leak if the diaphram in the top leaks or is not given the proper clearance.

i have 5 & 1/2  83 carbs & mine are all the same. i have spent DAYS & DAYS studying this system (because something like this will bug me that much) trying to understand how it's supposed to work, & the way it's set up, it can't possably do a thing except leak....

i suspect you might have a small leak or if you've changed that diaphram in the top from the locktighted bolt in the kit, not set exactly right.  although in theory it should repsond slower if it leaks when pluged in rather than unpluged...this is a Vision.

--Lucky

[jasonm.]

Mine surely does not stop the accel pump from pumping. But I think that it keeps it from refilling unless the bike is running. I do remember you mentioning this possible problem years ago. Maybe my no mile carbs has a leak here? They did sync up rather oddly. But so did the originals. I have had always to open the front carb a bit to get them to sync up at 5000. But the carbs just being not level to each other can cause this. Can I use my mighty-vac to test this for a leak ?..also you seem to suggest that just keeping it plugged/capped. AND never connecting it, won't cause issues ???

[Rick G]

The '83 carbs were a cure for a problem that didn't exist!!

[Lucky]

Mine surely does not stop the accel pump from pumping. But I think that it keeps it from refilling unless the bike is running. I do remember you mentioning this possible problem years ago. Maybe my no mile carbs has a leak here? They did sync up rather oddly. But so did the originals. I have had always to open the front carb a bit to get them to sync up at 5000. But the carbs just being not level to each other can cause this. Can I use my mighty-vac to test this for a leak ?..also you seem to suggest that just keeping it plugged/capped. AND never connecting it, won't cause issues ???

i tend to only fix things when they are broke, or at least presenting symptoms, but if i can sit at my desk & hold it in my hand i'll examine something till i have a clear understanding of how it works.  not to sound immodest, but that is why i understand what every hole, casting & tube does in both 82 & 83 carbs & how their circuts operate.

with the exception of this one.  i understand what it was INTENDED to do, but it's 'unfinished'..

That said, when i rebuilt, broke & repaired the control valve on mine (and since replaced with a stock unmolested one) i discovered that if the locktited brass bolt with the square cut o-ring isn't set just right, it can cause an INTERNAL vacuume leak.  this a partial assumtion because at the time the rear cyl was running badly lean, no amount of carb spray would change the idle, & replacing it cured the problem (it wasn't a bad gasket)

unfortunatly at the time my vacuume guage was awol, & i didn't own a mighty vac, so honestly, that was theory, but i suspect it would have been easy enough to prove by pinching off the vacc line, just didn't occure to me at the time....

i would say capping the line probably isn't enough, i'd cap the fitting under the valve as well.

Also Jason, there may be some validity to what you said about the system not refilling, i just haven't tried it.  can't say i want to load up my engine with fuel when it's not running though..

anyway, if you play with this some more, post what you observe.

--Lucky

[jasonm.]

As far as my carb sync assumption refering to the hose to the rear carb. I think now...that I am totally wrong. I did my sync again. Let's just say..."no big diff." But I was sure I saw something to make me think it should be plugged. Don't know how I had the idea in the 1st place. Guess, I was having flashbacks from another carb tuning day.  My apologies. Now, I know the accell refills without the vacuum thingy connected. Because I have filled dry 83 carbs and watched the accel nozzles squirt. Usually takes a couple pumps of the throttle. Maybe the vacuum assist on the '83 is to make sure it's full when running. I do know from the old mag. articles they had lessened the total squirt on the '83s. I did test both sets of carbs w/Mighty Vac. One tested perfect. The other an extremely slight leak. Would have taken days to leak all the vacumm. Then, I did disassemble and clean. Now no leak.  BUT, I have to rectify my carbs' other issues.  The damn emulsion tubes break rather easily. ALSO, does anyone know of gasket material around as thick as the OEM stuff and not make from cork. I have the Felpro 3157. But it's still not as thick.

[Brian Moffet]

ALSO, does anyone know of gasket material around as thick as the OEM stuff and not make from cork. I have the Felpro 3157. But it's still not as thick.

What gasket (assuming 83 carbs).  I might have one from the keyster kit at home.

Brian

[jasonm.]

I have an '83 keyster kit. But need a second gasket and was going to make my own and use the keyster as a template. Thus the need for best material. I only use the best parts I can find. Also, how do the Keyster's seem to hold up? They don't look as thick or tough as the OEM.

[Lucky]

I've had my Keysters apart several times (somehow that just sounded wrong...) with no problems as far as sticking, leaking or sealing.  I think the only difference the thickness of the gasket would make would be with float hight, which would be negledgable, and perhaps with the accelerator pump nozzle pressing against the top of the carb, but i haven't seen anything to indicate this would be any sort of issue. the other passages seem to be sealed just fine.  RickG makes all his own gaskets.

[Brian Moffet]

I used the original main floatbowl gaskets when I rebuilt my carbs, so I have some spares I didn't use from the keyster.  Let me know which one you need and I might have it.  I'll send it out if I do and you need it.  But you'll have to respond soon, I'm off for vacation starting Sunday.

Brian

[Rick G]

I buy my gasket material at Napa, They keep changing suppliers (probably  to get a lower price) i like the grey one they had during 2005 and 6 . The brown one they have now is ok and works well , but for some reason I just don't like it as well. I have limited options out here, in the Great Mohave  desert.

[jasonm.]

the grey stuff at NAPA is the Felpro 3157.  1/32"....which in reality is .79mm. The OEM is 1mm. Plus I believe the OEM compresses less. I guess I will try the Felpro. Also turns out both my emulsion tubes were cracked at the heads...probably from me over tightening...dumb ass me! But it's a sh*t design.  I fixed one by making a new head for it. Which solders to the shaft tube. Now, the second , may just have to be replaced. So now I am looking for '83 emulsion tube or a whole unmolested carb set from an '83.  Maybe as a last resort find a perfect '82 set of carbs.  Brian, I am in no hurry now for the gasket. I will let you know if I need it. Which likely won't be till the emulsion issue is fixed.