Missing carburetor ball

[Paul@Sheffield]

When I cleaned my carbs. I had to remove the accelerator pump nozzle (Lucky CD Haynes Manual pg104 fig 4.2) I noticed that the wieght was present but the small ball-bearing was not present. I reassembled and have been running the xz with no problems until today.
In slow moving traffic at standstill the engine sounded as if it was misfiring. It was irregular - occuring at 1,500 revs. occaisionally.
This did not happen under acceleration or when revving the engine.
Is this related to the ball bearing or is another problem developing?
Any ideas would be appreciated Thanks.

[h2olawyer]

The accelerator pump nozzles don't operate at idle or in slow moving conditions, so that missing ball shouldn't be causing the rough running.  How warm was your bike running?  When mine gets hot - sitting in traffic (even with the cooling fan running) - I get real bad stumbles, coughs, etc.  That's why they added the fuel circulation system on the 83 carbs.  The fuel in the 82 carbs heats up & you get vapor locking.

Happened to me in a loooooooong construction delay yesterday.  A couple miles of moving at idle.  No time to shut the engine off.  That sucked!  Had to continually rev the throttle to keep the fuel flowing & the bike running.  It even died on me once & was a real b!&@# to get restarted.  At least I kept up with traffic by pushing with my feet.   ::)

H₂O

[ironb12s]

Why dontcha just put the petcock in Pri when you get to that type of driving condition?  Let gravity alone get the fuel to the carbs?

I had my times in conditions that you relate, but my Vision had nary a problem aside from not wanting to turn the engine over after it had been stopped.  It would start if you "bump" started, and I rue the day that the OEM's took the kick off of the street bikes...

[Paul@Sheffield]

Thanks for your advice guys.
H20- The bike had been running a while so it shuold have been at optimum temp. and it was hot weatherwise.

ironb12s- I'll try that next time.

How difficult would it be to fir '83 carbs to '82 bike?

[ironb12s]

Extra hose to the petcock on the '83 Vision.  If it's a vent of some sort, you can likely get away without taking it to the petcock, or at worst, replace the petcock?

[Night Vision]

How difficult would it be to fir '83 carbs to '82 bike?

not as easy as you'd think... you'll also need the 83 airbox and 83 rear engine mount (or mod an 82 mount?) I think Superfly and/or the leftcoast guys would know exactly what's involved....

Paul, I prolly have one of those balls or two kicking around... pm me with addy and if you're patient, I'll get one or two to ya if you need 'em

[ironb12s]

Can ya ditch the old plenum and go with pods?

[h2olawyer]

83 carbs on an 82 is not "just a carb swap".  The second line is a fuel circulation system, not a vent.  That requires the 83 petcock.  The 83 petcock does not fit the 82 mounting holes on the tank, so you need to modify it or get an 83 tank.  The upper rear motor mount for the 83 has a larger opening to clear the carbs.  The airbox base is 'notched' for more clearance.  The motor mount can be modified to clear.

I'm currently working on the swap.  Was reluctant to get into it because of all the ancillary parts required.  Managed to find them all, so I decided to go ahead.  Should be ready for installation by Spring, 2008.  Tank needs de-denting, liner & paint.  Carbs need total rebuild (have the kits).

As I understand it, the airbox is necessary on the Vision to stop the stumble.  Individual filters have been tried, but without much success.  It's probably doable, but the problem with these carbs is airflow velocity, not volume.  The vacuum flapper door helps create the velocity.  If it ws a successful option, I'd love to get rid of the large airbox & reshape the tank to hold more fuel.  Another gallon would make it an incredible sport tourer.   ;D

H₂O

[ironb12s]

As an aside, GMANINDUSTRIES make auxiliary tanks for the Suzuki V-twin cruiser line.  Add up to 2 gal in the space under seat in front of the swingarm.  I'm working with Predator to make a SS 2-1 system for my VS1400, and we may be able to do something with GMAN along the same lines.

[Lucky]

If Night Vision doesn't have the balls  ;D ;D, i do....

Blake did a lot of testing with a VFR meter trying to get pods on them & came close, doing a lot of jetting changes, but never got them to work.

the fact is, these carbs flow more air cfm's than the engine can handle. the vacuum flapper in the airbox is there to restrict airflow & also induce low pressure over the carb throats. 

it's a lot like when everybody used to put 750 double pumper Holleys on 350 chevy engines because they saw all the car magazines using them in build ups.  what they didn't bother to note was that those engines also had Edelbrok intakes, Headman headers, crane cams, retarded timming, ported heads, lighter flywheels, etc, etc, etc.

--Lucky

[ironb12s]

"Would be you'd get most poetical 'bout yer pecker... "    (catch it, Aelwulf?)    ;D

Aelwulf and I know the reference, just kiddin' Lucky...   :D  It's a Firefly thing.

Ah, to be young and stupid once again...I recall those days, when I had that '71 Challenger with a 318cid and Rochester 2-bbl carb (which, strange as it might sound, strongly resembled the carbs on a Vision) tuned with vacuum guage, terrorizing unsuspecting Corvettes and the like with that Slap-Stick shifter...  But, we're getting off topic again.  ;)  But it's akin to what the Vision does to those unsuspecting Hardley-Ablesons...   LOL  And why the carbs were the least of my worries when I first got Viky.

Yammie did what they could to keep meddling hands out of the airflow, din't they?  So be it, where there's a will, there's a way, and given time someone will break the lock.  We're working on a 1 or 2 to 3 intake with pods for the Yammie triples...no damper door on them beasts to hold us back.

Better stick to the '82 carbs then, unless you're looking for a challenge.  :)  I'd be happy just to work on mine, and like I posted oin another forum recently: work may suck, but being without sucks more.  JMHO, that.  ;)

[Paul@Sheffield]

Thanks everybody? As the the problem isn't a big issue (at the moment) I'll stick with the '82 carbs.
The missing ball does not seem to be an issue, from these posts.
I haven't done the throttle valve mod yet. I can't remember where I read it-something about sticking a coin to one side off it.

[YellowJacket!]

Dare I say the two most despised words in NASCAR?  Restrictor Plates? If its too much airflow for a modded air filter, why not restrict the flow below the carbs?  Would that work?

David

[ironb12s]

Has to have variance is why it isn't a plate that is bolted on, as in NASCAR.  I suppose the restrictor in the XZ case COULD be another butterfly in the boots to the head, but space is limited and it would require twice the hardware to pull off... not to mention, 2 more things that need adjusted when tuning the carbs.

I will have to look for that door when I work on Viky again...never noticed it before, and might explain a few things...there is a vacuum hose involved with the movement of said door, no?

[Lucky]

there is a vacuum hose involved with the movement of said door, no?

only on late 82 & all 83's.  early 82's were spring operated (sudden throttle opening creates low pressure, pulling the door open)

Yamaha offered a free factory update that included ft carb top, disk filter for the front carb, upgrade rear p.a. jet, replacement airbox top & filter.

[ironb12s]

Now you really have me wondering about my XZ.  I have NO IDEA what is at work on mine, never dug that deep into, or don't recall what I found.   ???

[ironb12s]

Lil' while back, H20 told you that the pump doesn't work at idle or low speeds, that's not entirely correct.  It operates when you twist the throttle from any speed, but only when there is movement of the throttle cable.  It sends a spurt of fuel into the throats above the butterfly, to augment fuel delivery to the bores.  It takes a little while for the vacuum to pick up in the bores after you open the butterfly, and vacuum/venturi effects are what draw the fuel out of the bowl.

There's a good how-to thread in the Technical section of the top banner.  I'll be referencing it when my time comes...

[ironb12s]

Lucky, don't you mean that sudden throttle opening lowers the vacuum in the intake path?  So, it's less 'negative' pressure that causes the door to close, slowing the airflow into the intake path?  As the engine picks up speed and vacuum with it, the door is "pulled" open.

The highest vacuum occurs at the moment of the butterfly closing, and the engine is still overdrawing the mixture until it can slow to match the butterfly.  Fuel is drawn mainly from the Pilot/Idle circuit when the butterfly is shut.

There is no vacuum controlled slide on the XZ carbs, is why it reminds me of the Rochester 2-bbl that I had.

[h2olawyer]

I know the accel pump operates with the throttle at any speed, but at a constant, low RPM, it shouldn't be causing the problem he describes.  Guess I could have been clearer.  Was going for brevity.

H₂O

[Lucky]

Hey, i'm just glad Ironb12s is here to set things straight...