Where does the third vacuum hose on 82 Front Carb connect to?

Started by Evan, August 07, 2007, 09:59:11 AM

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Evan

I have now put 35 miles on the 82 V ("Candy" by name, since she is factory faded red).  It has a fairly good stumble, and it is in part to me not getting all the hoses correct.  I am correcting the hoses, and getting the (new) tubing all set.  Looking at Lucky's diagram, there is a third vacuum connection (very top front of front carb) that I am not sure where it goes to.  I modified the diagram and attached it for clarity.

Where should it be attached to?


dj

I believe that that line is capped off.  Can't remember right off the top of my head, but that is what comes to mind.  I am sure that someone else can answer that with more certainty.
2008 Honda Rebel (Black)

Tanno

Mine's capped. I'm going to use it eventually for a vac gauge.
Industrial Technician by trade -- Curiosity by nature, tinkerer by choice.
"Handle every situation like a dog would. If you can't eat it or screw it; Piss on it and walk away!" -- Unknown

pat sullivan

I believe the line you are referring to is connected to a small air filter and then vented to atmosphere.  It was provided by the carb modification kit that Yamaha released as a fix.  I don't think it should be plugged as it is a vent for the front carb.

Pat S

h2olawyer

Looking at your question on the diagram, Pat Sullivan is correct.  You are looking for a small, grey disc type air filter attached to the right side of the front carb.  That is where the line from the carb top runs to.

H2O
If you have an accident on a motorcycle, it's always your fault. Tough call, but it has to be that way. You're in the right, and dead -on a bike. The principle is not to have any accident. If you're involved in an an accident, it's because you did not anticipate. Then, by default, you failed.

Lucky

it's not a vent.
on the modified carbs (only) it's the air feed for the main fuel well & has to be open to the atmosphere, hence the disk filter.

you'll notice, if yours is equiped with the update, that one of the holes on the top of the carb next to the pilot air jet is plugged with a ball bearing on the front carb.  this is normaly the air feed for the main curcit, but on the modified front carb, yamaha redesigned it to get it's air flow from a source external to the flapper controlled air box.

i sound so smart...  :D

--Lucky
1982/3 XZ550 Touring Vison, Gold on Black

Evan

UPDATE
Since that vacuum hose had the vent, I just replaced the rubber, and left it that way.  I was not sure from the Diagram what it should have been connected to.

Pulled the carbs off last night to finish off the rubber replacements (This time without dropping the engine, just loosen, twist, front down & out to the left -- much faster!).  Pulled the carbs to make it a little easier, but also to check the pilot jets (I think I got the right ones) -- they were both seated.  So, set them to 2.5F & 4.5R.  I remember when I rebuilt the carbs, there was so much rust/crap underneath the cover screws, I could not even see the pilots.  Put is all back together, and it seems to be working differently.

Powerband is different with no real stumble now.  Much more stable at low rpm/idle (YICS is capped, since I only have leaky ones).  Have noticed that the choke does not seem to make any difference (starting or running -- but it does move freely).  Going to double check the carb sync after I ride home today to see if that is off now.  If the choke is still not doing anything, then I did read a post by cdnlouie about a small opening to check.  I am really not keen to rip the carbs all apart again, since I did do a complete rebuild with Keyster kits just over a year ago!

Evan

Further UPDATE:

Which are the pilot screws that should be adjusted to 2.5F & 4.25R?

I thought initially that they were the ones facing up, that are accessed by removing a cover screw from the bottom.  Then I was reviewing the diagram in the Yamaha manual yesterday, and saw another pilot screw that made much more sense.  So, I pulled the carbs (getting really fast at it now!), lightly seated the ones that I had backed-off, and adjusted the ones on the lower throttle body.  Then all back together, re-synced the carbs, and I think it is running closer to what it should be (Need to plan to get together with QBS to get a local 2nd opinion, QBS being my NVR [Nearest Vision Rider] or NROV [Nearest Rider of Vision]).

I am thinking of taking it out on Saturday morning for a few hours of non-commutting riding.

h2olawyer

The pilot screws are accessed from the side of the carbs.  No reason to remove the carbs to adjust.  The 2.5 & 4.25 turns are just a starting point to get it to run.  Every Vision carb adjustment is different & needs to be done with the bike running.

QBS should be able to help quite a bit.

H2O
If you have an accident on a motorcycle, it's always your fault. Tough call, but it has to be that way. You're in the right, and dead -on a bike. The principle is not to have any accident. If you're involved in an an accident, it's because you did not anticipate. Then, by default, you failed.

Evan

UPDATE:  Took it out for ~170 miles on Saturday morning.  Ran fairly well.  Discovered or experienced a few good roads around here, and a few not so good (did a little bit of gravel!).  Lots of cyclists and a few motorcyclist on the same roads.  Put some Seafoam in the tank before I left.  Still not convinced the idle is right because it fluctuates with how hot it is (from ~1300 down to 800/stall, but if I crank the idle up a little, then it is over 2500!).  Think I experienced a little vapor lock on the way back when I stopped to call my wife -- had to put it on prime to get it to restart.  It has been between 96 - 101+ here the last few days (we have been having heat advisories, since the heat index is putting it over 110).

All in all, bike ran well, handled well.  Did not notice any major flaws in operation/stability.  Do need to put that Shark fairing back on though!

YellowJacket!

Quote from: Evan on August 10, 2007, 08:39:59 AM
Further UPDATE:

Which are the pilot screws that should be adjusted to 2.5F & 4.25R?

I thought initially that they were the ones facing up, that are accessed by removing a cover screw from the bottom.  Then I was reviewing the diagram in the Yamaha manual yesterday, and saw another pilot screw that made much more sense.  So, I pulled the carbs (getting really fast at it now!), lightly seated the ones that I had backed-off, and adjusted the ones on the lower throttle body.  Then all back together, re-synced the carbs, and I think it is running closer to what it should be (Need to plan to get together with QBS to get a local 2nd opinion, QBS being my NVR [Nearest Vision Rider] or NROV [Nearest Rider of Vision]).

I am thinking of taking it out on Saturday morning for a few hours of non-commutting riding.


Evan,

Glad to hear you are making progress.  I had YellowJacket apart this weekend and was able to take some pics that may help you (and others) out with finding the much misunderstood Pilot Screws. (I was one of those who misunderstood them)

On the left side of the bike looking straight at the carb, the pilot screws are the small brass screws just above the sync rod.



The vacuum ports you were asking about are in the next pics.



Looking down at the front carb in the picture above, the vacuum port that goes to the small air filter is at about the 3 o'clock position.

In the above picture, the vacuum port at the 6 o'clock position goes to the vacuum acuated flapper inthe modified airbox.

In the pic below, you can see what that little filter looks like.



Hope these help.

David




Living the dream - I am now a Physician Assistant!!   :-)

haunter

82 with fairing, rejetted, 83 turbo seca fork and brakes coming whenver I acquire the rest of the parts, and she stops breaking long enough to be in the garage for an upgrade instead of a repair.