82 carb rebuild.

Started by stephenn, October 15, 2006, 06:58:16 PM

Previous topic - Next topic

stephenn


After waiting around two weeks for the rebuild kits, I got a chance to finally tackle them this weekend
Last night I managed to get the carbs out (thanks only to Lucky's advice to BREWSKI that they really
DO come out the left side).  Today I tore them down.  Most of the adjustments seemed to be standard,
but they were fairly gunky.  A few questions to those who've done this before:

1) I was clumsy and managed to crack one of the floats.  Any suggestions on how to patch it? Or do I pretty much need to find another set of carbs to cannibalize?

2) I think I found all the service parts, but I can't figure out where the ball bearing in the rebuild kit goes...  Hmm.. looking at Lucky's site, it seems that it's underneath the accelerator pump nozzle.

3) Is there any reason to remove the venturis themselves?

4) Is there any reason to open up the fuel pump too?  The keyster carb kit doesn't contain the gaskets for it, so I'm leery about opening it up.

5) Where does the pilot fuel jet go?

Steve

louthepou

Re. Float bowls: many of us must have a few spares.

Re. Fuel pump: never had any problem with them, so my advice is keep it closed.

Re. Venturis: I can't see why you'd remove them

Lou
Hi, my name is Louis, and I'm a Vision-o-holic

Lucky

Steve,

1) I have a spare float for you, pm me & we'll haggle  :)
2) yup, under the accel nozzles, there is a trick for getting them out safely (& the floats too) pm me your ph # & i'll call you, it's easier than trying to explane the whole thing..
3) nope, not unless you can wiggle them, then the gasket needs to be replaced.
4) not unless everything else is gunky too, then assume the pump is. it's a seperate kit from Keyster
5) pilot fuel jet goes under the flathead screw under the bottom of the bowls, you need a good, skinny, WELL FITTING screwdriver to get it out. it'll hopefully break free with a *CRACK!* you don't want to round off the slots for it, if you do, then clean it out as best as you can & live with it, or buy a replacement bowl (i have 'em of course)

6) (you forgot #6) install a good quality (read 'sintered bronze') fuel filter between the pump & petcock, don't even THINK of trying to start the bike without one.

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

stephenn


I got the accelerator pump nozzles out with a small (3-4 inch) set of locking pliers.
They were almost perfect for twisting them, although they left a little bit of marking
on the brass.    (I really love those...  I don't remember where I got them,
but they always seem to come in handy when *nothing* else works)

All in all the carbs were pretty gunky, but not really gritty.  The bike had a fuel filter
on it when I bought it; I think it's probably worth replacing too, but it did it's job:
all the grit was in the fuel line.. :)

I'm a little bit confused about the jetting.  There appear to be two different main jets
for each carb (one on the top inside the throttle body, and one on the bottom left side, accessed
behind a plug).  The top was 125 front, 130 rear.  The bottom was 130 on both.  I've
heard lots of people talk about rejetting, but I had no idea there were two separate jets...
I assume one is actually for the idle circuit or something?  The service manual just labels them
both as 'main jet'.   I assume they should actually be the same?

Steve



h2olawyer

Top jets (pilot air) for the 82 are 130 front & rear.  The main jets (on the sides, behind the brass plugs) are two different sizes.  122.5 (f) & 127.5 (r).  My dealer replaced the pilot air jets with 135s when he did the carb / airbox upgrade.  (before I bought the bike)  This is the most common re-jetting done on 82 carbs.  This setup works well from about 500ft up to 12,800ft.

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.

stephenn


OK H20, so 125/130 should give a little bit richer mixture (right?), which probably makes sense since I'm in the
bay area (sea level and pretty cool).  I suppose I should pull the plugs and check them out, too.

BTW: this bike doesn't appear to have the airbox mod:
My plan is to see how well things work after doing thish before adding more complexity to the situation...

Steve

h2olawyer

Steve -

The 130s in the pilot air position will decrease the amount of air introduced into the carb circuits.  This will create a richer fuel mixture.  I know several folks have gone to 135s even in low altitudes - but they also use the modified air box.  You can tell if yours is upgraded very easily.  Look for a vacuum diaphragm and arm attached to the flapper door in the air inlet to the top of the airbox.  One suggested modification for the non-upgraded air box is to epoxy a couple nickels to the flapper door.  This slows down the opening of the door & restricts air going to the carbs.  Not as effective as the vacuum system but I hear it has a positive effect.

The 130 pilot air jets were factory original.  My dealer installed the 135s back when the bike was brand new.  I bought it in Steamboat Springs, CO - elevation about 7,000 ft.  I now live in Ft. Collins (@ 5,000 ft.) and regularly ride over the continental divide & other mountain passes - all over 10,000 ft. - so I regularly see pretty drastic elevation changes.  I'd say to either stay with the 130s or go up to the 135s.

Make sure you have the 122.5 front & 127.5 rear main jets.  The different exhaust pipes from each cylinder & the slightly higher operating temp of the rear cylinder are the reasons for the different jet sizes.  I've tried going both up & down one jet size in the main jets & it just doesn't run right with anything but the original sizes.

Hope this helps you get your V running better!

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.

stephenn


I think I must have typed things in wrong (my notes are back at home)
I think/hope the main fuel jets must were 125/130 and the main air jets were 130/130.

So,
moving fuel jets from 122.5/127.5 to 125/130 makes the mixture richer at all throttles.
moving air jets from 130 to 135 makes the mixture leaner at all throttles.

I'm not sure what the goal of the flapper modifications are: it sounds like the goal is to make the mixture leaner, tho.

I guess I'll first try out the stock configuration and see how well that works.  Anybody have any advice for tuning at Sea Level?  I doubt I'll ever make it to the continental divide.  Probably 5K would be a maximum  ( I think that's about the elevation of Yosemite Valley).

Steve


Steve

YellowJacket!

OK, Im confused now and this may be why my sync was so far off when lucky and I adjusted it.  My pilot air jets (top of carbs) are 122.5 front and 127.5 rear and the 130s are on the bottom of the carb.  I also have the updated airbox/carbs
I'm almost certain thats the way I have it set up.  I'm off work tomorrow, so I'll check it out and post my results.

David


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

h2olawyer

Quote from: DaveTN on October 16, 2006, 05:38:48 PM
OK, Im confused now and this may be why my sync was so far off when lucky and I adjusted it.  My pilot air jets (top of carbs) are 122.5 front and 127.5 rear and the 130s are on the bottom of the carb.  I also have the updated airbox/carbs
I'm almost certain thats the way I have it set up.  I'm off work tomorrow, so I'll check it out and post my results.

David

And it runs!?!

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.

zore

Dave unfortunatly, the jets are all the same size, but the 130s go in the top of the carb, the smaller number jets go in the bottom (where the fuel is).  I would imagine your fuel mileage is pretty bad.
1982 Yamaha XZ550
1995 Ducati M900

YellowJacket!

Yeah,
I'm getting ready to start my nw tank project and will be pulling the old tank...mainly to replace my fuel lines and some vacuum lines.  Since I'll have the tank off, I'll pull the airbox too and take the jets out to look at them.  I'll let y'all know.

David


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

Lucky

you don't have to pull the jets in the airhorn to read them. the #'s are stamped on the top. a jewlers loupe helps though.
1982/3 XZ550 Touring Vison, Gold on Black

dminor

Steve & Dave.
  This is how the jets go with a mod-ed air box;
122.5 in the bottom of the front carb, 130 in the top.
127.5 in the bottom of the rear carb and the 135 in the top.
then set the front pilot to 3 turns fron lightly seated and the rear to 4&1/4 from lightly seated. Then sync the carbs. This should fix most if not all stumble and idle problems.
  Don ::)

stephenn

I was incorrect...  Main fuel jets were 125/130, Main air jets were 130.
So that seems to just be a 'rich' tune.

dminor: my pilot screws were only 2 1/2 turns out...  I knew this was
somewhat of a point of contention, so I was sure to track it.. :)

Steve


YellowJacket!

#15
Quote from: DaveTN on October 16, 2006, 05:38:48 PM
OK, Im confused now and this may be why my sync was so far off when lucky and I adjusted it.  My pilot air jets (top of carbs) are 122.5 front and 127.5 rear and the 130s are on the bottom of the carb.  I also have the updated airbox/carbs
I'm almost certain thats the way I have it set up.  I'm off work tomorrow, so I'll check it out and post my results.

David

Well, I confirmed it and they were mixed up!!

I put a 122.5 in the top front and a 127.5 in the top rear. (see pics)
The lower ones are 130's.  Now, how the heck did this thing run and run so well???



Further update:
I removed the brass plugs and checked the jets on the lower left of the carb.  Front was 130 and rear was 135.  So if i understand this correctly, the 130 should go in the top of the front carb in the intake and the 135 in the top of the rear.  The 122.5 should go in the bottom left of the front carb behind the brass plug and the 127.5 should go in the bottom left of the rear carb behind the brass plug.  Correct?    ???   ???

David


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

Night Vision

Quote from: DaveTN on October 17, 2006, 01:48:04 PM
Now, how the heck did this thing run and run so well???

I'm not surpised it ran well.... I've seen one run with a paper towel stuffed in the carb throat  ::) 'course it did not run well  :D

like someone said here before... these things (carb settings) are all over the map. By syncing and adjusting the idle screws, you may have balanced it out...

question.... if it runs good, gets good mileage.... why screw with it? 
if it ain't worth doing it the hard way....
it ain't worth doing it at all - Man Law
;D


if it ain't broke..... take it apart and find out why


don't give up.... don't ever give up - Jimmy Valvano

h2olawyer

Quote from: Night Vision on October 17, 2006, 04:36:29 PM
question.... if it runs good, gets good mileage.... why screw with it?

It can always run "better"!   ;D

(Actually, I tend to agree with you, N.V.)

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.

YellowJacket!

OK, here is what I got and some observations.  I changed out the pilot air jets to 130 on both tops.  I have a 135 that I can put on the top rear.  Should I?
I put the 122.5 front and 127.5 rear pilot fuel behind the brass plugs on the lower left of the carb.  I put the tank back on, hooked everything back up, primed the bowls, set the choke on half, gave two quick throttle snaps and it started right up! The idle was a bit rough but the sound is different.  It has more of a crisp bark to it...am I immagining that?  I went out for a quick ride and the bike seemed more responsive and did not stumble (but my YICS is off the bike at the moment and the hoses are plugged)

Two more questions:
1. do you think I'll have to re-sync the carbs?

2. Should I change the rear pilot air from the 130 to the 135? I only have one 135.  And I have the updated airbox.

Man, I feel like  a newbie again.  :o

David


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

dminor