(Attention: Pete) Thoughts on carb removal procedures

Started by QBS, November 23, 2009, 07:06:08 PM

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QBS

Am in the process of removing the carbs from my '83.  It seems that the accelerator pump isn't pumping.  As much as I hate to contemplate it, it looks like I'll have to separate the two carbs to fix the pump problem.  This is really sad as the synch is perfect.  They are currently still together.

After tearing into it and much cogitation, it seems that it would be much easier to remove the carbs separately after removing their attachment braces.  Installation would be the reverse. That is, install the carbs and then  install the braces.  Of course, they would then have to be synched.

If one knows that the carbs will have to be synched after installation anyway, why go to all the trouble and gymnastics to remove and install them as a unit?


Brian Moffet

I removed them from my 83, I removed them as one piece and put them back that way.  I didn't find too much difficulty, I seem to recall I removed them from the left side but I don't remember. 

The reason I put them back in one piece is so that I was able to make sure that all of the nuts, bolts, screws, etc were torqued to the right amount without having to try and get around the frame.

Just my 1 cent.

Night Vision



sure go ahead... do it the easy way  :P

I think as long as the screws cooperate, and you can get them apart, that would be a feasible plan...
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

akvision

Hey Q!
We took the carbs out of the AkVision in Denver and did a small jet / atomizer cleanup and re-assembled the units just like they came out.  We did not change any settings and was perfect.  We disconnected the accelerator connecting rod but left the locknut settings in place.  If you do not disturb the locked settings it should be the same.
1960 BMW R-50 "Hanz" reborn April 24, 2009 , Ketchikan
1982 "V" AKBluv, Denver, traded for BMW R1100S
1977 BMW R75/7, "Gertie"
1977 BMW R75/7, Green Lantern Cafe Project
Deep In the INSIDE PASSAGE, Alaska

Armored_Hearse

I'm a newbie here, but getting the carbs out was easy, at least on my '82. Had to remove them to solder the accelerator nozzle back in after it came loose during adjustment. Oops.
They do come out as a set. Just be patient. I pulled the fuel pump off, and then got all the hoses and wiring to the outside of the frame.
I rotated them so the front carb came out of the left side of the bike first. You have to wiggle them a little, but it worked. Went back in just as easy.
I'm sure there will be other that chime in. I read it could be done here at ROV so I made it happen.  --  John

QBS

I've had the carbs out before.  But that was long ago and faraway.  This time is different.  On '83s' the accelerator pump is mounted in between the carbs on the rear carb.  There is no way to get to it without removing the obstruction that the front carb represents.  That is the dilemma.

Bottom line is, if one knows that their carbs are out of synch before they are being installed, or knows that they will be after they are removed, then it may be that the easiest removal/install approach would be to remove them separately.  Assuming of course, that the brace attachment screws cooperate.

Thanks to all for your responses.  I'll let you know how it turns out.

Lucky

#6
QBS, two tips to make getting the carbs in & out as one unit a whole lot easier:

1) unclip the wire harness from the frame on the left side of the bike (above the carbs) and move it out & up. it may not seem like it, but there is enough slack in the harness for this.

2) do the same for the coolant lines on the other side.  

tyhis gives you plenty of room to lift the rear carb, swivel the front one ccw, down & out followed by the rear.

easy peasy

i can pull a set of carbs in under 5 min...

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

George R. Young

FYI, if you have a problem on one cylinder, you can reverse the carbs as a diagnostic technique.

This didn't solve my problem, but it eliminated carbs as the problem.

akvision

I do believe that they are spacific as to placement and jetting.  They cannot be reversed.  There is a front carb and there is a rear carb and they are not interchangable. 

If they are. My XZ 550 does not allow this to happen. :-\   So please explain.
1960 BMW R-50 "Hanz" reborn April 24, 2009 , Ketchikan
1982 "V" AKBluv, Denver, traded for BMW R1100S
1977 BMW R75/7, "Gertie"
1977 BMW R75/7, Green Lantern Cafe Project
Deep In the INSIDE PASSAGE, Alaska

inanecathode

Quote from: akvision on November 28, 2009, 12:13:59 AM
I do believe that they are spacific as to placement and jetting.  They cannot be reversed.  There is a front carb and there is a rear carb and they are not interchangable. 

If they are. My XZ 550 does not allow this to happen. :-\   So please explain.

Mmmmm, really, stock you can't switch them because the jetting *is* different, however its not *that* different, in fact i've read some people running the same jetting front and rear. As far as placement, i dont have them right in front of me, but the only thing i can think of that would limit where they can go is how bendy the fuel line gets, and where the throttle cable goes.
Then again, i would think the whole thing would be moot as actually reversing the position of the carbs as a diagnostic technique is a little silly lol.
//////////////////////////////////////////////////////////////////////////////////////////
If you can't tell your friend to kiss your ass then they aren't a true friend.
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Re-Vision

Keep known good spare carbs if you are going to use them for troubleshooting, all Visioneers should have a parts bike. I believe carbs are interchangeable but not worth the effort required to swap them.  BDC

QBS

Update:  Have gone where no American has gone before.  Finally got the carbs out as a unit and have separated them to gain access to the accelerator pump.  Have confirmed fuel flow through both throttle bore spray nozzles.  Have also confirmed fuel flow through the pump output orifice to the spray nozzles.  Am now trying to confirm the fuel flow supply channel to the accelerator pump diaphram.

Questions:
(1) Is the synchronization messed up if the synch rod length is not disturbed, even though the bodies are separated?

(2) Where does the accelerator pump diaphram get its' fuel from?  I see the two holes on the wet side of the pump diaphram and have identified which one is the output orifice.  I'm pretty certain that the other hole is the pump fuel intake hole.  What part of the carb body feeds that hole?  I need to know so that I came confirm that it isn't plugged up.

Re-Vision

1. Everyone I've talked to say that that they will have to be resynchronized if one carb is loosened from brackets that tie them together.

2. Fuel comes from bottom of the float bowl and goes into the 3 o'clock hole where accelerator pump mounts and is pumped out through the 10 o'clock hole to the rear nozzle and the rubber hose going to the front carb nozzle.  The float bowl has a small hole near the bottom that could easily become clogged.  I am looking at an 82 carb but I think they are about the same as the 83 for this circuitry.  BDC

Lucky

yours is an 83 so DO NOT try to remove the diaphram from the plate on the upper control valve!

which pump isn't pumping ft or rear?

since just tightening the jam nut on the synq rod changes the synq, the resynqing after having them apart just makes sense.  besides syncing a carb is quick & fairly simple.

the accelerator pump has a spring loaded check ball that you can see from the diaphram side.  you can force some carb cleaner in there, or if your really brave, drill out the brass plug over the spring & claean it all out, but i don't reccomend it unless you've had a lot of experience at that sort of thing..

if they were working 'till recently, i doubt you'd need to do that anyway.
1982/3 XZ550 Touring Vison, Gold on Black

QBS

#14
Lucky said: "yours is an 83 so DO NOT try to remove the diaphram from the plate on the upper control valve!"
QBS responds: What does this "upper control valve" do?  What is its' purpose?  I see that it is vacume powered.  I haven't torn into it.

QBS said: "Have confirmed fuel flow through both throttle bore spray nozzles.  Have also confirmed fuel flow through the pump output orifice to the spray nozzles."
Lucky said "which pump isn't pumping ft or rear?"
QBS responds:There is only one pump.  It is on the rear carb and, for as yet unknown reasons, it is not pumping.

Lucky said: "the accelerator pump has a spring loaded check ball that you can see from the diaphram side.  you can force some carb cleaner in there, or if your really brave, drill out the brass plug over the spring & claean it all out, but i don't reccomend it unless you've had a lot of experience at that sort of thing.."

QBS responds:  I have proven fuel flow backwards, starting with the front spray nozzle, proceeding through the rear fuel nozzle, and coming out of the pump output orifice on the wet side of the fuel pump diaphram.  The diaphram shows no tears and the dry side of the fuel pump is dry.  The next thing in between the wet side of the pump and the fuel bowl appears to be the "spring loaded check ball that you can see from the diaphram side".  What does this check valve do?  Should I be able to spray carb cleaner through it, either from the bowl to the wet side of the pump or visa versa ?  Right now I can't get carb cleaner to penetrate into the bowl from the wet side of the pump.  Haven't tried visa versa yet.

The original problem was a huge flat spot right off idle.  Once past the flat spot the bike runs great.   Suspecting an accelerator pump malfunction, I investigated the accelerator spray nozzles for output and found none.  Thus strengthening my suspicion of a faulty accelerator pump.  Subsequent diagnostic efforts have eliminated the spray nozzles as the problem, leaving the pump as the most likely problem.  The wet side output orifice is clear to the first nozzle.  This would seem to leave the check valve as the only place left to prevent the float bowl from supplying the wet side of the diaphram.


Lucky

lets start simply, because you gave me too much info & i'm confused...

1) do both nozzles spray? if so, that's not the source of your flat spot.
btw, you can test the accelerator on the bench. remove the top from the rear carb, fill3/4 with gas & operate the throttle, the nozzles should spray after a few 'twists'

2) if only one nozzle sprays, you either have a blocked nozzle, or a bad hose if it's the ft one.  if the nozzle is blocked, pull it, clean the ball & weight, & clean the nozzle with the wire from a needle threader.

3) if you haven't done anything else but not ride the bike & it developed a flat spot, just clean the carbs thouroughly & re synq & adjust the pilots.  make sure there is no water in the tank (from ethanol gas)

4) the accererator controll pump is supposed to keep the pump from spraying unless the engine is running to prevent flooding, but as far as i can determine, it's an 'unfinished project'.  the passages actually go nowhere & cannot possably affect the operation of the pump.  if the diaphram leaks though, it causes an internal vaccume leak & all kinds of stupid problems. the whole assembly is...dumb!

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

QBS

Lucky, have you ever been into the "spring loaded check ball"?  If so, please explain what it consists of.

Brian Moffet

I think this is what Lucky is talking about, these are the photos I took of the  accelerator pump when I took my bike apart:



It's not really a ball, but a rounded rod.  Lucky can verify whether this is the right thing or not.

The full gallery:

http://www.pbase.com/moffetb/accelerator_pump&page=all

QBS

Brian, thank you for the reply.  The part you are showing is the accelerator pump diaphram.  I'm trying to find out what is inside of the check valve that is inside the float bowl.  This check valve prevents fuel backflow into the bowl when the diaphram is compressed during throttle on and allows fuel to refill the accelerator pump when the throttle is released.  I think that my check valve is clogged up and not allowing fuel to fill the accelerator pump.  Before I invade the check valve I want to know what to expect.

Brian Moffet

Ah, that I didn't take apart.  I just sprayed it out really well with cleaner and air...