Carb question

Started by 2002_wrx, September 26, 2010, 01:15:58 PM

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2002_wrx

Hey guys,
     Just in the middle of rebuilding my first set of carbs and stumbled across something I find strange.  This is going to be tough to explain without pics but I'm on my iPod.  Looking down from the top of the carbs there are three passageways cast into the large cylinder part of each carb. The biggest of these contains a brass screw (pilot air jet? - I'm not sure what everything is called yet).  My question lies in one of the smaller adjacent passages. As I look down one in one carb, it looks like there is a little brass ball blocking it.  However, on the other carb there is nothing.  This doesn't seem right to me.  Is this a problem and if so, how should I go about solving it?  I'll try to post some pics later.  Thanks in advance for the help.

Rikugun

QuoteThis doesn't seem right to me

When it comes to theses carbs, when something seems wrong, it's probably the way it's supposed to be!  ???  :D

I'm kidding of course (sorta) but it seems like what your describing is exactly as it should be. I think it's the front carb that has the ball bearing. It vents through the little filter attached to that carb with a short hose instead.
It is far better to grasp the universe as it really is then to persist in delusion, however satisfying or reassuring.  Carl Sagan

2002_wrx

Heres some pics:
   
This is what I'm assuming is normal (in the smallest hole)

And here's the other carb:
   

Lucky

Nope, that's correct. it is the way it should be.

that passage provides air to the main jet (called a 'bleed')
you have the updated version of the 82 carbs.  On that version the front bleed has been blocked off, & rerouted to that little black & grey round disk on the front right of the carb. that disk is a filter.

basicly, what they have done is decided to feed air for that bleed from outside the airbox instead of thru the airbox filter.  the reason is that with the flapper update, it cause undesirable effects on the air bleed due to pressure changes.
1982/3 XZ550 Touring Vison, Gold on Black

2002_wrx

Quote from: Rikugun on September 26, 2010, 03:18:13 PM

When it comes to theses carbs, when something seems wrong, it's probably the way it's supposed to be!  ???  :D



Haha, I am coming to realize that!   :)
      Just posted some pics (ignore that the brass screw is missing in the carb in question - i took it out for cleaning)
   So the ball bearing is supposed to be there in one, and not the other as shown?   Should I have tried to remove it for cleaning?  I'm not sure how I'd ever be able to haha. 

Lucky

nope, leave it alone, it doesn't come out.
1982/3 XZ550 Touring Vison, Gold on Black

2002_wrx

Quote from: Lucky on September 26, 2010, 03:18:47 PM
Nope, that's correct. it is the way it should be.

that passage provides air to the main jet (called a 'bleed')
you have the updated version of the 82 carbs.  On that version the front bleed has been blocked off, & rerouted to that little black & grey round disk on the front right of the carb. that disk is a filter.

basicly, what they have done is decided to feed air for that bleed from outside the airbox instead of thru the airbox filter.  the reason is that with the flapper update, it cause undesirable effects on the air bleed due to pressure changes.


Great!  Thanks so much guys...you're all a ton of help

Lucky

Hey! i'm only 210 pounds of help...not a ton, lol
1982/3 XZ550 Touring Vison, Gold on Black

Rikugun

WRX -  just curious, what number(s) are the jets?
It is far better to grasp the universe as it really is then to persist in delusion, however satisfying or reassuring.  Carl Sagan

Hartless

whooooah buddy!210 pounds? seems like its time for a diet
Ride Hartless or stay home


"strive for perfection , settle for excellence"

Hartless

just kidding , i weigh 270
Ride Hartless or stay home


"strive for perfection , settle for excellence"

2002_wrx

Quote from: Rikugun on September 26, 2010, 03:32:09 PM
WRX -  just curious, what number(s) are the jets?


Sorry but I didn't check.  I know one is a 120...the other I didn't glance at.

I may have screwed up bad tonight while putting everything back together.  I broke one of the small plastic inlets at the bottom of the carb while fitting a small tube onto it.  No idea how I'm going to fix this one yet...the plastic was so brittle that it shattered into pieces so I don't think epoxy-ing it will work. 

Tiger

Quote from: 2002_wrx on October 03, 2010, 12:55:42 AM
I may have screwed up bad tonight while putting everything back together.  I broke one of the small plastic inlets at the bottom of the carb while fitting a small tube onto it.  No idea how I'm going to fix this one yet...the plastic was so brittle that it shattered into pieces so I don't think epoxying it will work. 

:) Don't worry, your not the first one to do this  :o ::). Been there, done that...and fixed it, several years ago  ;).

I had an old, worn out front carb manifold and removed the thinner of the two brass spigots. Filed the broken plastic flat and then drilled in to it about 1/8" - 3/16". I then used epoxy to install the brass spigot...VOILA!!!

You can, more or less, use any type of tube as long as its gas proof to do this repair... 8)

8).......TIGER....... 8)
Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well-preserved body, but rather to skid in sideways, body thoroughly used up, totally worn out and screaming HOOOOYA lets go again baby !!!!!!

'82 Vision, Pearl Orange finish, lots of up-grades!!!

2002_wrx

yeah, I'm going to try to rig something up today.  I figure it's not too critical of a part. 

Any tips for trying to start up the bike for the first time?  Might have a go at it tonight but I'm unsure of what will happen.

Rikugun

Nah, it's not too critical...just diverts leaking gas safely away from the hot engine is all.

My tip is have a fire extinguisher handy!   ;)  :)
It is far better to grasp the universe as it really is then to persist in delusion, however satisfying or reassuring.  Carl Sagan

2002_wrx

Well, got it all put together and had the first start up.  It started up relatively easy, but I've got a few problems. 
     1) Fuel dripping out of the overflow tube.  I'm assuming that this means there is too much fuel in the float bowls.  While cleaning the carbs, I replaced the needle and seat valves...the new ones were the same size, but stuck up a bit farther, forcing the floats to rest at about a 20 degree angle from where they were supposed to be.  To compensate, I bent the small tabs on the floats so that the floats rested level, as they were before.   So...where did I screw up?  haha

     2) Bike started up pretty easy, but won't run well.  Symptoms include a self sustaining but surging idle,  (Will idle around 1300 rpm and surge up to 2200ish) and no power.  Like it struggles to get to higher rpm...and seems like it will die if I give it more gas.  Long story short - it sounds like its getting too much fuel.  Can this be corrected by synchronizing the carbs?  Is this related at all to the fuel dripping from the overflow.  I kept everything as it was when I disassembled the carbs...at least to the best of my knowledge.  It ran pretty well before I started all this; it just wouldn't start one day so I began the cleaning process.  Why is it running so differently now?
 
    Sorry for so many questions...this is a learning experience for me and I appreciate the help.

Cdnlouie

Measure from the bottom edge (outside tip of float)of the float to the carb top and it should be about 35mm, that is the ballpark anyway.  If you're less than that your fuel level is too high.  You can also use a clear tube (hold it vertical beside the carb) on your float bowl drains (do them one at a time), and actually measure how far the top of the fuel is from the carb top which should be about 22mm ballpark.

You can do the latter without taking them off again.  Now, that is if you have not broken off all your plastic drains  :(.  It sounds like you have a set of Canadian carbs with the 120 pilot jets on top, as that was standard up here.

2002_wrx

Quote from: Cdnlouie on October 05, 2010, 12:10:37 AM
Measure from the bottom edge (outside tip of float)of the float to the carb top and it should be about 35mm, that is the ballpark anyway.  If you're less than that your fuel level is too high.  You can also use a clear tube (hold it vertical beside the carb) on your float bowl drains (do them one at a time), and actually measure how far the top of the fuel is from the carb top which should be about 22mm ballpark.

You can do the latter without taking them off again.  Now, that is if you have not broken off all your plastic drains  :(.  It sounds like you have a set of Canadian carbs with the 120 pilot jets on top, as that was standard up here.


Well, went out and messed around with the bike tonight.  It's sporadic and I can't get it to behave consistently.  Today it wouldn't stay idling by itself, and would alternate between reving like normal and running horribly.  Most of the time it would run with some throttle, but if I gave it any it would bog down and almost die. 

Tried checking the fuel level using a tube connected to the drain pipes.  Not sure if this is right but I would let the bike run for a minute or so, attach the clear tube to the drain, hold it vertically and loosen the drain plug a bit so fuel would come into the line.  I then measured this level from the carb gasket line.  Once or twice it was right around 20mm, but more often than not it would be around 24-25 mm.  Also, the rear carb level was often lower.

Are they both supposed to be at the same level?  Is this associated with replacing the needle valves?

On a side note: when looking down the carbs from the top, the accelerator pump nozzles were spraying fuel in a good pattern when I twisted the throttle so I assume they're not clogged up anymore.  This was when the bike wasn't running.  However, when the bike was running poorly and I took off the tank to look, both nozzles would just sputter and not spray anything.

Anybody experience anything like this?  I really have no idea what I'm doing haha :-\

Mike Jacobs

Quote from: 2002_wrx on October 05, 2010, 11:26:56 PMOn a side note: when looking down the carbs from the top, the accelerator pump nozzles were spraying fuel in a good pattern when I twisted the throttle so I assume they're not clogged up anymore.  This was when the bike wasn't running.  However, when the bike was running poorly and I took off the tank to look, both nozzles would just sputter and not spray anything.

Anybody experience anything like this?  I really have no idea what I'm doing haha :-\

If you're looking down the carb throats with the engine running and the airbox off, you are _not_ going to see visible fuel spurting from the accel pump nozzles in a straight line or fan pattern as you did when it was not running - the 30 inches or so of vacuum in those twin venturis is going to suck that go-juice right into the hole and vaporize it faster than you can see it.  Wait, did you say you looked down the tubes with it running _after_ you checked them while not running and found the accel pump nozzles to be clean, or only _before_ you cleaned them out, while the bike was running poorly?   Not that looking at them now with the engine running would show you anything, anyway, due to the effect of the abovementioned vacuum suction.
Mike Jacobs
Columbia, MD
1985 Honda VF700S Sabre
1984 Moto Guzzi V65SP
1982 Yamaha XZ550 Vision US
1978 Suzuki GS550 standard
1996 Kawasaki EX250 Ninja

2002_wrx

Before I cleaned the carbs, I took the airbox off and looked down the top of the carbs.  When I twisted the throttle (bike not running), a stream of fuel came out of the front accelerator pump nozzle and not the back one.  I assumed this was my problem since the bike was stalling out and not starting.

After cleaning - the bike sporadically ran normal(ish).  While it was running like this, I took the airbox off to look and fuel would come out of both nozzles when the bike was off and throttle was twisted.  However, the bike started running bad.  When I took off the airbox to look again, I wouldn't see streams of fuel, only sputtering from the pump nozzles while the bike was off and throttle twisted.