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What did P.O. do? Carb hose routing question

  • Thread starter Thread starter 78550Detroit
  • Start date Start date
7

78550Detroit

Guest
Ok you all might remember that I am trying to track down the problem with pipes on 3 & 4 being cold while 1&2 are hot.After checking several things I decided to pull the carbs tonight and can't figure out what is up with the way the previous owner had the hoses run.Here is a pic the main line I removed cause it had a fuel filter on it and it was a bad splice so I am just going to get rid of it and replace it with a regular fuel line no filter.
550carbs.jpg



Any help in how these are suppose to be run would be appreciated and also wondering if this could be the cause of the original problem with 3&4 being cold?
 
The lines coming off the bottom of the carbs are overflow lines and should just be routed past the back of the tranny. The line on 3 and 4 look like they are connected to the vent for the bowls for atmospheric pressure. They should either all have the lines or not at all. It usually depends on the state of tune. The one coming from the bowl on 2 should not be hooked up to anything, it should be like the other three. They thought they were pulling vacuum off of 3 for the petcock. Vacuum ports are usually on the head side of the carb, not where they have it hooked up.
 
Billy Ricks said:
The lines coming off the bottom of the carbs are overflow lines and should just be routed past the back of the tranny. The line on 3 and 4 look like they are connected to the vent for the bowls for atmospheric pressure. They should either all have the lines or not at all. It usually depends on the state of tune. The one coming from the bowl on 2 should not be hooked up to anything, it should be like the other three. They thought they were pulling vacuum off of 3 for the petcock. Vacuum ports are usually on the head side of the carb, not where they have it hooked up.
Click to expand...
So which one should go to the smaller fitting on the petcock or should it be nothing at all? Should I get rid of the top line on 4 then and just leave that open?
 
78550Detroit said:
So which one should go to the smaller fitting on the petcock or should it be nothing at all? Should I get rid of the top line on 4 then and just leave that open?
Click to expand...
I'm not well versed in the old VM carbs so someone else will have to answer what to do with the vent lines. I can tell you they should either all have them or nat at all. Do you have a vacuum port on the intake side of the carbs? That's normally where the vacuum line for the petcock goes so it pulls decent vacuum.
 
Billy Ricks said:
I'm not well versed in the old VM carbs so someone else will have to answer what to do with the vent lines. I can tell you they should either all have them or nat at all. Do you have a vacuum port on the intake side of the carbs? That's normally where the vacuum line for the petcock goes so it pulls decent vacuum.
Click to expand...

The side facing you in the pic is the side that connects to the airbox. The line coming of the top on three is on the other side. So that would be the intake side?
 
On the VM carbs, #2 and #4 are vents. Run those hoses to atmosphere if you have a stock airbox, or remove the hoses if you are running pod filters. #3 goes to the petcock.

I'll bet #2 carb has a float problem and leaks. ;-)
 
renobruce said:
On the VM carbs, #2 and #4 are vents. Run those hoses to atmosphere if you have a stock airbox, or remove the hoses if you are running pod filters. #3 goes to the petcock.

I'll bet #2 carb has a float problem and leaks. ;-)
Click to expand...

There were no leaks before I took the carbs off. It does have the stock airbox. The bike is stock no modifications on it. Not sure what you mean by atmosphere?
 
I think I know what you mean by two having float problem. Your saying that is why the po had the line run that way. By atmosphere you mean just run the lines out towards the back like the overflow lines?
 
Forgot to mention in original post this is on a 78 GS550.Well I routed the hoses correctly and just put the carbs back on last night. I started the bike up this morning and let it warm up for about 5 min then hopped on it and took it for a ride around the block a few times.Everything was working fine cylinders 3&4 were firing now (getting hot ) now all of sudden my idle jumped to 3k and I tried turning it down with idle screw but won't come down. Could this be from not having the throttle cable adjusted right?This bike has the two throttle cable system but the second throttle cable is missing could this be an issue? Or is it maybe a stuck float or float height etc? Should I pull the carbs back off and rebuild them? Kinda nervous about doing this since the last time I tried to rebuild a carb on my F-150(inline 6 /2 barrel carb ) I had to end up buying another carb from the junkyard.
 
The second throttle cable is a back up from what I understand in case there is a problem with number 1. You could either have a throttle adjustment problem or a stuck float in the carb(s). At minimum, check the throttle cable to see if it's too tight/incorrectly routed/wrong size and run some seafoam and carb cleaner through it if it's a stuck float. I had some success with that so far on my Honda (going through a similar idle issue), and a lot of gunk has run out when I drain the bowls. I'm hoping the seafoam and cleaner will be enough for now to avoid a complete tear down and cleaning of the carbs until Fall. Might work for you, too :-D

78550Detroit said:
Forgot to mention in original post this is on a 78 GS550.Well I routed the hoses correctly and just put the carbs back on last night. I started the bike up this morning and let it warm up for about 5 min then hopped on it and took it for a ride around the block a few times.Everything was working fine cylinders 3&4 were firing now (getting hot ) now all of sudden my idle jumped to 3k and I tried turning it down with idle screw but won't come down. Could this be from not having the throttle cable adjusted right?This bike has the two throttle cable system but the second throttle cable is missing could this be an issue? Or is it maybe a stuck float or float height etc? Should I pull the carbs back off and rebuild them? Kinda nervous about doing this since the last time I tried to rebuild a carb on my F-150(inline 6 /2 barrel carb ) I had to end up buying another carb from the junkyard.
Click to expand...
 
78550Detroit said:
Forgot to mention in original post this is on a 78 GS550.Well I routed the hoses correctly and just put the carbs back on last night. I started the bike up this morning and let it warm up for about 5 min then hopped on it and took it for a ride around the block a few times.Everything was working fine cylinders 3&4 were firing now (getting hot ) now all of sudden my idle jumped to 3k and I tried turning it down with idle screw but won't come down. Could this be from not having the throttle cable adjusted right?This bike has the two throttle cable system but the second throttle cable is missing could this be an issue? Or is it maybe a stuck float or float height etc? Should I pull the carbs back off and rebuild them? Kinda nervous about doing this since the last time I tried to rebuild a carb on my F-150(inline 6 /2 barrel carb ) I had to end up buying another carb from the junkyard.
Click to expand...

On the VM carbs you need both cables. The carbs can "hang up" on decelleration and not close all the way. Check your cable to see if it's too tight, and check to see if the throttle is closing all the way. Get another cable.
 
Thanks for the info. I saw that the pepboys by my house has the spraycan seafoam.Where would I spray that in at? Also would the throttle cable be available still? Are they the same size could I use the main throttle cable from my 79 GS550E?
On a sidenote I am in need of the frame cover for the battery side for that bike also. I have e-mailed bikebandit.com a few times but they have never e-mailed me back. Have any of you ordered from them?If you did how long did it take to get your parts?
 
78550Detroit said:
Thanks for the info. I saw that the pepboys by my house has the spraycan seafoam.Where would I spray that in at? Also would the throttle cable be available still? Are they the same size could I use the main throttle cable from my 79 GS550E?
On a sidenote I am in need of the frame cover for the battery side for that bike also. I have e-mailed bikebandit.com a few times but they have never e-mailed me back. Have any of you ordered from them?If you did how long did it take to get your parts?
Click to expand...

Well what has worked for me so far has been to get the Seafoam gas additive and follow directions along with the spray in carb cleaner (misc. brand) and spray it into every opening (drain and where tubes connect) possible and follow directions.

As for the throttle cable, I only know how it works for my Honda: the second cable is called a push cable and on some models they are the same size, some are not. I'd check out bikebandit.com and research the parts fiche there to see if it's available. Even if it's not available as OEM, there is probably an aftermarket for it. Check out this link here http://www.thegsresources.com/_forum/showthread.php?t=93439 for a list of other sites where you can get parts. I've found that a few are easier to search than Bike Bandit and have better pics, and cross reference non-OEM parts to the fishe, so do your research to get the best deals and finds.

Side covers (I think that is what you meant by frame cover :-D) for any old bikes can be hard to find. Ebay can be your friend or your enemy (big bucks) as far as that goes, and seek out nearby bike bone yards. Do a search here on side covers and you'll find lots of info, including repair techniques if you have the originals but they're cracked.

Best wishes and keep us updated!
 
I looked on bikebandit.com and it appears that they have the side cover and both throttle cables.So I am probably going to order from them. Thanks for all the info again.This site has been a lot of help for me so far lots of great people with good info.
 
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