Changing to gravity flow petrop tap.

[Guest]

Hi Folks, apologies if this topic has been covered before but can anyone tell me about changing the petrol tap from the standard vaccum type to a gravity flow type. To explain, I'm using an old mustang style tank on a GS 550 L that I got in pieces some months ago the standard tank was beyond all redemption so hence the mustang. I've been told that you can blank off the vaccum pipes and use a universal gravity tap. Is this the case. My second question is regarding the carbs themselves, I've stripped and cleaned the carbs, replaced the jets but I did'nt seperate the carbs from the connecting plates. I notice that there may be a joining pipe missing between carbs 2 and 3, at least thats what it looks like as the other carbs have a T piece swivelling gadget between the carbs.
In other words I have a fuel pipe and two other pipes coming from the carbs, I think the pipe nearest the petrol tap is the vaccum pipe and normally connects to the smaller nipple on the tap in my case this should be blanked off to use the gravity fed tap. What purpose do the other pipes serve, are they vents and how many pipes should I have coming from the carbs. Confused yet ???. I know little or nothing about CV carbs so any help would be greatly appreciated.

[Brendan W]

There is the fuel delivery hose, the vacuum take off, needs to be blanked off and two vent pipes from the swivelly tees between the outer pairs.
You will need to remember to shut the fuel OFF. Relying on the float needles will result in a pool of gas the day one hangs and a smoker will be walking by and............

Wiring diagrams and service manual

http://members.dslextreme.com/users/bikecliff/

Parts diagrams

http://www.cmsnl.com/suzuki-gs550l-1981-x-e01-e02-e04-e21-e22-e24-e25-e26-e34-e39_model13482/partslist/

[Grumpy]

Many Thanks, I have a feeling the carb assembly was put back together incorrectly at some stage as it has only three pipes coming from it. it seems like a bits gone missing.

[Brendan W]

The vents are often forgotten on assembly and are tricky to get back on after because the tee swivels. They are often then left off, one or both. Mine had one missing, didn't seem to affect it too much although it might be hard to tell in the middle of doing all the things needing work in the early stages.

[Grumpy]

You can see how it would happen alright. I'll make up a T piece and replace the missing bit while the carbs are off the bike. Thanks for your help.😊

[Brendan W]

There are o-rings to go in there as well.
These guys are in Aughrim and have loads of old GS stuff - more than they know when you go rummaging down the back.

http://www.firstchoice-bikebreakers.com/

[Oldman99]

Not sure of the year,but heres a guess.

Parts outlaw

Also, I agree with the others on having some way to shut off the fuel.
20161008_202306.jpg

[Grumpy]

Thanks a million, I'm right handy at rummaging.

[Grumpy]

I can imagine a pool of petrol could be a wee bit of a disaster alright. I'll use some type of after market tap with an on off lever.

[Steve]

Changing to a manual tap is easy enough, but you need to know which carbs are on the bike. Easiest would be to know what year the bike is. The first-year 550L was '79, it had VM carbs. Later years had BS carbs (also called 'CV-type'). The carbs in the picture that oldman99 showed are the newer BS carbs.

On the VM carbs, the vacuum tap is on carb #3. Carbs are numbered from left to right, as you sit on the bike. #1 is under your clutch hand, #4 is under your throttle hand. On the BS carbs, the vacuum tap is on the #2 carb. All you need to do is put a short piece of hose on the vacuum nipple and insert a small machine screw or bolt to block it off.

The hoses on the Ts between the carbs are your vent hoses. There is not one between #2 and #3 because they are connected to #1 and #4, respectively. Since you mention the Ts, I am going to say that you have BS carbs. Neither one of those hoses should be connected to anything except the T on the carbs. They are supposed to be routed over the airbox and sit in a small square loop on the filter housing.

.

[Grumpy]

Changing to a manual tap is easy enough, but you need to know which carbs are on the bike. Easiest would be to know what year the bike is. The first-year 550L was '79, it had VM carbs. Later years had BS carbs (also called 'CV-type'). The carbs in the picture that oldman99 showed are the newer BS carbs.

On the VM carbs, the vacuum tap is on carb #3. Carbs are numbered from left to right, as you sit on the bike. #1 is under your clutch hand, #4 is under your throttle hand. On the BS carbs, the vacuum tap is on the #2 carb. All you need to do is put a short piece of hose on the vacuum nipple and insert a small machine screw or bolt to block it off.

The hoses on the Ts between the carbs are your vent hoses. There is not one between #2 and #3 because they are connected to #1 and #4, respectively. Since you mention the Ts, I am going to say that you have BS carbs. Neither one of those hoses should be connected to anything except the T on the carbs. They are supposed to be routed over the airbox and sit in a small square loop on the filter housing.

.

The bike is a 1980 L

[Grumpy]

The bike is a 1980 American spec L. The vaccum nipple is on #2 carb so I guess they are BS type carbs. You saved me a lot of hassel and time breaking the carbs apart. Thanks.