Fuel line question

[Guest]

OK, I'm working on my 82 GS 650 L Been putting it back together over the winter. I see two hoses coming from the carbs, one is 1/4" inside dia,..the other 3/16" dia. Witch one goes to the petcock, and witch goes to the fuel level sending unit? Thanks

[tom203]

Big hose from petcock to carb rack is 8mm ...on back of petcock there is a smaller hose 6mm that connects up to a nipple on #2 carb (engine side) ...this is a vacuum connection to operate the petcock. At bottom of fuel sending unit there is a connection for a drain hose,in case tank leaks.
certain inch sizes of hose will do fine,


E5A36FC8-4ECF-4E35-B47B-14F85BF0D095.jpg

[Rich82GS750TZ]

In other words, the hose from the fuel sending unit does not connect to the carbs at all. It should run over the carbs and in front of the battery box to a space behind your engine block to the ground. Your battery vent line runs to the same place, also if your airbox has a drain hose, it runs to ground at the same spot. The carbs have 1 line for fuel, one line for vacuum. They go to separate nipples on the petcock. Bigger is fuel, smaller is vacuum. These are shown in the pic that tom203 posted. Carbs have 2 other lines that are vent lines. Only one of these is shown in toms pic. The 2 vent lines will look the same and on the same side of the carb rack. The vent lines run up over the airbox and are left open to still air. They all have to be hooked up right for carbs behave.

see pg. 72

this and many other useful things like owners manual and service manual are on BikeCliff's website linked in my signature.

[abaton6]

Thanks Tom. Got it all back together. Now waiting for the gas spill to dry up before trying to start this thing for the first time in ?????? years It only has 4,200 miles on it

[abaton6]

In other words, the hose from the fuel sending unit does not connect to the carbs at all. It should run over the carbs and in front of the battery box to a space behind your engine block to the ground. Your battery vent line runs to the same place, also if your airbox has a drain hose, it runs to ground at the same spot. The carbs have 1 line for fuel, one line for vacuum. They go to separate nipples on the petcock. Bigger is fuel, smaller is vacuum. These are shown in the pic that tom203 posted. Carbs have 2 other lines that are vent lines. Only one of these is shown in toms pic. The 2 vent lines will look the same and on the same side of the carb rack. The vent lines run up over the airbox and are left open to still air. They all have to be hooked up right for carbs behave.

see pg. 72

this and many other useful things like owners manual and service manual are on BikeCliff's website linked in my signature.

Thank you for the additional info. Very helpful.

[tom203]

4200 miles....?? Is this a barn find?
Note that this not a “choke system”, it’s an enricher system - extra shot of fuel- which relies on all throttle plates staying closed during cold cranking in order for fuel to be sucked into cylinders and life to return to this critter.

[abaton6]

Ok , hooked up the fuel lines, tried it, and the plugs are dry. I even set the fuelcock to prime, ..still dry. Do y'all think that some starting fluid would get things going? Or am I looking at taking the carbs off and cleaning?

[Cipher]

yay ether! now all the whackos can rant about the devil incarnate

one shot of ether is fine it will prove if youve got sufficient compression and a functioning ignition system

[Rich82GS750TZ]

While cleaning the carbs is never a bad idea, before you do that, I’d first check that each plug is getting spark. Start at #1 ( everything is 1,2,3,4 left to right as you sit on the bike). Uncap the plug, remove plug, recap the plug and hold plug cap in hand with the base of plug against the head. As you pull the clutch with your other hand, and press the start button with your 3rd hand, you should see the plug spark. Repeat on the other 3 cylinders.

if you need starter fluid to start your bike, you likely have carb and / or air intake leak issues.

if you’re getting spark on all 4, I’d go and check the carbs. You could slightly open the drain screws one at a time just enough to see if each carb bowl has gas in it. Have a rag below, on top of the starter motor cover to catch the mess.

[Cipher]

airbox is on? filter installed?

[Steve]

Ok , hooked up the fuel lines, tried it, and the plugs are dry. I even set the fuelcock to prime, ..still dry. Do y'all think that some starting fluid would get things going? Or am I looking at taking the carbs off and cleaning?

You had it far enough apart to have the carb hoses loose and DIDN'T clean the carbs?

Dare I ask if you have checked valve clearances?

.

[abaton6]

You had it far enough apart to have the carb hoses loose and DIDN'T clean the carbs?

Dare I ask if you have checked valve clearances?

.

I did not have the carbs off yet. The valves have not been checked. Bike has 4.200 miles

[abaton6]

airbox is on? filter installed?

Airbox is on and no filter or cover on yet.

[abaton6]

yay ether! now all the whackos can rant about the devil incarnate

one shot of ether is fine it will prove if youve got sufficient compression and a functioning ignition system

I'll pick up some soon and give it a try.

[Grimly]

I did not have the carbs off yet. The valves have not been checked. Bike has 4.200 miles

They might have bee hard miles in the hands of the PO. Anyway, 4K miles is a good interval to check them at, but more especially as you don't know what they are on a new-to-you bike.
Also, bear in mind a lot of the less, shall we say, competent mechanics just listened to the rustle of the valve train and checked them by ear.