79 gs850 gas line question...

[Anonymous]

hi

i'm getiing back into this after a long layoff, and new to this kind of bike. so please bear with me. i haven't gotten my repair manual yet, which would probably have the answer to my question. so hear it goes...

i just got a 79 gs850, that apparently has run recently. the ad says it did but, of course, when i went to pick it up it wouldn't start. i started to check into it today. the bike just keeps cranking and won't turn over. i noticed gas on the floor. and there's gas in the tank. gas leak! so, did some digging and like i said i'm a little clueless at this point, there is one house coming off the petcock that goes into a filter and i believe into the carbs. there are 3 other hose just hanging there. one from the gas tank, and the other 2 i didn't have time to finish looking for. the right side of the petcock just has a hole. so my question is . what is the proper flow of these hoses from the gas tanks to the petcock and to the carbs? i'm assuming one has fuel flowing through it, one an over flow, and one a breather or vacuum hose. i don't know. any help will be appreciated!!!! thanks!!!!!

p.s. i've been lurking for a few weeks, and finally signed up. i love this site, thanks to the creators!!
jim

[QuaiChangKane]

I don't know if this is any help, but I'll describe what's on the tank of my '83 750E.


Petcock - two fuel lines, the large one is the supply from the petcock to the carbs, the other is the vacuum line which opens the diaphragm in the petcock and allows fuel to flow from the tank into the carbs only when the engine is running. Vacuum petcocks can be quirky, but they're great when you want to remove the tank - no fuel will leak out if it's in the "on" or "res" position. "Pri" bypasses the vacuum circuit to allow fuel to flow freely into the carb float bowls in case the bike's been sitting so long that the fuel has evaported from the bowls.

Fuel sender - from this side, there is a pair of wires in a plastic sleeve (may look like a hose?) which power the fuel guage, plus a vent hose that simply runs along the frame and exits over the rear tire. I believe this is simply for allowing air into the tank while fuel is being sucked into the engine.

I'd check the fuel supply hose for leaks, and check the petcock diaphragm as well. If you do a search hear for "petcock", you'll find plenty of info for rebuilding and troubleshooting them.


Good luck,

-Q!

[SqDancerLynn1]

To start with the hoses You have the older slide carbs. The fuel line hooks up between the #2 & 3 carb. There is a vacuum line from the petcock that goes to the # 3 carb. On carb 2 & 4 is a fitting for a vent/overflow hose routed down to the swing arm. There are also 4 hoses connected to the bottom of the float bowls(overflow) also routed to the swingarm
The hose under the tank is to drain fuel away from the engine incase the fuel sender leaks it also routes down to the swingarm and is not connected to anything
SO you should have 7 hoses routed down to the swingarm
Check the fuel petcock for proper, If the carbs still leak you should take them apart and clean them
CHeck/ change the oil it may be contaminated with fuel?

[SqDancerLynn1]

Additional note--while working on it remember IT WILL NOT run properly without the airbox assembly installed. They are normally noisey when they are idling, and are almost bullet proof. Have fun with your 850
I love mine

[Anonymous]

ok this is helping me a ton!!

2 questions

where does the hose from the tank go? to the petcock?

is the hole on the right side of the petcock normal then?

really thanks a million!!

jim

[SqDancerLynn1]

The hose under the tank from the fuel sender routes back to the swingarm, left open not connected to anything Im not sure what you are refering to as the hole There are two hoses that connect to the petcock, FUEL and a vacuum line that goes to the #3 carb. When you try to start the bike turn the fuel valve to prime for 2-3 seconds to make sure the carbs are full, then turn it back to ON. Pull the choke all the way on and start the bike DO not give it any throtle. after it starts you can vary the throtle with the choke

[frosty5011]

The thicker nipple on the petcock, the one closest to the handle, connects to the fuel inlet on the carbs.

The smaller nipple, further to the "back" is the one that connects to the vacuum line (usually on #3 carb with VM carbs) - however, be aware that someone previously may have had the carbs disassembled and switched the #2 and #3 carbs around. The way to know for sure is that the carb to which the vacuum line should be connected has an extra hole at the 2 o'clock position on the "engine side" of the carbs. Or you could just feel with your finger if there is "suction" at the end of the hose when trying to start the bike.

[Anonymous]

ok....i'm getting this straight....i was thinking that there should be a hose from the tank to the petcock.....duh! the hoses appear to be set up right now...but the holes(there's one on the left side around 7 o'clock) and then one on the right of the petcock don't seem to make sense to me. why are they there? it looks like there should be a reason. it seems to be leaking from there. thanks again!!!!!!!!!!!!!