Carburator Help

[headlight]

Ok here's the story, helping out a friend with his 78 GS750, I cleaned the carbs, and now I"m trying to reconnect them and nothing is going right. Basically I'm having trouble with the vacum and gas lines. If somebody could post up a pic of the carbs minus the airbox that would really help me out.

[mark]

Don't have time to do the pic thing, but here's how your vacuum and gas lines are hooked up. You have three nipples on your #2, #3, and #4 carbs located just to the left of the slider tube and above and left of the carb air intake. #1 doesn't have such a fitting. #2 and #4 are for open vent lines. The hoses simply vent to atmosphere.

Your petcock vacuum line goes to the #3 fitting.

Your gas line hooks up to the T-fitting in between #2 and #3 carb.

Good luck!

[headlight]

Don't have time to do the pic thing, but here's how your vacuum and gas lines are hooked up. You have three nipples on your #2, #3, and #4 carbs located just to the left of the slider tube and above and left of the carb air intake. #1 doesn't have such a fitting. #2 and #4 are for open vent lines. The hoses simply vent to atmosphere.

Your petcock vacuum line goes to the #3 fitting.

Your gas line hooks up to the T-fitting in between #2 and #3 carb.

Good luck!

Thank You I will give it a try

[headlight]

OK got everything hooked up per the above post but the bike still won't start, the gas is only dribbling into the filter from the tank. The petcock is stuck in the down position and will not move. Do I have a problem there?

[frosty5011]

OK got everything hooked up per the above post but the bike still won't start, the gas is only dribbling into the filter from the tank. The petcock is stuck in the down position and will not move. Do I have a problem there?

Take the filter off. Run that fuel line into a ittle container, no fuel should be passing at this time.

Apply suction/vacuum to the vacuum line going to the petcock, now, the fuel should pour out freely.

Eventually, you need to get the petcock rebuilt/replaced if it is truly stuck in down position.

Since carb bowls are empty after the rebuild....it will take a while to fill them up ......you'll need to apply suction to the vacuum line for about 10-20 seconds to fill them before bike will start (since Prime function isn't working), or seriously task your battery/starter. Just suck on the vacuum line...no fuel should pass in that line at all.

[headlight]

Let me ask this, there is something bolted to the innner left of the tank with a hose coming out of it. What is this and where does that hose go?

[edbot]

I've got a stock 78 GS750E and the only thing bolted to the tank is the petcock.

[Steve]

Headlight,

That "something bolted to the innner left of the tank with a hose coming out of it" would be the sending unit for the fuel gauge. The hose (which is probably attached to a large plastic piece that covers the whole thing) is merely a drain in case the gasket leaks. That way, if it does leak, it will not drip raw gas on top of a hot engine.


.

[ptm]

Headlight,

That "something bolted to the innner left of the tank with a hose coming out of it" would be the sending unit for the fuel gauge. The hose (which is probably attached to a large plastic piece that covers the whole thing) is merely a drain in case the gasket leaks. That way, if it does leak, it will not drip raw gas on top of a hot engine..

That would be the most likely culprit except that the 78 750 didn't have a fuel gauge. It may be a tank off a different bike. If the hose goes to a contraption on the inside side of the tank (the cover on my 850 is metal, but could be plastic) then that's probably what it is, in which case it just drains to the ground.