Stuck on one carb

[dkruitz]

Hi All:

My brother-in-law and I are trying to get his project '82 GS450GA (semi-automatic shaft drive) going and are still stuck on the carbs. We found it had flowed into the crankcase and have drained the oil now. We're pulled the carbs and have one that we can't keep overflowing - it comes out the hole to the right of the inlet on the left carb. The thing that gets us is when we pull the bowls and emulate the floats rising it stops the flow of gas, even if we don't have the springs on the needles fully compressed. Any ideas?

We sprayed carb fluid down the right side hole and it appears to be coming out the main jet into the bowl - is this correct? Or do we have some internal issue with the left carb?

Any thoughts are appreciated!

Dan

http://www.elginoutboard.com/jonsbike/

[shotblaster]

carbs

You may have several problems. Fuel coming out of the side of the carb sounds like a dirty or worn needle and seat. That is the little spring loaded plunger that the float moves up and down with fuel level changes.this is at the hinge point of the floats. If you have raw fuel coming up through the main jet, this can happen if the needle and seat are not sealing, and the main jet is not being sealed by the fuel needle attached to the slide.I would remove the fuel needle from the cv carb diaphram and slide combo, and check to see if its bent, or dirty. Sometimes the residue from old fuel can be the problem.Make sure no green or tan crust is in the carb, or needle reciever. I wonder how much can flow with a vacuum operated petcock. Your left cylinder will now have no oil in the oil ring, I would add a teaspoon of oil down each cylinder before running. It will start easier, believe it or not.

[dkruitz]

I forgot one of the things we thought of to try to troubleshoot this - we took the float, needle and seat assembly from #1 and moved them to #2 to see if the problem went or stayed with the carb. It stayed with the carb. Does that tidbit help? We were doing these steps with the carbs on the bench and still got gas out that right side hole - we use an oil can to shoot it down the gas line.

Thanks for the oil tip - we'll try that we're going to reoil it tomorrow as it's dripping out now. We'll probably change it again after a run or two to be sure to get it as non-contaminated as we can.

[trdhrdr007]

On my carb bank one of the float posts had been broken off & JB welded by the PO. This made the float sit slightly off-center, where it hit the side of the float bowl & wouldn't cut off the fuel flow. A little work with a dremel & a tiny washer shifted the float enough to clear the side of the bowl.

First thing I'd check would be the petcock. If it was working properly fuel wouldn't flow to the carb while the engine was off. No vacuum should mean no fuel flow.

[dkruitz]

The posts look good and the carbs appear unmolested. We're confirming the overflow with the carbs off the bike.

»We were doing these steps with the carbs on the bench and still got gas out that right side hole - we use an oil can to shoot it down the gas line.«

So there's little gas pressure pushing the gas down, just the fuel line.

I could hold the floats up just touching the needles - spring not compressed and it would stop the flow of gas, but once the bowl is on, #1 will overflow. I don't see any obstructions stop the bowls from moving . Any ideas?

[dkruitz]

Possible solution?

I was just rereading the GS carb cleaning series PDF, and found a reference on page 24 of 53 of a part that is not on either of these carbs - the pilot jet PLUG. If it's missing on these carbs could this be the problem? Does the plug complete close off the bottom of this jet to the bowl?

[Suzuki_Don]

I could hold the floats up just touching the needles - spring not compressed and it would stop the flow of gas, but once the bowl is on, #1 will overflow. I don't see any obstructions stop the bowls from moving . Any ideas?[/quote]

Hi. Don't know much about 450s as I own a 4 cylinder, but if fuel cuts off OK with float bowl off carb and carb overflows with float bowl on, then to my way of thinking there has to be some interference which is stopping the float from rising up enough to close off fuel flow. In other words the fuel valve is still open allowing the flow of fuel and as it fills up it flows out from the hole in the side of the carb.

[dkruitz]

Yes there's something going on - any idea if my earlier comment about the pilot jet plug is valid? I just found out these carbs don't have a plug - they may be missing from a previous owner - would/could the plugs missing cause it to overflow?

[Suzuki_Don]

I wouldn't think so. I would say that it has to do with fuel level in the float bowl. Have you looked on the Alpha Sports site at the carby illustration for your bike. If not it would be a good idea to do that and do a comparison with the parts you have pulled out of your carbies.
The site link is as follows:

http://www.alpha-sports.com/suzuki_parts.htm?gclid=CM_FivP74owCFRuxgAoddH9X1A

If you can't work out how to look up your model post back and I can give instructions.
Cheers

[SqDancerLynn1]

Your bike has a varaition of the BS carb. Do you have brass floats ? could have a pin hole leak? Replace the O ring on the needle seat & clean them- should fix the problem

[dkruitz]

Great site link - thanks - that's going in the permanent bookmark folde! :-)
Looks like we need the plugs but I don't if that will stop the flooding - I'll hit the Suzuki dealer on Tuesday when they're open again and see what happens.

I wouldn't think so. I would say that it has to do with fuel level in the float bowl. Have you looked on the Alpha Sports site at the carby illustration for your bike. If not it would be a good idea to do that and do a comparison with the parts you have pulled out of your carbies.
The site link is as follows:

http://www.alpha-sports.com/suzuki_parts.htm?gclid=CM_FivP74owCFRuxgAoddH9X1A

If you can't work out how to look up your model post back and I can give instructions.
Cheers

[dkruitz]

Nope, they're the black (solid foam?) type. They float well and aren't gas logged - bike was sitting dry for a while before we got to it. I can check the o-rings on the needles but they seemed decent and not too compressed.

The next thing we're going to do is put the bowls back on and use wire or a pick to verify the floats are moving and not obstructed somehow.

Your bike has a varaition of the BS carb. Do you have brass floats ? could have a pin hole leak? Replace the O ring on the needle seat & clean them- should fix the problem

[dkruitz]

OK we think we have it now

After much troubleshooting we think we have the answer. (assumptions: #1 carb is the left side carb when seated on the bike)

I found a pair of pilot jet plugs aka passage plugs at the Suzuki and Aprilia dealer - I cleaned out suzuki's inventory of 1. The Aprilia dealer (AF1 Racing) gave me a plug for free! We put them in and it still floods out the #1 carb from the hole to the right of the airbox inlet.

We fiddled around and think we have the answer - venting! Please see the photo if it helps explain things. We are assuming someone messed with these quite possibly....

Photo Description:
The vent on the bottom of the #1 carb goes up and through the side and out the short vent hose that goes into the matching barb on the #2 carb. Next to that, is a brass barb with a hose on it, that we've never been able to figure out where it attaches to (still don't).

Now, here's the problem the #2 carb where the #1 vent hose attaches to on the side is plugged - or actually, never drilled through into the vent hole that the brass barb and hose use to vent the #2 fuel bowl! So in effect the gas coming into the #1 bowl creates an air pocket in the top of the bowl (because it cannot vent) and new gas coming in forces the smallish amount of gas up and out the needle jet to flood out the hole. Chances are there's not enough fuel for the floats to rise and shut off the needle/seat. Fuel pressure from the #2 bowl is also contributing to this as it has a higher fuel level and is transfered via the little gas line joining the two bowls to keep the fuel level even.

So we think, all we need to do is either drill out the pot metal barb on the #2 carb to match the #1 vent, or do we just run a longish vent hose out into the air for the #1 vent hose like the #2 vent hose? Whatcha think?

[Dave8338]

I don't see why you can't just drill it out as you have mentioned. It is just a vent tube...nothing moving or regulating fuel in that "plugged" tube. IMHO

[Calvin Blackmore]

fromt eh fiche it looks like the vent hoses only attach to one carb each then disappear somewhere to get unfettered atmospheric pressure

If the hos is being forced onto the nub that appears to be a blocked air vent wouldnt that cause the carb to be unvented and thus produce some bad results.

I wouldnt drill that hole
try it with bot vent hoses free first