Carb Question

[Dreef1999]

RE: 1977 gs550 Running before carb tear down.

Hello,
I have a problem/question and I feel like I need the wisdom of the group to make a decision. Inside my carbs I have a short squishy spring on my needle, a short stiff spring on my pilot air screw/side screw, and a longer medium-stiff spring on my pilot screw.

Now for some reason one of my side air screws has the longer spring which is like the pilot screws. I can only assume a PO did this but I have no idea how important this spring is or if it is a problem. Should I try to order a replacement spring of the correct stiffness and size or will I survive with the wrongly fit spring?

I also inspected my intake boots which feel reasonably springy but on the inside there is some peeling or exfoliation of the rubber. The problem area isn't big and it doesn't appear to go through but I was just wondering if anyone had any thoughts on this kind of damage.

Lastly. I have one sticky float needle valve. The pin doesn't compress smoothly and sometimes sticks slightly at either extreme. How big of a problem is this? Any tips on what might rehab this float needle? I will replace if necessary but it would be nice to avoid that if possible.

All springs

problem springs

intake

Float

Thanks!

[hampshirehog]

The wrong spring on your airscrew won't hurt as long as the screw is unable to turn 'under its own steam' when adjusted i.e. the spring is only there to provide tension on the screw to keep it adjusted. You'll just have to gauge this yourself - does it feel as secure as the other 3 screws.

With your boots, as long as there is plenty of rubber keeping the things airtight and none of the flaps of rubber are loose and able to come off I'd say they're good to go. Looks like your O ring is flat though and should be replaced.

With the sticky float needle it's key that it works properly or else you'll be running too high or too low a level in your float bowl. Try soaking in thinners / boiling in water with a drop of washing up liquid added. If you can't cure it I'd recommend replacing.

[Dreef1999]

Any advice on the best place to buy the intake boot o-rings?
They are still very flexible but the cross-section is very flattened.

[renobruce]

Any advice on the best place to buy the intake boot o-rings?
They are still very flexible but the cross-section is very flattened.

I think Mr. Barr sells them, or maybe Nessism. Try www.cycleorings.com If neither of them have them, you can get them from Suzuki.

And I agree with Hamp. That needle might just need to be cleaned better. Squirt it with some carb cleaner and try and work it in and out. If no luck Z1 enterprises sells them at a reasonable cost.

[LarryA_Texas]

RE: 1977 gs550 Running before carb tear down.


Lastly. I have one sticky float needle valve. The pin doesn't compress smoothly and sometimes sticks slightly at either extreme. How big of a problem is this? Any tips on what might rehab this float needle? I will replace if necessary but it would be nice to avoid that if possible.

Thanks!

You have to fix that needle. I have had some luck with a very small file if there is just a burr that needs to come off the seat. Also you might check to see if the needle seat is out of round maybe due to too tight a squeeze of the pliers when pulling it out.

Anything that keeps the float needle from moving freely both up and down will cause severe problems later. If it sticks open you'll be overflowing your bowl and leaking gas. If it sticks closed you're going to run out of gas in that cylinder.

Make sure the float needle rides up and down freely and that you can rotate it while in the seat.

[zathros]

The fact that all the screws came out is a Godsend. I would order new screws and springs. Make sure that cleaner will go through the holes and there isn't a piece of needle screws blocking them. Buy new needle valves for the float, it is too crucial a part to screw around with and you'll have many problems tracing back to it. To be honest, when I replace a carb part, such as these, I usually replace for all carbs. It levels the playing field.

[Dreef1999]

The fact that all the screws came out is a Godsend. I would order new screws and springs. Make sure that cleaner will go through the holes and there isn't a piece of needle screws blocking them. Buy new needle valves for the float, it is too crucial a part to screw around with and you'll have many problems tracing back to it. To be honest, when I replace a carb part, such as these, I usually replace for all carbs. It levels the playing field.

Well, the slide assembly wasn't so fortunate and I had to drill out 4 of those tiny Phillips screw. the rest I could get to with an impact and I was very preemptive about whacking them before they stripped.

I think I might take my chances if I can get the needle valve to feel smooth. Just write down which carb it is.

[gs850cmc]

A few years back I partially rebuilt the carbs on my GS850 and I had the same problem with the #1 float needle. It was stuck causing a flooding problem, so I soaked it in carb cleaner overnight. This worked as the pin was free and seemed to bounce fine on its spring. However, now i'm in the middle of a complete rebuild and found the same needle stuck again. This time I replaced all four from bikebandit, changed seats and needles.

[Dreef1999]

OK, I have rebuilt and now running. But more questions now of course.
Air Screw 2 turns (Manual spec)
Fuel Screw 1 turn (manual Spec)
Jets stock
air box stock

The main symptom is that if revved from idle the idle sticks way too high, around 5,500k. I understand this is a symptom of being lean?

Do I have to turn my fuel screw out more to increase the fuel?

Could I have an air issue.

[TheCafeKid]

I would go another half turn out on the fuel screw, If helps, but doesnt make it completely better, go a half turn back on the AIR screw...let us know..we'll work from there..


BTW, did you replace the intake boot orings?? If not, thats where you are leaning out...

[Dreef1999]

Turned out Fuel Screw 0.5 and the bike does seem to be slightly better. It was idling ok enough for me to ride it and warm it up.

2 miles into the ride the idle started staying high again. Air screws didn't help with this.

I am going to turn the fuel screws out another 0.5 turn hoping that fixes the problem. This will put me a full 1.0 turn further on my fuel screw than the maintenance manual suggests.

1. I replaced my boot o-rings and am 100% positive the boots are ok. The only place i could have an air leak is on the airbox side of the carbs. What specifically would I look for to identify a leak on the airbox side?

2. How much of a difference would the float height make? I had conflicting numbers on what to set my float height to, between several sources i saw 24mm and 26mm.

Thank you great GSR hive mind.

[Dreef1999]

ok some progress.
Fuel screw 2 turns out
Air screw 2 turn out
Stock airbox & exhaust

Running almost right now. Bike runs better when colder. Also once warmed up the revs don't drop as quickly to idle. Air screws made no discernible difference either in or out 1 turn.

I think I need to turn my fuel screws out even further? 2.5 turns out instead of the 1 turn which is recommended in the carb spec sticky.

[renobruce]

Pull your plugs and have a looksy. It sounds like you might still be running lean. If the plugs are white, go another 1/4-1/2 turn on the fuel screws.

[Dreef1999]

Pull your plugs and have a looksy. It sounds like you might still be running lean. If the plugs are white, go another 1/4-1/2 turn on the fuel screws.

I turned the fuel screws out 1/4 of a turn and have pretty acceptable results now. I don't notice any times when the idle is slow to drop after revving.

I am getting a slight bog when I first hit the throttle but it clears up with more gas which I assume is just b/c it gets me out of the pilot circuit.

This means I still need to do a little work on my pilot screws so I think I have a few rounds of plug chops coming. First time doing plug chops so this should be fun. I think I might post pictures of my plugs so my novice eye doesn't misinterpret them.

I am still wondering how much the 2mm float bowl height difference might make. I think I set my floats at 26mm but several sources say 24mm.

[renobruce]

set them at 24mm with the gasket removed, measuring to the highest point on the float.