carb confusion - My head hurts

[swedge61]

I just received a set of carbs from 3btc. He answered my plea for a number 2 carb for my 83 gs1100gk after I broke mine removing the float pin. Thanks Bryan.
Here is my questions (I have searched but still confused):
1. Is there anyway of determining what carb body you have if the numbers on the side of the number 4 carb is no longer there?
2. The carbs look alike but the air screws look different. The ones from my bike do not have a hard shoulder but taper gradually and have a rounded point. The ones in the carbs I recieved have a shoulder on them and have sharper point on them. Will both work in my carbs? My carbs were rebuilt by the previous owner, so I don't know if things are correct.
3. How do I determine if I have 170 air scews, 115 main jet, etc. Do I measure them or is it stamped on them.
As you can see I am lost here.
I am going to rebuild the carbs and check the valve clearance and possibly change the coils.
Thanks
Swedge61

[Steve]

1. sometimes the numbers are printed on the carbs. Also, sometimes they are worn off with cleaning or chemicals.

2. Your bike does not have "air screws", it has "idle mixture adjustment screws". They should have a very sharp, almost needle-like point on them.
I would recommend making sure they are all proper before trying to start the bike.

3. Again, you don't have "air screws", let alone size 170. The idle mixture adjustment screws are pretty much universal in the BS series carbs (like yours). The "pilot air jet" that lives in the carb intake (about the 8 o'clock position) could easily be a 170, the number will be stamped on the jet. The mains also have their sizes stamped on the jets. The "pilot fuel jet", the needle jet and the jet needle will also have their sizes stamped on them, you can compare them with the stock sizes in the carb sticky at the top of this forum.

.

[erw]

I just received a set of carbs from 3btc. He answered my plea for a number 2 carb for my 83 gs1100gk after I broke mine removing the float pin. Thanks Bryan.
Here is my questions (I have searched but still confused):
1. Is there anyway of determining what carb body you have if the numbers on the side of the number 4 carb is no longer there?
2. The carbs look alike but the air screws look different. The ones from my bike do not have a hard shoulder but taper gradually and have a rounded point. The ones in the carbs I recieved have a shoulder on them and have sharper point on them. Will both work in my carbs? My carbs were rebuilt by the previous owner, so I don't know if things are correct.
3. How do I determine if I have 170 air scews, 115 main jet, etc. Do I measure them or is it stamped on them.
As you can see I am lost here.
I am going to rebuild the carbs and check the valve clearance and possibly change the coils.
Thanks
Swedge61

I am no carb genius at all, so take this with a grain of salt, but... Shouldn't you be able to tell what carb it is by it's set up. Start with carb 1 looking at the air intake side, it should have just a throttle linkage and both a fuel line and vent line on its right side. Carb 2 will have the vacuum port, carb 3 will have the throttle linkages, and carb 4 will have the fuel and vent lines, but on the other side (left). Am I mistaken or should you not be able to instantly tell which carb you are looking at at all times?

[swedge61]

Thanks Steve, apparently when the carbs were rebuilt before they put in a different idle mixture adjustment screw. The points are round not pointed. I will check the part numbers after I dip the carbs. Now I am suspicious of the parts replaced in the last rebuild.
Thanks again
Swedge61

[swedge61]

ERW, There is suppose to be a number printed on the number 4 carb that indicates what carb set you have. Mine has been removed due to cleaning of the carbs. I was curious if there was another way of to figure out what carb set I have so I could check the carb specs to see if I have the correct parts in the carbs.
Swedge61

[erw]

ERW, There is suppose to be a number printed on the number 4 carb that indicates what carb set you have. Mine has been removed due to cleaning of the carbs. I was curious if there was another way of to figure out what carb set I have so I could check the carb specs to see if I have the correct parts in the carbs.
Swedge61

O I C... I guess you could measure the output sizes with a micrometer to make sure you at least have the correct size, then you would know a little more... I know my bike has CV 34's on them. You could also try and backwards deduce by your main size, needle, etc... Sorry for the misunderstanding. I just rebuilt my carbs a week ago, so it is fresh on my mind if you have any questions...

[erw]

I just received a set of carbs from 3btc. He answered my plea for a number 2 carb for my 83 gs1100gk after I broke mine removing the float pin. Thanks Bryan.
Here is my questions (I have searched but still confused):
1. Is there anyway of determining what carb body you have if the numbers on the side of the number 4 carb is no longer there?
2. The carbs look alike but the air screws look different. The ones from my bike do not have a hard shoulder but taper gradually and have a rounded point. The ones in the carbs I recieved have a shoulder on them and have sharper point on them. Will both work in my carbs? My carbs were rebuilt by the previous owner, so I don't know if things are correct.
3. How do I determine if I have 170 air scews, 115 main jet, etc. Do I measure them or is it stamped on them.
As you can see I am lost here.
I am going to rebuild the carbs and check the valve clearance and possibly change the coils.
Thanks
Swedge61

The mains should be stamped. I know the stock ones are. It is a tiny screw with a hole in the middle directly above the fuel bowl. It will be stamped on the visual side, so you don't even have to remove it.

https://www.phatperformanceparts.com/photos/MikuniJets.jpg

That is what it will look like...

[erw]

I just received a set of carbs from 3btc. He answered my plea for a number 2 carb for my 83 gs1100gk after I broke mine removing the float pin. Thanks Bryan.
Here is my questions (I have searched but still confused):
1. Is there anyway of determining what carb body you have if the numbers on the side of the number 4 carb is no longer there?
2. The carbs look alike but the air screws look different. The ones from my bike do not have a hard shoulder but taper gradually and have a rounded point. The ones in the carbs I recieved have a shoulder on them and have sharper point on them. Will both work in my carbs? My carbs were rebuilt by the previous owner, so I don't know if things are correct.
3. How do I determine if I have 170 air scews, 115 main jet, etc. Do I measure them or is it stamped on them.
As you can see I am lost here.
I am going to rebuild the carbs and check the valve clearance and possibly change the coils.
Thanks
Swedge61

Sorry for continually posting but good news. You have BS34SS carbs stock, aka the EXACT carbs I have. I have a set on my bike and a set on my bench, which I will also be rebuilding, so I can get you a picture of ANY part you need. I know I had 115 stock mains, but unsure what you should have... According to your carb kit you have
"Kit includes:
includes float gasket; float needle and seat; 107, 115, main jets; 170 air jet; 45, 40 slow jet; air screw and spring; plug and misc"O" rings and packing as applicable"

[TheCafeKid]

Be aware that MANY of the GS's used BS34SS carburetors (the same size carb your GK SHOULD have on it) however they are NOT all the same jetting, nor will they have the same needles in the slides. The next larger or smaller size carb will be roughly 2mm smaller, so with a set of micrometers, you should be able to tell instantly by measureing the throat. Otherwise, there wont be much VISIBLE difference between a set of 32s and a set of 34s. 36's will have a different top to em. If you can, post up some pics of the ones you have vs what you got, we might be able to tell you more that way.

Also, if your mixture adjustment screws are ROUND, and have no point, then something is wrong, and you either bought, or were sent, the wrong rebuild kit (honestly, you dont NEED rebuild kits..they are a waste of money, and of poor quality) and they arent going to function correctly in your carbs. Hope you can get your money back on em

[swedge61]

I have 34s. The carbs were rebuilt by the previous owner. When I seen that the mixture screws had round tips not pointed like the ones in the carbs that were sent to me I became concerned that the po put in the wrong or a bad rebuild kit. I am in the process of rebuilding my carbs and am trying to make sure I put the correct parts back in it.

Swedge61

[swedge61]

I found another difference. Carbs on bike have a black throttle valve and the jet needle can be pulled down some like I am pulling against a spring. The extra set of carbs have a silver looking throttle valve and the jet needle can be pushed back up in the throttle valve like I am pushing against a spring.

The difference in the way the jet needle works cause the ones in the bike to be shorter since the spring pushes up and not down like the extra carbs. Which one is correct?

I have determined that the main jet is a 115, the jet needle is a 5D58, the needle jet is a X-3 and the pilot air jet is a 170. I can't figure out what piece is the Main air jet.
Swedge61

[Steve]

The main air jet is in the carb intake throat, just across from the pilot air jet. The pilot air jet is at the 8 o'clock position, the main air jet is at the 4 o'clock. It is also rather permanently installed, no real way to determine the size. The only time I have heard of anything being done to the main air jet is with some Dynojet kits, they have a sleeve that is pushed in there to make it a bit smaller.

About your jet needle and 'throttle valve': I think what you are calling a 'throttle valve' is actually the slide. The actual throttle valve is the butterfly that is just downstream of the slide. Not sure that the color matters all that much, but I have never seen anything but silver on GS carbs. (The carbs on my son's Yamaha do have black slides, though.) When the needles are installed, the spring goes in the hole first, which means that the needles get pushed UP, and you can pull them down a bit against the spring. Sounds like the ones in your black slides were installed correctly.

.

[swedge61]

Thanks Steve for the information. I will use the black slides, they are the same size as the silver looking ones as far as height and diameter. I used the term throttle valve for the slides because that was the name indicated in the how to rebuild a CV Carb pdf. I am getting most of my information there.
Hopefully this will be my last question but I doubt it. I am in almost over my head here.
Can I use wd-40 or a silicone spray on the rubber o rings when assembling the carbs? Also can I use either of those to help slide the carbs on the boot intakes?
Thanks again
Swedge61