1980 GS1100, odd mods by PO

[Guest]

Hey everyone, I'm new here. I just picked up a 1980 GS1100E from a college student who got it from his uncle. He didn't know a thing about bikes, never touched it, and sold it to me since he found a job in maryland.

Anyways, the gas tank was left with gas sitting in it for a long time. The liner is peeling off quite badly, and there is a little bit of surface rust. (I'm thinking of dipping the entire thing in muriatic acid?)

The PO installed a 4-into-1 V&H exhaust, a k&n drop in filter, and took off the airbox cover while not changing the jetting. I disassembled the carbs, dipped them, replaced the o-rings and plan on using a 122.5 main for that setup.

Now I don't know much about the petcock setup on this bike, but the PO has blocked off the fuel return line to the tank (pardon my ignorance) with a screw. Would this yield any benefits?

TL;DR - PO blocked off carb fuel return line, what's the point?

[tom203]

Do you have a petcock without a lever ? (I hope not !).That blocked off line is a vacuum connection that automatically (in theory) allows fuel to flow from petcock just when engine is running. Maybe PO thought it was leaking, but the leverless petcock needs coaxing to get going ,so if it is leverless someone might have fiddled with its innards .

[posplayr]

Hey everyone, I'm new here. I just picked up a 1980 GS1100E from a college student who got it from his uncle. He didn't know a thing about bikes, never touched it, and sold it to me since he found a job in maryland.

Anyways, the gas tank was left with gas sitting in it for a long time. The liner is peeling off quite badly, and there is a little bit of surface rust. (I'm thinking of dipping the entire thing in muriatic acid?)

The PO installed a 4-into-1 V&H exhaust, a k&n drop in filter, and took off the airbox cover while not changing the jetting. I disassembled the carbs, dipped them, replaced the o-rings and plan on using a 122.5 main for that setup.

Now I don't know much about the petcock setup on this bike, but the PO has blocked off the fuel return line to the tank (pardon my ignorance) with a screw. Would this yield any benefits?

TL;DR - PO blocked off carb fuel return line, what's the point?

Bike looks nice, but a larger picture we would be able to confirm that fact for you(hint hint)

Sounds like about the right thing on the jetting. By the time you go to PODS4:1 you would need the DJ132 with a 47.5 pilot jet. There is a guy now posting with a 83 GS1100ED (more lift on the intake cam) and at sea level he is lean running the DJ132. So he should probably go to the DJ138.

So if anything without pods, the 122.5 might even be a little rich but let us know.

[mrbill5491]

Hey everyone, I'm new here. I just picked up a 1980 GS1100E from a college student who got it from his uncle. He didn't know a thing about bikes, never touched it, and sold it to me since he found a job in maryland.

Anyways, the gas tank was left with gas sitting in it for a long time. The liner is peeling off quite badly, and there is a little bit of surface rust. (I'm thinking of dipping the entire thing in muriatic acid?)

The PO installed a 4-into-1 V&H exhaust, a k&n drop in filter, and took off the airbox cover while not changing the jetting. I disassembled the carbs, dipped them, replaced the o-rings and plan on using a 122.5 main for that setup.

Now I don't know much about the petcock setup on this bike, but the PO has blocked off the fuel return line to the tank (pardon my ignorance) with a screw. Would this yield any benefits?

TL;DR - PO blocked off carb fuel return line, what's the point?

There is no fuel return line, so it has to be the vacuum line from the #2 carb to the petcock or he has blocked off the overflow line from the tank. Your carbs also have two vent lines that route to under the seat. You do have the ick leverless vacuum petcock (pain in the butts they can be). As far as the 4into1, and drop in K&N filter, all I would do is up the main jets and put the air box cover on and not mess with pods. I have the same set up on my 750, 4into1, drop in K&N, and upped the jets. Runs just fine. Just make sure all the rubber boots are sealing up along with the air box. Air leaks can be quite the problem. Oh yeah don't forget to set the idle mixture and do a sync on the carbs. What about the valves, any idea when they were last adjusted? If not do them as well.

[DFWSpeedster]

There is no fuel return line, so it has to be the vacuum line from the #2 carb to the petcock or he has blocked off the overflow line from the tank. Your carbs also have two vent lines that route to under the seat. You do have the ick leverless vacuum petcock (pain in the butts they can be). As far as the 4into1, and drop in K&N filter, all I would do is up the main jets and put the air box cover on and not mess with pods. I have the same set up on my 750, 4into1, drop in K&N, and upped the jets. Runs just fine. Just make sure all the rubber boots are sealing up along with the air box. Air leaks can be quite the problem. Oh yeah don't forget to set the idle mixture and do a sync on the carbs. What about the valves, any idea when they were last adjusted? If not do them as well.

Here is the location of the blocked off line and a picture of the petcock. I've learned the hard way with pods on CV carbs, so I'll stick with the airbox for now.

[DFWSpeedster]

Bike looks nice, but a larger picture we would be able to confirm that fact for you(hint hint)

Sounds like about the right thing on the jetting. By the time you go to PODS4:1 you would need the DJ132 with a 47.5 pilot jet. There is a guy now posting with a 83 GS1100ED (more lift on the intake cam) and at sea level he is lean running the DJ132. So he should probably go to the DJ138.

So if anything without pods, the 122.5 might even be a little rich but let us know.

I got the 122.5 from a V&H 4-into-1 instruction sheet I remember looking at, I believe it said to remove the airbox lid and run a 122.5 main. However, I could be wrong

Also, updated the OP with a bigger picture!

[Big T]

That's an aftermarket petcock, probably a Pingle

[Katarat]

Same bike & setup, with the airbox top off I run 115 Mikuni jets {dynojet jets are not the same number to number as mikunis are } and 3 turns out on the mixture screws and a dynojet needle set in the middle notch. Im at 3500 ft here though

[DFWSpeedster]

Same bike & setup, with the airbox top off I run 115 Mikuni jets {dynojet jets are not the same number to number as mikunis are } and 3 turns out on the mixture screws and a dynojet needle set in the middle notch. Im at 3500 ft here though

Hmmm, well I do recall now that when I cleaned the carbs the main jets were 114's. Is that the stock configuration?

[Carter Turk]

114 sounds like a DJ size, where the Mikunis come in 2.5 increments from what I've seen over the years. Maybe the PO installed a DJ stage 1 kit, but since the sizing is different between the two, that 114 might be closer to a 110 Mikuni or less. No expert here though. Can't remember what stock 1100 jetting was-107.5? I think I ran 115 Mikunis, shimmed the stock needle, drop in K&N with lid off and RC Engineering 4-1 on my 80 1100ET.

[Steve]

Dynojet 114s are the same size as Mikuni 107.5.

The stock main jet on the '80/'81 1100E was 107.5.

Would you mind translating "TL;DR" into English, please?

.

[Griffyn]

Would you mind translating "TL;DR" into English, please?

.

Too Long; Didn't Read

Internet shorthand for 'if you're either functionally illiterate or can't be arsed, here's a summary.'

[Katarat]

114 is not a Mikuni size, it is a Djet size. Mikuni would be 112.5 then 115 then 117.5

[Steve]

Too Long; Didn't Read

Internet shorthand for 'if you're either functionally illiterate or can't be arsed, here's a summary.'

Interesting that those letters appeard at the END of a lengthy post.

.

[lonerider00]

That's not a vacuum petcock, nor is it a fuel return line. The line from the carb that's blocked off is the vacuum that would activate the stock petcock. Since you don't have a vacuum petcock, don't worry about it.