GS1100e carb help (1982) (Dynojet kit)

[Guest]

I'm trying to restore a 1982 GS1100e. The carbs were modified by the former owner, but I'm not entirely sure what he did to them (or what else may have been done to the engine).

Short questions: What is the stock AIR JET for the 1982 GS1100e? Mine has #170 jets in it, but the former owner gave me a bunch of carb parts with #160 air jets.

Also, what is the stock hole diameter in the slide? I believe my slides were drilled per the directions of the Dynojet Stage 3 carb kit.

Thanks in advance. Introduction and more detailed information about this problem below.

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Hi folks. New to the forum here. For introduction, I'm 52, a former mechanic, and a longtime Suzuki fan. Current personal ride is a 2007 Hayabusa. Bought GS Resources member MetallicMetalGod's 1985 GS550e for my son. That bike runs great after a little carb work. Also have a 2007 Harley 1200 Sportster for my wife, a 1972 Honda CB350 in restoration, and a 1989 hotrodded Sportster mothballed until I get to it. That's just the current list, and the list of motorcycles from the past would be very long. As for my latest problem child.....

I bought a 1982 GS1100e for too much money mostly because it looked decently restorable and I always wanted one. The bike was barely running when I bought it. It has a V&H 4-into-1 exhaust and K&N individual pod filters. I thought it would be a simple carb cleaning to get this girl running, but should have realized the former owner was monkeying with it when he handed me a box of carb parts with all sorts of extra jets plus some D7EA plugs. That's a bad sign when the bike is not running.

Anyway.... I cleaned the carbs well and went through the Dynojet directions to reset everything to the "stock: positions, e.g., the Dynojet Stage 3 setup, which is intended for a bike with pipes and the K&N air filters. I figured those settings would be pretty sorted out and it would be best to start from there, especially since it barely ran the way the former owner had the carbs set up.

After cleaning a and returning to the Dynojet Stage 3 setup, the bike starts and idles ok. It revs to about 4000 rpm and sounds okay, but when you go up to about 5000-5500 it sounds like it's spitting and unhappy. She will rev a little higher, but it gets really bad and will start to fall off rpm as you open the throttle further.

There are two things I am not sure about:

1) The stock air jet size. This is the small air jet on the filter side of the carb, about 7 o'clock position. There is a #170 jet installed. The Dynojet instructions discuss installing different sizes, but generally recommends leaving it alone. There are #160 jets in my box of parts. WHAT IS THE STOCK SIZE, #160 or #170?

2) I'm assuming the ports (holes) in the bottom of the slides were drilled per the Dynojet instructions (Stage 3), but I don't have the drill in the box of parts. WHAT IS THE SIZE OF THE STOCK HOLE, or the size of the drill Dynojet supplies with their kit?

Last note: Air mixture screws were reset to the stock 2.5 turns out. They were set 3.5 turns out. Now that I'm thinking about it, this may have been set to accomodate the air jets currently installed.

Any help or advice will be appreciated!

[AJ]

Actually, I just found this on the carbs sticky for this forum:

1982 1100 EZ

Specs in mm.
Carb Type- Mikuni BS34SS
Bore Size-34 mm
ID# - 49220
Idle r/min - 1050 +/- 100 r/min
Fuel Level - 5.0 +/- 0.5
Float Height - 22.4 +/- 1.0
Main Jet - #110
Main Air Jet - 1.2
Jet Needle - 5D58
Needle Jet - X-1
Pilot Jet - #45
Bypass - 0.8, 0.8, 0.8
Pilot Outlet - 0.9
Valve Seat - 2.0
Starter Jet - #32.5
Pilot Screw - Pre-Set, Varies
Pilot Air Jet - #170
Throttle Cable Play - 0.5-1.0
Choke Cable Play - 0.5-1.0

I may set these carbs all the way back to stock configuration if playing with the mixture screw doesn't fix it. The only thing I won't be able to change (easily) is the drilled port in the slides.

[blowerbike]

do you have adjustable needles?
are you sure a st.3 kit was installed by the previous owner?
does it have dynajet mains...odd numbers and small in diameter?

[AJ]

do you have adjustable needles?
are you sure a st.3 kit was installed by the previous owner?
does it have dynajet mains...odd numbers and small in diameter?

Thanks, Blowerbike. My bad in writing my first post from memory. I am pretty sure it's a Dynojet stage 3 kit. The Dynojet comes with both Stage 1 and Stage 3 in the same box and all the stage 1 jets are in the box, the Stage 3 jets are installed, and, yeah, I think the jets are "odd numbers" like 143, but I don't remember exactly. The installed main jets match what is in the Dynojet directions. The low-speed jets are stock.

The needles are very tapered compared to the stock needles, and they really get skinny at the tip compared to the stock needles. Should flow a lot of fuel at WOT compared to stock.

The DJ instructions say put the needle clips at slot 3 from the top. The previous owner had them at 5 (raised needles). I put them at 3.

The DJ instructions say mixture screws at 2.5 turns out. The previous owner had them at 3.5 to 4 (they were not all set the same). I set them all to 2.5.

Any other thoughts?

[blowerbike]

if all the parts are dynajet parts for your year/make/model and you installed as per instructions and are still having problems then i'm not sure where to go after that.
there's a lot of good carb guys on here that should chime in throughout the day.
listen to the people on here that know and not to the guessers...
good luck.

[AJ]

if all the parts are dynajet parts for your year/make/model and you installed as per instructions and are still having problems then i'm not sure where to go after that.
there's a lot of good carb guys on here that should chime in throughout the day.
listen to the people on here that know and not to the guessers...
good luck.

Thanks again.

I'm pretty good with carbs, cleaning, adjusting, and generally getting them to run right, but modified carbs make me cautious. Generally, recognize a condition and make small changes until they are right. In this case I started with highly modified carbs and am not certain of all the modifications that were done.

For one thing, I don't really understand the drilling of the hole in the bottom of the slide. My guess is that it allows the pressure above and below the diaphragm to equalize more quickly. I'd appreciate it if one of our "carb gurus" might have a good explanation for this mod.

[blowerbike]

drilling the slide(air lift hole) lets it raise quicker or is it slower???
one of the 2....nothing more.

[AJ]

drilling the slide(air lift hole) lets it raise quicker or is it slower???
one of the 2....nothing more.

Umm, yep, that's what I figured too, but which one? LOL!

It sure would help to have a good diagram of this carb, one of those pics that shows the airflows, especially showing how each circuit works.

[koolaid_kid]

http://www.thegsresources.com/_forum/showthread.php?t=181463

[BassCliff]

Greetings and Salutations!!

Hi Mr. Ajay,

The suggested method of adjusting the idle mixture screws is to use the "highest idle method". You'll find an explanation on my little website along with some documentation for your bike.

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Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", "Top 15 Tips For GS Happiness", the Carb Cleanup Series, and the Stator Papers. All of these tasks must be addressed in order to have a safe, reliable machine. This is what NOT to do: Top 10 Newbie Mistakes. Now let me roll out the welcome mat for you...



Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

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Thank you for your indulgence,

BassCliff

[AJ]

Thanks to KoolAid and BassCliff for your advice and welcome.

Someone just linked me to a service manual for this bike responding to a post on the main forum. For general interest, I post the two following diagrams.

The first picture shows the low speed circuit. Here, air enters the air jet, routes across the pilot jet and takes the fuel and routes it up to the small ports modulated by the butterfly valve. So, putting a larger air jet in this port likely leans out the pilot circuit, and this can be compensated somewhat with the mixture screw (upper left corner). Since my bike is idling ok, I doubt that the air jet is negatively impacting that.

Looking at the second picture, you see two arrows on the right of each carb. The black arrow enters the oval port at the top of the carb and keeps pressure on the under side of the vacuum diaphragm. The white arrow is air flowing through the main body of the carb. As air moves underneath the slide, it creates a small vacuum (venturi effect) across the hole drilled in the bottom of the slide. The small curving white arrow coming out the bottom of the slide is air flowing out of the chamber inside the slide and above the diaphragm. This reduces pressure on top of the diaphragm and causes the slide to lift. So....

If you enlarge the hole in the bottom of the slide (per the Dynojet Stage 3 mod), it should let air out from on top of the slide more quickly, so that the slide raises more quickly when the throttle is cracked. When the throttle is chopped (closed), it should let air back in more quickly, letting the slide drop more quickly.

Thus, if the slide raises more quickly, the needle needs to let more gas out from the main jet, balancing the drop in air velocity that occurs from the slide raising more quickly.

With all that in mind, here's what I think is happening with my carbs. The low speed circuit is fine (it's idling). The mid-range is also ok, but as the throttle is cracked, the slide raises too fast, but there's not enough fuel to transition fully onto the main jet. Fattening the pilot circuit via the mixture screw may help a little here to provide more fuel through the transition from low-speed to high-speed circuits. Any thoughts?

[AJ]

here is the second figure. (are we limited to posting pics?)

[BassCliff]

Hi,

With all that in mind, here's what I think is happening with my carbs. The low speed circuit is fine (it's idling). The mid-range is also ok, but as the throttle is cracked, the slide raises too fast, but there's not enough fuel to transition fully onto the main jet. Fattening the pilot circuit via the mixture screw may help a little here to provide more fuel through the transition from low-speed to high-speed circuits. Any thoughts?

Raise the needles a notch or two. Some times you even have to use small washers for shims to get a "half notch" adjustment. Do some plug chops and read the plugs to confirm the mixture at 1/4, 1/2, 3/4, and wide open throttle settings.

See:

Plug Chops-Highest RPM Methods
(by Mr. tkent02 and Mr. psyguy)

CV Carb Tuning (Factory Pro)


Thank you for your indulgence,

BassCliff

[AJ]

Pretty much what I was thinking.

Thank you for your indulgence,
BassCliff

Thank you for your advice.

[koolaid_kid]

I am just finishing up a DJIII install/tune with my GPz. I had to purchase larger Mikuni pilot jets from Z1 b/c DJ does not include pilot jets in their kits. Although mine runs cleanly, the wideband indicates a lean condition on the pilots (I don't do chops, so I can't help you there). It is entirely possible that you are in the same boat.
Your stock pilots should be 45. (I just rebuilt a set of stock 82-82 1100E carbs and read it off the jet.)