78 1000 carb specs

[shwaz]

i found this chart on basscliff's site but it doesn't cover 78. anyone know where 78 GS1000EC info can be found, or if any of the below is relevant?

 

[Steve]

I think the '78 was the same as '79, but won't guarantee it.

The '77 was just a bit different with the way the needle mounted and possibly different jetting.

.

 

[7981GS]

For one, I believe that at least the main jets were 97.5's. IIRC
Later years had increasingly tighter emissions.

Eric

 

[chuck hahn]

Theres a service manual at his bikecliff website.

 

[BassCliff]

Hi,

Not sure how much this will help but here's an entry from the carb spec sticky:

http://www.thegsresources.com/_forum/showpost.php?p=673066&postcount=82

This section of Mr. first timer's post may be most applicable, but I think this is for a modified intake/exhaust:

sudco recomends for the GS750/GS1000 (A12)
#115 mains
.9 air jet
#25 pilot jet
5dl31-3 needle
0.6 needle jet
2.0 throttle valve (cut away)

This manual (GS1000C/E/S/L Service Manual (67MB)) ("C" being the '78 model year) has these specs for the stock VM26SS carbs:

Pilot Air Jet: 1.2
Pilot Jet : #15
Cut-a-Way: 1.5
Jet Needle: 5DL36-3
Needle Jet: O-2
Main Air Jet: 1.5
Main Jet: #95
Float Height: 23-25mm
Fuel Level: 3-5mm

And that's about all the research I have for you.

Thank you for your indulgence,

BassCliff

 

[Agemax]

the 78 EC had 95 mains standard

 

[Guest]

Service Manual here, you'll find what you're looking for in the lower of page 2-5 and the upper part of page 2-6. Takes a little time to download.
http://www.mtsac.edu/~cliff/storage/gs/GS1000_C-E-S-L_Manual.pdf

 

[Big T]

The 78s are the same-95 main,15 pilot

 

[shwaz]

i can't find the numbers on a bunch of the parts, but i can see for sure that the jet needle is 5DL36-3, which is the bone stock setup.

this bike, however, has a kerker 4-1 and pods. (i haven't had it running, just got it). does this mean that work was neglected, or could it run fine with pods and 4-1 with that same needle?

 

[Nessism]

With VM carbs you can often use the stock needle after you raise it some amount (not sure how much).

 

[shwaz]

With VM carbs you can often use the stock needle after you raise it some amount (not sure how much).

does "raise it some amount" mean changing which clip it's using? cause this one is still in position 3, same as stock.

 

[Big T]

does "raise it some amount" mean changing which clip it's using? cause this one is still in position 3, same as stock.

Correct

Placing the clip closer to the needle tip raises the needle, allowing more fuel in

You may need a magnifying glass to see the numbers

 

[shwaz]

Hi,


This manual (GS1000C/E/S/L Service Manual (67MB)) ("C" being the '78 model year) has these specs for the stock VM26SS carbs:

Pilot Air Jet: 1.2
Pilot Jet : #15
Cut-a-Way: 1.5
Jet Needle: 5DL36-3
Needle Jet: O-2
Main Air Jet: 1.5
Main Jet: #95
Float Height: 23-25mm
Fuel Level: 3-5mm

And that's about all the research I have for you.

Thank you for your indulgence,

BassCliff

With VM carbs you can often use the stock needle after you raise it some amount (not sure how much).

this bike does have the stock needle, and in the stock clip position. does that make sense for a bike that has 4-1 and pods?




i'm fairly certain this is the pilot jet, but it clearly says 17.5 on it. that's confusing given the manual says the stock is #15. is this just #17.5 or am i missing something

please correct me if i'm wrong here. i think this is the main air jet

it looks like it says 125, which i'm guessing is 1.25, which is smaller than stock. does that make sense for a bike with a 4-1 and pods?





thanks for all the help. trying to take stock of what i bought here and figure out what i should replace while it's apart, rather than possibly putting it back together with the wrong stuff

 

[Guest]

You need to get the stock 15 pilot jet back in there. It doesn't change with 4-1 pipes and pods. A Dynojet stage three jet kit makes it a lot easier to dial in, and has a better taper on the needles for the application. You will also want to remove the vent hoses on either side of the petcock vacuum port.

 

[shwaz]

You need to get the stock 15 pilot jet back in there. It doesn't change with 4-1 pipes and pods. A Dynojet stage three jet kit makes it a lot easier to dial in, and has a better taper on the needles for the application. You will also want to remove the vent hoses on either side of the petcock vacuum port.

managed to pull a set of 15s out of an incomplete spare set of carbs, so i should be ok for the pilot jet.

I'm not clear what all you get with the Dynojet. I understand that the needles have a different taper than stock; other than that it looks like they give you a choice of two main jet sizes but I can't even see what sizes they are to make an informed decision. at $100 that sounds pretty pricey.

 

[Guest]

The Stage three jet kit is relatively expensive compared to Mikuni parts (they also have a different jet sizing system). They include the needles, two main jets, and some needle shims if I remember correctly. However, the smaller jet gets you right in the ball park for most motors and the needle is designed for the application. The Mikuni needle is not, so it may or may not be possible to get it to transition properly with some motors. Some have luck with it, but by the time you get it dialed in properly you might wish you had gotten the kit.

 

[Big T]

this bike does have the stock needle, and in the stock clip position. does that make sense for a bike that has 4-1 and pods?




i'm fairly certain this is the pilot jet, but it clearly says 17.5 on it. that's confusing given the manual says the stock is #15. is this just #17.5 or am i missing something

please correct me if i'm wrong here. i think this is the main air jet

it looks like it says 125, which i'm guessing is 1.25, which is smaller than stock. does that make sense for a bike with a 4-1 and pods?


thanks for all the help. trying to take stock of what i bought here and figure out what i should replace while it's apart, rather than possibly putting it back together with the wrong stuff

Okay, the bike was jetted up with 125 main and 17.5 pilot, that's fairly typical for pods ad a header.

Whether the needle gets raised depends on how well it runs when you put it back together

 

[shwaz]

pilot jet size + pointiness of pilot fuel screw

pilot jet size + pointiness of pilot fuel screw

so two people, two contradicting opinions

4-1 header, pods - put back the stock 15 pilot jet, or leave in the 17.5's the PO had in?

i guess i'm inclined to leave it as is with 125 mains and 17.5 pilot and see how it runs unless someone tells me the bike will explode if i do that.




another question: pilot fuel screws == pointy || !pointy ?

all 4 of the ones coming out of this bank of carbs are flat on the end. they look smooth, no file marks, but some are a bit bent at the tip as well.
i have 4 pointy screws from a set of salvage carbs which i can use instead, but they're not cleaning up that nicely despite being dipped.
- are there different sizes for these screws, or can i just swap those pointy ones in?
- is there a (good) reason why the ones in this bike are all smooth at the end?

photo: carb 1, carb 2, and an example of one of the four pointy (but cruddy) ones

 

[Big T]

so two people, two contradicting opinions

4-1 header, pods - put back the stock 15 pilot jet, or leave in the 17.5's the PO had in?

i guess i'm inclined to leave it as is with 125 mains and 17.5 pilot and see how it runs unless someone tells me the bike will explode if i do that.




another question: pilot fuel screws == pointy || !pointy ?

all 4 of the ones coming out of this bank of carbs are flat on the end. they look smooth, no file marks, but some are a bit bent at the tip as well.
i have 4 pointy screws from a set of salvage carbs which i can use instead, but they're not cleaning up that nicely despite being dipped.
- are there different sizes for these screws, or can i just swap those pointy ones in?
- is there a (good) reason why the ones in this bike are all smooth at the end?

photo: carb 1, carb 2, and an example of one of the four pointy (but cruddy) ones

Broken fuel screws are common in VM carbs - just swap the pointy ones in, or order up a new set from Z1 today, they're longer and can be turned without pulling the carb rack. They can b cleaned with some reducer, like CLR (try it on a broken one 1st)

Be sure and check the carb bodies for the broken screw tips. There's a tutorial on this on BassClifff's site

As far as your carb jetting goes, starting out too rich is preferable to too lean, so you're OK with what you've got to test it out.

 

[Guest]

The broken needles are your biggest problem at the moment. The number 1 fuel screw really bothers me. Make sure that one has not enlarged the tiny hole in the carb body. As Big T said make sure the tips are not still stuck in the carb body and replace them. It will run with a # 17.5 pilot jet, but I'll bet they were changed to compensate for the broken fuel screws. It's never going to run right as it is. You will also need # 15 pilot jets in there to get the fuel needles dialed in properly ( between 1 to 3/4 turns out from lightly seated running low speed plug color tests). The DJ kit also recommends the # 15 pilot jets. I do know that setup works nicely on my GS1000, but all motors are a little different. I would start with a fairly well known quantity and then fine tune from there. If tips are still stuck in the carb bodies, they are going to require another dip, to clean those passages. http://www.z1enterprises.com/ItemDetails.aspx?item=SIK-1157SK