GS750 running way to rich no matter what I adjust

[7981GS]

This should shed some light on the subject...



Eric

[bubby]

this is awesome and very helpful

[allojohn]

You mention carb rebuild kits, these are known to be of poor quality. Likely there is nothing wrong with the original jets, they just need cleaning along with the the carb bodies (24 hrs in Berrymans) and a new set of o-rings.

Again, check the engine # to make sure you have the right jets, the '77 had two different main jets depending.

+1 on getting your machine running properly before jetting up and installing pods. You could have a right old mess on your hands if you rush things.

EDIT: Just read Eric's post, yep you've got the wrong jets.

[BassCliff]

Hi,

Everything is stock, the rebuild kit for the carbs were #102 main #15 pilot jets

BUT HERES SOMETHING FUNNY

its not all cylinders that are running rich, only the 3 & 4 cylinders.

Agreed. "Carb kits" are known to have inferior quality parts. You are much better off cleaning the jets, needles, etc, and re-using the stock parts. If you must replace a part use OEM parts. All you should need is an O-ring kit from http://cycleorings.com and a gallon of carb dip.

The boots to the airbox are not airtight at the airbox should I seal that?

The entire air intake system needs to be air tight so that it draws in air only from the intended orifices. Any extra air will wreck havoc with the air/fuel ratio.

Airbox Sealing
(by Mr. Roostabunny)
(CLICK HERE to download as PDF)

Air Intake Repair: (PDF file)
Airbox removal, intake boots and O-ring replacement

Also see:

Suzuki GS Series Carb Specs

Do you have the stock Mikuni jets installed? Do you think you might have Dynojet parts? Can you tell the difference? The Mikuni part has a logo that looks something like a square within a square. They Dynojet part has only the number.



This is a picture of stock stuff. The DJ needle has a much sharper taper.

Thank you for your indulgence,

BassCliff

[hampshirehog]

sry if i may have missunderstood you

102s do exist they are what where in the vm26ss i just purchased
that came off a 78 gs 750 and i know this sounds like a dumb question and may have nothing to do with your problem but are the carbs synced?

No, you're right. I should have been clearer. Mikuni 102 jets don't exist. And a GS750 in standard fettle wears Mikuni carbs - and they probably have 102.5 mains (some of them don't - depends on the engine number).

[xenoz]

The original jets were drilled out by the PO to get it running. I know him personally and didn't find out until after I paid him. That's why I bought a rebuild kit in the first place.

I think I have the dynojet rebuild kit because the needles are alot sharper and brass.

The carbs are synced, first thing I did after the rebuild. Then I put the colortune on it and have been trying to tune em since.

The airbox sealing might be why I have different readings on my plugs because the 1&2 boots have a better seal.

Ordered the 'right' (size 100 from jcwhitney) jets. I hope they work out.

I only want to put pods on for looks really.

What I would like to do is fab a cleaner/slimmer airbox and run the standard airfilter.

Also where is my engine number?

[allojohn]

If you're using carbs off a '78 750 then the engine # doesn't matter. You should have a Mikuni 100 main, although mine had a 102.5 in there before I re-jetted for pods.

[xenoz]

I'm not using carbs from a 78

[allojohn]

I'm not using carbs from a 78

Sorry, that was bubby's post. DOH!

[allojohn]

Engine # location.

[bubby]

a local vintage enthusiast and i have talked about pods and velocity stacks for some time i found taping the pods 3/4 of the cone and then putting a pre charger or filter cover on hides the tape and restricts air flow he is a machinist so had to 1 up me by machining a disc that fits in the carb with a whole cut out near the bottom and his theory worked well with the velocity stacks he used on his 1100 both of these methods where tried with no jet changes as far as the size of the whole in the disk would vary from engine to engine and im not sure what size his is. i like taping better because its easier to tune take some tape off or put it back on and cover it with a filter bag or precharger when i tape mine i tape it once with the sticky side up and again with the sticky side down so i dont get sticky stuff stuck to the filter element. i was wondering what you gsers think about these theory's since you are all knowledgeable and i respect your opinion

[xenoz]

I got the new jets today and they are genuine mikuni 100s

Tomorrow I'll go for a put and post pics of the plugs.

I sealed the airbox as well

[oldmandave]

taping your pods ? seriously ?

just buy a jet kit, or keep your airbox.

[Big T]

a local vintage enthusiast and i have talked about pods and velocity stacks for some time i found taping the pods 3/4 of the cone and then putting a pre charger or filter cover on hides the tape and restricts air flow he is a machinist so had to 1 up me by machining a disc that fits in the carb with a whole cut out near the bottom and his theory worked well with the velocity stacks he used on his 1100 both of these methods where tried with no jet changes as far as the size of the whole in the disk would vary from engine to engine and im not sure what size his is. i like taping better because its easier to tune take some tape off or put it back on and cover it with a filter bag or precharger when i tape mine i tape it once with the sticky side up and again with the sticky side down so i dont get sticky stuff stuck to the filter element. i was wondering what you gsers think about these theory's since you are all knowledgeable and i respect your opinion

Sounds like a lot of redneck engineering to obatain the airflow engineered into the stock airbox

[Steve]

Sounds like a lot of redneck engineering to obatain the airflow engineered into the stock airbox

True, but they will have that all-important "look" of the pods.

.