Carb rebuild advice needed (Slides, needles, jets)

[Sporty]

When I first got the 1993 GS500E. running and before starting "the rehab" the bike ran crappy with lean popping and one cylinder was much weaker than the other (with even compression test)

I disassembled the carbs last night and found some issues. This is the first time I've opened this model/style of Mikuni I really don't know what is normal.

The slides are not the same or one was modified.
In the photo you can see the bottom is different. One has "nubs" around the holes
The other looks as it's been sanded with a sanding roll.



Does this matter? Is it a known mod to the slide?


The needles are completely different one is a bent alloy needle with one clip slot.
The other is a steel needle with multi slots.


In the carb kit came the Y492 needle.  I don't find that number anywhere else.



The carbs have 37.5/130 jets.  The bike has a K&N lunch box and a slip-on F1 muffler
From reading this forum and the wiki, I ordered 40/140 jets and picked up some #4 brass washers.

The kit came with 37.5/ 122.5 jets.

Does anyone know how the Y492 needle compares to what should be in there? Am I going to be pig rich with the needle and 140 jets?

Any help is appreciated! Any general advice for a good rebuild or links too! The thrash continues!

TIA

[Trwhouse]

Hi back,
Sorry for the hassles you have uncovered, man, but it's one of the hazards of used almost 30-year-old motorcycles. There's always a chance that someone has butchered or badly modified something and you won't know until you take things apart.
It's no fun.
I hope you at least bought it cheap. 
You know what I'd do?
I'd either find a replacement set of carbs in good condition from someone you trust (I just literally sold a set of these to another guy here on the board yesterday!) or you start ordering NEW Suzuki OEM parts and replace the stuff that's not right so you have it right from here on out.
I'd replace the needles, their clips, the little plastic washers and all the o-rings (the little tiny ones just under the black carb top --- wehich are likely missing since the person who worked on it before likely didn't replace them) and the float bowl gaskets, the air screw o-rings, the needle jet o-rings etc.
Then maybe buy new slides as well, but they will not be cheap.
I just bought all those o-rings to rebuild my 1991 GS500E carbs, and the orings and gaskets were under $50 with shippinf from PartsFish.com. They sell original equipment Suzuki parts.
Don't work with the junk parts you have.
Start with fresh parts and go from there.
And if you need them, I do have one more set of spare, correct 1989-2000 GS500 carbs that I was saving in case I ever need them. I'd be willing to sell them if you need them. You'd still need to buy o-rings and gaskets and new correct jets but you'd be starting with a good set of carbs.
Breathe man, this will be a journey.
Have you seen the great tutorials here on the site that help with this job???
They are very helpful.
I can post the links for you if you have not seen them.
Hang in there and do it the right way for less frustration, man.
Best wishes,
Trwhouse

[Sporty]

Hi back,
Sorry for the hassles you have uncovered, man, but it's one of the hazards of used almost 30-year-old motorcycles. There's always a chance that someone has butchered or badly modified something and you won't know until you take things apart.
It's no fun.
I hope you at least bought it cheap. 
You know what I'd do?
I'd either find a replacement set of carbs in good condition from someone you trust (I just literally sold a set of these to another guy here on the board yesterday!) or you start ordering NEW Suzuki OEM parts and replace the stuff that's not right so you have it right from here on out.
I'd replace the needles, their clips, the little plastic washers and all the o-rings (the little tiny ones just under the black carb top --- wehich are likely missing since the person who worked on it before likely didn't replace them) and the float bowl gaskets, the air screw o-rings, the needle jet o-rings etc.
Then maybe buy new slides as well, but they will not be cheap.
I just bought all those o-rings to rebuild my 1991 GS500E carbs, and the orings and gaskets were under $50 with shippinf from PartsFish.com. They sell original equipment Suzuki parts.
Don't work with the junk parts you have.
Start with fresh parts and go from there.
And if you need them, I do have one more set of spare, correct 1989-2000 GS500 carbs that I was saving in case I ever need them. I'd be willing to sell them if you need them. You'd still need to buy o-rings and gaskets and new correct jets but you'd be starting with a good set of carbs.
Breathe man, this will be a journey.
Have you seen the great tutorials here on the site that help with this job???
They are very helpful.
I can post the links for you if you have not seen them.
Hang in there and do it the right way for less frustration, man.
Best wishes,
Trwhouse

Thanks for the reply.

I found the main carb sticky, but all the photos are gone. I did check out the link provided, to another site with carb tutorial. 

I bought the bike cheap, but I'm trying to keep the whole project to $1k USD. Including new tires, chain and sprockets, brake pads and then a whole bunch of other used part. That and a LOT of elbow grease.

I'm running out of budget, so will have to try the carbs with the kits I have. Just wanting to know about some of the issues uncovered. If the carbs prove untunable (and they might) I'll have to go as you recommend.

[Sporty]

So I've looked at enough photos now and the slide on the left (with nubs) is correct. 

The one on the right has been modified to sort of fit.

The rest of the carbs look ok.  I need one slide. New is available from Suzuki, but I'd be happy with a good used one.

[The Buddha]

The nubs are the modification, and your thin needle is a DJ. Its like someone put a dj kit in 1 carb and forgot to put itin the other carb.
You need 1 stock slide - without nub, and 1 stock needle - not the one that has the super thin tip and US spec needles dont have adjustable e clip.
Shop around for a stock 89-00 carb rack.
Cool.
Buddha.

[Sporty]

Look at the difference between the slides when installed in the holders/guides. I doubt this could have would ever run properly.

[Sporty]

About the Y492 jet needles.

As far as I can tell, they are close to the Mikuni 5D8H. I measured them in a few spots,  top, bottom, and along the taper.

The carb kit is Taiwan made, and seems to be for the E-03 calibration. It had the 37.5/122.5 jets.
the quality seems good and it had a lot of parts. The only thing I had to buy extra was the little float tube seals.

E-03 (from the service manual)



This is the kit, seller had good feedback specifically on the carb kit quality.

[The Buddha]

Look at the difference between the slides when installed in the holders/guides. I doubt this could have would ever run properly.

What exactly are you referring to here ? Cos I am not seeing it - maybe its a camera angle or lighting issue that I cant see it.
Your lower slide seems to be sitting off the guide - the lower air opening seems larger - but you know that's just at idle right.

Now you had a DJ in 1 and a stock needle in the other right -

BTW I can almost bet I can get a 1 cyl DJ and 1 cyl mikuni jet carb rack working to be on the nose in every throttle position - or atleast within the margin of error in a stock carb rack guaranteed.
What I need is a pair of O2 sensors fitted right at the head - before that cross pipe and a few days of test time.
Now we set carbs identically cos its just easier to do that and not futz about with these random parts.

Anyway just buy a good known carb rack, your parts are going to cost you more than that anyway.

Cool.
Buddha/

[Sporty]

Look at the difference between the slides when installed in the holders/guides. I doubt this could have would ever run properly.

What exactly are you referring to here ? Cos I am not seeing it - maybe its a camera angle or lighting issue that I cant see it.
Your lower slide seems to be sitting off the guide - the lower air opening seems larger - but you know that's just at idle right.

Now you had a DJ in 1 and a stock needle in the other right -

BTW I can almost bet I can get a 1 cyl DJ and 1 cyl mikuni jet carb rack working to be on the nose in every throttle position - or atleast within the margin of error in a stock carb rack guaranteed.
What I need is a pair of O2 sensors fitted right at the head - before that cross pipe and a few days of test time.
Now we set carbs identically cos its just easier to do that and not futz about with these random parts.

Anyway just buy a good known carb rack, your parts are going to cost you more than that anyway.

Cool.
Buddha/

Misshapen opening and larger opening. That's with slide holders out on the bench. My thoughts were that difference will always be there.

Carbs are assembled with good used slides and complete rebuild kits. I'm into the carbs for $48 with all parts. Let's hope it works out. I'm way over budget now!

[Jhonesy]

Look at the difference between the slides when installed in the holders/guides. I doubt this could have would ever run properly.

I know this is an old thread, but how did you remove the slide holder/guides? And the main jet holder, also. Did you just pull them out?