Adjusting Idle Mixture

[rapidray]

I would also replace the airbox to carb boots if they aren't soft. Ray.

 

[Chris P]

They are still pliable, when i bought the bike, the guy mentioned he had just changed the boots. Could you point me in a direction of a diagram of the carbs, Im just trying to associate the vocabulary you used earlier with some images of what those pieces look like.

 

[tom203]

Yeah, replace those boot o-rings- they probably no have longer a round crosssection, i.e. they won't seal well!

Look at this pic -lots of hiding places for goop.( note that the idle/air mixture screw on upper left is not marked.)
Nessism's tutorial spells out the specifics-

 

[Chris P]

hey ray, I know its been a little while but I finally got around to breaking down the carbs and soaking them and the parts for 24 hours. I pulled out all the "replacement kit" parts and i have installed the originals. I replaced the o-rings on the boots and im getting ready to gang the carbs back together. i have the air/mixture screws turned out 2 turns. I've inspected the air box and it seems pretty well sealed up. Before i put these carbs back into position, is there anything else I should take care of while this space is open? Any other suggestions to get this girl running would be appreciated as well. Starting to get warm in this area and Im getting antsy. Thanks in advance.

 

[eil]

I'm not Ray but it sounds to me like you're on the right track.

 

[Chris P]

Thanks eli, Im just sitting down to bench sync them right now. Doing a bit of reading on the forum on the appropriate steps. Have you done this before on yours? Thats probably a dumb question. Im wondering if this is right: Carbs 1,2,4 the butterfly valve is open just enough so I can see the first hole at the top of the inside of the carb. Carb 3, is completely closed. The throttle screw is backed off completely. Does this sound right?

 

[Ms Mitchell]

Thanks eli, Im just sitting down to bench sync them right now. Doing a bit of reading on the forum on the appropriate steps. Have you done this before on yours? Thats probably a dumb question. Im wondering if this is right: Carbs 1,2,4 the butterfly valve is open just enough so I can see the first hole at the top of the inside of the carb. Carb 3, is completely closed. The throttle screw is backed off completely. Does this sound right?

Did you get her running good? Im in the process myself of deep cleaning my carbs.

 

[Chris P]

Honestly, No. The carbs are clean as a whistle and soaking them each for 24hrs was without a doubt the way to go. Ive replaced the seals around the engine boots as well. Im starting to think the bike doesnt like me. She still will not start up right away. She eventually gets going and when I begin to do the adjustments she usually stalls out. I think the next thing im going to do is adjust the valve shims. If that doesnt work, you'll see another post on the forum for more help, and knowing the people that are on here, Im sure to get some. Good luck with your carb rebuild and I hope you have better like than I do.
Cheers

 

[JTGS850GL]

Adjust the valves first before you waste time trying to get it running right. GS's are very sensitive to valve adjustment and will not run correctly if any of the valves are too tight.

After that, you should have read this:

CV carb rebuild tutorial

If you didn't do it EXACTLY per the manual then rebuild the carbs again. Make sure you adjusted the float heights correctly without the float gaskets in place using an accurate gauge.

Second, you didn't do the bench sync correctly. You need to adjust carb #3 using the idle adjustment screw just enough that a paper clip will slide through with just a slight amount of drag. Then adjust carbs 1,2 and 4 to match #3.

Once started, you need to allow it to warm up. Once warmed up, you need to do a proper vacuum sync using a 4 carb sync tool. Adjust the idle to around 1500 to 2000 RPMs when doing the sync with the choke off. After the sync, adjust the idle to around 1100 RPMs.

All of this should be done with the air filter in place and the airbox all sealed up.

 

[Chris P]

Thanks for the to do list. Im looking into the valves shortly, was wondering if i should purchase the "real gasket" or the stock cardboard one, also do you think its a good idea to order new half moons (dont know the actually term for these but thats what they look like)?

 

[Steve]

i have the air/mixture screws turned out 2 turns. I've inspected the air box and it seems pretty well sealed up. Before i put these carbs back into position, is there anything else I should take care of while this space is open?

Whenever I have rebuilt a set of carbs (and I have done dozens), I start with the mixture screws out 3 full turns, not 2. After the bike is warmed up, you will adjust each screw until it gives you the highest idle speed possible. They might end up in the 2 to 2 1/2 turn range, but starting at 2 turns might be just a bit too lean to run properly, and you still won't think you have it right. Starting with 3 turns is like having the "choke" partly ON, it gives it a richer mixture, making it easier to start.

Thanks eli, Im just sitting down to bench sync them right now. ... Im wondering if this is right: Carbs 1,2,4 the butterfly valve is open just enough so I can see the first hole at the top of the inside of the carb. Carb 3, is completely closed. The throttle screw is backed off completely. Does this sound right?

No. Don't worry about the first hole at the top of the inside of the carb.
Don't worry about using a paper clip, either.
Adjust the master idle speed knob until you see a very slight sliver of light under the butterfly. Turn the center sync screw until you see a sliver the same size under carb #2. Then do the same thing with the left sync screw to get the same-size sliver under #1. Finally, adjust the right screw to adjust #4. Here is what you are looking for:

Note the light under the butterfly. When you can operate the idle speed control and see that ALL the butterflies close at the same time, you have done a good bench sync. Turn the idle speed in a couple of turns and put the carbs back on the bike.

Keep in mind that #1 is always the LEFT carb, and the LEFT carb is always on the LEFT side of the bike as if you were sitting on it, ready to ride.

Thanks for the to do list. Im looking into the valves shortly, was wondering if i should purchase the "real gasket" or the stock cardboard one, also do you think its a good idea to order new half moons (dont know the actually term for these but thats what they look like)?

I tried the Real Gasket on one bike, but sold it soon after, so I don't know how well they really work. I have had no problems with the stock 'cardboard' gaskets. Just use a light film of oil or grease on them, they will come off easier at your next valve clearance check and can be re-used several times. New half moons are a good idea if you have just gotten the bike. They are cheap insurance.

If you do decide to go with a Real Gasket and new half moons, install the half moons (with a thin film of RTV on the curved surface only) and then install the valve cover with no gasket at all. You only need to install the outer bolts, snug them down to clamp the half moons into place overnight. When the cover is removed, the half moons will be sitting flush with the head, and will not leak right at the corners. A cardboard gasket will push them into place right away, a Real Gasket will not be installed with enough force to do that, so take your time, do it right.

.

 

[Badooka]

Thanks for the to do list. Im looking into the valves shortly, was wondering if i should purchase the "real gasket" or the stock cardboard one, also do you think its a good idea to order new half moons (dont know the actually term for these but thats what they look like)?

Real gasket was a waste of 25$ for me. They would not refund or issue a partial.
Use the OEM and never worry about leaks.

 

[Chris P]

Thanks for all the info. Im going to order the stock gasket but there seems to be a question of 16 holes or 17 holes. This is a picture of where my tach comes in. Can anyone tell me if i need the 17 hole pattern. Obviously when i count the bolts there is only 16, but Im not sure if a hole is required for the tach thingy. Sorry, Im new.
Also dont know why the pic rotated but it should be rotated 90 clockwise, hopefully that helps
Cheers

 

[JTGS850GL]

16 bolt. The tach has nothing to do with it.

 

[Steve]

Thanks for all the info. Im going to order the stock gasket but there seems to be a question of 16 holes or 17 holes. This is a picture of where my tach comes in. Can anyone tell me if i need the 17 hole pattern. Obviously when i count the bolts there is only 16, but Im not sure if a hole is required for the tach thingy.

If you count 16 bolts, then that is what you have.

The question is not "holes", but "bolts". :-\\\

Sorry, Im new.

Yeah, we're sorry you're new, too.

Also dont know why the pic rotated but it should be rotated 90 clockwise, hopefully that helps.

Did you take the picture with an iPhone, iPad or other device that auto-rotates a picture? :-k

It knows which way is 'up', but doesn't bother to tell that to a REAL computer.

.

 

[Chris G]

Adjust the valves first before you waste time trying to get it running right. GS's are very sensitive to valve adjustment and will not run correctly if any of the valves are too tight.

This is the way to go, I was chasing a poor idle / lean running issue did the clearances made it a much easier process after they were sorted, idle now sounds very good, blip the throttle and she drops back to idle no problem.

 

[Chris G]

Is that a plug lead in the pic? appears to be cracked / damaged

 

[Chris P]

Did you take the picture with an iPhone, iPad or other device that auto-rotates a picture? :-k

.

It was taken with an iphone, damn you Apple!!!!
Thanks for helping me sort out the hole/bolt situation there.

 

[Chris P]

Good to know it works. I feel like if this doesnt work, I dont know what else is left to do. Ill be sure to keep the thread updated.

 

[JTGS850GL]

Did you take the picture with an iPhone, iPad or other device that auto-rotates a picture? :-k

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