Carb synch questions GS1150

[renobruce]

OK, so I only want to do this once! I'm ready to synch the carbs on the 1150 (stock, '85) after taking them off and cleaning them. I bought a mercury synch tool and I have the manual, and I just wanted to verify a few things first.

1. The manual says "A correctly adjusted carburetor has the steel balls in the NO 1 and 4 tubes at the same level, and those in the NO 2 and 3 tubes also at the same level, but lower by one half of the ball diameter than the NO 1 and 4 tubes (as shown)". OK they are compensating for the fact that 1 and 4 have #120 jets and 2 and 3 have #122.5 jets (right?). How much lower do I set 2 and 3 with my merc. guage? Or do I?

2. The manual is synching the carbs @1750 rpm only. I've read elsewhere to synch at idle and at a higher rpm. What is your advise?

3. The manual is saying the adjustment screws are for adjusting #2, #1, and #4 carbs, in that order. So everything is adjusted to #3? If that's true, then why would I need to adjust in that order? I thought I read somewhere that the screw on one side adjusts the pair (say, 1 and 2), the screw on the other side adjusts the other pair, and the one in the middle synchs the pairs. Do I follow the manual on this?

I know synching the carbs is needed and this is my first go at it. Thanks in advance for any advise you can give.

[renobruce]

I hooked up the synch guage, and as I suspected, they are way off. #1 is highest, #2, #3, and #4 go lower, lower, lower (like a ladder). Some answers to my original questions would be a big help right about now! THANKS!!!

[sv650]

Re: Carb synch questions GS1150

OK, so I only want to do this once! I'm ready to synch the carbs on the 1150 (stock, '85) after taking them off and cleaning them. I bought a mercury synch tool and I have the manual, and I just wanted to verify a few things first.

1. The manual says "A correctly adjusted carburetor has the steel balls in the NO 1 and 4 tubes at the same level, and those in the NO 2 and 3 tubes also at the same level, but lower by one half of the ball diameter than the NO 1 and 4 tubes (as shown)". OK they are compensating for the fact that 1 and 4 have #120 jets and 2 and 3 have #122.5 jets (right?). How much lower do I set 2 and 3 with my merc. guage? Or do I?

2. The manual is synching the carbs @1750 rpm only. I've read elsewhere to synch at idle and at a higher rpm. What is your advise?

3. The manual is saying the adjustment screws are for adjusting #2, #1, and #4 carbs, in that order. So everything is adjusted to #3? If that's true, then why would I need to adjust in that order? I thought I read somewhere that the screw on one side adjusts the pair (say, 1 and 2), the screw on the other side adjusts the other pair, and the one in the middle synchs the pairs. Do I follow the manual on this?

I know synching the carbs is needed and this is my first go at it. Thanks in advance for any advise you can give.

1) try about 0.5cm of mercury

2) trying to synch at a higher RPM will likely suck the mercury out of the guage.

3) Everything is synced to #3. Whille you can sync them in other orders, it is easiest to sync 2&3, then match 1 and 4 (or 4 &1).

SV

[Anonymous]

If anyone else has more suggestions, I too would like to hear them. Im going to be in the same situation with my GS1000 in the next month, and could use all the help I can get so I only have to do it once.

[KEITH KRAUSE]

Re: Carb synch questions GS1150

OK, so I only want to do this once! I'm ready to synch the carbs on the 1150 (stock, '85) after taking them off and cleaning them. I bought a mercury synch tool and I have the manual, and I just wanted to verify a few things first.

1. The manual says "A correctly adjusted carburetor has the steel balls in the NO 1 and 4 tubes at the same level, and those in the NO 2 and 3 tubes also at the same level, but lower by one half of the ball diameter than the NO 1 and 4 tubes (as shown)". OK they are compensating for the fact that 1 and 4 have #120 jets and 2 and 3 have #122.5 jets (right?). How much lower do I set 2 and 3 with my merc. guage? Or do I?

2. The manual is synching the carbs @1750 rpm only. I've read elsewhere to synch at idle and at a higher rpm. What is your advise?

3. The manual is saying the adjustment screws are for adjusting #2, #1, and #4 carbs, in that order. So everything is adjusted to #3? If that's true, then why would I need to adjust in that order? I thought I read somewhere that the screw on one side adjusts the pair (say, 1 and 2), the screw on the other side adjusts the other pair, and the one in the middle synchs the pairs. Do I follow the manual on this?

I know synching the carbs is needed and this is my first go at it. Thanks in advance for any advise you can give.

1) try about 0.5cm of mercury

2) trying to synch at a higher RPM will likely suck the mercury out of the guage.

3) Everything is synced to #3. Whille you can sync them in other orders, it is easiest to sync 2&3, then match 1 and 4 (or 4 &1).

SV

I agree with the 0.5 cm of mercury advice. Sounds about right if you want to follow your manual. Since the tools are different, I don't know how you could figure out something better. My factory manual for my '79 GS 1000 also shows the ball type synch method. My mains are all the same though.
Are you sure your mains came that way from the factory? I can understand your reasoning regarding the larger mains for 2 and 3 and the lower ball setting. But it seems strange that the factory would want a little richer mixture by using larger mains, and then tell us to lower the vacuum a little in those same two cylinders. Lowering the vacuum will make the jets draw less fuel, in effect, leaning the mixture (compared to the two outside cylinders). Also, the mains only regulate fuel flow at 3/4 throttle and above. This is not the throttle position you're using while synching. Anyway, I've never followed that "lower ball" procedure. I use the carb stick style of mercury vacuum tool. I've synched a lot of carbs and I just get all the levels to within 1 cm of each other. No problems.
As for what rpm to synch at, I adjust mine at 3,500 rpm. I spend more time riding around near that rpm than at idle or 1,750. Works for me and I've never had a problem with sucking mercury in. Just don't close the throttle quickly. Always back it off slowly.
I've never synched your model, but I would follow their suggested synching order. Why not? You have to do the same amount of work? If they all come out fairly even in the end, that's what's important.

[Anonymous]

Where do you find the carb sync tool and how much are they usually?

Also, which screw are you adjusting, and how hard is it to get to when its on the bike. I looked, and there isnt much space for anything!

[KEITH KRAUSE]

Where do you find the carb sync tool and how much are they usually?

Also, which screw are you adjusting, and how hard is it to get to when its on the bike. I looked, and there isnt much space for anything!

I use a "Motion Pro" mercury tool. About $40. You can find them everywhere. Dennis Kirk, Bikebandit? You'll also need a couple of fans to cool the motor, especially when you're just learning to synch.
You have to remove the tank and take off the top covers on the carbs.

[Anonymous]

I use a "Motion Pro" mercury tool. About $40. You can find them everywhere. Dennis Kirk, Bikebandit? You'll also need a couple of fans to cool the motor, especially when you're just learning to synch.
You have to remove the tank and take off the top covers on the carbs.

Alright, after actually READING my factory manual I now have an idea, but I have a few questions.

1. What is the "special tool" I need to adjust the throttle valve adjusting screw?

2. Does the synch tool come with adapters to plug into the manifold to get the vacuum? If not, where do I get them?

[Dink]

Yes it is supposed to have #120 in the number 1 and 4 carbs , and #122.5 in number 2 and 3, you DO NOT need to remove the carb tops.
The CV carbs are adjusted via screw and locknuts between each carb, you can purchase a "special tool" to use on the se adjusters (Suzuki part number 09913-14911, $29:49 at http://www.ronayers.com/main.cfm) similar tools are available through most tool suppliers.
Dink

[KEITH KRAUSE]

Dink. DDman joined into this topic and he has a GS1000, which requires the carb tops be removed to get to the adjusting screws.
DDman. The adjustment can be made with a slotted screwdriver and a 8mm wrench. Yes, the adapters come with the tool. If you use your removed gas tank to supply fuel while synching, I suggest buying about 30" of 5/16" and 3/16" clear fuel line to supply fuel and vacuum. You can also cap the vacuum at #3 carb and put the petcock on "prime" to get one hose out of your way.

[renobruce]

Thanks, guys. I'll go get after the synch. Hey, one more question. The manual seems to be using the throttle stop screw to set the RPM prior to synching. If I synch at 3500 RPM, do I use the throttle stop screw or the throttle on the handlebars, or does it matter?

[Anonymous]

Ya...sorry to cause any confusion between the GS1000/GS1100

I thought they were similar enough, but at least now I have a good idea as to what Im gonna have to do.

Thanks!

[Anonymous]

Thanks, guys. I'll go get after the synch. Hey, one more question. The manual seems to be using the throttle stop screw to set the RPM prior to synching. If I synch at 3500 RPM, do I use the throttle stop screw or the throttle on the handlebars, or does it matter?

It probly doesnt matter, I would assume using the stop screw would be easier with 1 person because u can do it without keeping your hand on the throttle AND the synch tool at the same time. If you had a friend it would probly be doable without messing with the stop screw.

[mpogue]

Where do you find the carb sync tool and how much are they usually?

I'm planning to do exactly the same on my GS1150EFF. I've been looking around for a carb synch tool (technical term is manometer from what I've read) and have decided on a Morgan Carbtune II. http://www.carbtune.com They're priced at ?52 GBP which is about $96USD or $130 CAN. They also sell the carb tool for ?8 ($15USD). They're made in Belfast, Ireland, so shipping is extra of course.

I don't know what its like to get something shipped internationally in the US, but in Canada you get nailed an extra $25 min. for Customs handling. I've learned how expensive my parts have become. Lucky for me, I have a neighbour going to Belfast at the end of the month and is willing to pick one up for me.

Does anybody know off hand the size of the nut used on the throttle valve adjust screw? I can order one from my dealer, but I also can get one from Morgan. They say its for an 8mm nut. I haven't priced one from my dealer yet, hope to this weekend.

[renobruce]

The nut is 8MM. I bought my mercury manometer at the Suzuki dealership... $39.99. Made by Motion Pro.