first time starting since carb rebuild/cleaning

[Wingsconsin]

crap. i forgot to plug the vacuum line.

This was going to be my suggestion about the #2 problem as I was reading through the thread. Even a small leak at the plug can and will mess up the synch process. Using a screw to plug the line can lead to a leak as the air moves down the threads of the screw... I like to use a GOLF TEE .. or some other like item as it plugs the line completely without leaks...

Looks like you are well on your way now.... :clap: :dancing:

 

[growler]

perfect. thanks!

Just add a little 3in1 or graphite oil to the throttle shaft where they go into and out of each carb. Should help things slide along better.

 

[growler]

i bought a small assortment of vacuum caps (line/tube caps, etc) from the auto parts place when i was picking up a new battery for my truck this weekend. 2 bucks, but got a bunch of different sizes. i'll try again, this time with it plugged.

This was going to be my suggestion about the #2 problem as I was reading through the thread. Even a small leak at the plug can and will mess up the synch process. Using a screw to plug the line can lead to a leak as the air moves down the threads of the screw... I like to use a GOLF TEE .. or some other like item as it plugs the line completely without leaks...

Looks like you are well on your way now.... :clap: :dancing:

 

[growler]

it's amazing how much better it ran with the vacuum line plugged.

hah! number 2 is firing and no wet tip anymore. for the first time since i've owned it the bike started fine on choke, and after warming up for about a minute was idling at 1000 rpms off choke without issues. i didn't have much time last night to do anything, but i did try using the highest idle method to set the air mixture screws. i couldn't really find that sweet spot. maybe my ears aren't accustomed to tuning them just yet, but after i set idle at 1300 and begin trying to work on the mix of #1, i was having a hard time hearing an obvious gain/loss in idle. maybe my lack of time rushed it. i was happy with a steady idle off choke with no random surges in idle.

maybe i'll vacuum sync since it's idling fine and then try to adjust the air mixture screws.

 

[Wingsconsin]

Baby steps towards enlightenment and success

Baby steps towards enlightenment and success

I have experienced the same issue with #2 during a carb synch and tuning - the vacuum 'plug' was leaking and it never came up to temperature like the others...once it was plugged -- much better

Our resident expert - STEVE - needs to come on here and explain his method of setting & tuning carbs using the vacuum synch as a guide. His theory is that the vacuum is highest when the carb is pulling properly and all the carbs are in synch. he can explain it a lot better than I ...

I watched him do it on my GS850 GL and it runs like it is brand new (maybe better) ...

 

[850 Combat]

That is a nice-enough tool (I kinda wish I had one :-\\\), but it will be "fun" trying to fit it on the center adjuster.




That tool is for reaching under the VM carbs (1979 and older bikes) to adjust the fuel screw. You won't need it for your bike.

.

You just remove the choke cable bracket.

I like it for my CV equipped bikes. Its much easier.

 

[Guest]

I accidently discovered you can use your synch tool to set the idle mixture screws. I had my synch gauge hooked up and was about to do the fastest idle method when I noticed the the levels were changing on the synch tool as I was working on it. So I more or less did an experiment with it. I went through each mixture screw and watch how it corresponded with the synch. Once I got the mixtures set pretty even then went on to synch the carbs. I've never heard that motor run that smooth before. Even new!

 

[Guest]

I accidently discovered you can use your synch tool to set the idle mixture screws. I had my synch gauge hooked up and was about to do the fastest idle method when I noticed the the levels were changing on the synch tool as I was working on it. So I more or less did an experiment with it. I went through each mixture screw and watch how it corresponded with the synch. Once I got the mixtures set pretty even then went on to synch the carbs. I've never heard that motor run that smooth before. Even new!

I've never used the synch gage to set idle, but it does sound interesting.

So you essentially turn each mix screw (one-at-a-time) until you achieve the highest level of vacuum with each carb? Then synch the carbs to each other using the butterfly adjusters?

Is that pretty much it?

 

[Wingsconsin]

Resident Experience Now Required

Resident Experience Now Required

Paging STEVE --- :-\\\

 

[Steve]

OK, I heard ya.

The idea is close, but the sequence needs to change.

1. Do a vacuum sync, get all the levels where they are supposed to be.

2. NOW, do a fine-tuning of the mixture screws.

The reason I feel the order is important is that if one cylinder is basically closed off on the vacuum sync (really high vacuum level), it is basically not contributing to the overall running of the engine, and it won't matter how much you turn the mixture screw, it won't make any difference. Do the vacuum sync first so you know that each cylinder is contributing to the overall running, then you can see the difference that each mixture screw will make.

The theory behind using the vacuum gauge to set the idle mixture is this:
The cylinder is trying to draw in a certain amount of air, the throttle is restricting it, causing a vacuum. If you can get the engine to run faster with the same throttle opening, the vacuum level will be higher. When you adjust the mixture screw to find that "happy" mixture, the engine will run faster, creating more vacuum. Please note that it will not just go up in that one cylinder. Since the whole engine is running faster, ALL the cylinders will show a higher vacuum.

.

 

[Guest]

OK, I heard ya.

The idea is close, but the sequence needs to change.

1. Do a vacuum sync, get all the levels where they are supposed to be.

2. NOW, do a fine-tuning of the mixture screws.

The reason I feel the order is important is that if one cylinder is basically closed off on the vacuum sync (really high vacuum level), it is basically not contributing to the overall running of the engine, and it won't matter how much you turn the mixture screw, it won't make any difference. Do the vacuum sync first so you know that each cylinder is contributing to the overall running, then you can see the difference that each mixture screw will make.

When adjusting the mix screws after the sync, is the end result they should all be at the same level ? I'm envisioning having one carb optimized at a certain vac level, while another (also optimized) is now at a different level. By optimized, I mean set to the highest vac level it can go.

Yes?

 

[Steve]

When adjusting the mix screws after the sync, is the end result they should all be at the same level ?

After the vacuum sync, all your vacuum levels will be basically the same. Yeah, the factory manual says to adjust the outer ones a little higher than the inner ones, but I don't know anybody that actually does that. Yeah, the levels will dance around a little bit with respect to each other, but the average heights will be consistent.

When you adjust the mixture screws, NONE of the butterflies are being moved, but ALL the cylinders are moving faster so ALL of the vacuum levels will move, pretty much the same amount and all at the same time. Stated another way, when doing a mixture adjustment, you will not see one vacuum level change and not the others.

I'm envisioning having one carb optimized at a certain vac level, while another (also optimized) is now at a different level.

After you do the vacuum sync, the only way to get one carb's vacuum level different from the others would be to re-adjust the sync screw. Once you have done the vacuum sync, leave the sync screws alone, only adjust the mixture screws. When the vacuum level changes due to mixture adjustment, ALL the vacuum levels will change.

.

 

[850GT_Rider]

After the vacuum sync, all your vacuum levels will be basically the same. Yeah, the factory manual says to adjust the outer ones a little higher than the inner ones, but I don't know anybody that actually does that. Yeah, the levels will dance around a little bit with respect to each other, but the average heights will be consistent.

When you adjust the mixture screws, NONE of the butterflies are being moved, but ALL the cylinders are moving faster so ALL of the vacuum levels will move, pretty much the same amount and all at the same time. Stated another way, when doing a mixture adjustment, you will not see one vacuum level change and not the others.


After you do the vacuum sync, the only way to get one carb's vacuum level different from the others would be to re-adjust the sync screw. Once you have done the vacuum sync, leave the sync screws alone, only adjust the mixture screws. When the vacuum level changes due to mixture adjustment, ALL the vacuum levels will change.

.

So, to re-state it for us fuzzy-headed ones.... We are following the principle and procedure of the highest-idle method, but using the VISUAL (vacuum level) in place of the AUDIBLE (listening to the rpm)?

You've found the vacuum method to be more precise?

 

[growler]

cannot wait to put these comments to work. is it 5 o'clock, yet?

thank you everyone, especially you steve.

 

[growler]

with my 82 gs850g(z) it appears i have a premuffler. so i'd be going for #2 and #3 to read approximately 1-2 cm Hg lower than #1 and #4?

if your experience has been that it doesn't matter, maybe i'll just make them level.

After the vacuum sync, all your vacuum levels will be basically the same. Yeah, the factory manual says to adjust the outer ones a little higher than the inner ones, but I don't know anybody that actually does that.

 

[GateKeeper]

and it will look like this......

joy of sync'd carbs

.

 

[Guest]

I've never used the synch gage to set idle, but it does sound interesting.

So you essentially turn each mix screw (one-at-a-time) until you achieve the highest level of vacuum with each carb? Then synch the carbs to each other using the butterfly adjusters?

Is that pretty much it?

Like I said, I was experimenting with this too see what it did. Seemed to work for me. I would watch the vacuum levels and listen to the engine as well. I kept playing with it until I found that "sweet spot" for each carb and went on from there. Engine was idling really smooth. Though after reading Steve's comment on the procedure, that makes alot of sense as well. All I can say is try it and see what your outcome will be.

 

[Guest]

So, to re-state it for us fuzzy-headed ones.... We are following the principle and procedure of the highest-idle method, but using the VISUAL (vacuum level) in place of the AUDIBLE (listening to the rpm)?

You've found the vacuum method to be more precise?

I used both RIDER. The vacuum method lets you know where the carbs are in relation to each other. Though remember I did the idle mixture first.

 

[growler]

gonna work on this today, and i'll post results. however, i don't have a morgan carbtune. i'll be working with this type of gauge. carbtune is on the list of things to eventually purchase.

 

[growler]

Well, I'll have to continue on this sync tomorrow. I don't think I'm using the gauges correctly. Anyway here's a video of progress.

http://youtu.be/zmTNqxlpSJQ