Better info needed on how to sync.

[Yard Dogg]

Depending on how far off the mix screws are or how far off the sync is, you may have to RADICALLY change the idle screw mid way.....When doing 'Sunshines sync, i didnt really know what 'bench sync' meant...even after reading the posts....sooooo i did it anyway...my bench sync must be WAY different that the guru's, cuz it was "on" enuf to run, but "off" enuf to run like crap...but that coulda been cuz of the mix screws being WAY off... I got her started, set idle to around 1200 rpms.....shut her down, put color tune on #1. Plug showed evidence of being LEAN. backed screw out while running until blue color was present...idle went up to almost 1800 rms....had to back it down...Same story with #2. #3 was RICH..backed it down,and idle dropped a bit...#4 was lean also....idle went up. I set it back down... Hooked the guages to the carbs, and was relatively close. i dialed in the sync....then checked with colortune again...everything seemed okey dokey. Throttle response was smooth and exact. cant wait to get the brakes fixed to try it out!!!

Sorry TomRodgers, I had a hard time reading your message. I seemed to be a bit distracted

[Yard Dogg]

Well, last night I did some serious bedtime pondering. And I think I'll take a scientific approach to the bench sync. I know my engine is in great shape, but I only have a vacuum gauge to work with. Since my carbs are completely clean and fuel residue free, I'm gonna rig up a vacuum cleaner as my vacuum source to sync the carbs. I think this will be a much better approach because the vacuum will be consistent and to start with I can completely close off my pilot jets. I know I can get em dead on that way. Then I was thinking of rigging up a small suction cup to a vacuum line, putting the suction cup over the little port hole for the mixture screw, and adjusting them that way. That part is probably ridiculous but don't bash me, I just want to try it. Last thing I'll do is a fuel level check. I'll let you know how it all turns out in a few days.

FOR ANY OF YOU WHO WOULD LIKE TO TRY THE VACUUM CLEANER APPROACH TOO, DON'T DO IT UNLESS YOUR CARBS ARE COMPLETELY RESIDUE FREE AND CLEAN CLEAN! I once read of some poor 16 yr old kid who tried to siphon gas out of a car with a vacuum and blew himself up. Poor guy.

[cywelchjr]

Well, last night I did some serious bedtime pondering. And I think I'll take a scientific approach to the bench sync. I know my engine is in great shape, but I only have a vacuum gauge to work with. Since my carbs are completely clean and fuel residue free, I'm gonna rig up a vacuum cleaner as my vacuum source to sync the carbs. I think this will be a much better approach because the vacuum will be consistent and to start with I can completely close off my pilot jets. I know I can get em dead on that way. Then I was thinking of rigging up a small suction cup to a vacuum line, putting the suction cup over the little port hole for the mixture screw, and adjusting them that way. That part is probably ridiculous but don't bash me, I just want to try it. Last thing I'll do is a fuel level check. I'll let you know how it all turns out in a few days.

FOR ANY OF YOU WHO WOULD LIKE TO TRY THE VACUUM CLEANER APPROACH TOO, DON'T DO IT UNLESS YOUR CARBS ARE COMPLETELY RESIDUE FREE AND CLEAN CLEAN! I once read of some poor 16 yr old kid who tried to siphon gas out of a car with a vacuum and blew himself up. Poor guy.

This won't work! The point of the pilot screws is to adjust the mixture, and is NOT done by measuring vacuum. Then the sync is done with the screws BETWEEN the carbs, not on the carbs, and is specific to the engine they are on. The bench sync is only to get the butterfly valves as close as possible to the same, and has nothing to do with the pilot screws.

The point of carb syncing is to get all 4 cylinders pulling the same amount at idle, which will keep them pretty much even at all settings. You cannot do this off the bike with any chance of having it good enough to be done with, and you will spend far more time trying to use a vacuum cleaner and will still have to sync them on the bike, your going to have wasted your time.

[randy]

+1

A waste of time.

[Yard Dogg]

I'm sure your right. I know the fuel air won't work. But the throttle flaps will be adjusted better than my engine. Engine vacuum between 4 cylinders will vary and so will everything after that. I want to make sure the carbs are all pulling the same vacuum to begin with. The fuel air I will do by ear. I'm more experimenting with it at this point. I'm laid off, bored, and have no where to go on it right now anyway.

[psycoreefer]

I only have one vacuum gauge as well and here is how you do it.
1. Go to the auto parts store and buy 5 or 6 ft of vacuum hose sized to fit the vacuum nipples on the carb boots. I can't remember the size.
2. On the way stop at a pet store, go to the fish section, buy an airline splitter with at least 4 taps. You want a good brass or other metal one, not the cheapy plastic one.
3. Hook your vacuum gauge to the "in" port of the splitter, it won't have a valve.
4. Hook each "out" port of the splitter to one of your carb boot nipples.
5. Open the valve for the carb you want a reading on, I think I start by finding out what #3 is.
6. Now close #3's valve and open #4's, adjust the screw till #4 matches what you saw for #3.
7. Now double check by closing #4 and opening #3
8. Repeat 5 - 7 for other combinations of carbs until your balanced.


This valve assembly I got


Other option is build a DIY manometer, I'm sure if you search you'll find directions;

[psycoreefer]

I'm sure your right. I know the fuel air won't work. But the throttle flaps will be adjusted better than my engine. Engine vacuum between 4 cylinders will vary and so will everything after that. I want to make sure the carbs are all pulling the same vacuum to begin with. The fuel air I will do by ear. I'm more experimenting with it at this point. I'm laid off, bored, and have no where to go on it right now anyway.

The whole idea is to adjust the butterfly valves in the carbs to match your engine. You can't do that with the carbs off the engine. If you set them all equal that is a starting point but you'll still have to adjust them to match your specific motor.

[cywelchjr]

I'm sure your right. I know the fuel air won't work. But the throttle flaps will be adjusted better than my engine. Engine vacuum between 4 cylinders will vary and so will everything after that. I want to make sure the carbs are all pulling the same vacuum to begin with. The fuel air I will do by ear. I'm more experimenting with it at this point. I'm laid off, bored, and have no where to go on it right now anyway.

Actually your making an incorrect assumption. Each cylinder pulls a slightly different amount of airflow from the others. They are close, but not 100% equal. The throttle settings MUST match this to get best performance and running, you cannot do this off the engine. You can't even do it on a different engine and change engines without doing another sync, because it WILL be at least a little different. If you do it this way, you may well be far further off than the bread tie sync, and you will have spent many times the hours doing it, and you WILL still have to do the sync on the engine afterwards.

You just can't get around it. One thing I can't understand is those who come on here and ask for advice about a procedure, and the proceed to ignore the advice they get and go do their own thing anyways. I mean, why bother asking for info on how to sync and then go do your own thing? If you really don't think you can do it with a single gauge, there may be someone close enough to you to come by with a set and assist. I know if there were someone in this are that needed to sync their carbs and didn't have guages I would be willing to drop by and assist with my set of guages, or have them drop by my place to do it. It would be better to not bother doing the task at all, then to now do it right IMHO.

[Yard Dogg]

Did you read anything I said? I ****ing know what you are saying. Take a midol and have a nap. Have a smiley!

[Larrym]

The Perfect Storm

I'm laid off, bored, and have no where to go on it right now anyway.

Yup. I can relate. Having a superbike and time on your hands is usually a great combo. That "laid-off" thing puts a kink in the revenue stream though.

Could be worse: You could be retired with the time and the money but stuck in WA on the other side of the mountains where the weather conspires against you each time you do wanna hop on a fully functional XS.

The folks that live in the lower latitudes with fairer riding weather and sunny dispositions to match are such a nuisance at times.

They can't help it though: They probably rode their bike in the last week.

[DGXSER]

I'm sure your right. I know the fuel air won't work. But the throttle flaps will be adjusted better than my engine. Engine vacuum between 4 cylinders will vary and so will everything after that. I want to make sure the carbs are all pulling the same vacuum to begin with. The fuel air I will do by ear. I'm more experimenting with it at this point. I'm laid off, bored, and have no where to go on it right now anyway.

I am all for experimentation on machines, that is how we learn. If it will not break it or blow anything up, have fun and learn.

That being said, do take care you dont hook your vacuum cleaner to the wrong spot and pull your carb diaphragms so hard you tear them or something. I guarantee you that vacuum cleaner is pulling easily three times more than the engine will.

As previously stated, the entire point of the synchronizing is that, as you stated, each of your 4 cylinders will vary with the amount of vacuum it pulls at idle when given the same amount of fuel at any given mixture.

The tuning process is designed to give your cylinders their own individual preferred mixture of fuel, and the synching process is designed to get all four cylinders pulling the same vacuum (note this is not a specific vacuum level but the SAME vacuum level as others have stated.)at idle by adjusting how much of their preferred mixture they are getting.

The fun part is that once you synch them, then you tune them to their preferred mixture, it changes how much vacuum they pull so you have to go back and readjust how much they get, which can then change what the preferred mixture is again....round and round the horsey goes...

In all honesty, your making a mountain of work out of the "bench synch" and can not possibly attain any closer result for it. But, your bored and interested, don't break anything and have fun.

[cywelchjr]

Did you read anything I said? I ****ing know what you are saying. Take a midol and have a nap. Have a smiley!

Ok, I understand you want to experiment. And frankly up there I can't blame you. Hopefully if your going to go all scientific on this you will do the normal method and come up with some way to measure the results and then the other and measure. Then you can report back on the results, and who knows, maybe you will prove us wrong, and since you can't ride, you may as well wrench eh?

[cywelchjr]

Yup. I can relate. Having a superbike and time on your hands is usually a great combo. That "laid-off" thing puts a kink in the revenue stream though.

Could be worse: You could be retired with the time and the money but stuck in WA on the other side of the mountains where the weather conspires against you each time you do wanna hop on a fully functional XS.

The folks that live in the lower latitudes with fairer riding weather and sunny dispositions to match are such a nuisance at times.

They can't help it though: They probably rode their bike in the last week.

Well, some of us are not able to ride because we are in the middle of needed repairs, and with a combination of a recalcetrant fork cap, and a spinning insides, I have a fork with oil running down it. Not a good combo for working brakes . But replacement forks should be delivered sometime today, and will be installed and given a test run tonight . Then the rain will start back up (of course it would be sunny while the bike is down and then rain as soon as it's back up). Not totally true, it rained all week so far until today, but we are getting one day of sun and then it's supposed to be rain showers tomorrow and over the weekend (there goes the weekend ride. )

Update: While writing this message I got an IM right after I pressed save telling me that my forks have arrived. Yay!

[Yard Dogg]

That's right. I'm not trying to waste people's time, I just think out of the box. I have a theory. If 1 cylinder pulls more vacuum than another, it makes more sense to me to sync the carbs identically for longevity. Because in reality that higher compression cylinder is pulling more air. So if I cater to the cylinder by changing the airflow through the carb to allow more air, then the piston rings and valves will experience even less blow by than the others and will keep compression longer than the others. Also I would have to open up the air fuel mixture screw to allow even more fuel into the cylinder, so now I will have more fuel and more air going into that one cylinder making a bigger pop. But if I make sure the carbs are allowing the exact same air flow to all cylinders, then maybe the cylinders will wear out more evenly over time. I'm gonna make it a science project.

[Larrym]

Unauthorized Research Grants Available?

Might end up with a new Tech Tip:

"The ElectroLux Carb Bench Synch."

I want Photos. No Long winded text descriptions allowed.

Video would be nice.