Carb sync guys. is my logic flawed?

[whitestroke]

Figured I'd try syncing carbs by the heat coming out of exhaust 6 into 6, I can feel each cylinders exhaust separately.  Just to see if this sync thing is my problem.

I have 4 pipes blowing hot exhaust and 2 blowing cold exhaust. #3 cyclinder nonadjustable is cold!


#1.....I turned the sync screws on the 4 pipes blowing hot exhaust in 1 turn, this lowered  the idle until it died.
#2.....I then adjusted the idle knob till I got back to 900rpm's, approximately 1 turn.

not much difference in the 2 cold cyclinders that I haven't touched the sync screws on., so I did this 2 more times.  So now screws are turned in 3 complete times on the 4 hot cylinders.

Seems like 1 of the cold cyclinders is a little warmer now, but #3 is still cold.

Bike seems to run about the same, but will go for a longer ride tomorrow.

Should I continue on with this tomorrow or is 3 turns of the sync screws crazy?  

Is my logic flawed i.e. turning the hot cylinders sync down till the cold cylinders work hard enough to generate heat also?

[John Schmidt]

In a word...yes.  To sync the carbs, you need a gauge or series of gauges if you want to hook all six up at the same time.  All the sync does is make certain all six carbs are generally operating at the same level. But to do it right, you need to FIRST adjust all six of the Pilot screws so they're set at the same point. The Pilots set the fuel/air mixture which affect the varying temps you're feeling. THEN....using a gauge, sync the carbs by matching all to #3 which is your base. That's the middle cylinder on the right side. What you're doing now is like spitting in the wind....useless.

[GOOSE]

Whitestroke......The way that you are thinking/doing it IS NOT going to work.  This carburetor system is geared this way....The #3 carb (The middle carb on the right side...when you are sitting on the bike.) is a set carb with no adjustment.  All 5 other carbs are set to the #3 carb.

[whitestroke]

Goose
I'm turning down the other carbs so that #3 carb starts to contribute.

Maybe a more appropryate question would be, does turning down other cylinders make  #3 cylinder produce more heat?  It is now blowing cold air.

[Cliff]

Goose
I'm turning down the other carbs so that #3 carb starts to contribute.

Maybe a more appropryate question would be, does turning down other cylinders make  #3 cylinder produce more heat?  It is now blowing cold air.

Likely clogged slow jet causing it to be cold at idle.

[Patrick]

What ??!!  What screws are you turning? No matter which screws you are turning, it ain't gonna work.. If the engine ran smoothly from 1200-1500 and beyond then the jets are probably clear.. If the engine idled poorly then it probably just needs a sync.. Set the pilots at 2.25 turns and sync the carburetors correctly.. A plain ole vacuum gauge works just fine.. Unless someone has really screwed things up, those screws don't need to turned much at all..

[Ricky-D]

Just as a little note here about synchronizing the carburetors:

Those screws that turn to make adjustments do not all turn the same way to make similar adjustments.

You have to look closely at how they interact with each other.

***

[bscrive]

Holy crap guys, it only cost me $60 to get a motorcycle shop to sync the carbs.  It only took then a half hour to do it.  It was going to cost me more than that to buy the stuff to do it myself.

[larswlvs]

You're way off base and now you have to be way out of sync,All synchronizing the carbs. does is make them open and close at the same time so they are working together.It has nothing to do with the heat of your exhaust. Your carbs. can and should be in sync even when the engine is not running.

[whitestroke]

What ??!!  What screws are you turning? No matter which screws you are turning, it ain't gonna work.. If the engine ran smoothly from 1200-1500 and beyond then the jets are probably clear.. If the engine idled poorly then it probably just needs a sync.. Set the pilots at 2.25 turns and sync the carburetors correctly.. A plain ole vacuum gauge works just fine.. Unless someone has really screwed things up, those screws don't need to turned much at all..

Turned the sync screws in 3 turns on the 4 cylinders that are hot. Simple to turn them back, as I did mark them.
Bike has a barely noticeable miss if you ease on gas from idle.  At 3K and above it's unnoticeable, wish there was someone in So. Cal. with a Valk to test ride it.  If you've driven twins all your life like myself you wouldn't even notice the miss, until you spend some time on the bike.

[GOOSE]

Whitestroke.....You cannot sync. carbs the way that you are doing it.  The carb sync. has nothing to do with the heat that you are talking about.  Put the bike in a wheel chock where it is sitting straight up and down, and start all over again...matching all the other carbs to #3.  All you are basically doing is making all the carbs open , and close at the same time.  The way you are going about doing it, will result in the bike NOT running the way that it was designed.

[PharmBoy]

I'd suggest that you check in with the Cal. Valkyrie group.  Surely there is someone around close that can get you on the right path.  There is a correct sequence to tuning the Valkyrie.  That is what all these guys have been trying to convey to you...Jim

[Ricky-D]

I have to respectfully disagree with some of the stated assumptions posted in this thread and further post my agreement with whitestroke to a degree.

You can use the heat of the exhaust as an indicator when trying to adjust the synchronization of the carburetors.

It is not a very accurate method however, and results can be mixed. Especially if you are using a poor temperature measuring device such as your hand.

And you must realize that a cylinder that is loafing will not produce much heat when compared to a cylinder that is doing the work of keeping the motor idling.

Now you couldn't do this exercise with a stock exhaust system but with a 6 into 6 exhaust system where each cylinder has it's own exhaust pipe out to the end it is entirely conceivable.

***

[larswlvs]

hmmm...."entirely conceivable"? Ok what if the pilot jets are not all set the same,which can happen if you use a tech. and set them independently.   I can see where that would make a difference in the heat of the exhaust but not in sync.if something (anything) is in sync it moves the same way and the same time. I know Harley riders with one carb that have different tempature exhaust readings.I'm not trying to be argumentative just trying to see where your line of reasoning is   

[Patrick]

If the engine runs fine from 3K and beyond, but, runs poorly below that engine speed, then, its pretty much a sure sign of varnished low jets or related passageways.. It could possibly also be a sign of someone really screwing up a pilot adjustment or a sync.. So, the low jets need to be clean, the pilots set at 2.25 turns[#35s] or 1.5 turns for #38s.. Then the vacuum should be set on all cylinders/carburetors to that shown on #3.. The carb idle stop screws should never need to be turned 3 turns.. Honda got this set-up right, carburetor assembly is simple, easy to adjust and bullet-proof, or at least it usually is..

[Robert]

Take the carbs off clean and rejet them then resync ,    just get it over with already.   Or at least run some Techroline through them.