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How Often Do you Sync your Carburetors?

Started by dan7uk, Sat 09, Aug 2025, 14:46:19

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dan7uk

How often do you sync your carbs if ever?  

Valker

In the 26 years and 248,000+ miles I've had my Valk, I've checked the carbs twice with my DigiSync, but they've never needed to be touched. They are still set as they were from the factory.
I ride a motorcycle because nothing transports me as quickly from where I am to who I am.

TTG53#1717

My '97 Std. was bought new and the dealer said it required a setup that would take 2 days. I drove it home in pouring rain and did a good break in for the 1st 500 miles. Having owned, chopped and built Harley's for the 26 years prior, the Valk was a whole new and very impressive beast.

I kept reading about 2nd gear breaking the tire loose and 30+ mpg. Not mine. No chirps and a best mpg of 28.

3 years on...
After moving here to TX I hoped a 6 degree wheel might help things and was referred to an Indy with a good rep and lots of certifications.

When I picked up the bike a few days later he commented " I was surprised at how far out of sync your carbs were."

A couple blocks warm up to the highway entrance ramp and my first 2nd gear chirp. Not even trying.
34 mpg and lots of smiles. It certainly wasn't the degree wheel, but having the carbs now in sync .

So my factory/dealer set up was $hit and needed some serious tweaking.

I don't own a carb sync tool and I just confirmed that the two trusted wrenches here have closed up shop so I'll see what the future brings when I finally get my clutch fixed.
'97 Standard Purple/White
'13 XL Seventy Two
'54 KHK
VRCC 1717

Chrisj CMA

#3
I did it once at well over 100,000 miles. Now I m close to 200,000 and am contemplating doing it again

Willow

Not often.  Once synced there's no reason for them to become unsynced.   

Dirty Dave

Good to know.

I synched them once and never looked back. It runs so well I never bothered.
It's weird being the same age as old people

98valk

#6
Quote from: Willow on Sun 10, Aug 2025, 18:02:14
Not often.  Once synced there's no reason for them to become unsynced.  

plenty of reasons, screws vibrate lose, and leakage linkage wears over time.

service manual requires all screws, bolts nuts to be checked.
1998 Std/Tourer, 2007 DR200SE, 1981 CB900C  10speed
1973 Duster 340 4-speed rare A/C, 2001 F250 4x4 7.3L, 6sp

"Our Constitution was made only for a Moral and Religious people. It is wholly inadequate to the goverment of any other."
John Adams 10/11/1798

Willow

Quote from: 98valk on Mon 11, Aug 2025, 20:34:57
Quote from: Willow on Sun 10, Aug 2025, 18:02:14
Not often.  Once synced there's no reason for them to become unsynced.   

plenty of reasons, screws vibrate lose, and leakage wears over time.

service manual requires all screws, bolts nuts to be checked.

LOL!  We will agree to disagree.  With my hundreds of thousands of miles on Valkyries I have checked them once in a great while. 

98valk

Quote from: Willow on Tue 12, Aug 2025, 09:21:33
Quote from: 98valk on Mon 11, Aug 2025, 20:34:57
Quote from: Willow on Sun 10, Aug 2025, 18:02:14
Not often.  Once synced there's no reason for them to become unsynced.   

plenty of reasons, screws vibrate lose, and leakage wears over time.

service manual requires all screws, bolts nuts to be checked.

LOL!  We will agree to disagree.  With my hundreds of thousands of miles on Valkyries I have checked them once in a great while. 

so u don't know if they have gotten out of sync?  and that was suppose to be  "Linkage"
1998 Std/Tourer, 2007 DR200SE, 1981 CB900C  10speed
1973 Duster 340 4-speed rare A/C, 2001 F250 4x4 7.3L, 6sp

"Our Constitution was made only for a Moral and Religious people. It is wholly inadequate to the goverment of any other."
John Adams 10/11/1798

WintrSol

When I got my DigiSync, I found two significantly out, and the other four 'close enough'. I guessed (hoped) they were set at the factory, and either had vibrated out, or a PO had fiddled with them. Rechecked a few years later, and they were still very close, but needed a little nudge (I'm anal that way).

It's been more that a few years since, so I plan to check again soon.
98 Honda Valkyrie GL1500CT Tourer
Photo of my FIL Jack, in honor of his WWII service

98valk

Quote from: WintrSol on Tue 12, Aug 2025, 10:11:58
When I got my DigiSync, I found two significantly out, and the other four 'close enough'. I guessed (hoped) they were set at the factory, and either had vibrated out, or a PO had fiddled with them. Rechecked a few years later, and they were still very close, but needed a little nudge (I'm anal that way).

It's been more that a few years since, so I plan to check again soon.

earlier this yr on FB a guy was telling every one to sync them every oil change. now that's anal.   ;D
1998 Std/Tourer, 2007 DR200SE, 1981 CB900C  10speed
1973 Duster 340 4-speed rare A/C, 2001 F250 4x4 7.3L, 6sp

"Our Constitution was made only for a Moral and Religious people. It is wholly inadequate to the goverment of any other."
John Adams 10/11/1798

Valker

Quote from: 98valk on Tue 12, Aug 2025, 10:36:30
Quote from: WintrSol on Tue 12, Aug 2025, 10:11:58
When I got my DigiSync, I found two significantly out, and the other four 'close enough'. I guessed (hoped) they were set at the factory, and either had vibrated out, or a PO had fiddled with them. Rechecked a few years later, and they were still very close, but needed a little nudge (I'm anal that way).

It's been more that a few years since, so I plan to check again soon.

earlier this yr on FB a guy was telling every one to sync them every oil change. now that's anal.   ;D

Depends on how often he changes the oil.....
I ride a motorcycle because nothing transports me as quickly from where I am to who I am.

TTG53#1717

52 years back when I was in a M/C mechanic trade school we had a couple days with carb sync equipment and techniques. Basically the more cylinders and carbs, the less a carb or 2 out of sync is important. Our flat 6 engines will follow through with hardly a hiccup. Take a dual carb vertical twin and it's pretty impressive when you do that 1st in school sync. Triumph 650, Honda 450 and even a 2 stroke Bridgestone 350 all responded well to the relatively primitive sync gauges we had back then.

Graduated and went straight to an H-D dealership. No worries about sync gauges there.
'97 Standard Purple/White
'13 XL Seventy Two
'54 KHK
VRCC 1717

John97

Mine were synced when they got rejetted after the Cobra pipes were installed. That was in 1998 I believe.

clanky

I used the DIGISYNC device once at 197000 miles (17 years after purchasing new bike) only because two carbs suffered hydro lock.  Refurbished all the carbs with new seals, gaskets, floats ect ect.  I checked the system at 220000 miles and the carbs were still spot on.

Beer van Huet

I do it about twice every year with a digital sync.
Sometimes they are a little bit off and I found getting them smack on saves me fuel.
Performance wise, they are always well within Honda limits.
#7609

Cracker Jack

I have two interstates, both over twenty years and neither have been synced since I've had them. They both run great.
However, if I had a digisync I would do it at least monthly to make sure my money for the digisync was spent wisely. If you have a digisync, that would be my recommendation for you.
If you don't have a digisync and your bike idles smoothly, don't worry about it. :cooldude:

Hook#3287

Quote from: Cracker Jack on Sat 20, Sep 2025, 11:56:08
I have two interstates, both over twenty years and neither have been synced since I've had them. They both run great.
However, if I had a digisync I would do it at least monthly to make sure my money for the digisync was spent wisely. If you have a digisync, that would be my recommendation for you.
If you don't have a digisync and your bike idles smoothly, don't worry about it. :cooldude:

I have 2 Digisyncs, I bought one then won one at a Inzane auction.

Do you suggest I sync bi-monthly?

bassman

Quote from: Hook#3287 on Mon 22, Sep 2025, 06:21:32
Quote from: Cracker Jack on Sat 20, Sep 2025, 11:56:08
I have two interstates, both over twenty years and neither have been synced since I've had them. They both run great.
However, if I had a digisync I would do it at least monthly to make sure my money for the digisync was spent wisely. If you have a digisync, that would be my recommendation for you.
If you don't have a digisync and your bike idles smoothly, don't worry about it. :cooldude:

I have 2 Digisyncs, I bought one then won one at a Inzane auction.

Do you suggest I sync bi-monthly?


Which......twice a month or every other month??   :D

Hook#3287

Quote from: bassman on Mon 22, Sep 2025, 09:59:06
Quote from: Hook#3287 on Mon 22, Sep 2025, 06:21:32
Quote from: Cracker Jack on Sat 20, Sep 2025, 11:56:08
I have two interstates, both over twenty years and neither have been synced since I've had them. They both run great.
However, if I had a digisync I would do it at least monthly to make sure my money for the digisync was spent wisely. If you have a digisync, that would be my recommendation for you.
If you don't have a digisync and your bike idles smoothly, don't worry about it. :cooldude:

I have 2 Digisyncs, I bought one then won one at a Inzane auction.

Do you suggest I sync bi-monthly?


Which......twice a month or every other month??   :D
I could be wrong, I offen am, but I thought bi-monthly means twice a month.

I've modified that definition,  I meant bi-weekly  :)

Thanks for the correction  :cooldude:

F6Dave

I think twice a month would be semi-monthly, though I rarely hear that term used. I often think of the bi-centennial in 1976 to remember the usage.

bassman

Quote from: Hook#3287 on Tue 23, Sep 2025, 06:50:07
Quote from: bassman on Mon 22, Sep 2025, 09:59:06
Quote from: Hook#3287 on Mon 22, Sep 2025, 06:21:32
Quote from: Cracker Jack on Sat 20, Sep 2025, 11:56:08
I have two interstates, both over twenty years and neither have been synced since I've had them. They both run great.
However, if I had a digisync I would do it at least monthly to make sure my money for the digisync was spent wisely. If you have a digisync, that would be my recommendation for you.
If you don't have a digisync and your bike idles smoothly, don't worry about it. :cooldude:

I have 2 Digisyncs, I bought one then won one at a Inzane auction.

Do you suggest I sync bi-monthly?


Which......twice a month or every other month??   :D
I could be wrong, I offen am, but I thought bi-monthly means twice a month.

I've modified that definition,  I meant bi-weekly  :)

Thanks for the correction  :cooldude:

Hook, NOT intended as a correction just the ambiguity of the term which can mean either twice a month or every other month.  This has given me more angst in my life as I always have to stop and try to figure out what the heck the intended usage was meant to me.  It's always been like a foreign language to me that I just can't seem to grasp.   :cooldude:

Valker

"Bi" means every other. "Semi" means half of.
I ride a motorcycle because nothing transports me as quickly from where I am to who I am.

Willow

Quote from: Valker on Tue 23, Sep 2025, 16:58:26
"Bi" means every other. "Semi" means half of.

The prefix bi means two.  According to Merriam Webster bimonthly can mean twice each month or once each two months.

Valker

Quote from: Willow on Tue 23, Sep 2025, 17:36:34
Quote from: Valker on Tue 23, Sep 2025, 16:58:26
"Bi" means every other. "Semi" means half of.

The prefix bi means two.  According to Merriam Webster bimonthly can mean twice each month or once each two months.
I was speaking only of time. Bicycle is two wheels, yes. We are bipeds because we have two legs.
I ride a motorcycle because nothing transports me as quickly from where I am to who I am.

Willow

Quote from: Valker on Tue 23, Sep 2025, 18:39:34
Quote from: Willow on Tue 23, Sep 2025, 17:36:34
Quote from: Valker on Tue 23, Sep 2025, 16:58:26
"Bi" means every other. "Semi" means half of.

The prefix bi means two.  According to Merriam Webster bimonthly can mean twice each month or once each two months.
I was speaking only of time. Bicycle is two wheels, yes. We are bipeds because we have two legs.

I too was speaking of time as was the dictionary in its examples.  I don't understand your confusion.

We are off topic at this point.   ;)

Hook#3287

Quote from: Willow on Tue 23, Sep 2025, 17:36:34
Quote from: Valker on Tue 23, Sep 2025, 16:58:26
"Bi" means every other. "Semi" means half of.

The prefix bi means two.  According to Merriam Webster bimonthly can mean twice each month or once each two months.
So I was both right and wrong.

Interesting  :)