My experience with Carb Sync

[Chrisj CMA]

Ok, so I don't want to add to the drama of another post, but I do want to start a conversation based on real results YOU had.  Don't reply if it was someone else's results you heard about or thought that's what happened.

I had my standard that now looks like a Tourer for 15 years and had never had the carbs synced.  I was one of them that kept saying "Don't need it...runs perfect"

OK so a friend of mine accidentally created a couple serious vacuum leaks on his bike that he didn't know about.  Then tried to get it running right by messing with the carb sync screws.

His bike was WAY out, was popping and sputtering.  I told him if he would buy a Twin Max I would fix his bike.  He did and long story short, once I learned the ins and outs of that little contraption we got his bike running like a top.  Note here, the key to any carb sync is first making sure there are no vacuum leaks!

So I got that little box out and did the Cobra bike even though I did not think it needed it.  Well maybe 2 carbs were spot on the other 3 needed to be adjusted a very little bit.  So one might say, it didnt really need it.  I didnt think it was going to make a difference.

Results:

Started (still starts) easier
Idles smoother
Is more enjoyable at very slow speeds as the power upon very small throttle input is more precise.

What did not happen:

No more power
No better gas mileage
Didnt make me or the bike any better looking

BTW the above was true for both bikes the one that was WAY out and mine that was a tiny bit out.  Except the popping and sputtering stopped on the bike that was WAY out.

I dont believe ANY sync device could have done better, but hearing how that digi sync works, it may be quicker and easier.

[RWhitehouse]

I have no idea about any prior "drama" on this issue but this was my experience. I checked on my '98 with a Digisync. The previous owner of the bike had claimed to rebuilt the carbs several years ago, which I have no reason to doubt. The bike runs great. When hooked up, the spread between the highest and lowest was only around 8 "digits", which is fine. A couple quick fiddles had had them essentially perfect, +/- 1 digit.

The tach readout also help set the idle, mine was a bit slow at only ~750 or so. Bumped it to 850, which makes it start a bit easier. At very low speeds the throttle is maybe a touch smoother, idle maybe a smidge more even, but otherwise I noticed no difference to performance or fuel economy, nor was I expecting one.

Recently I put a basket case Vulcan 500 back together that had been sitting for the better part of a decade. Once the carbs were rebuilt and running, I checked the sync- one side was like 6 digits off the other- still well within spec, on a quite abused and neglected setup. The twin cylinder seemed a bit more sensitive to sync than the six, as correcting the sync did noticeably smooth out the idle- it wasn't "bad" before, but was better afterward. Noticed the little shake in the mirrors had largely gone. Necessary? Not really.

My Vmax was notorious for "losing" sync, and the idle quality would noticeably degrade. A fresh sync always made starting and idling noticeably better. I'd do it probably every 6 months or so and there was always a decent spread.

I've used dial and tube style manometers before. They work fine and with the right adapters/reducers, can be as accurate as needed. I just like the Digisync for the ease of use, accuracy, and I enjoy having neat little tools.

My experience is that unless sync is WAY out, you're not likely to notice adverse affects to fuel economy or idle quality. Some bikes seem more sensitive than others, to me the Valk is not one of the fussy ones.

[old2soon]

Not noticeably better fuel mileage. Where I do notice the before and after of having the digisync done was on the pull from launch to hitting the chip. Or just before the hitting of chip the pull is just THERE. I guess fer lack of a better description it-the pull-is Very linear. Even over 100 M P H it Still wants to pull when you twist the throttle. I also notice in cold weather being able to come off of the choke/enrichener sooner. Been high 80s low 90s here all day if I wuz to go out and start her now it might turn over 2 turns and be running sans choke. My Brother-da prez-when doing work on another Valkyrie also does the digisync. Not by ANY means accurate But the seat of the pants dyno sez it run betta after digisync! RIDE SAFE.

[Hook#3287]

Had to look it up in my journal.

I did my first carb sync in 2001, but I can't remember if I did for a reason or just because.

I do remember once up in NH I could hear and feel a slight stumble, did a sync and gone.

Best thing about the DygiSync is the ease.

You hook up all carbs, turn it on, start her up and adjust away.

None of the, "take the cap off, unhook this hose, hook up that hose, put the cap on, opps I forgot that cap"  stuff.

[Valkorado]

Having two bikes, I took the Digisync splurge.  I'm mighty glad I did.  I had pretty much the same results (except I think the synch may have made me even better looking, somehow) and both bikes are just happier, for lack a better word.  BonS is a wizard!

[Gryphon Rider]

Mine was very little out of sync, according to the DigiSync, and I noticed no obvious difference, although shortly after syncing, Trump got elected.  As for getting better looking, I think tuning up my bicycle might be more effective.