Vacuum Balancing Throttle Bodies

[kevperro]

Has anyone actually done this yet?   I was thinking of buying the DigiSync tool and having a go at mine. 

https://thedigisync.com/

[rcannon409]

Kev, have you synced a set of throttle bodies on these modern bikes? I'm sure you used our old sticks filled with Mercury.  Those were awesome, but we know how that goes.....

 I know this tool is good, but once you start a tb sync procedure you'll find it is difficult if not impossible to balance them a closely as this tool is capable of balancing to. Once you are close to being balanced, you don't gain anything by trying to be dead on.  Especially on an inline 4.  You can get a tiny improvement on a v twin, but that's about it. Even at that, once you are 90% balanced, not much else changes.

It would be like torquing lug nuts to 70 lb, on our car so we buy a 2500.00 snap on torque wrench that's accurate to .0001%.  The wrench would be amazing, but way more accurate than we need.

That Morgan carb sync tool is on Amazon for 130.  It's plenty good enough for a tb sync and it doesn't need batteries.

This expensive tool talks about the bouncing needle.  If that bothers someone while doing the sync, you can buy the 1/8" regulators they use on aquariums.  Add these in your sample tubes and you can stop the bouncing.

This eBay ad sells 5 of them for 1.63.

https://www.ebay.com/itm/363892901680?chn=ps&var=633130971810&_trkparms=ispr%3D1&amdata=enc%3A1NJySiFdOQwW3Jngz85uPsw84&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&mkscid=101&itemid=633130971810_363892901680&targetid=1584739237574&device=m&mktype=&googleloc=9029738&poi=&campaignid=15275224983&mkgroupid=131097072938&rlsatarget=pla-1584739237574&abcId=9300697&merchantid=584893168&gclid=CjwKCAiAuOieBhAIEiwAgjCvcsklvwVi3THrR_FTYO9IaZ3C0aIz_JRl_6ztGMcQJTCBsanj8hn8VhoCJOoQAvD_BwE

I spent a whole summer messi g with sync on my sv 650.  With that bike it was possible to ride around with the sync gauges attached.

Once I did that it was interesting because the bike may have been dead on at 1300 rpm, but at 2500 it wasn't balanced anymore.  If you played with it enough you could minimize vibration at low throttle openings, and that was it.  By the time you had the throttle opened more than 1/4, balance meant nothing.

[zed9]

I think if I had to buy a new unit I’d by the four channel unit. I currently use a mercury balancer but you have to be careful with it as mercury is expensive and hard to find. It is the one tool I flat out won’t lend to anybody.
When friends bring their bikes by I’ll balance it for them but I always end up scolding them not to touch the throttle because they’ll always try to rev the snot out of their engine and the mercury bounces high like it’s going to get sucked into the engine.
This is what friends do. 

[kevperro]

Originally Posted by rcannon409

Kev, have you synced a set of throttle bodies on these modern bikes? I'm sure you used our old sticks filled with Mercury.  Those were awesome, but we know how that goes.....

I've never balanced one so it is new to me.      I'm not surprised it just has to be in the ballpark though because I've had inline fours and never balanced one yet.     But I'm a tool junkie and especially anything that gives me a chance to toodle with my bike.

[rcannon409]

I'm with you. I love good tools.

I swear I would spend 230.00 on a screwdriver that let me adjust the by-pass screws without needing help from a trained monkey. I think that would help with accuracy more than this tool would.

I have every one you can buy and nothing works very well. The Motion Pro tool is ok, but it's way too large.  I'd pay 230 for one that was 1/4 size.