Balancing Throttle Bodies?

My Triple is coming up due for its 18k mile service. Looking over what needs to be done, most of it is pretty easy and totally within the scope of my skills. The only thing that looks beyond my skills/tools is balancing the throttle bodies.

First off, I'm not even sure exactly what that means or what the purpose is? Is it basically getting them in sync so they open the same amount all the time? Sounds like this is just a throttle smoothness and fuel economy deal, not an actual safety or wear one.

The shop manual says I need a specific Triumph diagnostic tool to perform the service. Obviously I don't have this. Is it something that can be done with a generic tool by a good local mechanic? Do I need to drag the bike the 2.5 hours down to the nearest Triumph dealer? Will it cause issues if I leave it undone for a while? Or can I just do the other service points myself and let it be until it is convenient to get down to a shop?

I don't think you need a Triumph specific sync tool. I own this one;

http://www.motionpro.com/motorcycle/partno/08-0411/

Note: I've never used it, so I can't saw how awesome it is. You can also make your own with clear tubing and use something like ATF. Big board, bunch of fluid in each, I've seen this on the web and it looks... like a big mess. I paid the money. But those work and are obviously cheaper.

The purpose is to have all trumpets flowing the same rate of air at a given RPM. This is indeed a smoothness and power thing and not wear.

Find a copy of the shop manual for your bike, it will describe how to do this. On my EFI VFR, you adjust what Honda calls "starter valves" which seem just like idle bleed screws on a carb. One trumpet, for cylinder number four, is set and is your constant. The others are adjustable and are the variables that you play with to match the rate of flow back to the constant. This is done at some set RPM, and the technician is instructed to use a more accurate tach than that on the bike, like a Digital Volt/Ohm Meter back probing some connector to get RPM via the DVOM's tach function (so you need an automotive oriented DVOM for this). Sound like fun? The sync tool attaches to vacuum ports on each trumpet and shows how much each trumpet is pulling. Get equal, button the bike back up, done. If you don't have a lot of stuff to pull out of the way, it should be a pretty quick job.

If you don't already have one, shop manuals can usually be found online, I found mine on a VFR owner's forum for low low cost as a digital download.

Uni-Syn?

In reply to pres589:

I have a shop manual. The shop manual says to use the special Triumph tool.

In reply to Beer Baron:

See what the special tool is and see if the aftermarket stuff is similar or not?

I use a Uni-Syn to sync the GSXR ITB's on my 4AGE Locost.

It works, but it's a bit of a pita since you can only see one at a time (I have only one Uni-Syn; I have only two arms).

It not just for smothness it also helps each cyl make the same power ( in therory) so they all share the load and stress the crank less.

I'm old school i still have mercury sticks no fancy electronics to break, i can see 4 cyle at once and never had any problem with them.

Call the local shop and see what they realy use.

http://www.jcwhitney.com/emgo-universal-carburetor-synchronizer-standard-4-gauge-kit/p2004169.jcwx?filterid=u0j1

Beer Baron wrote: In reply to pres589: I have a shop manual. The shop manual says to use the special Triumph tool.

Why would it say otherwise?

Balancing throttle bodies is just like balancing carburetors. All you're trying to do is get all the cylinders working together (same vacuum reading).

If they are not the same, you'll have some cylinders providing power, others coasting and not providing power. Doesn't matter while sitting there idling, but when decelerating lightly (like coasting down a hill) you get lumpy surges and sometimes backfiring if the carbs/throttle bodies aren't balanced.

The tool Dr Hess linked is a very good tool for the job, and quite cheap. I've used one for many years.

Do a search online... there are guys who use clear vinyl tubing with glasses of water. The key is to use tubing that is big enough that it can't actually suck water into the engine, but small enough to show accurate differences.

And yes, its pretty crucial to have accurately sync'd TBs. Its not quite as critical as carbs, but the computer is injecting fuel evenly across all cylinders based on its input. At part throttle and tip-in, unequal TBs can cause some pretty wide variations in A/F ratios.

I used to have one of these bad boys but... I broke it. FYI, mercury is very hard to pick up off the floor.

I expect that would work fine but I've never actually owned a bike with fuel injection so figuring out where to hook up the mammometer is left to the reader

In reply to curtis73:

What's funny is that Honda's spec for the 6th gen VFR actually has the technician set the throttle bodies at different flow rates. Number 4 pulls the most vac, 2 and 3 a touch less, and number 1 less yet.

And reports from the Internet (grain of salt) is that things are better if you ignore that and just balance normally.

In reply to Giant Purple Snorklewacker:

I have one of those. I refer to it as "the toxic octopus".

On the 2002, there was enough vacuum spike to pull mercury through the intake tract...

I'll be switching to a different variety of tool; in the meantime, it'll be fun to even transport the thing to the local hazardous waste dump.

The tube diameter shouldn't matter too much. It's not having enough vertical inches that will suck the fluid out of the manometer.

Hick version - 3 snapple bottles taped together- 1/3 filled with fluid, rubber stoppers with tubes stuck through them. All the bottles interconnected with tubing and one tube to each throttle body. Tweak until there's no flow between bottles.