TB balance

[Baldini]

Rich,

 

In other thread you mention TB balance as a reg maintenance. I don't even know what TB stands for...fueling...Throttle balance? bodies? Can you enlighten me?

 

Thank you, KB, Wales

[Cliff]

Throttle body will do it. Its the EFI equivalent of balancing the carburators.

 

It's very easy to do. You just need a set of vacuum guages to do it. This can be one of the newer solid state gauges or a set of mercury gauges.

[RichMaund]

Sorry for that. I thought TB was a common abbreviation for throttle body.

I prefer a Twin Max to gages or Hg sticks as it is more accurate.

[al_roethlisberger]

Baldini,

 

I would recommend picking up a copy of "Guzziology" from Moto International in Seattle, or just from Amazon.com

 

It describes all these procedures step by step..

 

However in the case of balancing the TBs, it's actually the easiest of all the regular "tune-up" items I would argue.

 

As Rich stated, you simply use a set of vaccuum gauges, mercury guages(sticks), or easiest of all, the Twin Max balancer.

 

You attach these to the vaccuum inlets on your intake runners that your emissions hoses attach to, and hook up the Twin Max(or other). After setting a base level, run the bike up to about 3k RPM and use the white nylon thumb-screw under the TB linkage on the left of the bike to adjust the "balance" of the TBs such that the Twin Max reads "even"(which is zero) or similarly your mercury sticks balance.

 

Once this is done periodically, your engine will run and idle much more happily.

 

Again, that was the "quick and dirty" and "Guzziology" has far more detail on the procedure.

 

 

Here's a related question though: Without a gas analyzer, how does one properly set the CO and air bypass screws accordingly. This seems like a critical thing for setting idle, etc, however it doesn't sound like one can do it as a shade-tree in their garage?? My idle is a tad high, and I've let off the throttle set-screws as much as I can. This only leaves the air bypass screws, and I don't want to tinker with them since they were last set at the shop since I don't know how to set them correctly.

 

 

al

[dlaing]

 

Here's a related question though: Without a gas analyzer, how does one properly set the CO and air bypass screws accordingly. This seems like a critical thing for setting idle, etc, however it doesn't sound like one can do it as a shade-tree in their garage?? My idle is a tad high, and I've let off the throttle set-screws as much as I can. This only leaves the air bypass screws, and I don't want to tinker with them since they were last set at the shop since I don't know how to set them correctly.

 

 

al

Good question. On the carbed bikes of yesteryear, I think the technique was to set it so it runs best.

If your idle speed changes at varying operating temperatures, I think that might indicate the screws are set incorrectly.

 

I ran into a similar problem that probably indicates an air leak.

I could back mine off enough, but not evenly.

I backed the left set screw off all the way and then balanced as much as I could with the right set screw, getting the idle almost right. but the set screws only offer a small degree of adjustablity. So I had to adjust the bypass screws to get the balance right at idle.

I ended up with about a full turn further out on the right bypass screw. It may be time for me to calll in the professionals....But the bike is running great....

[docc]

David,

 

I wonder if you have acracked intake beween the "TB" and the head. It's quite common and would explain why your bypass screws would be so different.

 

I, too, would like to know what my CO actually is. It's tthe one wild card that colors all of our information sharing on tuning the FI.

[RichMaund]

Here's an old fashioned way to set up those bypass screws:

Slowly open one up about 1/16th of a turn at a time until the idle speed just peaks. Congrats! You've just achieved a nearly ideal low speed mixture. Set the other screw to the same setting. Or... screw them back in 1/16th of a turn if you prefer a idle mixture slightly richer than ideal. Mine are like this and I occassionally foul plugs. I probably should open them a tad. (I was just trying to keep it cooler running at idle.)

Use the individual Allen set screws to balance the linkage at idle. There's enough slop in th elinkage to allow for that usually. Adjust one air bleed bypass screw though if you must to get them balanced. Then balance them at 3-4k rpm with the white knob.

I do this after each valve clearance check using a Twin Max.

The bike rips at speed and behaves wonderfully around town!

Of course, YMMV!

[dlaing]

David,

 

I wonder if you have acracked intake beween the "TB" and the head. It's quite common and would explain why your bypass screws would be so different.

Docc, I have wondered the same. I have tried spraying silicone spray aroung the intake area to check for a change of idle, but could determine no leakagage. could be the leak is where I cannot get the spray....

 

And good tips Rich,

The only thing I can add is check the open throttle balance then the idle balance then the open throttle balance then the idle balance then the open throttle balance then the idle balance then the open throttle balance then the idle balance then the open throttle balance then the idle balance then the open throttle balance then the idle balance then the open throttle balance then the idle balance then the open throttle balance then the idle balance then the open throttle balance then the idle balance then the open throttle balance then the idle balance then the open throttle balance then the idle balance then the open throttle balance then the idle balance then the open throttle balance then the idle balance then.

 

....well, you get the idea, but do not overheat the engine!!!

 

A couple of check "the open throttle balance then the idle balance then the open throttle balance then the idle balance then" will do.