Throttle Bodies?

[Whizz]

Hi all, a technical question from one who freely admits that a spanner in my hands could easily be considered to be a lethal weapon.

I have just got my ST back from a 42K service and the tech has noted on the paperwork that he "Balanced the throttle bodies - Balance was a long way out". He also told me over the phone that it should feel like a different bike, which is does, much smoother and more responsive (if that's possible!!).

Can some-one explain, in not too technical language, what balancing throttle bodies actually means in terms of ride etc. The bike does feel better without doubt, and seems quicker, but maybe that is just my imagination. Would appreciate any clarity that our resident gurus can shed on this for me.

Cheers All

Whizz
 

[Brock]

The throttle bodies allow the right amount of air to be mixed with the fuel in the engine for proper combustion. (its what carbies did). By balancing, the same amount of air is being drawn in to each cylinder to mix with the fuel, allowing the same bang, hence a smoother feel. The air mix is determined by measuring the vacuum at each body, and making adjustments until they are the same.

A similar process is done on the 1100s as well.

[alans1100]

I know in a carby fuel system that multiple carbs need to be balanced. Meaning the vacuum should be the same on all of them so that all carbs suck in the same amount of fuel at the same.

http://classicmotorcycles.about.com/od/serviceandrepair/ss/Carburetor-Balancing-Using-Vacuum-Gauges.htm

That's okay for my 1100 but for EFI bikes as you can use software (e.g. TuneECU) with the appropriate data cable to monitor the throttle bodies while adjusting the balance.

Hope that helps........others my offer more insight as I believed that EFI tuned itself on the go.

 
Alan
 

[saaz]

As far as I am aware, the only balancing you can do on the EFI system is the low speed or start up circuit.  There is no way to do a balance of the throttle bodies like on the ST11 for higher speed running.