Throttle body balance.

[Pale Rider]

Ok so earlier I decided to check the throttle body balance with my vacuum gauge thing, I disconnected the stepper motors and fired it up, both pretty much bang on but if I increased the revs the right hand one takes a dip before it returns to being equal with the left one, is this normal?? Thanks.

 

[botus]

2 to 3 k RPM slightly open throttle is where you want the bike to run well - idle is a waste of space you don't ride there

do the valve clearances and check air cleaner first - then get the thing to operating temp and fit a fan by the oil cooler so its not overheating, and do it with the throttle grip held just open, so the butterflies are on the cable not anything else - then snap throttle open and closed a few times to settle things - then recheck after a 5 min ride and it will have flipping changed all over again

if you really want it right - carb cleaner and some elbow grease to get ALL the crude off the butterflies and throttle body first

 

[botus]

recent updates on diagnostic tools you can get - seem to now have a setting to pull the stepper motors out the way - but as I mention above idle is not much cop... you want it to run best as it picks up revs on the cable on tiny throttle openings

 

[dirty_t]

I did my 2012 recently using just the tube manometer. A week later while out on a ride with some friends, one of whom is a very good mechanic and knows these bikes well noticed my bike sounded wrong at idle while we were taking a break. I told him I’d just synced it and he said if I didn’t use a GS911 I’d never get it sorted. Fortunately a buddy of mine had just gotten one and offered to let me use one of the slots on it, so I borrowed it and did the sync using it. Game changer.

 

[Pale Rider]

Ok, so I’ve managed to get the balance bang on 2000 and above by disconnecting stepper motors but idle is a good way out still and sometimes gently increasing the revs from idle results in the engine caughing and stalling.
I’ve read somewhere about base settings, so do i need to set this up first to get it even at idle and then go onto setting the 2000-3000 range with the cables afterwards?
Btw I don’t have access to a gs911.
Thanks.

 

[botus]

Ok, so I’ve managed to get the balance bang on 2000 and above by disconnecting stepper motors but idle is a good way out still and sometimes gently increasing the revs from idle results in the engine caughing and stalling.
I’ve read somewhere about base settings, so do i need to set this up first to get it even at idle and then go onto setting the 2000-3000 range with the cables afterwards?
Btw I don’t have access to a gs911.
Thanks.

which model ?

the early ones ran like a dog - a software update on 2007 models came out in mid 2008 and was applied to about 0 out of 4000 UK bikes - its both better and worse at the same time - the bad bits improved and the good bits were taken away

the twin cam one's seem better on first acquaintance but soon offend deeply once you're used to them

if you can't feel whats wrong - you are a car driver not a biker

there are choices on how to fix - none cheap

you might have a dying CAT sensor and they run mad with this in play - you can spot with a GS 911 looking at trim values - they go weird and randomly differ from each other - often never throwing any faults in diagnostics - but you do find 2 to 3k is the most offensive region

 

[Pale Rider]

which model ?

the early ones ran like a dog - a software update on 2007 models came out in mid 2008 and was applied to about 0 out of 4000 UK bikes - its both better and worse at the same time - the bad bits improved and the good bits were taken away

the twin cam one's seem better on first acquaintance but soon offend deeply once you're used to them

if you can't feel whats wrong - you are a car driver not a biker

there are choices on how to fix - none cheap

you might have a dying CAT sensor and they run mad with this in play - you can spot with a GS 911 looking at trim values - they go weird and randomly differ from each other - often never throwing any faults in diagnostics - but you do find 2 to 3k is the most offensive region

It’s a 2012 twin cam, was out on it yesterday and it was running lovely its just the initial take up from tick over to get through if you see what I mean.

Checked again on my return yesterday with the vacuum gauges and bang on, its just that slight hesitation or “chuggyness” just as it comes off tick over.

As I’ve no intention of selling the bike I think I’m going to have to invest in a 911 and see what’s going on.

Not owned a car since 1990 or 91

Thanks.

 

[Mistacat]

The amount of throttle at 2000 - 3000rpm opens the butterfly`s is a tiny amount compared to when the bike is being ridden ( under varying load conditions).
The only way to accurately balance the throttle bodies at 3000 rpm is on a rolling road with a calculated load applied.
The plastic control structure and cable formation does not allow for perfect balance throughout the range . there is only one TPS so it is never going to be spot on.
I always balance the throttle bodies just as it takes up the slack and comes off idle with the idle actuators locked.
Just for example data from my TC at 3300rpm 55mph cruise 7.84% throttle opening so you may as well balance it when it come off idle and get rid of the stumble.