Confused but it doesn't take much... Throttle Balance

Spud

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If I have both cables slack at the adjusters on the throttle bodies, I can set both Big Brass Screws at 2 turns out and the idle is more or less equal. As soon as I've set the right throttle cable with the .5 mm (ish) of free play and try to adjust the left for fast idle (2500 rpm ?) I can get the throttles to react equally but then the balance on the BBS go all to pot and they're totally unequal to get a balanced idle.
Am I doing something wrong ???
Using twin max, what sort of sensitivity setting should I be aiming to use?
Max seems WAY too sensitive, and if I turn it down it's quite easy to get "reasonable" balance...

Bike is a 2002 1150gs

Cheers
 
I never touch the left throttle body. I just check that there is minimal play in the cable. I adjust the right throttle body cable to obtain balance at 2500 rpm. The twin max sensitivity is adjusted towards more sensitive as the throttle bodies come closer to balance.

I then adjust the brass screws to obtain correct idle rpm and balance at idle.

Works for me and is the standard way of doing it.

why you are adjusting the left body is beyond me.

:nenau

Ian
 
Been "messed" with in the past and I wasn't happy with vibration when running.
.....
No paint on the throttle stop screws and left one "wobbly"
So little choice but to reset, which I've done, but thought BBS were supposed to be more or less equal on idle to balance them, but if not the case, I'm no longer worried ...

I'm sorry it was beyond you :D
 
You should treat the left throttle body as the reference. Everything is adjusted to it. The left throttle body has the Throttle Position Sensor for the motronic. The TPS value is set when the left body is closed, That is when it is on the throttle stop. The throttle cable should not be pulling it off the throttle stop.

Provided the throttle stops have not been adjusted, you should be OK to slacken off the left body cable adjuster until you have the minimum play. Then repeat the procedure adjusting only the right cable adjustment to get your balance at 2500 rpm. Then sort out the idle balance using both brass bipass screws.

Ian
 
Unfortunately it was the left hand throttle stop screw that has a "wobble" and so I wasn't happy that the TPS sensor was set anything like correctly. I've reset it with a multimeter and an idle voyage of .340 (as described in many threads) I can then have slack in both cables, the BBS screws set equally and it idles lovely.
It's only when I get the 2500 rpm setting balanced that the BBS screws need adjusting again and about 3/4 a turn apart from each other to get the smooth idle back...
If that's acceptable, then I'll not worry and just ride it !
I can't get my head round why setting the right hand throttle cable to give a 2500 balance knocks the idle balance out !!
(I think I explained that correctly) :)
 
It is a bit crude. The bike is never silky smooth, all I ever manage to achieve is as smooth as possible at that time.

In order to get the bike as smooth as possible the valves need to be adjusted first, then carry out the throttle sync.

You'll get the hang of it. The Twin max is probably not the best tool to use, because of the sensitivity. But it is possible to get a reasonably good balance using it.

I use one. Practice makes perfect.

:thumb2
Ian
 
Spud said:
Been "messed" with in the past and I wasn't happy with vibration when running.
.....
No paint on the throttle stop screws and left one "wobbly"
So little choice but to reset, which I've done, but thought BBS were supposed to be more or less equal on idle to balance them, but if not the case, I'm no longer worried ...

I'm sorry it was beyond you :D
Click to expand...

So you've done a zero=250 reset before setting the TPS, or have you just adjusted the TPS to read correctly?
Once you have reset zero=250 you can then lock the left side cable and any further adjustments are only made to the right cable for balancing at around 2.5k rpm, taking the BBS screws out and cleaning them up might help but they will never be an identical amount of turns out although they should be pretty close.
 
mspenz said:
So you've done a zero=250 reset before setting the TPS, or have you just adjusted the TPS to read correctly?
Once you have reset zero=250 you can then lock the left side cable and any further adjustments are only made to the right cable for balancing at around 2.5k rpm, taking the BBS screws out and cleaning them up might help but they will never be an identical amount of turns out although they should be pretty close.
Click to expand...

Yes, did the zero=250 then set idle at 340.
After that left alone and just did right hand side .....
 
As a home mechanic, modestly comfy with my skill set and experience, and always keen to improve and learn, I went to one of the GSer workshop days last year with Mikeyboy and a bunch of monkeys from here. It gave me confirmation on a lot of things, and I picked up some great tips from the day. One of my weak points was throttle body balance, but after watching, listening and asking some numpty questions it gave me the foundation I needed to go it alone. That week I picked up a carbtune, got reading and got to work on my bike, an 1150GS.

http://www.carbtune.co.uk/index.html

It didn't work. It wouldn't settle. It was lumpy. Impossible to get even results on the scales, unsettled tick over, too high, too low...

But that was last year and I've persevered since then and learnt this -

my bike goes off after approx 3500 miles, so I now do it around the 2500 mark.
I get the best results just after doing the valves, which are done every 5000, along with an oil change.
My throttle cables are probably original and though there is only ever a tiny amount to be adjusted, they are probably stretched / rusty / full of mice ( bike's done 110000 plus...)
it needs to be done when the bikes hot after a run, of at least half an hour, and sat to cool for 5 minutes

I've got better at it, a lot better, and the recent service was the best yet, steady (for a donkey old 1150) tick over at 900 to 1000, crisp off the throttle and pulls well under load.

Stick with it spud, you'll get better. Just this afternoon I was chatting away with a very experienced mechanic, and I mentioned my learning and improvement with my little journey and he mirrored my sentiments... Stick with it. Listen, feel, think, you'll get it.
 
knucklemoto said:
As a home mechanic, modestly comfy with my skill set and experience, and always keen to improve and learn, I went to one of the GSer workshop days last year with Mikeyboy and a bunch of monkeys from here. It gave me confirmation on a lot of things, and I picked up some great tips from the day. One of my weak points was throttle body balance, but after watching, listening and asking some numpty questions it gave me the foundation I needed to go it alone. That week I picked up a carbtune, got reading and got to work on my bike, an 1150GS.

http://www.carbtune.co.uk/index.html

It didn't work. It wouldn't settle. It was lumpy. Impossible to get even results on the scales, unsettled tick over, too high, too low...

But that was last year and I've persevered since then and learnt this -

my bike goes off after approx 3500 miles, so I now do it around the 2500 mark.
I get the best results just after doing the valves, which are done every 5000, along with an oil change.
My throttle cables are probably original and though there is only ever a tiny amount to be adjusted, they are probably stretched / rusty / full of mice ( bike's done 110000 plus...)
it needs to be done when the bikes hot after a run, of at least half an hour, and sat to cool for 5 minutes

I've got better at it, a lot better, and the recent service was the best yet, steady (for a donkey old 1150) tick over at 900 to 1000, crisp off the throttle and pulls well under load.

Stick with it spud, you'll get better. Just this afternoon I was chatting away with a very experienced mechanic, and I mentioned my learning and improvement with my little journey and he mirrored my sentiments... Stick with it. Listen, feel, think, you'll get it.
Click to expand...


Thank you, kind words. It frustrates me, I've sprinted and hill climbed Caterhams in the last, always done my own "spannering" including balancing side draught Webers etc. I've taken engines and gearboxes out quite happily, but this has got me somewhat "frustrated" But I'm determined, for now !
 
Ian J Hartley said:
You should treat the left throttle body as the reference. Everything is adjusted to it.
Click to expand...

Nope.

You can adjust whatever side gives the cable slack you're happy with.

Some people like a tight cable others a bit of slack.
 
Or just turn the sensitivity down to Min.... Looks perfect all the time then !! :)
 
Spud said:
Unfortunately it was the left hand throttle stop screw that has a "wobble" and so I wasn't happy that the TPS sensor was set anything like correctly. I've reset it with a multimeter and an idle voyage of .340 (as described in many threads) I can then have slack in both cables, the BBS screws set equally and it idles lovely.
It's only when I get the 2500 rpm setting balanced that the BBS screws need adjusting again and about 3/4 a turn apart from each other to get the smooth idle back...
If that's acceptable, then I'll not worry and just ride it !
I can't get my head round why setting the right hand throttle cable to give a 2500 balance knocks the idle balance out !!
(I think I explained that correctly) :)
Click to expand...

I think what's happening is that you have minimal slack in the throttle cables, which is good, but when you go to balance at 2500, you are shortening one of the cables and making it a teeny bit too tight.

Try getting the balance at 2500 by only turning the cable adjust "in" and use the cable required to get balance, meaning use the left or right but only turn the adjuster clockwise.

Added: This explains cable adjustment: http://forums.bmwmoa.org/showthread...nd-Zero-Zero&p=1003851&viewfull=1#post1003851
 
Roger 04 RT said:
I think what's happening is that you have minimal slack in the throttle cables, which is good, but when you go to balance at 2500, you are shortening one of the cables and making it a teeny bit too tight.

Try getting the balance at 2500 by only turning the cable adjust "in" and use the cable required to get balance, meaning use the left or right but only turn the adjuster clockwise.

Added: This explains cable adjustment: http://forums.bmwmoa.org/showthread...nd-Zero-Zero&p=1003851&viewfull=1#post1003851
Click to expand...

Thank you Roger, I've just read that and know exactly where I've been going wrong. I've been removing the slack and then trying to balance using just the right side, but it was leaving the right side cable "too tight" and hence knocking the idle way off as soon as it was set be synched at 2500 rpm.
I've just been hitting myself on the head as it's SO obvious now !!

(I used your zero=250, and idle at 340mv by the way, idles lovely until I touch it :D )

Thank you :rolleyes:
 
Roger 04 RT said:
I think what's happening is that you have minimal slack in the throttle cables, which is good, but when you go to balance at 2500, you are shortening one of the cables and making it a teeny bit too tight.

Try getting the balance at 2500 by only turning the cable adjust "in" and use the cable required to get balance, meaning use the left or right but only turn the adjuster clockwise.

Added: This explains cable adjustment: http://forums.bmwmoa.org/showthread...nd-Zero-Zero&p=1003851&viewfull=1#post1003851
Click to expand...

Roger, you are an absolute star !!!
20 minutes when I got in, including setting up and the BBS are now equal with an idle of about 1100. Absolute mininimal deviation on meter, even at full sensitivity...
Just needed someone to point me in the right direction !!!
(And for me to put my brain in gear !!)
Thanks again, much appreciated
Spud..
 
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