Throttle Body Balancing

[Seweryn]

Hi All,

I am trying to properly balance the throttle bodies in my 1200 Sport.
After reading many guidelines I haven't found an answer to the question and I would appreciate your opinion:

When I finish setting up the idle speed vacuum balance by opening one of the air bypass screws (after ballancing the throttle bodies at speed - say at 3.5k rpm), should I ignore the missbalance just created off idle then?  Do you ever re-check the ballance at speed (again) after the final adjustment with the air bypass screw?

[Huzo]

I understand your point and have often wondered that too. Do you notice a small alteration in the high speed after you’ve done the idle ?
I can’t see why you cannot just tweak the high speed again if necessary, then go back and look at the idle. I would think that the idle air bleed is so minuscule, that it has close to zero effect on the high speed reading, but for sure if you run through a second time, you are going to zero in on the right setting.
Don’t forget to reset the TPS.

[Seweryn]

I understand your point and have often wondered that too. Do you notice a small alteration in the high speed after you’ve done the idle ?
I can’t see why you cannot just tweak the high speed again if necessary, then go back and look at the idle. I would think that the idle air bleed is so minuscule, that it has close to zero effect on the high speed reading, but for sure if you run through a second time, you are going to zero in on the right setting.
Don’t forget to reset the TPS.

Thanks,

Sure, I notice the alteration at higher speed after completing the idle balancing.  I would then tweak the linkage screw to compensate for the changes.  Not sure this is the correct procedure as no instruction explains it that way.

[GuzziOrDeath]

It will make little to no difference to how the engine runs after you adjusted the air bleed to set idle balance, even if it seems to change the high-speed balance.

Do not "tweak" the bell-crank screw to change the high speed balance after the idle balance is done. If you do that, you must reset the TPS again. You're just chasing your tail.

[Huzo]

It will make little to no difference to how the engine runs after you adjusted the air bleed to set idle balance, even if it seems to change the high-speed balance.

Do not "tweak" the bell-crank screw to change the high speed balance after the idle balance is done. If you do that, you must reset the TPS again. You're just chasing your tail.

I’ll just add a bit to your comment G.O.D.
When you set the high speed first time, you are doing it with BOTH air bleeds closed and this is fine and correct.
Then if you set the air bleed (only one), you will make some small change to the high speed.
But.
If you then re set the high speed, (it should still be very close), you are doing it from a datum of (close to) correct, from the air bleed perspective.
At this point during the high speed adjustment), the air bleed is damn close to where it ought to be, so when you go back to re tweak it, there will be a relatively smaller adjustment required.
I’d do it…
Again make sure you DO NOT adjust the linkage length, only the appropriate adjusting screw.
Again re check the TPS and have a look at the CO setting if you’re chasing a nice idle.

I’d still like to do the balancing with the engine pulling some load @3,000 rpm versus in neutral as we currently do…
Simply because under load, the plate is open more and is representative of it’s position in real world conditions, but I’ll admit it doesn’t seem to matter.

[Seweryn]

I’d still like to do the balancing with the engine pulling some load @3,000 rpm versus in neutral as we currently do…
Simply because under load, the plate is open more and is representative of it’s position in real world conditions, but I’ll admit it doesn’t seem to matter.

I was just planning to attach the vacuum gauges to the bike and do the test on the road under load for the above reason.  Not sure it would make a massive difference, but handy for reading under various conditions.

[Huzo]

It will make little to no difference to how the engine runs after you adjusted the air bleed to set idle balance, even if it seems to change the high-speed balance.

Do not "tweak" the bell-crank screw to change the high speed balance after the idle balance is done. If you do that, you must reset the TPS again. You're just chasing your tail.

Yes, you are “chasing your tail”, but your tail is getting closer.
The second time you look at the high speed, the idle bleed is a lot closer to where it will ultimately need to sit, so the high speed is being set at “real world” conditions, then the final re tweak will get you the closest.

Also we need to be mindful of using the ambiguous term “bell crank screw…”
For those still finding their way, that could mean the adjusting screw located mid way between the TB’s or the “sacred screw…”
99.87% (but not all) of us, know that these are to be not touched..!

I resurrected an almost new set that had been molested grossly, by taking a dump time from a low pressure vessel into a known good one, then set the molested one to the same flow rate.
It worked very well, but was a LOT of messing around !

[Huzo]

I was just planning to attach the vacuum gauges to the bike and do the test on the road under load for the above reason.  Not sure it would make a massive difference, but handy for reading under various conditions.

Bloody hell..!
I’ll be very keen to see if the readings are different, please report back. Good for you 

[GuzziOrDeath]

Also we need to be mindful of using the ambiguous term “bell crank screw…”
For those still finding their way, that could mean the adjusting screw located mid way between the TB’s or the “sacred screw…”
99.87% (but not all) of us, know that these are to be not touched..!

It is not ambiguous. The 'bell crank' screw is the screw to adjust the balance. The 'sacred screw' is the throttle stop screw.

If this is too difficult to comprehend, you shouldn't be touching your throttle bodies.


Furthermore, all the faffing about chasing your tail trying to get your balance perfect will won't make a lick of real world difference when your riding.

[Huzo]

It is not ambiguous. The 'bell crank' screw is the screw to adjust the balance. The 'sacred screw' is the throttle stop screw.

If this is too difficult to comprehend, you shouldn't be touching your throttle bodies.


Furthermore, all the faffing about chasing your tail trying to get your balance perfect will won't make a lick of real world difference when your riding.

Well, there are a lot of things that we probably”shouldn’t be doing” but we develop skills through a lifetime of misadventure, ignoring advice and then taking it on, seeking the advice of known and respected persons and all that….

I said that I accept 98% of us know what we’re doing, but I’ll wager that we got that way by making errors, my point is that pointing out the possible source and location of where those potential trouble spots may reside.
Furthermore.
My second point was that if you perform the TB balance procedure as published, you’ll be “successful enough”, if you do nothing you’ll be successful enough if you’re prepared to accept mediocrity.
But it’s a non debatable point, that if you perform the first procedure then go back and finely adjust it, you’ll zero in closer to where you seek.
Do you need to…?
No

Will it take you closer to where you want to be..?
Yes.

Do you need someone else telling you the degree to which you should involve yourself with YOUR bike…?
Demonstrably not.

[Huzo]

Furthermore, all the faffing about chasing your tail trying to get your balance perfect will won't make a lick of real world difference when your riding.

It actually will make a difference if it makes you feel better.  We both know that if Dr John himself came back from the grave and tuned your 1200 Sport within an inch of it’s life, it still will not go close to out performing it’s counterparts from Aprilia or Asia.
But that is not and never was the point, you would have a DR JOHN tuned bike and that’d be enough to make it worthwhile for some.
Do I go along with that ?
Again no.
But I’m not about saying what I would do, it’s about appreciating another’s motives and not talking down to them from a great height.
The guy just wants to know if he has a point…I think he has.

[GuzziOrDeath]

Well, you've driven me off this forum before with your wanker shite, and congratulations you've done it again.

If any other members lap up your crap, I feel sorry for them.

[Seweryn]

Thanks Guys,

I appreciate your opinions.  After thinking about it again, I believe the difference under load (and wider open throttles) would be small enough not to worry about it.  However, as my engine is not running the way I would like, I keep chasing better results the best I can.  I will update when I manage to provide some imrovements.

[Huzo]

Well, you've driven me off this forum before with your wanker shite, and congratulations you've done it again.

If any other members lap up your crap, I feel sorry for them.

Ok..
‘Bye now.

[Bulldog9]

Hi All,

I am trying to properly balance the throttle bodies in my 1200 Sport.
After reading many guidelines I haven't found an answer to the question and I would appreciate your opinion:

When I finish setting up the idle speed vacuum balance by opening one of the air bypass screws (after ballancing the throttle bodies at speed - say at 3.5k rpm), should I ignore the missbalance just created off idle then?  Do you ever re-check the ballance at speed (again) after the final adjustment with the air bypass screw?

It can't hurt, but is likely unnecessary. The Bellcrank adjuster balances the TBs at speed, the air bleeds are mostly IDLE. I've experimented with the air bleeds up to 1500RPM, and bellcrank from 1500-4500/5000, and found that I was chasing my tail, so stick with 4K and Idle.

You really need Guzzidiag to do this right. Mostly so you can reset the TPS and learning parameters (AKA fuel trims).

Here is my process from my notes.

1. Close both air bleeds on the TB's.

2. Connect Guzzi Diag and confirm it is communicating with the ECU. **Key on, kill switch in RUN.

3. Connect manometers to the manifold ports. ***If you have NOT deleted or disabled/blocked the Evap system, stick a golf tee or similar in the vacuum lines you removed from the ports on the TB's.

4. Start the motor and warm it up until it is close to 60*C as shown by Guzzidiag. **Test Stepper Motor and check over values while warming up.

5. Once warmed up, hold the engine speed at 3,500-4,000 RPM and use the screw on the bell crank that controls the linkage rod between the TB's to bring the TB's in balance. **DONT touch sacred screw!!

6. Once the high speed balance is equal or very close allow the throttle plates to fully close. AKA let it go to idle, snap the throttle open and closed a few times to make sure throttle plates and linkage settle. ***I check this several times to ensure any slop or variance is mitigated.

7. Kill the motor with the kill switch, (Not the key or Guzzidiag will disconnect and you'll have to reconnect).

8. Use the 'Re-set TPS' function in 'Actors'.

9. Use the 'Re-set parameters' function in actors.

10. Re-start the engine, blip the throttle a couple times and let it settle to idle.

11. Check the manometers and open the air bleed on the TB with highest vacuum until both are equal. Blip throttle again and readjust as necessary. Shut off motor, and turn ignition key off.

12. Unplug manometer and reinstall blanking plugs/vacuum line. Disconnect Guzzidiag and remove cables.

**A few other things. I do this AFTER a valve adjustment. I also spray a bit of carb cleaner or spray a little Seafoam into the stepper motor for good measure.

Also, When I deleted the Evap system, I connected the TB vacuum ports with a vacuum hose. This REALLY helps with balancing the intake side of things, much in the way the H pipe does in the exhaust. I noticed an improvement in a more stable and smoother idle. I have this on my 1200 Sport and old Norge. The Griso evap system is just plugged with ball bearings in the vacuum lines to the ports, and having the check valve disabled by running a drill bit through it. MI did this mod back when the bike was new with it's original owner. It runs great, and I have left it alone as I like the look with the Evap canister in place.

I've also found that over the years (9 with Griso, 4 with 1200 Sport) that once set, things really don't change. I 'check' mostly when I am bored, and find the balance remains spot on.

I've rarely gotten everything PERFECT, but mostly close.

[Seweryn]

3. Connect manometers to the manifold ports. ***If you have NOT deleted or disabled/blocked the Evap system, stick a golf tee or similar in the vacuum lines you removed from the ports on the TB's.

Thanks Bulldog,

Do I assume correctly that the EVAP system is fitted to US spec. motors only?

[Bulldog9]

Thanks Bulldog,

Do I assume correctly that the EVAP system is fitted to US spec. motors only?

I really don't know, but I can't imagine EURO bikes having less pollution controls than the US.

The Evap system on the 1200 Sport/Breva/Norge runs from each throttle body and the fuel tank vents to a couple check valves and a charcoal canister under the rear seat at the back. The idea is to prevent any fumes from the gas tank escaping into the air. Most of the EVAP systems malfunction, usually the check valve. This causes pressure (positive and negative) in the fuel tank and can effect running.

Removing the canister gives you a nice bump in underseat storage, but some inspections mandate it is not removed.

[Seweryn]

I really don't know, but I can't imagine EURO bikes having less pollution controls than the US.

The Evap system on the 1200 Sport/Breva/Norge runs from each throttle body and the fuel tank vents to a couple check valves and a charcoal canister under the rear seat at the back. The idea is to prevent any fumes from the gas tank escaping into the air. Most of the EVAP systems malfunction, usually the check valve. This causes pressure (positive and negative) in the fuel tank and can effect running.

Removing the canister gives you a nice bump in underseat storage, but some inspections mandate it is not removed.

Thanks, I don't think this is fitted to my bike, I have never noticed anything like it.
Also, there are no periodic inspections for motorcycles in the country.

[Pescatore]

This video by Peter Roper was extremely helpful to me:   https://m.youtube.com/watch?v=BDshMp-bM_0
 It doesn't talk about the "tail chasing" discussed here, but it gave me more confidence to get setup Guzzidiag, etc.

I think I found the link in a post in this forum, may have been from Huzo.  Apologies for not giving proper mention, but to Mr. Roper 

[Seweryn]

Thanks,

I am familiar with how the throttle bodies work, but still worth listening to an experienced mechanic.

I ran the vacuum test on the road on Friday, then made final adjustments yesterday and now the engine runs a bit better.  I have learnt that the stationary test as described in the manual and here by the experts is all you need to follow to achieve the optimal result.  I believe that having the engine warmed up well is more important than other factors.

[Huzo]

Checked the TPS ?

[Seweryn]

Checked the TPS ?

Yes, TPS reset done and self learning after that.

[Bulldog9]

Thanks, I don't think this is fitted to my bike, I have never noticed anything like it.
Also, there are no periodic inspections for motorcycles in the country.

If your bike has it, it will be at the rear of the bike under the seat, basically mounted above the rear fender. Removed, or without, it give a nice bump in underseat storage.

[Seweryn]

If your bike has it, it will be at the rear of the bike under the seat, basically mounted above the rear fender. Removed, or without, it give a nice bump in underseat storage.

It must be installed in some markets then - I can store a can of tyre repair spray beside the battery and a few small items as well.

[Bulldog9]

It must be installed in some markets then - I can store a can of tyre repair spray beside the battery and a few small items as well.

All have the large area by the battery (which is great) the canister on US models is farther back right in front of the taillight under the seat.

[Nate78]

So, I'm hoping to jump in on this thread as I coincidently was just attempting to balance the throttle bodies on my 1200 sport for the first time. I believe that it has not been done before as the yellow paint was still on the screw, the bike only has 1500 miles on it. My concern is that the high speed adjustment required several turns out to be balanced. I was expecting it to be closer than that, as in a turn or two. The bike does seem to run smoother, but what do I know, I thought it ran good before...
Also, I did not touch the sacred screw and I did reset the tps.

[guzzisteve]

Sounds like success to me, congrats. Must be nice bike w/low miles. In turning more than 1/2 turn or so on big end I have had the idle increase a bit unless it was way off from factory. That does happen, that's why you have 1st service. Dealer can catch if it wasn't done on set-up.
Just reread which way you went, out is better than in w/adj, in too much moves the plate where you get increased idle.

[Seweryn]

Less than 2.5k km from new?  How is that possible and why?  I drove more in the first week after buying the bike in July   .

[Seweryn]

Do you know if the throttle bodies are interchangeable between the 1200 multivalve engines, i.e. Stelvio / 1200 Sport / Norge / Griso?

Part numbers:

976697 and 880270.

[tris]

When I had my B1100 I discovered that the ICV leaked if driven to the fully closed position
More one side than the other.

At 3k RPM this wasn't noticeable,  but at idle it was and needed dialing out with one of the air bleed screws

Now,  if you put a ICV isolating valve in the idle circuit,  this issue goes away, and balance doesn't change between 3k and idle

As an aside a chap in NZ (can't remember his name) worked out that isolating the ICV  gave a repeatable 1k drop in idle revs.

Now, this knowledge allows you a good chance to reset a sacred screw that has been messed with as it takes out a key variable.

I bought my B1100 with a futzed sacred screw before I knew that it was something to avoid,  but this knowledge got it dialled back in pretty close

Method
1) isolate ICV
2) balance TBs
3) adjust idle using sacred screw to 1k below target
4) repeat 2 and 3 to be sure to be sure 

Just something to ponder