Throttle Body Sync on M1100

[Yogi]

Does anyone know for sure if the procedure for balancing the throttle bodies on an M1100 is the same as for previous Monsters?
I have tried setting my bike up as per the workshop manual but I find the air Bleed Screws make hardly any difference to vacuum (not as sensitive as I would have thought).

My bike has the Rexxer Flash and is "Open" fuelled (no O2 sensors). From what I have observed, adjusting the Air Bleed Screws seems to be compensated for by the the Idle Air Valve in maintaining RPM.

Maybe I should chase Mixture rather than Vacuum?

I have a five gas analyser would I hook it up to the plugs in the headers or use the same holes the O2 sensors used to live in?

Thanks in advance

[brad black]

on an idle control valve bike i let that control the idle speed and go the mixture as required.  but the problem you face is that you can't adjust the mixture on the m3c, so you do what you can with the air bleeds.

i always go mixture over balance.  use the small ports in the headers if you have the right adapters.

make sure the balance with the throttles open and air bleeds closed is good first.

[Yogi]

Thank you Brad.
Is there a sweet spot in RPM in which to Balance Throttles?
I would normally set an IL4 around 3000RPM would this be the same for a Ducati?

[oldndumb]

Thank you Brad.
Is there a sweet spot in RPM in which to Balance Throttles?
I would normally set an IL4 around 3000RPM would this be the same for a Ducati?

Help an old dude to understand this a bit better.  
I've always balanced TBs at idle because an increase in RPM gradually takes the TB bleed circuit out of the equation. Where am I going wrong, and what is an IL4. 

[EEL]

IL4 - In Line 4 (Cylinder)

[EEL]

Help an old dude to understand this a bit better.  
I've always balanced TBs at idle because an increase in RPM gradually takes the TB bleed circuit out of the equation. Where am I going wrong, and what is an IL4.  

You want to balance to the beginning of your engine's sweetspot. That way you get a smooth power delivery at the most useable RPM. I believe that is 4000 RPM on a monster. I dont think it would matter if you balanced a bit higher (like 4500 RPM)

You'll never get your airflow to be accurate at all RPM's so its a matter of choosing where you want to balance. Since most people run their bikes most of the time between 4k-6k, thats the range to tune to.

AS ALWAYS, PLEASE CORRECT ME IF I'M WRONG.

[oldndumb]

You want to balance to the beginning of your engine's sweetspot. That way you get a smooth power delivery at the most useable RPM. I believe that is 4000 RPM on a monster. I dont think it would matter if you balanced a bit higher (like 4500 RPM)

You'll never get your airflow to be accurate at all RPM's so its a matter of choosing where you want to balance. Since most people run their bikes most of the time between 4k-6k, thats the range to tune to.

AS ALWAYS, PLEASE CORRECT ME IF I'M WRONG.

See, that is where I am confused. All of the bikes I have worked on were not affected by idle bleed air adjustments at and from the mid range transition. The idle bleed air is so minimal as to be ineffectual/inconsequential at higher RPMs. Guess I ought to take it as another learning opportunity and just try it myself and see if what happens.

IL4....doh! 

[Yogi]

@ Oldndumb You are correct in your assumptions. Maybe I should have elaborated, I was thinking of adjusting the Throttle Butterflies with both the Air Screws Closed using the sprung adjuster between the throttle bodies. As per Brads post.

@EEL Spot on  this is how I see it.

Does anyone know what the CO should be, the manual says "check that the CO level in both cylinders exceeds 0.4%"? Nothing specific.

[oldndumb]

Thanks, Yogi. That really makes sense.

Guess I should have figured that out by reading the earlier posts a bit closer.

Now we need a group buy on a Gunson.

[EEL]

Can someone elaborate on one item. I understand the need to balance TB's but I dont understand the importance of measuring CO and adjusting it at idle

What is the reason behind this and what does it accomplish.

[Yogi]

The Air Bleed Screws provide unmeasured air to each cylinder. Because its unmeasured its technically an air leak that the ECU does NOT know about and on an Open system like mine (no O2 Sensors) there is no way to compensate for this unmeasured air. The IAV Idle Air Valve is controlled by the ECU and the ECU will adjust mixture according to the amount the IAV is operating.
As mentioned before all this is only relevant at the lower end of throttle angles,  The influence of the stepper motor air flow is present to approximately 30° throttle angle; no correction is required for greater angles.
On Carb'd IL4s EU spec we would only use Air Bleed screws to correct minor imbalances of up to 20mmHG anything over this you use the Sprung loaded Butterfly adjusters. I wouldn't say it was critical to get the Idle CO right but if your idle is overly rich you may have hesitation off idle or stumbling especially if you have been sat at traffic lights idling for a while. Too weak is not good period.

"What is the reason behind this and what does it accomplish." Smoother throttle off idle.

[brad black]

the throttle opening you get with a free rev in neutral is much lower than what you see on the road.  pull the clutch in at highway speed without closing the throttle and it'll probably hit the limiter.  so revving it up on the bench doesn't get you that high.  I always rev them fairly high when checking balance, and it's always a compromise.  some models are generally good, some appalling (749/999).

on a model with an adjustable idle trimmer, setting it references the mapping where it theoretically is meant to be.  sometimes you have to manipulate mapping if this isn't the case.

or, for example, on 1198 i have a map that is richer on one cylinder, but leaner on the other so i can use a certain trimmer setting (range) and have both air bleeds wound full in (one is always wound in on an idle control valve bike) to keep the idle speed down, as they cannot control themselves.  this is compounded by them generally being out of balance (vertical shut down) seemingly to help control the idle speed.  that's how most of the ones i see are initially set up anyway.  balance them up and the idle speed is borderline with both air bleeds fully shut.  so i made a map that worked as required.

if you don't have an idle trimmer, like a siemens conti ecu bike, i'd be using one of the airbleeds to balance the mixture.  but if it's too far off, then the person who did the mapping didn't do it properly.  it's mainly an idle quality thing, generally at least 3% co makes them idle nicely.  it really comes down to the quality of the mapping, and idle mixture is one part of that, as important as any other really.

[EEL]

Yikes!! Way more complex than I thought.. I'll have to read that a dozen times and do some more research.

You gotta talk to us like you're talking to a 4 year old. You're so far ahead of us that what comes easy to you is like greek to us normal humans.

It's starting to make more sense after the 3rd read.