Stock V11 bin file fuel map analysis

[Meinolf]

25 minutes ago, 80CX100 said:

If I loaded your map with a Mistral Crossover/Oval Exhaust with .15 & .20 clearances would it be less wear and tear on the valve train? Would it run poorly?

If your map is designed for .25 & .25 clearances, am I understanding it correctly that if I change from those clearances that I will screw up the timing built into the map?

Hi Kelly,

valve play and timing have no connection. I've never measured AFR with a mistral crossover and oval exhaust. My setup is standard crossover and TI exhaust (which flows significantly better than the stock exhaust, but is quite loud)

Again using a picture from Motoguzznix's file for visualization, the timing is dependent on the camshaft. It's best practice to adjust the point at which the intake and exhaust valve have the same lift to 2-3° before TDC and not at TDC. Or even behind, which is the reality in Guzzi engines after some time because the chain has worn a bit.

The main issue with the V11 valve train are the guides, you will typical see a much larger play than factory specs after some time.

So, changing the valve play versus the 0.25mm I've used will impact AFR and not timing or wear and tear. Disregarding all other factors, decreasing the play would reduce the airflow, which would lead to a richer mixture than I intended. Increasing it, within reason, would slightly improve airflow and lead to a leaner mixture.

But as I wrote previously, the V11 camshaft is a good one, stay with 0.25mm.

Cheers
Meinolf

[80CX100]

Hey Meinolf,     Thank you so much for taking the time to respond with such a detailed reply, and especially how variations in the valve clearances would affect the fueling.

I'll be studying this and a lot of the other material you've previously posted, I look forward to being able to get this bike tuned up and running as sweet as I can.

Your generosity in sharing your knowledge and expertise, is very much appreciated.

Tks

Kelly

[68C]

On 3/16/2020 at 7:01 AM, Meinolf said:

Disregarding all other factors, decreasing the play would reduce the airflow, which would lead to a richer mixture than I intended. Increasing it, within reason, would slightly improve airflow and lead to a leaner mixture.

Bit confused by this,  surely if you opened up the valve clearance to a ridiculous amount the valves would hardly open and so there would be little gas flow.  In the same way if you tightened the clearance to almost zero the valves would open further and pass more gas.

So how can "decreasing the play would reduce the airflow" make sense?

[Meinolf]

21 minutes ago, 68C said:

Bit confused by this,  surely if you opened up the valve clearance to a ridiculous amount the valves would hardly open and so there would be little gas flow.  In the same way if you tightened the clearance to almost zero the valves would open further and pass more gas.

So how can "decreasing the play would reduce the airflow" make sense?

Hi,

sure, a ridiculuous amount would be nonsense and result, amongst other things, in little gas flow. Keep in mind my remarks "...Disregarding all other factors..." and "...Increasing it, within reason, ..".

The ultimate goal is get as much air mass into the combustion chamber at the time it's needed and can be utilized. This is expressed as volumetric efficiency. If you have a pump (cylinder/piston) with 1l volume, the largest air volume which can be brought into the pump is 1l, which is a volumetric efficiency of 1. Now consider a combustion engine to be a flow machine.

Before opening the valves the air is waiting to get into the combustion chamber. When the valves are opened it can stream into the combustion chamber. The faster the valve opens the faster it can get into the chamber. The speed of valve opening is determined by gradient of the camshaft. By increasing the valve play the controlled (and slow) ramp-up is partly skipped and  the opening time (fully closed to fully opened) is shortened, the valve is actuated faster because it's already at a high gradient part of the camshaft. Hence, the air flow will increase.

Decreasing the valve play would result in an earlier opening of the valves, but only a slight gap one. The air waiting to get into the combustion chamber is trickling instead of charging, overall volumetric efficiency will decrease. Hence, less air mass arrives in the combustion chamber at the end of the cycle.

Having said this, this is a rather theoretical discussion because other factors, such as max. acceleration/deceleration, spring rate, weight of the moving parts of the valve train, surface pressure and so on need to be taken into account.

Cheers
Meinolf

 

[68C]

Thank you for your clear explanation.  I see now by having the valve follower making contact further up the cam it will 'snap' open quicker. The small difference in total valve opening is unimportant.

[Meinolf]

Hi,

18 hours ago, 68C said:

Thank you for your clear explanation.  I see now by having the valve follower making contact further up the cam it will 'snap' open quicker. The small difference in total valve opening is unimportant.

I don't want to niggle, but make sure no wrong conclusions are drawn from above. Using different valve play values should be done only if all relevant factors are known.

Simply increasing valve play to garner the benefits of better VE without having a measured the camshaft and valve lift would be a dangerous game. Skipping the ramp up portion entirely is comparable to hammering the valve and all involved components instead of having them smoothly brought up to speed. And, as the total valve lift will happen during a shorter time, the acceleration would increase. Which might lead to valves simply being torn apart or overshooting because the springs can't cope with the increased inertial moment.

Just sayin`
Meinolf

 

[68C]

If you set your valves to the wider setting and do not make any changes to the valve timing I understand the valves will open later and close earlier.  With our V11s we cannot fine tune valve timing without buying special vernier sprockets.  Does the difference between standard and wide valve clearances make much difference to effective valve clearance?   Also get your point about the larger setting misses the quieting ramp on the cam.

[Meinolf]

Hi,  

5 hours ago, 68C said:

If you set your valves to the wider setting and do not make any changes to the valve timing I understand the valves will open later and close earlier.

Yes, that's what it boils down to.

5 hours ago, 68C said:

With our V11s we cannot fine tune valve timing without buying special vernier sprockets.

Well, you don't need special vernier sprockets. Re-boring the index hole in the sprocket with the desired offset is the way I do it.  

5 hours ago, 68C said:

Does the difference between standard and wide valve clearances make much difference to effective valve clearance? 

I don't understand the question. What do you mean by effective valve clearence?

Cheers
Meinolf

[gstallons]

Hmmmm . Too much thinking about valve clearance ? I was only aware of "hot" & "cold" .

[Tomchri]

6 hours ago, 68C said:

If you set your valves to the wider setting and do not make any changes to the valve timing I understand the valves will open later and close earlier.  With our V11s we cannot fine tune valve timing without buying special vernier sprockets.  Does the difference between standard and wide valve clearances make much difference to effective valve clearance?   Also get your point about the larger setting misses the quieting ramp on the cam.

And would that be possible to hear ( the quieting ramp ) with some help,, like a big screwdriver, not the doctor gear ?

 Cheers tom 

[Lucky Phil]

4 hours ago, gstallons said:

Hmmmm . Too much thinking about valve clearance ? I was only aware of "hot" & "cold" .

Yes, I do believe so.

Ciao

[gstallons]

No ship ! Too much time with a mouse & not enough with a throttle grip .

[68C]

6 hours ago, Meinolf said:

don't understand the question. What do you mean by effective valve clearence?

Sorry, I meant to say effective valve timing.  I must have the virus!

[Koudy01]

Hi guys, I read this topic. Especially Meinolf's setup for his BIN. But I don't understand to this point: "Idle sync using the two throttle stop screws". One throttle stop screw moves with both throttle butterfly valves, because butterfly valves are connected by a rod. So I don't know, how is it possible to sync the idle by those screws? Can you explain me this method please? Thank you.

[Tomchri]

52 minutes ago, Koudy01 said:

Hi guys, I read this topic. Especially Meinolf's setup for his BIN. But I don't understand to this point: "Idle sync using the two throttle stop screws". One throttle stop screw moves with both throttle butterfly valves, because butterfly valves are connected by a rod. So I don't know, how is it possible to sync the idle by those screws? Can you explain me this method please? Thank you.

Hi 01

Balancing only,  right?  Take the B rod of, adjust throttle screws so they just touch the stopper,, I use a 0.05mm blade, or a piece of paper, then I turn them both in about 1sixth of a turn. My Greenie starts fine without the balance rod connected. Easier to set the idle with the left stop screw,, just do the same adjustment to the right side. Adjust the balance rod with the white nob so it slips on without moving anything.  Then use your balancing instrument and the white nob for final tuning. Seems to me they all have different souls and behaviors .   Cheers tom.