Fuel/Timing Mapping for 2010 450F


11 replies to this topic
  • eazrider

Posted March 09, 2010 - 01:10 PM

#1

It seems there is a knowledge base on this forum that would (or should) be able to help most of us understand how the different mapping changes available with the Yamaha Tuning tool translate into real world responses, I.E. If you advance/retard ignition timing, if you enrichen/lean fuel mixture at specific throttle openings, how might that affect throttle response etc. Any one can play with it till the cows come home, but if someone understands and can share, at least the theory on how specific mapping changes (for example, more fuel/less timing at 1/8 throttle diminishes the "surge" at intial throttle opening) might affect power characteristics, it would benefit all of us that have questions about where to make mapping changes to acquire a specific outcome...Is there any literature available, other than the manual that comes with the tuner, which explains the mechanics, but not the theory of MAP changes....
I'm jus' sayin':ride:

  • grayracer513

Posted March 09, 2010 - 02:52 PM

#2

On the fuel delivery side of things, there is one "stoichiometric" air fuel ratio. This is the ratio of air to fuel which will leave no unburned fuel or surplus oxygen behind after combustion. For gasoline, by mass, this is typically 14.7:1, but blending alcohol or other oxygenates into the fuel can alter this.

While stoichiometry may yield chemically ideal combustion, it usually doesn't result in maximum combustion pressure yield, or power. For that, the mix needs to be closer to 13:1 or even richer, sometimes.

At part throttle, the engine runs smoother and cleaner at a leaner mix, but responds more crisply to sudden throttle openings if the mix is richer, or if it can be enriched immediately on the increased opening.

On the ignition side, it's helpful to understand why ignition timing has to be in advance of TDC, and why it's so critical. The internal parts of an engine move at speeds that are hard to imagine. As the piston moves up the bore during compression, the ignition spark occurs, and combustion begins. But combustion is NOT and explosion (That's detonation. It is destructive to the engine, and must be avoided). It is a burn that starts at the spark plug and spreads outward, igniting the fuel it comes in contact with, and building pressure in the combustion chamber due to the rapid expansion of gases from the burning fuel. But remember that the piston is moving extremely fast, and will go down the bore regardless. If we want the expanding flame to apply any pressure to it as it runs down the bore, we have to start the flame burning soon enough to give it time to build a significant amount of pressure before the piston reaches TDC, so that that pressure will add to or maintain the piston's speed as it continues.

If the flame starts too late (retarded timing), the piston runs away from the flame before it can build any real pressure on it, or add any power. If we ignite the fuel too soon, pressure will rise to an excessive level before the piston goes over the top, and will actually slow it down as it approaches TDC. The other thing this will lead to is the detonation I mentioned before. As the flame spreads and fills the cylinder, it increases the heat and pressure on the yet-to-be-burned air fuel mix being pushed out in front of the flame. If the pressure and heat rises too far too fast, the entire remaining unburned fuel mass may reach the point at which it ignites spontaneously, all at the same time, rather than burning in a controlled "wave". As I said before, this can be tremendously destructive.

So, then, what does the tuner do? If the engine were built with the optimum fuel air mix and timed for maximum power output throughout the throttle and speed range, you would have something on the order of a late '60's Plymouth Street Hemi, or a '70 Chevelle LS7; an engine that had so much power everywhere that you basically couldn't touch the throttle with causing some level of mayhem, and was really only good for accelerating in a straight line. The '03 YZ450 and the CR500 were something like that. To alter the power delivery, the builders can (and did) pull the timing back a little during early acceleration, for example, to make the engine a little less abrupt. It was harder to do with a carb, but since we saw earlier that air/fuel ratio can affect power, we could tweak that, too.

Now, understand that the 2010 YZ450 engine IS NOT delivered with everything set at its optimum for the most possible power at every point in the curve. Understand further that the tuner gives you the ability to move it either toward or farther away from that optimum at 9 different points on a matrix of speed and throttle opening, and you will have the basic concept.

Look at the maps claiming to reduce the off-idle jolt the bike comes with, and you'll see that they mostly pull back on the ignition timing at low rpm.

I think you'll find the timing most useful for controlling the power, and that the fuel side can be used to fine tune once the ignition is adjusted. The 3 throttle positions listed are roughly analogous to main jet, needle position, and needle diameter, from most open to least.

  • moto278

Posted March 09, 2010 - 07:12 PM

#3

i had this same question just had not gotten around to asking anyone yet. thanks greyracer. took me a couple read throughs to understand everything but i think i get it! :banana:

  • C64DK

Posted March 12, 2010 - 07:16 AM

#4

On the fuel delivery side of things, there is one "stoichiometric" air fuel ratio. This is the ratio of air to fuel which will leave no unburned fuel or surplus oxygen behind after combustion. For gasoline, by mass, this is typically 14.7:1, but blending alcohol or other oxygenates into the fuel can alter this.

While stoichiometry may yield chemically ideal combustion, it usually doesn't result in maximum combustion pressure yield, or power. For that, the mix needs to be closer to 13:1 or even richer, sometimes.

At part throttle, the engine runs smoother and cleaner at a leaner mix, but responds more crisply to sudden throttle openings if the mix is richer, or if it can be enriched immediately on the increased opening.

On the ignition side, it's helpful to understand why ignition timing has to be in advance of TDC, and why it's so critical. The internal parts of an engine move at speeds that are hard to imagine. As the piston moves up the bore during compression, the ignition spark occurs, and combustion begins. But combustion is NOT and explosion (That's detonation. It is destructive to the engine, and must be avoided). It is a burn that starts at the spark plug and spreads outward, igniting the fuel it comes in contact with, and building pressure in the combustion chamber due to the rapid expansion of gases from the burning fuel. But remember that the piston is moving extremely fast, and will go down the bore regardless. If we want the expanding flame to apply any pressure to it as it runs down the bore, we have to start the flame burning soon enough to give it time to build a significant amount of pressure before the piston reaches TDC, so that that pressure will add to or maintain the piston's speed as it continues.

If the flame starts too late (retarded timing), the piston runs away from the flame before it can build any real pressure on it, or add any power. If we ignite the fuel too soon, pressure will rise to an excessive level before the piston goes over the top, and will actually slow it down as it approaches TDC. The other thing this will lead to is the detonation I mentioned before. As the flame spreads and fills the cylinder, it increases the heat and pressure on the yet-to-be-burned air fuel mix being pushed out in front of the flame. If the pressure and heat rises too far too fast, the entire remaining unburned fuel mass may reach the point at which it ignites spontaneously, all at the same time, rather than burning in a controlled "wave". As I said before, this can be tremendously destructive.

So, then, what does the tuner do? If the engine were built with the optimum fuel air mix and timed for maximum power output throughout the throttle and speed range, you would have something on the order of a late '60's Plymouth Street Hemi, or a '70 Chevelle LS7; an engine that had so much power everywhere that you basically couldn't touch the throttle with causing some level of mayhem, and was really only good for accelerating in a straight line. The '03 YZ450 and the CR500 were something like that. To alter the power delivery, the builders can (and did) pull the timing back a little during early acceleration, for example, to make the engine a little less abrupt. It was harder to do with a carb, but since we saw earlier that air/fuel ratio can affect power, we could tweak that, too.

Now, understand that the 2010 YZ450 engine IS NOT delivered with everything set at its optimum for the most possible power at every point in the curve. Understand further that the tuner gives you the ability to move it either toward or farther away from that optimum at 9 different points on a matrix of speed and throttle opening, and you will have the basic concept.

Look at the maps claiming to reduce the off-idle jolt the bike comes with, and you'll see that they mostly pull back on the ignition timing at low rpm.

I think you'll find the timing most useful for controlling the power, and that the fuel side can be used to fine tune once the ignition is adjusted. The 3 throttle positions listed are roughly analogous to main jet, needle position, and needle diameter, from most open to least.




Great write-up!! Thanks.

So from my understanding, putting negative numbers into the ignition program will retard the timing, therefore giving less performance in that area of the curve.

So if I want to lessen the hit at the bottom, I would put in negative numbers at the bottom line (or if I want more hit I put positive numbers). Is this right?

Also, I'm guessing that on the FI side, negative numbers mean Lean and positive numbers mean Rich.

I'm guessing that making it more rich (positive numbers) will Increase performance in that area up to a point (I'm assuming it won't let you flood it out to the point that increasing fuel will decrease performance). So again, it would seem that negative numbers would decrease performance in that area, while also improving fuel economy and possibly increasing temp.

Do I have this right????

Thanks,

DK

  • grayracer513

Posted March 12, 2010 - 08:16 AM

#5

That post was based on general information, limited specific information, and my conclusions. Subject to revision as hard facts come out regarding the specifics of the 2010 YZ450 and the power tuner, but it should be close to right.

So from my understanding, putting negative numbers into the ignition program will retard the timing, therefore giving less performance in that area of the curve.

So if I want to lessen the hit at the bottom, I would put in negative numbers at the bottom line (or if I want more hit I put positive numbers). Is this right?

Probably. It kind of depends on where the base timing and fuel curves are in relation to the theoretical optimum I mentioned. That's how I would assume it was until I tried something and found out otherwise.

Also, I'm guessing that on the FI side, negative numbers mean Lean and positive numbers mean Rich.

I'm guessing that making it more rich (positive numbers) will Increase performance in that area up to a point (I'm assuming it won't let you flood it out to the point that increasing fuel will decrease performance). So again, it would seem that negative numbers would decrease performance in that area, while also improving fuel economy and possibly increasing temp.

Do I have this right????

Except for the part about rich vs. lean and performance improvement, probably so. The effect of changing the Air/Fuel Ratio could potentially be much less predictable than the timing curve. Richer may not always be better. It's likely that there will be times when more advance will require you to add more fuel, and other times when a leaner mix will run better.

As far as the limits of the tuner's ability to change things, I imagine (speculating again) that the whole sweep from -9 to +9 is a fairly low percentage of the whole. It could be that a +2 or +3 or even more is necessary to move the timing one full degree advanced. I'd also think that you'd be unable to do a great deal of harm with the unit, but it's possible you could advance the timing far enough to cause detonation (pinging), or richen or lean out the mixture to the point that the bike actually runs poorly. When experimenting, take a systematic, incremental approach, and you should be fine.

  • Quilla

Posted March 12, 2010 - 10:00 AM

#6

That post was based on general information, limited specific information, and my conclusions. Subject to revision as hard facts come out regarding the specifics of the 2010 YZ450 and the power tuner, but it should be close to right. Probably. It kind of depends on where the base timing and fuel curves are in relation to the theoretical optimum I mentioned. That's how I would assume it was until I tried something and found out otherwise.

Except for the part about rich vs. lean and performance improvement, probably so. The effect of changing the Air/Fuel Ratio could potentially be much less predictable than the timing curve. Richer may not always be better. It's likely that there will be times when more advance will require you to add more fuel, and other times when a leaner mix will run better.

As far as the limits of the tuner's ability to change things, I imagine (speculating again) that the whole sweep from -9 to +9 is a fairly low percentage of the whole. It could be that a +2 or +3 or even more is necessary to move the timing one full degree advanced. I'd also think that you'd be unable to do a great deal of harm with the unit, but it's possible you could advance the timing far enough to cause detonation (pinging), or richen or lean out the mixture to the point that the bike actually runs poorly. When experimenting, take a systematic, incremental approach, and you should be fine.

According to the YZ Power Tuner Manual the ranges of adjustment are:
3% fuel change per FI Map digit (+1 = 3% more fuel) so range is -7 to +7 ( -21% to +21%)
1 degree per Ignition Map digit (+1 = 1 degree advance) so range is -9 to +4 (-9 to +4 degrees)

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  • grayracer513

Posted March 12, 2010 - 10:06 AM

#7

See what happens when you read the book?

The range of adjustability is about what I would have guessed. I had a different picture of what was available in the tuner itself as far as the +/- range.

Four-strokes are very tolerant of AFR's either richer or leaner than optimal, and it takes a pretty big error in setting them to make the engine actually run badly. I'm also not surprised at the fact that the timing is limited to 4 degrees advanced.

Thanks!

  • jellybean

Posted March 12, 2010 - 02:51 PM

#8

I am planing on getting the 2010 in a few weeks, I'm a big fan of Yamaha! At first i was going to get the 09 to save some money but i found out they changed the 2010 to a fuel injection system, and i have heard alot of good things about it. I know my way in and out of a carburetor but i don't know the first thing about the fuel injection system. Is it alot harder to work on then the older model bikes? Because reading your posts about the mapping i kinda scratched my head :/ but also I'm the type of person that needs to work on something to understand it. I also noticed they have done some other cool stuff with the engine. When you buy the bike does it come with that mapping tool/computer or is it an additional charge? :banana:

  • grayracer513

Posted March 12, 2010 - 03:16 PM

#9

The mapping interface tool is an additional purchase, and they run around $270.

Once you understand EFI, it's simpler in many ways to work on that carbs ever were, and tweaking the map is certainly simpler than manually changing jets.

  • C64DK

Posted March 12, 2010 - 05:29 PM

#10

The mapping interface tool is an additional purchase, and they run around $270.

Once you understand EFI, it's simpler in many ways to work on that carbs ever were, and tweaking the map is certainly simpler than manually changing jets.


Agreed! I tried 3 different settings today, and it only took about 3 minutes for each change. Try that with jets!

The tuner cost me $270 and it's very easy to use.

  • jellybean

Posted March 13, 2010 - 11:10 AM

#11

Wow, cool man thanks for all your info guys!! I was reading up on a couple of the threads about "2010 problems" every bike has to have a flaw somewhere no bike is perfect, and if all i have heard is that there is some oil leaking out because of a bad gasket, I'm pretty stoked on getting the bike its a miner set back but if will just give you better knowledge of the bike when you have to tear it down :lol:

For every new bike i have gotten before i ride it i always rip it down re-grease it and check everything up and down, I'm not saying that Yamaha isn't doing there job... Its just when you make a bunch of these bikes i think they just throw it together for the most part. Me personally i like knowing that my bike is in tip top shape before i go and race. :banana:

  • fraser

Posted March 15, 2010 - 01:31 AM

#12

After hearing all the stories of the massive low down hit, and coming off a 250f, I started out using the 'mxa preferred' smoothed out profile. After running in and putting a few laps in I switched back to the standard profile.
First thing I noticed was a big change in the engine note at mid revs. Yes there was a bigger hit, but nothing too scary, infact in slower corners I felt it helped as you could run a higher gear with less chance of stalling.
Next session out I switched to the Jay Marmont race profile, and that's what I'm currently using. Traction, power are awesome, just done my first race meeting on it. As an indication of this, its torn the all the knobs at the base on the outside edges of the rear tyre.Hopefully that's to do with the stock pirelli as I really don't want a new tyre every race. Loving this bike though, immediate improvement in my results from last year.





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