Can I? Stock ecu and Termis

[Paigecm]

I am waiting for an ecu to be reflashed.  Can I install the Termis and open air box with my stock ecu and run it like that for a week or so?  Will it possibly cause any harm?  Basically I am anxious to install these.

[Howie]

I am waiting for an ecu to be reflashed.  Can I install the Termis and open air box with my stock ecu and run it like that for a week or so?  Will it possibly cause any harm?  Basically I am anxious to install these.

You will be running very lean. particularly with the open air box.  If you avoid constant high speed and load you will probably cause no harm, but why not wait the week?  If your bike is a DSS Monster the exhaust will make little little difference but the air box will.

[ungeheuer]

Open airbox? How so?

[booger]

Open airbox? How so?

Does it make sense to imagine that an increase in airflow both at the intake and the exhaust would necessitate a concomitant increase in fuel delivery?

The stock ECU does not provide the required increase in fuel delivery, as it is programmed for the flow of the stock airbox and exhaust.

You may run the bike with the Termi mufflers only, but if you go further and add the open airbox you will run quite lean as howie has stated. The bike already runs lean in stock condition to begin with, it's not smart to push it even leaner. You may have popping, surging, ridiculously hot operating temps, general shitty running, or all these combined. Proper fuel/air ratio is important. Damage to the engine could occur.

It's best to tame your anxiety and wait until you have everything. You can still ride a stock bike.

[Punx Clever]

Interesting fact:

The hottest operating temperatures are created EXACTLY at stoich. fuel ratios.  Leaning the mixture (or enriching the mixture for that matter) from stoich will only lower combustion temperatures. 

Leaner than stoich: less fuel to burn, less energy, lower temperatures (but interestingly higher fuel mileage). Richer than stoich: un-burnt fuel carries away energy because it can hold more energy in it's complex molecules than exhaust gasses can.

I'll stop there because I don't rightly know if our bikes come from the factory mapped closer to the 14.7:1 stoich ratio, or the 12:1 higher power ratio... but I would assume it's closer to stoich.

[booger]

Interesting fact:

The hottest operating temperatures are created EXACTLY at stoich. fuel ratios.  Leaning the mixture (or enriching the mixture for that matter) from stoich will only lower combustion temperatures.  

Leaner than stoich: less fuel to burn, less energy, lower temperatures (but interestingly higher fuel mileage). Richer than stoich: un-burnt fuel carries away energy because it can hold more energy in it's complex molecules than exhaust gasses can.

I'll stop there because I don't rightly know if our bikes come from the factory mapped closer to the 14.7:1 stoich ratio, or the 12:1 higher power ratio... but I would assume it's closer to stoich.

Not sure I buy that, it goes against everything I have ever read on the subject, and personal experience as well. Not trying to start a shitfight either. My avg oil temperature went down a few degrees after I ditched the stock ECU for a DP. You offer a pretty articulate argument, if I didn't already know better it would be totally believeable.

[Punx Clever]

Your gasoline engine will produce the most power right around 12:1 air:fuel because at that point you ensure that every last bit of oxygen gets used up without losing TOO much heat energy to the un-burnt fuel going out the exhaust.  You are losing heat though, and that leads to a cooler operating temperature.

At 14.7:1, you burn every bit of fuel introduced, and lose very little heat to the exhaust because gasses have a much lower specific heat (can carry less energy at a given temp & pressure).  On the flip side, power is limited by how much air you can burn, and a stoich ratio won't completely use up all the oxygen in the cylinder due to inefficiencies.  Thus, the stoich ratio doesn't produce as much power as the rich ratio.

At greater than 14.7:1, you aren't putting enough fuel in the engine to have the same temperatures as at stoich.

The common believe that leaner mixtures run hotter is because up until recently, gasoline engines have been set up to run between 12:1 and 14.7:1 air:fuel, with more emphasis on the 12:1.  Thus, the common knowledge says that anything above 12:1 is "lean" and less is rich, when in reality 12:1 is rich, and above 14.7:1 is lean.

From one standpoint, you are absolutely right.  But from another, you are mis-informed.

[booger]

From one standpoint, you are absolutely right.  But from another, you are mis-informed.

I do and I don't understand you Congressman

LOLz

[koko64]

Running the A/F ratio too lean can damage pistons and valves. It can contribute to the dreaded  condition of knocking or pinging. Don't open the air box until you can have your A/F ratio adjusted to suit that modification.

It's interesting that despite the theoretical ideal of the 14.7 A/F ratio, different engine configurations have different A/F reqiirements at various rev ranges and throttle positions.  Don't be surprised to find that your bike's motor may want anywhere from 12:1 to 13.5:1 A/F depending on what performance task you are asking of it.

Check out the Bikeboy, Hordpower and MPS sites to see how much friggin around with tuning occurs to make a motor happy. Sometimes tuners give a motor an extra dollop of fuel as a safe margin. Aftermarket tuning guides sometimes say,"then go one size richer, for a safety margin". This can be useful with air/oil cooled motors in particular.

It's fascinating stuff.

[Punx Clever]

It is fascinating, especially when you get into newer fuel-efficient cars running 15-16:1 air fuel.

[Howie]

Combustion temperature will be reduced as you go leaner than ideal, but the incoming charge helps cool the cylinder.  The lean incoming charge does not cool as well, therefore overheating occurs.  

[booger]

^Agree, lean runs hot.

[sgollapalle]

Don't the newer models come with Oxygen sensors?? If they do, then the ECU will automatically adjust the amount of fuel to keep the stock AF ratio..

In which case, though you put in more air (via open air box), the ECU will put in more fuel.. All that should theoretically happen is more power and less mpg

[koko64]

It depends what A/F ratio the program corrects to.
Ask Ungehuer, he's been through this.
Thankfully the watercooled 4 valvers will tolerate being too lean better than the air/oil cooled 2 valvers. Stock tuning is emissions compliant, so I wouldn't be making things leaner.

Do the mods properly and get the thing tuned for the mods.

[Howie]

Plus full throttle and high load are not closed loop, nor is cold start.  I don't know about the latest bikes, but closed loop used to be up to around 15% throttle opening and up to 5K RPM.