HGT Fuel Injection kit on our YZ 144 Project.

[falston1]

yes, you are right, i have no clue what i am talking about, and your f*cking ear is more accurate than a wideband o2 sensor.

you should market your services to various dynoshops.  ear-tuned.

get real.

Read reply #5. I totally agree that my ear can't compete with an o2 sensor. Never said it could. I said TBI FI was not going to cause noticeable improvements over a professionally tuned carburetor to most riders, but would lead to a small percentage of increased power because of the precision of FI. There are set formulas for finding the right jets for a carb. Once jetted, you have to set the float by ear if you don't have a dyno in your garage. With experience, you learn what to listen for. To fine tune the float position for maximum power, you ride the bike and observe the engine under load throughout the power band. Lean it out until it just starts to rev a little too fast and back off a little. Best power curve is there. FI is way more precise, but the difference cannot be felt by the average rider. The fuel atomization from the injector will be greatly improved over a carb and will cause a slight power increase, too. Jeremy, or whoever is riding this bike, may be able to feel the power increase because of the level of riding he does. I know, myself, that I have a greater room for improvement over my bike, so the extra power would really be of no practical use for me. It is only when the bike starts to have greater inefficiencies than the rider that something like this pays off.

[Suzuki TS250/185]

Electronic Fuel Erection has done wonders for the 4 strokes... It has provided numerous riders with the rest they needed this season as they were able to sit out motos they would have been forced to ride in had their bikes been carbureted. A complicated, frequently failing fuel injection system is just the thing on a hot summer day....

So... what is it we're supposed to get out of fuel injection? ...quick throttle response and performance that's vastly superior to similarly sized 4 stroke puttery??? Well... we've already got that, and with a simple and 100% reliable fuel system...

So far, fuel injection only sounds exciting from a jam band hippie point of view... It can only offer the same thing we've already got in terms of performance, but with much more complexity and less emissions.... BORING....   

[falston1]

Emissions should decrease about as much power increases with this setup.

[TMKIWI]

I agree with you falston1.
While an ear can't replace a O2 sensor, a well trained ear is a valuable tuning tool.
I have spent 25 years rebuilding and tuning carbs and have a fair idea what a motor should sound like.
Balancing multi carb sets can be done with a 5mm hose when a vacuum gauge set is not handy.
Old school still has its place if you know what you are doing.

[ford832]

I appreciate the old school methods myself and much of that knowledge base is lost on the next bunch coming up.However,
to use the aforementioned 02 as an example....
In years past,your typical o2 had a threshold of about .46V. As the reading fluctuated above and below this value,the pcm would add fuel,then take away,then add etc.It didn't matter whether it went .87 then .25 or .78 then .41.As long as it crossed that threshold,the result was the same.
In the last few years,the Oxygen sensor has been replaced with an Air/Fuel Ratio sensor.This is much more precise as the fuel that is added or taken away is dependent on the exact reading of the sensor and is metered to achieve as close to maintaining a steady ideal as possible rather than rich/lean,rich/lean.This increases mileage and hp both.
I like to think I've got a pretty good "feel" or ear for engines-but it's not that good.
As far as I can see,if the fate of the two stroke lies in being able to show the eco types that the emissions equal or surpass 4t's(like BRP),who could possibly argue against it.
One last note.The weather has turned colder here and the bay doors have come down and cars are being run with exhaust hoses.It's no big deal but in the carbureted years,I had a headache all winter long and likely took years of my life in the choking blue haze.In the early FI years,it was much better but today,it's not even a factor.Even a well tuned carb can't approach FI.You can reach similar peak HP numbers with each but the efficiency across the board isn't even close.

[scottydog]

I'm all for EFI on 2 strokes as the volumetric efficiency does change alot more through out the rpm range than 4 strokes, something you cant tune out with a carb.

[mrhp]

I'm all for EFI on 2 strokes as the volumetric efficiency does change alot more through out the rpm range than 4 strokes, something you cant tune out with a carb.

While people don't seem to give them much credit - modern carburation systems are highly advanced.

To top that off - they do something by fundamental design that many efi systems do not; meter what happens inside the engine upstream.
Now - MASS air flow style efi systems DO measure this, at a cost - flow hindrance and complexity of system.

On high performance two strokes, we also depend on the inlet system for a resonance to help boost output.  This can be hindered via a mass sensor.  On top of that, depending where the sensor is located, two strokes experience a serious flow reversal problem in some instances.
This is also hard to account for.

EFI has been tried at the highest levels of two stroke racing by various teams, and thus far has not truly suceeded.  My "sources" tell me it came down to a few highly dynamic, and difficult reasons to overcome.  One being the bulk pipe temperatures.  This means that if an engine were loaded on a long up hill in a situation where the rpm stays basically constant, the longer it is run - the hotter the average pipe temps get.

The change in pipe temperature influence the scavenging pulses of the pipe, and changes power output.  It's hard to adjust an FI system for this without a mass air flow sensor..but a carb adjusts automatically on demand (via metered velocity).

Also, when a two stroke is coming on and off the pipe, the fuel delivery requirements are all over the place!  It's hard, again, for fi to keep up with this.  Carb's just do it..

For the road racers, it came down to this scenario - when your leaned over doing 120mph around a fast corner, at max lean angle, and you are in a controlled slide - it's important that when you need that right hand connected to that rear wheel DIRECTLY and INSTANTLY with complete predictability you have that connection.  A hair too much throttle and your highsided up on your ass - crying for mommy.

With the FI systems tried - they never got to the point where rider input was perfectly matched with what the bike did.  This made it hard to ride.

For about 90 percent of motocrossers - who dont jet their bike well anyways - this is is non issue, and I'm sure the FI system will work great.

I know a few individuals who have done FI systems to their street RZ's in various states of tunes.  From what i gather, they have been fairly sucessful - but getting the perfect fuel map is REALLY hard and extremely time consuming.  This is true of any FI project.

Making it all work seemless on a dirtbike will be tough without a battery system - but that's a simple hurdle.

o2 sensors are almost worthless on a two stroke...egt monitoring and a good tuner (person/human) is much more effective...

[SachsGS]

Theoretically a Direct Injection equipped 2T would not require an expansion chamber but this is still an issue with a FI 2T.MRHP, when you refer to the pipe heating up and "Altering the scavenging pulses" is this due to the pipe physically enlarging?

I've ridden many 2T dirt bikes where the jetting changes with clouds blowing over.I'd rather move in the direction of FI.

[teriks]

Theoretically a Direct Injection equipped 2T would not require an expansion chamber but this is still an issue with a FI 2T.MRHP, when you refer to the pipe heating up and "Altering the scavenging pulses" is this due to the pipe physically enlarging?

I've ridden many 2T dirt bikes where the jetting changes with clouds blowing over.I'd rather move in the direction of FI.

A bit of topic, but I just cant resist this DI not needing a pipe stuff

A DI two-stroke needs a tuned exhaust just as much as a two-stroke with a carb, if you want to make serious power per displacement that is.
You can always do away with the pipe and add displacement to achieve the same power as the smaller piped engine (much like the four-stroke handicap in Pro MX ), and you will get similar results regardless of DI, FI or carb.

Normally when you talk about pipe temperature and tuning, you are referring to the temperature of the gas inside the pipe. -The speed of sound increase with increasing temperature. I.e. a hot pipe would be tuned for a higher rpm than a cold one of the same dimensions.
The effect of thermal expansion of the metal very small in comparison.

[2T Institute]

I think there is a possiblity to make the EFI work pretty good in 99% of cases. The twin injector could be the key to it, IF the ECU is fast enough and you have flexiblity in the software.
Getting the VE tables right will be a chore but the seem to closely follow a output of my simulator. Going to trial a cheap chinese kit on either a 85 cc or a in the frame "lost my licence" push bike engines.
http://www.ecotrons.com/2_Stroke_Small_Engine_EFI_kit.html
http://www.zbox.com.au/

[Bioflex]

Going to trial a cheap chinese kit on either a 85 cc or a in the frame "lost my licence" push bike engines.

That's gold. I bought one of these kits a few years back and enjoyed it for a while, sold it after some time to a friend who, you guessed it "lost his licence and needed to commute to work"!

I imagine that a massive amount of them are bought for this situations.

[SachsGS]

If you are injecting into the combustion chamber after the exhaust port is closed (in theory anyway),why would you need an expansion chamber exhaust?

[streaks383]

So who here has ever tested DI or FI on a performance 2T off-road bike?  If you haven't save all of your pillow talk for after its tested.  No one cares about 3  paragraphs or more with words and concepts you read or heard somewhere else and probably don't get, stating how bad DI is gonna be.  Put a sock in it until the test phase is complete.  As much as you are trying to discourage progression of the 2T I would bet you are employed by Honda.

[Shawn36]

So who here has ever tested DI or FI on a performance 2T off-road bike?  If you haven't save all of your pillow talk for after its tested.  No one cares about 3  paragraphs or more with words and concepts you read or heard somewhere else and probably don't get, stating how bad DI is gonna be.  Put a sock in it until the test phase is complete.  As much as you are trying to discourage progression of the 2T I would bet you are employed by Honda.

Who exactly is testing DI here?  This thread is for EFI, which on 4-strokes is not a real step forward.  It added weight, complexity, and cost without any real significant benefit.  Do tell me how that's a good thing. 

[citabjockey]

I do NOT have much experience with current 4T bikes -- but a question for those that do. Do you have to mess with the jetting at different altitudes for max power? What about for humidity conditions? What happens on a long trail ride that starts at sea level and goes up to 6000'? Now, for those that have a EFI 4T, does the injection computer take care of that for you such that the engine runs well despite the pressure/humidity changes? I know its a lot of hardware but that is an advantage. Just Sayin.

Of course my trusty XR500's back in the day didn't seem to have much trouble with altitude changes with its carb (I never even bothered to change the mixture) but then again I was hardly asking for tip-top performance.

So who here has ever tested DI or FI on a performance 2T off-road bike?  If you haven't save all of your pillow talk for after its tested.  No one cares about 3  paragraphs or more with words and concepts you read or heard somewhere else and probably don't get, stating how bad DI is gonna be.  Put a sock in it until the test phase is complete.  As much as you are trying to discourage progression of the 2T I would bet you are employed by Honda.

Who exactly is testing DI here?  This thread is for EFI, which on 4-strokes is not a real step forward.  It added weight, complexity, and cost without any real significant benefit.  Do tell me how that's a good thing.