HGT Fuel Injection kit on our YZ 144 Project.

[falston1]

Not to sound like a dick, but watch american icon the hot rod, they did an episode that included fuel injection and the first time fuel injectuon was used was sometime in the 30s or 40s and was first used in stock car racing, the cars running it instantly gained 30HP and were setting track records

This was mechanical FI and it is used for decent gains at constant rpms. Like I said a little earlier, it runs rich at lower rpms and lean at high rpms. If you set the system for WOT, there's two settings, idle and WOT. Anywhere in between is way too rich and the engine looses power.

[beaner]

HGT port injection doesn't inject oil separately.  You still have to mix.

I know, that's why I mentioned it.

They might get 5%, but you might be able to get that same 5% on tuning the carb. I'm pro FI. It is better, there is no question, but, assuming the TB and carb bores are the same, FI won't give you any more power over a properly tuned carb. You will get better drivability, starting, and fuel economy, but assuming airflow is similar, power will also be similar. I've worked extensively with both.

[Bioflex]

I am by no means an expert, infact quite the opposite however in my experience fuel injections greatest assest is it's ability to "tame" wild engines. I don't mean mellowing the power rather assisting mid range and low end and tuning out any trophs.

By putting fuel injection combined with a programmable ignition on a rotary engine (and obesrving many others) improvments in top end grunt are had as well as the previously mentioned benefits.

When you consider the biggest issues with 2 stroke currently is that they aren't the most ridable engines and struggle to get powere down, any advantage that FI may give there would be a huge benefit. I don't understand why people seem to be obesssing over the hope of getting a bit more top end hp, the benefit of fuel injection (if it is set up well) is that you get maxmium top end while having improvemenst everywere else.

The problems with carbies is that they seem to be much more compromised than fuel injection, if you size and tune a motor for maximum hp (particularly a 2 stroke) it will suffer everywhere else.

[ford832]

HGT port injection doesn't inject oil separately.  You still have to mix.

I know, that's why I mentioned it.

They might get 5%, but you might be able to get that same 5% on tuning the carb. I'm pro FI. It is better, there is no question, but, assuming the TB and carb bores are the same, FI won't give you any more power over a properly tuned carb. You will get better drivability, starting, and fuel economy, but assuming airflow is similar, power will also be similar. I've worked extensively with both.

Good post.I know nothing about this system but in a car,FI's biggest attribute is it's ability to automatically adjust to a wide range of external and internal variables.

[citabjockey]

There is one benefit of DI for performance (know we are talking about a FI kit here so this doesn't apply to this case -- at least not to the same degree). The DI will at least attempt to burn all the fuel tossed into the combustion chamber. Carbs and FI throw some out the exhaust. So where is the performance gain? Maybe a touch with the engine power, maybe a touch with the powerband and ridability -- but the clear gain would be when you ride an event that used to require a 3 gallon tank and now you can run 2 gallons. You just lost 6+ pounds off your bike.

[EJ]

Indeed, it will be interesting to see the difference in fuel consumption.

[citabjockey]

Between FE and a properly jetted carb I would not think much -- maybe a few percent. With DI it should be closer to 30%. Thats why DI makes engines cleaner too. FI should help accuracy through the temp/ambient pressure/rpm/throttle setting range so should help but the engine is still going to dump 20+% of the charge out the exhaust port before the spark plug can get to it.

How is progress on the project???

Indeed, it will be interesting to see the difference in fuel consumption.

[SachsGS]

DI would inject into the combustion chamber after the ports close (at low rpm at least) yielding an increase in low end torque.

[Premixed]

Yeah, but with experience you can adjust a carb by ear. You don't have to rejet a carb to tune it. Turn the float set screw. All you need is a small screw driver. That's easier than reprogramming an EFI system even if it only means plugging the laptop up for a few minutes. For a high performance bike, everything has to be right. If it is 85 degrees one day for practice, and it rains overnight and cools to 60 degrees for the race, that bike has to be richened up quite a bit to avoid burning through a piston. The pros reprogram their EFI before every race. There's no absolute air/fuel ratio. Just shared opinions on what's best. You have to know what you want as far as bike characteristics and test 'til you find it. Remember, this is not an out-of-the-box deal. It'll be interesting to see what happens. I'm pretty excited to see how she does!  

i'm sorry, but this is just old school thinking.  no ones ear is better than an o2 sensor, i dont care who you are.  and there IS an absolute. its called stoich's ratio.  its 14.7:1.  the goal is to get as close to it as possible, from idle to redline, without detonation.  detonation can be avoided by either adding more fuel, or pulling out ignition advance.  end of story.  all of this nonsense about "hearing' and "smelling" how it is running is just that.. nonsense.

[citabjockey]

Well, my ear can tell when its running REALLY wrong (like when its blubbering or pinging) but sure can't compare with high tech instrumentation!

i'm sorry, but this is just old school thinking.  no ones ear is better than an o2 sensor, i dont care who you are.  and there IS an absolute. its called stoich's ratio.  its 14.7:1.  the goal is to get as close to it as possible, from idle to redline, without detonation.  detonation can be avoided by either adding more fuel, or pulling out ignition advance.  end of story.  all of this nonsense about "hearing' and "smelling" how it is running is just that.. nonsense.

[falston1]

i'm sorry, but this is just old school thinking.  no ones ear is better than an o2 sensor, i dont care who you are.  and there IS an absolute. its called stoich's ratio.  its 14.7:1.  the goal is to get as close to it as possible, from idle to redline, without detonation.  detonation can be avoided by either adding more fuel, or pulling out ignition advance.  end of story.  all of this nonsense about "hearing' and "smelling" how it is running is just that.. nonsense.

Maybe thats cause you can't do it, but it is done and very done well. I've never read plugs on a dirt bike engine, but I have on a few car engines to diagnose what is burning in the engine. You can tell a lot from reading plugs, but that has no performance reasoning. It gets you in the ballpark as far as rich/lean. Smelling exhaust can also be useful. It is used by mechanics to determine if something is not working correctly like, for example, an o2 sensor. From there, you listen, and it DOES work. Stoich's ratio is an absolute, yes, but it does not always get you the most power in the real world, especially with variables such as air temperature/density changes and octane rating.

[motoxr377]

Sounds alright. I don't mind jetting though, and like the idea that in thirty years I can still rebuild a Mikuni when some guy is scouring the Earth for a NOS Ossa TR280i injector module.

Clogging an injector is way easier than clogging a jet!

[falston1]

I do too, that's why I don't really like FI for the average bike. It's a good idea/investment when it's going on a high output race bike, but for the the 99% of us that don't ride a 2 minute 45 second lap at Steel City, the .25 to 1.75 hp difference is offset by rider error. I have nothing against jetting, just don't think its always necessary to get peak output. Don't get me wrong, my yz 250 is jetted, but the carb was set up before I bought it. It's a good addition to other upgrades, but not so much for a stocker. 

Nice RM by the way!

[Mountain Goat]

Some of us also ride up to 10,000 feet.  FI is invaluable up there.

[Premixed]

i'm sorry, but this is just old school thinking.  no ones ear is better than an o2 sensor, i dont care who you are.  and there IS an absolute. its called stoich's ratio.  its 14.7:1.  the goal is to get as close to it as possible, from idle to redline, without detonation.  detonation can be avoided by either adding more fuel, or pulling out ignition advance.  end of story.  all of this nonsense about "hearing' and "smelling" how it is running is just that.. nonsense.

Maybe thats cause you can't do it, but it is done and very done well. I've never read plugs on a dirt bike engine, but I have on a few car engines to diagnose what is burning in the engine. You can tell a lot from reading plugs, but that has no performance reasoning. It gets you in the ballpark as far as rich/lean. Smelling exhaust can also be useful. It is used by mechanics to determine if something is not working correctly like, for example, an o2 sensor. From there, you listen, and it DOES work. Stoich's ratio is an absolute, yes, but it does not always get you the most power in the real world, especially with variables such as air temperature/density changes and octane rating.

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.