Two Stroke Motocross
Two Stroke Motocross Forum => General Two Stroke Talk => Topic started by: Charles Owens on September 29, 2011, 08:49:42 AM
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Hey guys, just an update.
The 144 motor will arrive in Colorado at HGT for the FI kit tomorrow.
As soon as we get it back we will be doing a test article on it.
We will be covering everythig from test/tune, installation, software, weight comparrison between carbed/FI. We will have a few guys with different styles and skill levels testing it out, on tracks and trails.
We will include different elevations and weather variations.
Let me know any specifics you guys want put to the test.
:)
(http://i813.photobucket.com/albums/zz58/cowenz/HGTkit.jpg)
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Water! How does it work under water? You know; stream crossings, extended heavy rain and mud, car washes. I think everyones biggest concerns with all FI is with the electronics. The 3 worst things for electronics are water, dust, and vibration. Pretty much sums up an off-road motorcycle!
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Mud/water is my favorite place to ride, I have several stream crossings and marshy areas I'll bury it in :)
This will be a thorough test, as any new product should receive. :)
We will have 3 or 4 riders testing it on MX/SX and Arenacross tracks. Trails, hill climbs, and flat field top speed runs included.
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Emissions. Does it help cut down on smoke, carbon monoxide, etc.?
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Charles, how much fuel pressure does that kit require to run? Is there some kind of inline fuel pump?
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Fuel pump is between the regulator and the zipties in the middle. I want to know if you'll have to reprogram it seasonally for the crazy temperature differences around here. A carb is petty easy to adjust, and four strokes usually run richer than they need to be with FI to be safe not to burn through a piston. Cuts down on power, but less failures for warranty to deal with. Two strokes like to have the mix pretty close to perfect for good response and top-end, especially on a smaller displacement. This all is fixed with more money/intelligence invested into the algorithms and quality software. So I'd like to hear about the company that manufactures the system, too. The power should be increased over a stock carb, but not too much of an increase vs. a professionally built carb because it is a tbi(the same principle as a carb). This is because of the precision involved with FI. Low end torque should only be effected by the CFM difference. Lower CFM means higher torque in the lower rpm range. High CFM gives the same amount of torque in a higher rpm. People that say it'll flatten out the power band may be pretty disappointed because those early FI tests that showed this were with Mechanical Fuel Injection. There is no change in the amount of fuel through the Rpm range with MFI so it runs rich at low rpms and lean at high rpms leading to a flat power band. I can't wait to see the results on the bike, though! Cool idea to try it on the 144 instead of the 296 (If i remember right) or a bigger bike. Hope it goes well! :)
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I'd be interested in all details and info from installation to seat of the pants observations before/after the install as well as price and weight difference.Sweet 8)
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Torque/horsepower chart comparison. ;D
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with all the user friendly software out today, EFI is easier to tune than a carb. no needles, no jets, no plug readings. just a fuel map on a laptop screen, and when youre finished you hit "upload". then you stick the o2 sensor in the silencer, rip a dyno run, and check the Air fuel ratio. adjust as needed. no more "its rich, its lean" its is now "it 12:1, its 13:1 ect ect." absolutes. no guesswork. no disassembly needed to change air fuels.
this isnt voodoo. 500cc grandprix bikes were running EFI in the mid 90s.
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How easy is it to take off and put the carb back on?
Do we need to update any software to run the carb after removing the FI system?
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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! :)
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this isnt voodoo. 500cc grandprix bikes were running EFI in the mid 90s.
Really? Are you sure about that? The only 2 injected 500's that were ever reported to have ever ran was Shinichi Ito's NSR500 in 95(bloody hell he's riding this weekend too :D) or so at Hockenhiem and Cagiva made one that Carl Fogarty rode once and described as "a peaky unrideable piece of shit" when it was mothballed along with the carbon fibre frame.
KTM FRR125 had an injector in the crankcase to prevent seizures on over run.
Unless all those magazine I have here are wrong?
How you going to get 12v to run the pump?
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im really excited about this.....i will be checking back neurotically for more!
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Don't forget that you're getting what is essentially version 1 of this product(for moto). Don't expect it to be perfect right out of the box.
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That was grouchy and wrong that I said that about cutting the thing off the engine...
But I'm very tired of crap being forced into the simple pleasure of riding by companies out to market garbage, and enviro-hippies who would be equally excited over an EFI two stroke that worked almost as well as a normally aspirated one, as long as you were willing to compromise... and a veggie based tire that worked almost as well as a real tire... as long as you were willing to compromise.....
It's WAY more complicated and there's no doubt about that. If that makes a differenct in performance that approximates the addittional complexity, then maybe it's worth it.
But, if all it does is change the character of the bikes emissions, I don't care about it and to me it isn't worth all the babysitting. At that point it's like it's the same bike for the rider, just carrying more mass and more potential problems. For the earthshoes treading softly along on their way to Bonaroo... it's exciting. But I don't care about that.
What is the main agenda? Is EFI being pushed as a performance enhancment? Because on 2strokes, it's obviously fallen flat on it's face a few times. Is it mainly something to improve the bikes from a green standpoint? What is the real deal?
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I am far from being a GREEN and short of having a pony tail, I am a long way from being a dirty hippy. But you have to recognize that unless we evolve into a greener sport, we will be legislated out of existence. We have seen 10's of millions of acres of land taken away from us. We have seen the end of 2T production street bikes. We've seen the end of 2T boat and lawn equipment - some with only the threat of law, not an actual law. Yes, the 2T is having a recovery but unless it evolves into a less polluting product, it will die.
So what can we do about it? We can accept the inevitable and find solutions to the actual problems. What is the problem with the 2T? It is a dirty pig (emissions wise), so we need a solution to that. Fuel Injection is one solution that still allows equal performance. That is a win. Yes, it is more complicated. Yes, it has its problems, but the solution is not to stick our collective heads in the sand and hide. It is not to (like my son does) plot down on our asses and cry until we get our way. Mommy will not come pick us up, give us kisses and let us do what we want.
I am excited for this product. I think it is the right way to go and something long overdue. I just hope that the AMA doesn't ban it's use (per the homologation rules) and it catches on.
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this isnt voodoo. 500cc grandprix bikes were running EFI in the mid 90s.
Really? Are you sure about that? The only 2 injected 500's that were ever reported to have ever ran was Shinichi Ito's NSR500 in 95(bloody hell he's riding this weekend too :D) or so at Hockenhiem and Cagiva made one that Carl Fogarty rode once and described as "a peaky unrideable piece of shit" when it was mothballed along with the carbon fibre frame.
KTM FRR125 had an injector in the crankcase to prevent seizures on over run.
Unless all those magazine I have here are wrong?
How you going to get 12v to run the pump?
All i could find was this quote;
,,...The new bike also ran fuel injection that the Aussie refused to use,
so Itoh was given the chance of developing the system.
At Hockenheim his NSR became the first GP bike to clock 200mph
but the PGM-FI never worked better than conventional carbs and was quietly dropped a year later.''
Source: http://www.superbikeplanet.com/NSR500.htm (http://www.superbikeplanet.com/NSR500.htm)
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All iin all,FI is a hokey bunch of sh!t.Also,disc brakes will never replace drums and the horseless carraige is simply a fad.The future may finally be here and bike wise,it's about 20 yrs overdue.Get over it you pony tail wearing hippies-embrace the future or get left behind :P ;)
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Well then, I am surprised someone hasn't said it yet, but great job Charles!
I don't know whether these HGI kits are any good, if it is possible to get FI working on a performance 2 stroke or anything at all about the real world changes it will bring.
I'm very glad TSM is giving it a go though and very much looking forward to following the project with interest.
Would be fantastic to see some dyno graphs! of before and after.
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As for the lack of a battery, i think a lot of people would be surprised at what a capacitor can do. Ever wonder how an airbag can deploy when the car's battery is destroyed in a front end collision? There is no power coming from the battery to deploy the airbag. The computer has capacitors in it that store electricity for when there is none. Granted, it uses the electricity up very fast, but how fast does a two stroke engine rev? It doesn't take very long for the stator to come around again and recharge the capacitors. Theres no reason to have a chemical battery when power is constantly being made unless you can't kickstart your bike. EFI is simple to experts, just like carbs are simple to people that know what they are doing with them. Its more people in the dirt bike world that know how to fix or upgrade a carburetor than EFI, so its easier(and cheaper) for the small team or rider to use a carb because thats all they know and grew up with. This is a very big step in the right direction though, even if it may not be for everyone yet. If you oppose it, don't put it on your bike. But in order to get the emissions down, we have to stop putting a 40:1 oil ratio in our fuel. You can't change the oil ratio with a carb. This can be fixed with direct injection. This EFI system can change the oil ratio as needed to be efficient. Burn less oil, be more environmentally friendly.
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Well then, I am surprised someone hasn't said it yet, but great job Charles!
I don't know whether these HGI kits are any good, if it is possible to get FI working on a performance 2 stroke or anything at all about the real world changes it will bring.
I'm very glad TSM is giving it a go though and very much looking forward to following the project with interest.
Would be fantastic to see some dyno graphs! of before and after.
Well said! TSM looks to be the leading innovator in 2 stroke motocross. Way to push ahead Charles!
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Hows the cap get charged and what is the current draw at 11,000rpm? Emmissions ?
EFI only continued with Ito's bike because he was a Japanese rider and towed the party line. Mick Doohan was far less diplomatic, explained in the preceding paragraph.
For the first time ever there was no doubt Honda had the best 500. So what did they do? Yup, they made it worse. With Doohan recuperating from his horrific leg injury, off-season development fell to team-mates Shinichi Itoh and Daryl Beattie. Neither man was brave or experienced enough to tell HRC they'd fallen back into their old habit of chasing ultimate horsepower at the expense of readability. When Honda's limping number-one first rode the bike he hated it. "It was a piece of junk and I told them so," he recalls.
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Ski Doo 600cc DI 2T, 120 HP, 29 MPG, emissions compliant.
Yamaha 1200cc 4T, 120 HP, 28 MPG, emissions compliant.
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I dont think they are pushing it as a emission improvement.
Only performance.
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I'm thinking it would be emissions (although injecting the oil separately is probably more important). You won't make any more power with FI than with a carb. Ridability might improve, but only if the tune is right, and it's not always easy.
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Correct me if I am wrong but DI has yielded substantial power increases in (4T) automobiles.
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FI has made it easier for you to just get in your car and go, but it hasn't yielded much power increases. It helps reliability for the people that can't listen to an engine thats not starting and realize they may need to pull the choke out or pump the gas pedal. If there were substantial increases, all performance cars would run FI. In drag racing, the really fast cars run FI (top fuel, top alcohol, ect.) because they pump so much fuel/air into the engines, carburetors would limit the airflow and not allow the fuel delivery. Just to show how much fuel they pump into the 500 ci engines in top fuel, when the engines 'blow' a gasket and make that big fireball, it is because the engine hydro-locked from having so much fuel in the cylinders and blew out the 1/4 inch solid copper head gasket. I think they use about 16 gallons per 1000 ft. Carbs can't deliver that much fuel, but they can keep up with FI on engines with less demands. FI was not introduced for performance, it was introduced for many other reasons like to get people to go to the dealer to work on their cars, so your car can start easier in 20 degree weather, so there can be more electronics that costed less than mechanical equivalents because they were made overseas, ect. My 1974 Plymouth Duster does just as well as any other car, I just have to listen to it in different conditions and know how to adjust the carb on the performance engine in it. If the engine was stock, all I'd need was a choke and it'd be just as good as any other stock 360 ci engine with FI. Don't get me wrong, I'm happy to drive my FI Suburban around because of it's convenience. But it has 275 hp when the 454 Chevelle had 450 hp in the '70s with the 800 cfm carbureted LS6 454.
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Correct me if I am wrong but DI has yielded substantial power increases in (4T) automobiles.
You can make a little more power with DI, but this is not DI, it's FI.
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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
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I'm thinking it would be emissions (although injecting the oil separately is probably more important). You won't make any more power with FI than with a carb. Ridability might improve, but only if the tune is right, and it's not always easy.
HGT port injection doesn't inject oil separately. You still have to mix.
HGT claims a 5% power increase in the scooters they've been doing.
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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.
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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.
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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.
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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.
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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.
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Indeed, it will be interesting to see the difference in fuel consumption.
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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.
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DI would inject into the combustion chamber after the ports close (at low rpm at least) yielding an increase in low end torque.
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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.
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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.
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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.
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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!
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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!
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Some of us also ride up to 10,000 feet. FI is invaluable up there.
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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.
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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.
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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....
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Emissions should decrease about as much power increases with this setup.
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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.
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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.
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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.
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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...
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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. ;D
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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. ;D
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 :P), 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.
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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.ecotrons.com/2_Stroke_Small_Engine_EFI_kit.html)
http://www.zbox.com.au/ (http://www.zbox.com.au/)
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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.
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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?
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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.
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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.
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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.
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I see efi helping 4 strokes with cold starts, throttle response, less bogging, etc. But I really dont see much of an advantage on a 2 stroke besides maybe less jetting. Carbs make more power.
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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?
Because you inject fuel only, -cant get much of a fire without air.
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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.
What comes two letters after DI in my post? Isn't TSM testing it, the point of this thread, so wait for the results before you claim no benefits. Unless you have already tested it???
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I realize that the crankcase is still being used as a (Schnurle loop) pump to both scavenge and charge the combustion chamber, however,if the fuel is injected into the combustion chamber after the ports are closed and those charging losses are mitigated - I can't see how an expansion chamber is required (in a DI engine - in theory).
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Maybe I can think of why an expansion chamber would help increase HP with DI. The expansion chamber would force more air back into the cylinder just before exhaust port closes. Think of this as "turbocharging" from the exhaust side. That's my theory or more accurately 2 cents. :)
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Sachs, without the pipe you end up with less air in the combustion chamber, basically what MikeD94 just wrote.
Less air - less fire - less power.
Getting eager to hear an update from Charles on the FI project :)
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HGT is waiting on the CNC flanges. Should be done tomorrow. :)
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Good stuff Charles, so does that mean yous will be takin it for a rip on the weekend?
I think its making some a little anxious not knowing the outcome.
Hope it works out and makes the 144 RIP!! :D
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Verrry interesting!
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Nah, I won't have it back by the weekend. They will get the parts tomorrow. I will let you guys know an ETA as soon as I get one.
I think its making some a little anxious not knowing the outcome.
Hope it works out and makes the 144 RIP!! :D
Me too! :)
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Sweet ;)
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SOOO is it on its way?