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Developing a direct injection 2 stroke?? IS it just money? .. Like injectors are measured in cc and how would that correlate with the size of a carb? Which would be a direct comparison? Where in the intake tract would it be located? Directly into the cylinder i presume but then wouldn't reeds be ruled out? Would the combustion chamber need to be enlarged to allow for proper combustion? And wouldn't ports be totally eliminated? Would the crank have to lubricated like a 4 stroke? Sorry for all the questions

1 cc = 1000mm

yz 250 carb = 38mm

Would the problem occur due to the size of the injector would have to be too small?? Im really interested in this

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Money, it costs millions to develop something like that. 1cc is one cubic centimeter, or 1000 cubic millimeters. A 38mm carb is 38mm in diameter at the narrowest point, so you can't equate them like that. Reeds would still be needed so that the air isn't pushed out of the intake when the piston moved up. A different type of lubrication system would be needed to keep everything oiled.

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couldn`t they push air true a smaller intake window (air pump)

use a air release valve (steel ball spring) so it keep air pressure at a cretain level

and plastick pump impreller

cant remember what its called a circle steel platet often used in boat carbs to adjust the air flow

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Just figuring out how to pressurize the fuel for direct injection on an existing engine would be a challenge in itself. As far as I know all the systems out there use a mechanical pump to reach the extremely high pressures necessary.

Add to that the fact that you would need a completely new head machined to incorperate the injector (and R&D to work out potential cooling issues caused by this), a different oiling system, software to run it all, etc etc. It all adds up. Throwing direct injecting on an existing engine platform would be a waste IMO. You want to start with a clean sheet, something that would be pretty hard for a garage tinkerer to do without millions of $$$ laying around.

Now adding a "regular" EFI setup would not be nearly as difficult, and some guys have done it on 4 strokes (check the XR650 boards). But on a 2 stroke standard EFI is just not that benificial, especially not for the cost and time it would take to do it yourself.

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bimota tried to do it with a 500 V-due a few years ago and it bankrupted them. they were trying to make it clean enough to pass emissions. they ended up throwing carbs on to get them sold

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Just figuring out how to pressurize the fuel for direct injection on an existing engine would be a challenge in itself. As far as I know all the systems out there use a mechanical pump to reach the extremely high pressures necessary.

Add to that the fact that you would need a completely new head machined to incorperate the injector (and R&D to work out potential cooling issues caused by this), a different oiling system, software to run it all, etc etc. It all adds up. Throwing direct injecting on an existing engine platform would be a waste IMO. You want to start with a clean sheet, something that would be pretty hard for a garage tinkerer to do without millions of $$$ laying around.

Now adding a "regular" EFI setup would not be nearly as difficult, and some guys have done it on 4 strokes (check the XR650 boards). But on a 2 stroke standard EFI is just not that benificial, especially not for the cost and time it would take to do it yourself.

Allthough I agree with you, DI actually provides a cooling effect, I think heating would be the least of concerns. Factory turbo cars that use DI acutally run more PSI or timing due the extra cooling and reduced detonation from DI over FI setups.

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I was simply refering to possible hot spots in the head since there would be an injector in an area that is currently a coolant passage.

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don't put the injector in the head. if you put the injector (2 of them to be persice) in the cases spraying right above the crank lobes one with oil and the other with gas and keep them constily spraying then their would be no need for a trigger or timing of the injector pulses and all you would need a pump to presser the oil and gas. for the pump it could run off the clutch basket gear (as it is connected to the crank) and make the pump a duel chamber centrifugal pump just like the water pump impeller then as long as the crank is turning you have psi. this would also lead to insane lucubration as the fog of oil could be sprayed directly onto the crank its self and their for use less oil for the same miles. everything else stays the same as far as intake goes. and if you really want to get persice you could make a air flap that operates a verable orifice in the pressure side of the fuel line to control the amount of fuel per unit of air. if you are wondering this is almost the exact same injection Porsche used for years on their 924 and 944 models it is called K-Jet tronic if you want to look up how it works. i think its doable but this is a very crude system compared to modern EFI systems.

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The Megasquirt project will be capable of DI soon. When there MS-II Sequencer is released. Currently they have beta testers. So I think its probably not that far off.

http://www.megamanual.com/seq/index.htm

So the electronics and timing, would be for the most part taken care of. Still a lot left though. Sticking the injector in the head would be difficult to get things optimized with what your working with. Oiling the bottom end and controlling the amount of oil and varying it...etc..

I think if you were motivated it can be done soon. I may look into it myself just for kicks and for the education.

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don't put the injector in the head. if you put the injector (2 of them to be persice) in the cases spraying right above the crank lobes one with oil and the other with gas and keep them constily spraying then their would be no need for a trigger or timing of the injector pulses and all you would need a pump to presser the oil and gas. for the pump it could run off the clutch basket gear (as it is connected to the crank) and make the pump a duel chamber centrifugal pump just like the water pump impeller then as long as the crank is turning you have psi. this would also lead to insane lucubration as the fog of oil could be sprayed directly onto the crank its self and their for use less oil for the same miles. everything else stays the same as far as intake goes. and if you really want to get persice you could make a air flap that operates a verable orifice in the pressure side of the fuel line to control the amount of fuel per unit of air. if you are wondering this is almost the exact same injection Porsche used for years on their 924 and 944 models it is called K-Jet tronic if you want to look up how it works. i think its doable but this is a very crude system compared to modern EFI systems.

If you are spraying into the crankcase, then you are still controlled by port timing when fuel can enter the cylinder. You lose all the benifits of going to direct injection. The system you mention is simply EFI, but with the injectors mounted a little further down the line, and injection pressures wouldn't have to be astronomical like DI, so an electric fuel pump could be used (no need for a crank driven system).

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don't put the injector in the head. if you put the injector (2 of them to be persice) in the cases spraying right above the crank lobes one with oil and the other with gas and keep them constily spraying then their would be no need for a trigger or timing of the injector pulses and all you would need a pump to presser the oil and gas. for the pump it could run off the clutch basket gear (as it is connected to the crank) and make the pump a duel chamber centrifugal pump just like the water pump impeller then as long as the crank is turning you have psi. this would also lead to insane lucubration as the fog of oil could be sprayed directly onto the crank its self and their for use less oil for the same miles. everything else stays the same as far as intake goes. and if you really want to get persice you could make a air flap that operates a verable orifice in the pressure side of the fuel line to control the amount of fuel per unit of air. if you are wondering this is almost the exact same injection Porsche used for years on their 924 and 944 models it is called K-Jet tronic if you want to look up how it works. i think its doable but this is a very crude system compared to modern EFI systems.

This is referred to has SDI. Semi-Direct Injection. Ski-Doo and Polaris also have snowmobile 2T motors that use this technology. It is a little better than regular EFI but not as good as DI.

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bimota tried to do it with a 500 V-due a few years ago and it bankrupted them. they were trying to make it clean enough to pass emissions. they ended up throwing carbs on to get them sold

Bimota used throttle body injection, not direct injection.

don't put the injector in the head.

Well then it wouldn't be direct injection and it would suck, comparatively.

I think it would be easier for Joe Schmoe to make his own D.I. head for an autolubed engine. That and I guess he has to re-engineer some kind of air-only intake system in place of the reed cage and carburetor.

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Still would use reeds, and would need a throttle body instead of a carburetor (probably with at least a throttle position sensor and either a mass airflow sensor or, more likely, MAP & temp sensors).

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just regular ole fuel injection is an improvement if done right on a two stroke.

But getting it right on a race bike is hard to do! Measuring the intake flow isn't that easy, as the pulses and gas dynamics are really tricky with the two strokes.

It's coming....hopefully moto sees it!

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1cc = 1cm x 1cm x 1cm

1cc = 10mm x 10mm x 10mm = 1,000 cubic millimeters

At the very basic end, you would need to know the volume of air pumped through the engine, not just the diameter of the carburetor.

Something like this may offer you a starting point:

http://cgi.ebay.com/ebaymotors/Throttle-Body-Assembly-for-1995-Arctic-Cat-EXT-580-EFI_W0QQcmdZViewItemQQhashZitem160318027649QQitemZ160318027649QQptZSnowmobileQ5fPartsQ5fAccessories

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just regular ole fuel injection is an improvement if done right on a two stroke.

But getting it right on a race bike is hard to do! Measuring the intake flow isn't that easy, as the pulses and gas dynamics are really tricky with the two strokes.

It's coming....hopefully moto sees it!

oh dear god please, I hope they do build it! so sick of overpriced, overweight 4 $stroke grenades.

Sigh ...They'll never build it. there's no money it it. 4 $stroke have been a gold mine for them ... why would they shut that down?

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I don't know about the seadoo system, but YAMAHA outbaords already have 2 stroke direct injection with a 60% increase in fuel efficiency. Why can't that be applied to mx?

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I don't know about the seadoo system, but YAMAHA outbaords already have 2 stroke direct injection with a 60% increase in fuel efficiency. Why can't that be applied to mx?

The computer controls/technology exists within yamaha. They also had teethign issues with it initially, I think ring failures because the top side of the ring didn't get enough oil - warrented new ring technology I believe.

But making it:

small

light

no battery requirement

is the hard part.

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1cc = 1cm x 1cm x 1cm

1cc = 10mm x 10mm x 10mm = 1,000 cubic millimeters

At the very basic end, you would need to know the volume of air pumped through the engine, not just the diameter of the carburetor.

Something like this may offer you a starting point:

http://cgi.ebay.com/ebaymotors/Throttle-Body-Assembly-for-1995-Arctic-Cat-EXT-580-EFI_W0QQcmdZViewItemQQhashZitem160318027649QQitemZ160318027649QQptZSnowmobileQ5fPartsQ5fAccessories

Too complicated ---- 1cc = 1ml

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