Direct injection Two Strokes

[STONEY!]

Why havent we got any? Seems to be old tech when it comes to outboard motors, surely would work well in a bike?

[chris-red]

Emissions.
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[temeluchus]

Probably no way to get around loads of partially combusted two stroke oil being pumped out the exhaust.
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[STONEY!]

The whole point of direct injection 2 strokes is that the emmisions are low and fuel economy is improved as well.

A normal 2 stroke throws fuel/oil out of the exhaust port every cycle whereas a DI two stroke injects exactly the right amount at the right time.

[pepperami]

I believe that Lambreta Scooters were working on a direct injection two-stroke engine a few years ago??
Would`nt it be nice to have a few more strokers on the road
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[chris-red]

Euro4 comes out in 2016 for bikes, I very much doubt a 2 stroke could meet it as from what I have heard it is a BIG change for four strokes.
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Well, you know what they say. If you want to save the world, you have to push a few old ladies down the stairs.
Skudd:- Perhaps she just thinks you are a window licker and is being nice just in case she becomes another Jill Dando.
WANTED:- Fujinon (Fuji) M42 (Screw on) lenses, let me know if you have anything.

[blurredman]

I never did hear any development from this..

https://www.cycleworld.com/2012/08/13/two-stroke-resurrection/
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[temeluchus]

[Kickstart]

Hi

There have been a few. Aprilia with a scooter and Bimota with the Vdue. Honda also had a few off road bikes.

Think part of the problem is that bike engines rev fairly high and it is difficult to cycle the high pressure injection system quickly enough for that (especially when it needs to inject fuel every turn of the crank).

Would be possible to seal the bottom end bearings from the mixture (both mains and big end). However you still need lube for the cylinder walls. But not that much, and if properly delivered (rather than just dumping a load in with the incoming air and hope a bit of it hits the cylinder walls) only a tiny amount.

Think the Aprilia Ditech scooters just used a blower though.

All the best

Keith
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[Mudshark]

yeh, I remember this with bimota

https://www.odd-bike.com/2012/11/bimota-v-due-500-bike-that-killed-bimota.html


as an oldie who had his fair share of t-stokes, I miss the hooligan element even now
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[temeluchus]

[Polarbear]

Two strokes in diesels is a completely different kettle of fish to 2 stroke petrol.

We have large, low reving 2 stoke diesels in the marine industry but they are basically normal diesels running a 2 stroke cycle.

By that I mean the have normally lubricated sumps, turbo blown charge air, quite often running an exhaust valve rather than ports, and fuel injections so there are no unburnt oils going out with the exhaust.

I don't know if that set up would be even possible in a bike petrol engine.
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[stevo as b4]

The normal two stroke diesel operating principle would be to heavy and too complicated for bike engines, even in petrol applications, as by adding all the extra bulk and parts, you may as well have a 4stroke engine instead.


I agree that DI two strokes for bikes got as clean as they were ever going to with the Aprilia Ditech etc. As Temelucus and Keith said, you still needed some oil (not nearly as much as std 2strokes) spraying into the air inlet to lube the motor. MPG is good with Di, and efficiency, but burning a little bit of oil constantly and deliberately is not so good, and would probably ruin any catalytic converter's that would be fitted, quite quickly.

The Marine outboards are about the last employer of DI strokers' but they get away with tiny amounts of oil added for a few reasons, one of them is the environment the exhausts dump into, and outboards could run 150-200:1 oil ratio's.

Also like Keith said the technology to switch very high pressure injectors on and off quickly enough for more rpms and bigger cylinders does not work very well. I'm sure Aprilia were quoted as saying that 125cc was the realistic limit for Ditech injection technology.

Also something I wasn't aware of until Iain said, was how badly Ditech systems on the SR50 have fucked up after a few years and needed really expensive spares to fix, making them un-popular and un-trusted as they get older and have faults. Then again 50cc Ped's were as much about how easy they were to tune, and how well they ran at 70cc with all the fancy parts added. I didn't think the Ditech's were very tunable in that sense and it was hard to re-map them or up the fuelling enough for high end tuning conversions, so they were not that well received.

Indirect two stroke injection works at least as well as carbs, and does offer some emissions and mpg benefits, but nothing like DI can.

Even new petrol car engines are all having to be DI designs now, if you want say a 2.0 petrol that makes 220bhp and still does over 40mpg. That would have been impossible 15years ago!

[onefourk]

Why does a DI two stroke need any oil in the inlet charge?

[Pol Anorl]

close enough

https://www.bikechatforums.com/viewtopic.php?t=279517
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[temeluchus]

[onefourk]

[Kickstart]