Bye bye 2 strokes!

[Rookie]

There's been a lot of talk about 2 strokes being phased out because of their fuel efficiency, and it looks like it's going to happen. There was a small article in MCN about a new 4 stroke engine which is more powerful, and I found an article from Honda:

[Nath]

Something I was thinking about the other night:

Is there any reason why you can't have a two stroke engine, but with with fuel injection and conventional inlet and exhaust poppet valves like on a four stroke? With sidevalves on opposite sides of the cylinder the mixture would not be immediately sucked out, and with the fuel injection forcing it in extra quick it should be possible to minimise the length of time that the valves need to be open simultaneously. With less mixture escaping with the exhaust gasses, and no oil being burnt, this would surely also create a less polluting two-stroke.

Or am I missing something pretty fundamental?
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Hard livin', hard luck.

[NSR Mick]

The 2 strokes best point in general day to day use is it's simplicity, you dont 4 stroke strimmers or sthil saws.
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If you dont like the way that I ride.......Stop trying to keep up!!!

[lilredmachine]

Since when were strimmers and saws 125 cc? or 50 cc for that matter?

There is no physical reason for 4 stroke 125s to be less powerful than 2 strokes, it's money and development time that sucks the cash. The quicker they phase out the 2 smokes, the quicker they can get on to giving us 30 bhp from a 4t 125.
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Bikes: too many, too much for one man to maintain anyway.

[Wave2k]

its about time.
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Ducati 1299 Panigale
2009 Corvette C6 z51
RS125->CBR400->RXS100->GSXR750K2->Ducati749S->CBR600RR5->TL1000R->DRz400->RSVR1000->Honda VTR SP1->CBR400->GSXR1000K6->Honda H100->CBR600RR3->Ducati1299

[NSR Mick]

Why is it about time?

As soon as you show me a 4t 250 that makes 60-70bhp without a turbo i may agree but until then even though no one actually produces a performance 2 stroke any more i may agree.
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If you dont like the way that I ride.......Stop trying to keep up!!!

[lilredmachine]

[BlackSheep]

[NSR Mick]

so lilredmachine there is as yet no reason for me to give up my 2t 250. My argument stands.
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If you dont like the way that I ride.......Stop trying to keep up!!!

[acwman]

[lilredmachine]

[DynaMight]

About time, 2t's have been dead for meny years.
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My bikes are at https://www.bikepics.com/members/dynamight/

[Kickstart]

[NC30UK]

Look how much 4 stroke bikes have progressed over the past 30 years. in the 60's a CB750 made 60bhp, now bikes of lower capacity that that make double the power. Its only a matter of time untill new 4 strokes make more power than 2 strokes, probably alot less time than that before 4 strokes are faster bikes thanks to increased usability and computer aids. 2 strokes are still more fun though!

Honda RC165:

https://www.motorrad-bild.de/images_fotoarchiv/ba_marken/honda/klassiker/rc164/rc164_sbsl.jpg

250 cc 4 stroke in line 6 making just over 60bhp in the late 60's

[NSR Mick]

[lilredmachine]

Come on Keith, you mean to tell me that that the new 800cc moto gp motors won't be producing the same power as the litre motors did in one year? That the New 2.4 F1 v8 won't be pushing 900HP within a season? You can't stop progress.

Obviously 4t have an initial disadvantage but it will eventually catch up, even if it is through forced induction.
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Bikes: too many, too much for one man to maintain anyway.

[DynaMight]

[Kickstart]

But exactly the same applies to the 2 strokes. Give the 4 stokes a couple of decades and they may get up to where the 2 stroke were 15 years ago.

The chances of the new 800cc MotoGP engines getting up to 300hp (pretty much where the 2 strokes were years ago in specific hp) is pretty remote.

You say you can't stop progress. You can. That is what the changes in the rules have done to 2 strokes, done to allow the 4 strokes such a massive capacity advantage that their performance has caught up.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[fuzz]

[Kickstart]

[lilredmachine]

[Kickstart]

[lilredmachine]

[Kickstart]

Hi

Rolling resistance is important, but nothing compared to the aerodynamics. Given that 125 bikes get to a true 95ish with about 21hp, with better aerodynamics it should take substantially less power.

As long as the gearing matches the speed to where the power is produced it will be fairly irrelevant.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[lilredmachine]

maybe we aren't meshing on this... This is a racing outfit. It has to go round corners, accelerate out of turns, and reach a decent top speed. Perhaps I confused you by listing top whack only... They don't want