Motori Minarelli Euro5 two stroke!

[bongtom]

"ITALIAN motorcycle engine manufacturer, Motori Minarelli, has unveiled a bit of a jewel at the recent EICMA show in Milan, going some way to prove that there is still plenty of life in the two-stroke yet."

https://www.visordown.com/news/general/motori-mina...


Ooh, yes. Yes! YES!

Here's a right geeza giving his view.
https://www.youtube.com/watch?v=wFxRvS8pcOQ

[Steve Bass]

As a 300cc single cylinder, it'll be suited towards enduro type bikes, not track racers. Singles don't make the rpm therefore the power of a twin etc so it'd be a bit pap in a racy frame...

Excellent however that they've achieved Euro 5 compliance though... bodes well for the mid term future of the smoker dirt bike...

[Shelsleyf2]

Steve Bass said:

As a 300cc single cylinder, it'll be suited towards enduro type bikes, not track racers. Singles don't make the rpm therefore the power of a twin etc so it'd be a bit pap in a racy frame...

Excellent however that they've achieved Euro 5 compliance though... bodes well for the mid term future of the smoker dirt bike...

Not sure where you got the idea singles don't rev. Many many years ago my 100cc two stroke kart engine was safe for 21000rpm. I can think of no engineering reason why a single cannot rev as high a multiple .

[Steve Bass]

Shelsleyf2 said:

Steve Bass said:

As a 300cc single cylinder, it'll be suited towards enduro type bikes, not track racers. Singles don't make the rpm therefore the power of a twin etc so it'd be a bit pap in a racy frame...

Excellent however that they've achieved Euro 5 compliance though... bodes well for the mid term future of the smoker dirt bike...

Not sure where you got the idea singles don't rev. Many many years ago my 100cc two stroke kart engine was safe for 21000rpm. I can think of no engineering reason why a single cannot rev as high a multiple .

Read my comment properly... As a 300cc..

The bore & stroke won't enable high rpm. Simple engineering calculations related to piston speed based on stroke will limit the useable rpm to an equivalent 25 m/s. Much beyond that and you're running into dangerous territory with the mass of the piston having to stop and start at the end of each cycle causing huge strain on the big end, rod and piston...So to achieve a 300cc capacity that will rev you'd need a ridiculously short stroke, stupidly big bore (which has further piston rocking issues) and would be useless for the intended purpose with very limited tractability or low end torque. so....it's a very good engineering reason actually
And as for 100cc kart motors, yes, they revved to 20k + but not for long.... and their bore & stroke was roughly squared at a typical 50mm bore and 48mm stroke.... and no, they were never 'safe' to 20k+... they would rev to that but need regular rod, big end and piston changes to maintain their performance. I know this as my 100cc TKM engine counted it's piston life in single digit hours at full race speed....

Details details details.....

Edit; Just looked up my old TKM service life.... piston & hone - every hour if max rpm reached 2 hours if outside 85% of max. New rod, bearings and other stuff, every 3 to 6 hours depending on max rpm reached.... new crank every 6 to 10 hours....

So, would you want that component lifespan in a road going bike????

Edited by Steve Bass on Thursday 15th December 16:19

[Bodo]

Nice to see 2 strokes with Euro5. The sound is like it should be! Somehow, 4 strokes below 300cc feel incomplete.

[rodericb]

Hopefully they make a scooter engine out of it and hopefully they stick it in the latest generation Italjet Dragster!

[Kuwahara]

Steve Bass said:

Read my comment properly... As a 300cc..

The bore & stroke won't enable high rpm. Simple engineering calculations related to piston speed based on stroke will limit the useable rpm to an equivalent 25 m/s. Much beyond that and you're running into dangerous territory with the mass of the piston having to stop and start at the end of each cycle causing huge strain on the big end, rod and piston...So to achieve a 300cc capacity that will rev you'd need a ridiculously short stroke, stupidly big bore (which has further piston rocking issues) and would be useless for the intended purpose with very limited tractability or low end torque. so....it's a very good engineering reason actually
And as for 100cc kart motors, yes, they revved to 20k + but not for long.... and their bore & stroke was roughly squared at a typical 50mm bore and 48mm stroke.... and no, they were never 'safe' to 20k+... they would rev to that but need regular rod, big end and piston changes to maintain their performance. I know this as my 100cc TKM engine counted it's piston life in single digit hours at full race speed....

Details details details.....

Edit; Just looked up my old TKM service life.... piston & hone - every hour if max rpm reached 2 hours if outside 85% of max. New rod, bearings and other stuff, every 3 to 6 hours depending on max rpm reached.... new crank every 6 to 10 hours....

So, would you want that component lifespan in a road going bike????

Edited by Steve Bass on Thursday 15th December 16:19

Is this why the Maico 700 was deemed a bit of a munter ,the single cylinder essentially started to work against what it was supposed to do…can’t remember where I read it but from an engineering standpoint it wouldn’t and couldn’t work as initially thought….