2 Stroke

[bennyboy]

Im just wondering why 2 strokes are rarely bigger than 250cc...... would a 1000cc 2 stroke just blow up? surely performace for a 1000cc 2 stroke would be amazing?
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[VFR400UK]

Yes a 1000cc 2 stroke would make something like 350bhp, but power isnt everything!
2 Strokes tuned for power tend to have a narrow sharp power band when all the power kicks in at once. There is not a chance in hell you would be able to control that much power coming through the back wheel in a sudden surge.

A 1000cc 2 stroke would cost about £2000 for a professional rebuild every 10,000 miles and would get about 3 miles to the gallon and about 200 to a gallon of 2 stroke oil.

There is nothing to say it wouldnt be completely reliable but realistically anything bigger than a 750 would have to be detuned quite a bit. 750 2 stroke race bikes exist, allthough they would shred a set of race tyres in about 3-4 laps!

[craigs23]

V-Due anyone?

[Gazdaman]

https://www.bikepics.com/pics/pics/bimota-500vdue-05-bikepics-324043.jpg

Sexy as hell, I want one.

500cc 2 stroke twin. (Never really took off sadly). My TZR has a bad enough fuel consumption, there are/were road production 750cc 2 strokes.

Gaz

[Kickstart]

Hi

Would be quite easy to get a reliable 1000cc 2 stroke giving 150~200hp, just never really been a market for them.

I do fancy a V-Due. Injected ones were meant to have a really viscious power band.

All the best

Keith
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[mchaggis]

https://www.smala.com/bikes/images/gt750.jpg

Me wants.
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[stinkwheel]

I think a lot has to do with the size of the cylinders. There is some sort of formula for working this out but 250cc per cylinder would seem to be the working maximum.

The really fast 2-strokes seem to work on 125cc per pot which would mean an eight cylinder 1000.

There are a few 750 2-stroke triples, the daddy of them was the Kawasaki H2 which is something of a beast.

https://www.rimfire-eng.com/images/H2-76.jpg

Yamaha and Suzuki both made liquid cooled 500cc fours for the road.

There is a guy who splices bits of two H2s together to produce a 1000cc inline five. Same guy made a 4 litre, 48 cylinder bike, totally unrideable but he only did it because he can.

https://www.saltmine.org.uk/pics/eng9.jpg
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[cc123]

Thats a cracking V-Due pic mate...

Did some guy from the UK not buy all the remaining 11 or so V-Due's and is still trying to sell them? I'm sure I read something about these bikes about a year ago?
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[craigs23]

Problem is, didn't they stop production of the RS250 recent due to new emission laws?

[Kickstart]

Hi

It was an Italian guy who bought up all the V Dues. Think there were 150 of them and enough spares to build another couple of hundred if them. He also got the rights to build even more.

They were up at about £6000 for an injected one, and about £9000 for a sorted carb one.

All the best

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

[cc123]

Well I got that one really wrong, but I'm sure it was in Fast Bikes about the English guy that had bought one, they done an article on it and thrashed it round a track I'm sure.
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[Kickstart]

Hi

Think it was the guy who run https://www.rsvr.net/ who bought one off the Italian bod and was acting as a UK contact.

All the best

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

[Davo]

There was a video on here a couple of months ago of some guy who dropped an RGV500 (I think) into an RS250 frame.

Looked nice, sounded the nuts, but according to the specs had a very viscious powerband (something along the lines of upto 93bhp to 12,000 rpm then jumping to 141bhp to redline). Oh and only doing 11mpg is not too good.

[MC19]

Yamaha made an RZ500 2-stroke in 1984, I have seen a few of them for sale in aus but i don't know much about riding 2-strokes let alone a 500cc 2-stroke.
I'm sure the power would be good though.

[stinkwheel]

[Andy99]

The RD/RZV 500's put out under 100bhp as standard so not the rip snorting power you would have thought. So less than a modern 600 to put it into perspective,but that was in the mid 80's. Even the reviews at the time were disappointed by the power especially the RG500 which the bikes at the launch alledgedly had quite a few more horses than the bikes us punters could purchase.
The thing thats really killed the big 2-strokes is the emission laws which is a shame as i've always loved them

A few years ago someone ran a 2-stroke with a wet sump to lube the crank in the Dakar,it was loads better on the emissions front but hasn't been taken up and put into production.
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[gavin]

lots of misunderstandings and myths about 2 strokes here.

2 strokes dont "just blow up" abuse and neglect kills them, like anything else. properly set up they are just as reliable as 4T's and require less costly maintenence, less often. they are also significantly lighter and smaller for a given output than a 4T.

2 strokes produce more torque than fours of the same capacity, but they are generally very easy and cheap to tune, and because there is no valve train to move, and cranks and pistons can be lighter, they are safe top take to high rpm's, thus producing their torque at high revs, and making high power.


for these reasons 2stroke engines are used in all sorts of applications, outboard motors, microlight engines, helicopter engines, hovercraft....etc etc


they generally have been used in small capacity bikes because they suit that application better than 4t's, and emission laws have stifled the development of large capacity strokers since the early 70's

it has taken years of development and exotic materials to get 4T's to rev as high, reliably, and now whats all this talk of titanium valves failing.....

[Vin]

Well said that man

[colin1]

i saw a nsr 400 at the wheel on wednesday. it has 3 exhausts
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[Kickstart]

[fast_tzr]

goddam I want one of those v-dues!! I'd been dreaming of an sb8k santamonica, but now I would love to have one of those! God damn me being so young. Would be a tidy investment when 2-strokes are ruled out all together, they'll become rare, and an exotic italian 500cc twin 2-stroke, produced in small numbers, how can you NOT gain on it?!? Bugger it I'll just have to find one in a few years and restore it to brand new condition. Now my new favourite bike, may not make all the power of a zx-10, but heck I bet its great to ride. Not that expensive either. Christ I'm beginning to consider stuffing my first car and saving for one of those!

[Kickstart]

Hi

The injected V Due was very clean running. Passed California emissions rules without needing catalytic converters.

All the best

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

[tater]

that V Due looks amazing! didn't know they existed.

There is nothing wrong with 2 strokes gavin has it spot on

I have owned a track aprilia rs250 it is a great little bike that is just easy and great fun to ride, i would have one for a road bike but fuel costs and bike costs are fairly high so gone with a zxr 400.

I really hope 2 strokes don't die out as i enjoy having 2 'types' of bikes around.

[muddycoffee]

And the smell of 2 stroke oil as a bike goes past is a wonderful thing, brings back memories of youth and 1980s for me.
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[Bomberman]