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Kawasaki Working on a 250cc Four-Cylinder?



According to the Indonesian publication TMC Blog, Kawasaki is working on a performance-oriented 250cc four-cylinder…and they have the supposed photos to prove it. The news should be well-received by those who remember the high-revving small-displacement Japanese machines of just a few decades ago.


Competition improves the breed, as they say, and with the small-displacement market in Southeast Asia becoming a hotbed of action for the Japanese OEMs, we once again may see some screamers from the Land of the Rising Sun. This bodes well for eclectic riders in the Western world, who yearn for small, light, relatively high-powered two-wheeled weapons.

Kawasaki seems to be poised to enter this space first with their four-cylinder machine, though expect the other OEMs to be hot on their heels. How high the revs will go is a matter of conjecture of course. It will be interesting to see how this news plays out though, but it certainly has our interest piqued.

Kawasaki Working on a 250cc Four-Cylinder?
 

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must be 18,000rpm to be interesting.
and also, to be even worth riding. thing'll be GUTLESS AS HELL below 12,000, I am sure.

Interesting to see Kawi being the one to go back to it. I really woulda pegged Honda as the ones to try it again, what with the popularity of their 4 cyl 250s, even know.
then again, Honda hasn't wowed me in a decade.
 

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It would make no sense to have so many parts and technology into a low hp/tq engine. the only reason we finally got fuel injection in our stateside engines is because it got cheaper than carbs.
 

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it would make sense if they oriented it as a performance bike a la the RC390.
 
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King of the Hopeless
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It also makes sense for other reasons. What if a country has a displacement graded license system and wants a low displacement but high performance product? What if insurance rates for younger riders make it prohibitive to purchase and ride higher displacement sportbikes? What if the manufacturers are finally getting it through their heads that if they offer low displacement high(er)performance bikes, they will attract younger riders who will be easier to insure and will have a better chance of remaining riders - and thus customers - for the rest of their lives.
Just some thoughts.
The issue though is how to make such an engine and then have the bike you put it in not cost so much that you price yourself out of competition.
 

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If i was the head of a motorcycle company and i was looking at building a performance bike in the 1/4 liter segment, i would consider redoing a 250 motocross engine or doing a 250 direct injection two stroke engine.

A brand new 4 cylinder engine is going to require tooling for more parts than a single.
 

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And a direct injected 2 smoke is a great idea. Till you try to fit everything in there .
 

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they need organization. a 350cc fuel injected 4cyl under 290lbs would make a huge splash and be a great class for the AMA.
 

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And a direct injected 2 smoke is a great idea. Till you try to fit everything in there .
no. a direct injection two stroke is an idea with a great deal of potential, that is hard to implement.

None of the di 2-stokes i have worked on could be put into a motorcycle frame, but that doesn't mean that you couldn't build a ground up di 2-stroke motorcycle engine.
 

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If i was the head of a motorcycle company and i was looking at building a performance bike in the 1/4 liter segment, i would consider redoing a 250 motocross engine or doing a 250 direct injection two stroke engine.

A brand new 4 cylinder engine is going to require tooling for more parts than a single.
You will have the swampies (Environmental Nazis) chasing you around with pitchforks if you type 2 stroke again. 2 strok3s are lighter, cheaper, stronger and more powerful the 4 strokes. However, the laws of physics have never given anything away. No free lunch from physics. 2 strok3s get their power from burning LOTS of fuel. The reliability in part is due to mixing OIL in the fuel which means in the combustion cycle. Massive pollution. No way to run a cat that I know of, back pressure being an essential part of the combustion cycle.
I would be surprised if it sold here in the states. Asia for sure and some in Europe, but little demand here.
Honda research found that less then 10% of their RR's sold in America ever got on a racetrack. I suspect that is normal for all race type bikes. So either there is a 'ell of a lot more street racing then anybody is aware of or a lot of posing. My money is on the posers.:eek:nfloor
When you are buying a SS or Superbike to look kewl and impress the fair sex, 250cc's don't get it done.
 

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first: catalytic converters increase exhaust back pressure, that is why they decrease an engines efficiency so much, and lower a vehicles mpg.

2nd: The 2-stoke rz-350 came with a catalytic converter, back in the 1980's
RZ350 cata
Yamaha RZ350 - Wikipedia, the free encyclopedia

3rd: laws of thermodynamics are the same for 2-strokes and 4-strokes. the ideal gas law, doesn't care about what kind of engine is doing what, it is what it is. the amount of energy released from oxidizing a mass of fuel is the same not matter what the engine configuration is.
 

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I always thought 2 strokes got worse fuel economy based solely upon engine size just because they a) are dated and typically run with older, less efficient carb setups, and b) fire twice as often as a 4 stroke.

I am sure a 2 stroke 500 is not much worse on fuel than the 30mpg that a 4 stroke 1,000 gets.
 

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They get less fuel economy because when outside of ideal RPM range for the exhaust wave super charging system to work properly, they blow part of their intake charge out the exhaust port. That is why you always hear about how awesome a direct injection two stroke is, they don't inject the fuel until after the port is closed. There is still some loss of efficiency outside of the supercharge range though due to reduced compression from air escaping vs on the pipe when it's packed back in. If they had more research and development put into them they would probably have variable length exhaust systems that greatly expand the power band and increase fuel mileage. Get it to allow max efficiency at cruising rpms and they should be about the same as four strokes if not maybe a bit better due to less rotational resistance and no wasted stroke.
Also, you can largely eliminate the accelerated bottom end wear and a big portion of the oil burning with direct oiling methods. It just isn't done on dirt bikes for simplicity and weight reasons. You're always going to have increased piston and ring wear though from the ports, but that's largely canceled out maintenance wise by not having a valve train.
 

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They get less fuel economy because when outside of ideal RPM range for the exhaust wave super charging system to work properly, they blow part of their intake charge out the exhaust port. That is why you always hear about how awesome a direct injection two stroke is, they don't inject the fuel until after the port is closed. There is still some loss of efficiency outside of the supercharge range though due to reduced compression from air escaping vs on the pipe when it's packed back in. If they had more research and development put into them they would probably have variable length exhaust systems that greatly expand the power band and increase fuel mileage. Get it to allow max efficiency at cruising rpms and they should be about the same as four strokes if not maybe a bit better due to less rotational resistance and no wasted stroke.
Also, you can largely eliminate the accelerated bottom end wear and a big portion of the oil burning with direct oiling methods. It just isn't done on dirt bikes for simplicity and weight reasons. You're always going to have increased piston and ring wear though from the ports, but that's largely canceled out maintenance wise by not having a valve train.

Overlap, so evil yet so awesome :banana
 

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Discussion Starter · #20 ·
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Kawasaki 250 four: update

THE idea of Kawasaki building a new 250cc four-cylinder sports bike in the mould of the old ZXR250 is a mouth-watering one – at least for riders of a certain age who may have owned or pined for the original screaming baby four-cylinder.


The latest information, coming from the sources of usually-accurate Indonesian motorcycling blog TMCblog.com, is that a new 250cc Kawasaki is definitely under development but that both twin-cylinder and four-cylinder versions are being worked on simultaneously. The development work itself is said to be happening in Indonesia, and later this year both designs are to be presented before Kawasaki’s bosses in Japan, who will make a final decision on which to build.

Unsurprisingly, the work is understood to be a reaction to Yamaha’s new parallel twin R25, which is sure to take a big bite out of Kawasaki’s Ninja 250 sales in the massive Indonesian market. TMCblog suggests that Kawasaki wants its new machine to be revealed in 2015, presumably as a 2016 model, giving just one year between the decision about the engine configuration and the start of production


Read more: Kawasaki 250 four: update - Motorcycle news: New bikes - Visordown
 
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