Re: Does no. of cylinder makes difference...

The CB 400 is still in production...I was referring to the smaller displacement Multicylinder engines when I mentioned the CBR 250RR, and the 5 and 6 cylinder engines .

Re: Does no. of cylinder makes difference...

Thats a good question but you forgot that in my previous post i have already said that keeping all parameters same, but in this case both engines are radically different.

The FZ(fi) version produces 13.1 ps of power with 12.8 Nm of torque at 8000 and 6000 rpm respectively. The engine is 149 cc with bore*stroke of 57.3*57.9 mm respectively.

The R15 produces 17 ps of power at 8500 rpm and 15 Nm of torque at 7500 rpm. The engine is 149.8 cc with bore*stroke of 57*58.7 mm.

Ok so here comes the difference, as you can see that the new FZ makes less torque and power than old FZ. The reason being that Yamaha has de-tuned it and nothing else. Previous FZ made 14 Ps of power and 13.6 Nm of torque.

Like in my previous post i have mentioned that engine of same capacity makes almost same torque only differing by 1-2 Nm and see here the same thing torque difference doesn't come out much. Except turbocharging torque cannot be increased by much, but turbocharging is like cheating as we are compressing more volume of air into smaller engine.

Can the R15 make the same torque as ZMR or P220. No its because they have more volume for combustion than R15. Yes we can increase the power by tuning and changing port geometry and valve lift, but not torque by much.

Now coming to difference in Fz and R15, then R15 is 4 valve engine and Fz is 2 valve. So what difference does it make.

Now let me make you understand the same thing in lay man terms.

Consider a water pump which you are using for washing bikes and cars. Without the nozzle water will come in a steady and fat stream. But when we are using a nozzle the pressure increases and the water falls under high pressure and moves a greater distance.

Lets consider the amount of water as torque and pressure as power. So in both case the torque is same as water displaced per minute by pump is same. But incase of nozzle the power is more as it pressurizes the water.

Same thing in 2 valve and 4valves. The 2 valve engine has one valve each for inlet and exhaust. so the valves are bigger and so is the port. But when the flow of air fuel mixture is done then it is done under suction as a result the thicker passage help in floe of mixture but without any pressure, so engine has to do more work in suction.

But in case of 4 valve engine there are two valves each for suction and exhaust. So the valves and ports are smaller. So when the mixture enters it enters with more pressure and better mixture due to better swirl. So the engine has to work less harder and makes more power.

In lay man terms you are asked to suck water through a straw. You are given a thicker straw and two thinner straw. Which one will you find easier?

But a four valve needs to rev higher than a two valve engine to make power becuase as the engine speed increases the four valve engines have better volumetric efficiency due to the above reason.

Re: Does no. of cylinder makes difference...

Lovely and informative thread.

Now coming to single cyl vs twin, we find single is more torque producing and the twin has to be revved hard.

Let me add to the confusion which was cooking in my mind for long.

N250 is a twin which makes power over 7000 RPM where as N300 being a twin from the same manufacturer makes power just over 5000 RPM. Could anyone explain.

Now turn for my questions :
1. For touring, I prefer a relaxed ride..so what should it be CBR250 or N300.
2. Since N300 makes power lower down the rev range, it should have a better fe than N250...right??

I am sorry if my questions sound stupid but these questions were bothering me for long.

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Re: Does no. of cylinder makes difference...

Does that mean more fuel is burned in the same cylinder-capacity to attain higher torque and power?

https://en.wikipedia.org/wiki/Kawasaki_Ninja_250R : WiKi points out that 250R mid-range issue was addressed in 2008 itself.

https://en.wikipedia.org/wiki/Kawasaki_Ninja_300 : WiKi says Ninja-300 besides giving out more torque and power, is also more fuel efficient.

Re: Does no. of cylinder makes difference...

Take example of Duke 200 & 390 they are doing all this things with single cylinder only, competing with multi cylinder very very well, isn't that prove that better metallurgical parts(metals) and selection of various technology in harmony related engine requirement are more important like DOHC vs SOHC, bore stroke ration valves timings etc.

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And take Inazuma twin cylinder where objective of designer was not to produce more power but smoother engine & higher torque( though it is not that much higher) for comfort ride sacrificing more power.

Re: Does no. of cylinder makes difference...

Absolutely true, by forcing more air and fuel into engine we make more power from a smaller engine. But that engine will be under load and the internal components will be have to made stronger and beefier for taking the additional load.

But the difference is there when we ride them as the bigger engine will be more drivable than smaller engine as the smaller engine will have to be on boil and in power band to make a pull.

Case is take the santro and any other modern cars with more power under same engine capacity. Now drive and see which is more driveable.


Yes you are right in case of Ktm Duke but till a extent. Yes the Duke uses DOHC, valve timing is aggressive with very little valve overlap and also the fuelling is different.

But i forgot to add a simple word in that statement, i.e comparatively.

The duke uses super short stroke with very short skirt piston, light fly wheel and light crank.

Now lets look at the specs of Duke 200, it makes 25Ps of power at 10000 rpm and 19 Nm of torque at 8000 rpm. The bore is 72 mm and stroke is 49 mm.

Now lets look at the specs of Duke 390, it makes 43 Hp at 9500 rpm and 35 Nm at 7500 rpm of power . The bore is 89 mm and stroke is 60 mm.

From the engine you see they are heavily short stroke and the lighter componenets make them rev higher. They have made a race spec engine from single cylinder.

But if with same specification of lighter components and short stroke a 200 cc engine with twin or three cylinder is made then it will rev till 19000 to 20000 rpm. Case is as psr sir has said Honda CB250RR which was a 250 cc 4 cylinder engine that revved till 19000 rpm and went like crazy.

So i have already mentioned it would have be in same state of tune. If with same specification a multicyclinder is made it will rev much higher than a single cylinder no doubt.

As for the inazuma, then suzuki has made a tourer and thus has stressed on driveabilty rather than power and racing. It is provided with longer stroke than race engines, doesn't use close ratio gearbox and doesn't feel stressed and needs to be revved to make more power.

Its because its tuning is like that and the flywheel and crank both are heavier for smooth and linear power delivery. What the twin cylinder did was made the bike smooth, and also increased the driveability as there are two power strokes in single rotation of crank.

Re: Does no. of cylinder makes difference...

Right, but the beauty is, Zuma still has a long-stroke engine & revs to 11k rpm redline, but the Dukes have a lower redline in spite of being short-stroke.

The Ninja however is a short-stroke though, that revs to a manic 13k.

Benefits of multiple pots for high rev smoothness & reliability.

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Re: Does no. of cylinder makes difference...

Thats because it is a twin cylinder, so each cylinder is 125 cc and thus is smaller than duke single 200. Thats what i am saying in the previous post itself.

And Ninja 300, ah thats like a night dream of that hot girl which you get but when you wake up you wish you would still have been in dream.

Re: Does no. of cylinder makes difference...

Yes, that is what I meant.

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Re: Does no. of cylinder makes difference...

Doesn't we both are saying same thing but with different style & emphasizing on different point, kindly take into continuation my previous post in this same thread.

Re: Does no. of cylinder makes difference...

You are right. In spite of being a high revving twin, they ensured low end drivability by keeping the stroke long.

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Re: Does no. of cylinder makes difference...

Hi Bikers,

I have been reading this thread, which started from single Vs multiple and in between relayed on to Torque and power outputs. I would just like to add something to it.

1) Torque and Power output, these figures are directly related to the Stroke/bore ratio. In simpler terms Lesser the ratio higher the Ps and lesser the torque. Higher the ratio lesser the PS and higher the torque.
e.g.

Duke 200 stroke/bore ratio is - 0.68 it gives 25BHP and 19 Nm of torque where as for P220 ratio is - 0.93 21 PS and 19.12 Nm. Also if we see for a Bullet 350 it is 1.28 and it gives 19 BHP and 28 NM. Also to some extent it is also dependent on engineering tech used for making engines. Hence a formula one car will have ratios in the range of 0.4 and Heavy duty engines will have it more than 1 limited to 2.

2) Some where in the thread i have read that >1 cylinders are more of free revving and produce higher PS at higher rpm. but the reality is as the engines rev on a higher side, more is the problems like floating Valve start arising. Hence it needs a lot more technological advancements like VVT (Variable valve timings). Which alas is not seen in Indian bike maker market. Also it may be attributed to higher the technological advancements higher the cost. That is the only reason you find a Ninja, Yamaha or a Honda engine be a more free revving than a bike like say Pulsar, bullet. Also correctly said rpm is also measured as feet/sec (Piston) and the highest to be measured is 5962 feet/sec by Honda. Believe me it is a technological marvel.

Also it is true that single cylinder bikes have more vibrations but can be reduces by proper balancing of crank, which for a twin or a 3 and 4 can achieve by simple pin offset.

An last but not the least. Refinement always comes with cost and this is the game every engine makers play keeping business in mind

Confused about cubic capacity of multiple cylinder bikes

When we say a " 4 cylinder 1000cc bike" does it have 4 250cc cylinders or 4 cylinders of 1000cc each?

Re: Confused about cubic capacity of multiple cylinder bikes

Merged the post with a thread discussing cylinders.

A 1000cc inline 4 means - 4 cylinders of 250cc each. If each cylinder were 1000cc, we'd have called the humongous contraption a 4000cc bike.

Re: Does no. of cylinder makes difference...

One question guys about same. Can a single cylinder last as long as the multiple cylinder? Does engine life has anything to do with cylinders?