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

Companies do have them, don't they? They're just expensive.

It's actually : each cylinder firing every 180⁰ rotation of crankshaft. It takes two full rotations for all 4 to fire. i.e. 720⁰.

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

Thanks buddy for appreciating. PSR sir has better understood the question I must say, and replied very correctly.

1. Friction creates heat, true, but not that much. Ok, alone they may make an engine touch 50-70*C or so... But 90-110* Celsius is often seen in modern engines due to combustion and its attributes like compression ratio, fuel quality, boreXStroke, etc... The main heat source is still the combustion of the engine. Friction's role mostly comes in form of engine depreciation.
Mean piston speed of under 22 metres/ second at redline, is good for life of the engine, but its no hard and fast rule.
Race bikes exceed them often, and then of course, they pay the price too, as the engines don't last beyond few races.

2. Right. Totally agree with you. Not only number of valves, but size of the valves too increases with this.

3. Right. Plus, undersquare engine loses breath quickly because of smaller valves, even if piston speed is not considered.
Its like, one will get tired quicker if he's made to run a marathon, with a smaller/ blocked nose opening.


The reason for most bikes being short stroke is associated with today's better tuning level and technology.
Today, the big bore motorcycles may give good low end too, due to a variety of reasons. A good example is the Ninja 650, which is an oversquare engine (short stroke), but when you ride it, its a good city and touring bike. Of course, its firing gap is a factor too.

Let's talk about Bandit 1250S- an inline 4 cylinder. It makes 108 NM @ just 3750 rpm.... Does 35 as well as 250 kmph, both in its 6th gear.
And guess what? Yes, its a short stroke. So, that almost clarifies the importance of Oversquare engines in today's world.


In an equally gapped (in terms of firing) 4 cylinder 4 stroke engine, there's no dead stroke, that's why it feels "smoother" and "linear".
In an equally gapped (in terms of firing) 2 cylinder 2 stroke engine, there's no DS either.


But if you're looking at a single cylinder engine with no dead stroke, that has probably not happened yet. Because that would require a power stroke every 180*, or everytime a piston travels from upmost (TDC) to the bottom (BDC) position, or reverse.

Maybe an electric motor has no dead spots. or some type of motors don't. Can't confirm this though.


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[MENTION=36366]SparKot[/MENTION] : Thanks buddy, for the wonderful diagrammatic expression of the concept! It will be very helpful to many.
As for the Boxer engine, I guess BMW had few twin cylinder Boxers in its lineup once... I don't remember exactly, but maybe it was the BMW HP2, which was a faired bike IIRC. And few more non-sporty engines may have had this config. before it.
But yes, clearly, its not the most "in-demand" configuration for a motorcycle, due to obvious reasons like horizontal size, frame suitability, etc.

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

My bad, i stand corrected.. it is actually 720⁰ and two full rotations required for all 4 cylinders to fire

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

Can't they come up with fuel-efficient 250cc twin with optimal mid-range?

Inazuma(GW250) is claimed to be a fuel efficient twin, does anybody know its ARAI mileage figure?

Is Honda CB400 is the smallest inline4 production motorcycle?

comparing a carburetted 100cc engine with a 200cc carburetted twin, we have

1. additional engine & head components
2. additional carburettor
3. exhaust(muffler) : could be combined in to one
4. modified crankshaft

what else?

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

As mentioned by someone earlier rpm of any cylinder is bound by meter/sec. of piston which is bound by Impact strength, Inertia and friction heat of metal used in cylinder, more exotic metallurgical marvel of cylinder/piston metal, other condition remaining same. Because rpm is directly proportional to meter/sec speed of piston

Now suppose we decided to design same power at crank with same displacement with single cylinder vs multi cylinder.

To increase the power we need certain amount of air fuel mixture and other variable like exhaust gas for single cylinder (i am talking about moving parts which creates inertia) we need more strength for parts and also size has to be increased I mean area and area is square of linear dimension therefore it increases four times as fast valve dimension port etc.

You got the point, we need more material for same amount air (to say) more spring strength, cam strength valve seat piston head cylinder lining etc. Therefore multi cylinder is due to inherent inertia wgt. advantage produce more torque or power. (consider talking about multivalve for both single & multi cylinder) Kindly note that no. of valve is on single cylinder is after a certain level becomes inefficient( increase in efficiency vs cost addition) due to various factor.

And also vibration is low due to canceling effect and inertia((ma2) of each piston. now its depend on manufacturer how he tries to design single cylinder by using expensive metal and and other technological selection like SOHC or DOHC bore x stroke, valve position(for ease of flow) etc they further customized the engine as per requirement. there fore single cylinder can be made to produce said rpm /bhp/torque defined by metallurgical limits.

But if given same metallurgy & technology level, multi cylinders clearly wins.

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Just in laymen terms every engine has some min torque also in practical engine cant run below certain rpm due to its own limitation, therefore if min torque exceeds the torque needed to turn the wheel for 35KMPH it will run and I think most modern bike high capacity they have generally enough min. torque for any gear( or you can design accordingly) for keep running the engine at low speed also in high gear. I dont think over square or under square will factor in much here.

Size does matter..... or if want more specific low rpm/speed engine design gear box accordingly.

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

An interesting deviation is the Two stroke Diesel Engine being used in Diesel Locos. These engine develop much more power and thanks to Electronic Fuel Management , Hardly emits smoke and is much more fuel efficient than a normal 4 stroke diesel engine of comparable displacement. The same was designed and tried on 2 stroke Petrol engines ie., 3 and 2 wheelers with great success......unfortunately due to blanket ban on 2 stroke engines, the technology and use met with early demise....
What is of interest with the 2 stroke Diesel engine is the Exhaust is controlled by Valves like in conventional 4 stroke engine, but inlet is by Port timed , like in 2 stroke engines...

2 Stroke Diesel Engine Animation - YouTube

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

To the best of my knowledge the smallest In line multicylinder production bike was the Honda CBR250RR which was a FOUR cylinder
engine capable of 19,000 RPM.
Other experimental,and Race Tuned bikes were the FIVE Cylinder 125cc and the RCC166 a SIX Cylinder 250cc bike...produced by Honda in 1966..

1966 Honda RC166 Exhaust Engine Sound

http://www.youtube.com/watch?v=eaRop_ZMwo0

Honda RC166 from 1966250cc on 6 cylinderamazing sound

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

2 stroke diesel has the highest volumetric efficiency in all variety of engine types, in laymen terms most power generated /volume of fuel.

It has very specific application in submersible vessel & and other critical vessel where total volume on vessel is very important.

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

I have seen those videos of CBR2500rr that was a hell machine and did not know about those so little five & six cylinder engines

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


Theres no blanket ban on 2 stroke engines. Mopeds from TVS are running fine across the country. They are 2 strokes. Kindly provide a link to Government notice that says it is banned.

Banned 2 stroke autos and banned 2 stroke engines are 2 different things.

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

Na na, you got it wrong! What he meant was, 2Ts couldn't continue production due to more stringent norms w.r.t pollution. Shogun came with a cat con for a short while IIRC. Later, norms got more stringent and 2Ts were permanently stopped.
It was all due to pollution norms, 2T plants shut automagically!

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


You are right Divya. This is what I wanted to hear. Ban and feasibility are 2 different things. There is no blanket ban by the government. If you can make a 2 stroke that meets all the environmental requirement nobody will stop you from selling it. Thanks for clearing that.

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

Yes it is not a ban on all 2 strokes. ..I stand corrected.

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

Ok this is an interesting thread and i tried to keep out of it but my brain brgan to itch so i came here. So let me tell you that there are a lot of misconception in this thread which i would like to clear.

Without first going into details of single and multi cylinder, i would first of differentiate between torque produced by engine.

So lets start with torque first:-

Torque- In simple terms of physics Torque is nothing but the twisting force. In engines it is the twisting force at crank. Torque is practically used anywhere and everywhere. Simple things like opening a bottle cap, we are using Torque. SO torque is the basis of all turning action.

Now coming to engines, torque is not dependent on engine stroke, i.e is long stroke or short stroke, but on the size of engine. As we know torque is the twisting force so in an engine it is the maximum amount of twisting force on the crankshaft which in turn is rotated by the force acting on the piston surface. So we see the volume of the engine is important here as the volume of engine determines the amount of air fuel mixture burning as also the force acting on piston.

So a engine with same size will produce same torque no matter it is short stroke or long stroke. Of course it may vary by 1-2 or few here and there variables but will be same.

What the short or long stroke does is it varies the way the torque is produced. A long stroke engine will produce torque much lower down the rev range. While a short stroke engine will produce torque at higher rpm.

However there are some variables, like forced induction, where more air and fuel is compressed into smaller cylinder. But these are like softwares to hardwares and like they say there is no replacement for displacement. Case is in case of Fiat Linea T-Jet, when we look at the power figure it makes almost same power as Honda City, but Honda makes it at 1.6 l engine with NA and Fiat makes it at 1.4 l with Turbo charged engine. But when you see torque it makes torque like diesel engines.

More over the type of fuel burned as in a diesel engine will produce more torque than similar size petrol engine because of the fact that calorific value of diesel is more and diesel engines thermal efficiency is more.

But when we consider NA engines with same state of tuning, bigger engine will produce more torque than smaller engines and also in relaxed manner.


Now coming to single and multi-cylinder then both has its disadvantages and advantages.

A multicylinder has the advantage that it has more power strokes in each cycle of engine. While 4 cylinder bike engine uses alternate firing of two cylinders but in bigger engines like in cars, there are sequence of firing 1-4-3-2 or something else which generates more number of power strokes in each cycle of engine.

Also by making multicylinder engine each individual cylinder is small and engine revs like crazy. Also vibrations are reduced due to reciprocating mass getting balanced. However multicylinder engines makes less torque than equivalent single cylinder engines because of the simple fact the each strokes brings in less amount of fuel than bigger engines, so the force acting on the piston in each power stroke is less, so torque is less. But the saving grace is that since they have more number f power strokes so they compensate it by making more power and rev quickly gaining speed quickly.

Have you thought why Buggati went for W16 engine than 8 or 12 cylinders. Its because for making so much power and also for engine to catch high rpm, the individual cylinders should be small and the engine should have enough power strokes for engine to gain so much of power. SO 16 cylinders increased the power stroke along with having the ability to rev higher.

Will a single sylinder such big be able to power so much and gain rpm and speed so rapidly. Frankly no, as it will not even rev till 2000 rpm, and also will not gain rpm quickly. But what it will have is humongous amount of torque at almost idle rpm. It will almost spin its tyres trying to send that torque to tarmac.

Case is with Volvo buses. They have 6 cylinder 7 litre engines. Case is that they could have done 10 or 12 cylinders and that could have helped them rev higher and would have much higher top speed.

But no because they want high torque and not power, as they need to haul passengers and huge body. Still they cross 130-140 with ease becuase the torque helps them to pull even in top gear till redline.

So the fact is that when the need is for more torque at lower rpm then less no of cylinders with more capacity and when there is need of more power for more speed and rpm, more no of cylinders are used. As simple as that.

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

Also please explain how Yamaha FZ 16/S (v2.0) and YZF R15 differ in torque & power delivery despite being of same capacity.


I thought CB400 is still in production, did they stop it?