Questions tagged [four-stroke]

Four stroke refers to the quantity of times a piston travel the bore of an ICE in order to complete the combustion process.

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What is happening when a two-stroke engine is said to be "four-stroking"?

Many years ago, I was involved in a hobby of building and flying model aircraft. The aircraft used alcohol-fueled 2-stroke engines with glow plug ignitions. When these engines ran rich (and always at ...
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16 votes
6 answers
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What makes two-stroke engines less fuel-efficient than four-strokes?

It is a commonly-held belief that two-stroke engines are less fuel-efficient than four-stroke engines, and some example BSFC figures appear to confirm this as well. But what is it that causes two-...
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12 votes
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Who came up with "suck, squeeze, bang, blow"?

A popular explanation of how a four stroke engine works is Suck, squeeze, bang, blow. The engine sucks in a mixture of fuel and air, then squeezes it together (compresses it), then it burns / ...
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Brake Specific Fuel Consumption of 2-stroke vs 4-stroke

How much fuel do various types of engines burn per power output? I'm especially interested in naturally aspirated piston engines, and comparing two-stroke to four-stroke. The wikipedia article gives ...
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10 votes
2 answers
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What is the efficiency delta between rotary and modern four-stroke engines

Background There is a lot of opinion out there regarding the efficiency delta between wankel rotary engines and four stroke engines of various configurations (forced induction, etc). This delta, ...
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10 votes
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More In Cylinder Pressure Testing Questions

So I was looking at a 06 Pontiac G6 2.4l with a complaint of low power on hills. Had been at another shop to have the transmission checked and they referred the customer to us. Road test confirms car ...
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7 votes
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Two-Stroke vs. Four-Stroke Diesel Engines - What is most commonly used in heavy vehicles?

I am not well versed in diesel engines. To prove my point, I've learned in the last month that a two-stroke diesel engine actually exists. My Question. What kind of diesel engine (four-stroke or ...
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5 votes
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Ignition timing of 4 stroke two wheeler

Gentlemen, So I work in this lab with a small dyno for a two wheeler engine hooked onto it. The engine hasn't been used for years and I had to correct few things in the wiring. I had to remove the ...
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Do 3 and 5 cylinder engines have uneven power delivery?

I know that they are out of production and only a few of them were made. For 5 cylinder engines... Do they have uneven power delivery? Would two cylinders share a part of the revolution to the crank ...
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Starting fluid, does it require a spark or autoignite?

If a four stroke gasoline engine (inline-four, digital fuel injection) starts with starting fluid (but not without it, and stops firing when the spray is removed), is this an indication that the spark ...
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What is meant by bore and stroke?

All engine specifications reflect a bore and stroke number. Example Aprilia Tuono V4 R 2012 Four stroke, longitudinal 65° V four , DOHC, 4 valves per cylinder 998.9 cc / 60.96 cu in Bore x ...
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Two-stroke vs four-stroke design

Besides the apparent differences in fuel-injection, ignition, and valve timing, are there any other differences in the design/build of two-stroke and four-stroke engines?
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3 answers
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Oil sump for 2 stroke vehicles

I do not know if there is any oil sump for a 2 stroke vehicle and basically it is mixed along with the gasoline. Why is that so in a 2 stroke vehicle. And can we have an oil reservoir or a sump of oil ...
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2 votes
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Motor oil requirements on exhaust system

I have been working with 2-stroke engines for quite a while with a motor oil that has doing a great job. It was kinda simple since there was literally only 2 different oils at the gas station for 2-...
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1 vote
1 answer
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Which engine type gives more HP- two or four cycle?

Same max. RPM and CC of course. And if possible, an explanation would be nice. Thanks!
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What are the dangers of too high TBN?

According to Wikipedia, Total Base Number (TBN) is a measurement of basicity that is expressed in terms of klk number of milligrams of potassium hydroxide per gram of oil sample (mg KOH/g). TBN is ...
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What is difference between stock CDI and racing CDI in a 4 stroke motorcycle?

The mechanic told me that stock CDI has a limit after certain speed but the local one has none hence increase in speed. While searching for that I came across this keyword of Racing CDI and become ...
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More difficult to start the MotorCycle

The bike Suzuki sling shot. When starting the bike every day its nearly takes 20 to 25 Manual kicks. Is this a engine fault or any other reason?. And the another thing is when riding The bike , When ...
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1 vote
0 answers
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2004 Yamaha Outboard 50HP vibrating around half throttle (2700-3100 RPM)

I've recently bought a 2004 Yamaha outboard, specifically a F50 TLRC (four stroke 50HP) and it is generally in good condition, takes a couple key turns on startup but always starts, a little rough on ...
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Removal of oil filter rotor lock nut and washer on 4 stroke

I am currently attempting a transmission repair on an old honda xl125 motor. I have been following the clives manual with very little issue. However upon attempting to remove the clutch I am being ...
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-1 votes
1 answer
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In a petrol engine, how does the first stroke happen when the gas pedal is first pressed?

I'm new to mechanics, so this may not seem like a good question. When the gas pedal is first pressed, how does a piston start the intake stroke? Does it have some direct connection like a rod?
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