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If you listened to episode 14 of this podcast, you’ll have a basic understanding of how an internal combustion engine works, and some common engine layouts.
But there were a few things that were left unanswered:
- “What is a 2-stroke?”
- “What is a 4-stroke?”
- “What is a ‘stroke?'”
That’s what this episode will dive into.
Tune in to learn:
- What a “stroke” really is
- The differences between a 2-stroke and a 4-stroke engine, and their pros and cons
Transcript
Hello and welcome to 30-minute motorcycling – a podcast for new aspiring and returning riders where you will learn something about motorcycles and other two-wheelers in 30 minutes or less.
If you listened to Episode 14, you should know by now, that your motorcycle, moped, or scooter has an engine, and that it’s either a 2- or 4-stroke. But do you know the differences between a 2 or 4-stroke engine?
And just what is a “stroke,” anyway?
That’s what this episode is about – in this episode, we’re talking about the difference between 2-stroke and 4-stroke engines, and the pros and cons of each type.
But before we dive deep into that topic, we need to learn what a “stroke” is.
What a “stroke is”
A stroke refers to a stage in the combustion process for an internal combustion engine – so in other words, this does not apply for electric engines.
Anyway, when you hear someone say that an engine is a “2-stroke” or “4-stroke,” it means that the engine needs 2 or 4 stages respectively to complete an entire combustion cycle.
Regardless of engine design, an internal combustion engine has four stages:
intake, compression, combustion, and exhaust –
informally referred to as “suck,” “squeeze,” “bang,” and “blow” – in that order.
If you’d like to know more about the internal combustion cycle, check out Episode 14 of the 30 Minute Motorcycling Podcast.
So with that said, what is a 2-stroke?
2-stoke
2-strokes are common on single-cylinder dirt bikes and smaller mopeds and only need two cycles to complete a combustion cycle.
Some advantages of two-stroke engines include high power at lower speeds, something which dirt bike riders appreciate – it’s easy to see why made dirt bikes have this type of engine.
2 strokes are also easier to not only build but also to work on since they’re less complex and have fewer parts (some of them don’t even camshafts) – making them popular in many developing countries.
However, they’re not good for higher speeds. After all, have you ever seen a Honda Gold Wing or a big Harley with a 2-stroke engine? Probably not.
2-stroke engines also don’t have a reservoir to store oil – this means that to lubricate the engine’s moving parts, you have to pre-mix the oil with the fuel by hand.
If that’s something you need to do, I’ve put a link in the shownotes to a YouTube video from Tomos America that explains how to mix 2-stroke oil with gasoline [https://youtu.be/8H4OaUgRCdY]
So what about four-stroke engines?
4-stroke engines
Most street bikes are 4-stroke, and the biggest advantage of a four-stroke engine is that it’s capable of handling higher speeds.
As I mentioned before, you don’t see touring motorcycles or big cruisers with two-stroke engines on them.
Also, a four-stroke engine has a separate oil sump – meaning that you don’t have to mix the oil and the petrol or gasoline by hand – it’s all done by the oil pump.
So far, so good – but even 4-stroke engines have their shortcomings.
For one thing, since a 4-stroke engine consists of more parts, if something should go wrong, it can be more expensive to repair when compared to two-stroke engines.
Also, these additional parts make a 4-stroke engine feel heavier – at least when compared to a two-stroke.
Essentially, there’s no “be-all-end-all” choice.
Whichever type you choose all boils down to what you’re going to do with your bike.
Are you going to just “cruise the ‘burbs” on the cheap with no highway travel whatsoever? Get a 2-stroke.
Are you going to do a lot of touring, spending hours on the freeway? Then a 4-stroke is more appropriate.
And that concludes this episode of 30 Minute Motorcycling.
If you’d like to know more about 2-stroke and 4-stroke engines, I’ve put a link in the show notes to a blog post on The Dual Wheel Journey about it.
Also, if you haven’t listened to the episode about how internal combustion engines work and some common motorcycle engine layouts, I’ve put a link in the show notes to that as well.
Until next time, keep your helmet on and your eyes on the road. Bye!
