Listen to the podcast

Some mechanical problems will cause your bike’s engine to run poorly. Others will cause the entire engine to stop (or “seize”, if you will).

Case in point – the engine seizure.

Tune in to discover:

  • What an engine seizure is
  • 3 common reasons for an engine seizure
  • Differences between a soft vs. hard engine seizure


Hello, and welcome to another episode of 30-minute Motorcycling – a podcast for those riders who are at the beginning of their own Dual Wheel Journey, where you’ll discover something new about how your motorcycle, moped, or scooter works – in less than 30 minutes.

There are a lot of things that could cause your bike to run poorly – some of which we’ve looked at in previous episodes – from overheating to “running rich.”


But in all those cases, at least the engine is still technically running. What about an issue so severe that your engine stops running completely?


Case in point – the engine seizure. But what is it? What are some common reasons why it happens? And what’s the difference between a soft and a hard engine seizure?


That’s what you’re about to discover in this episode. And to explain what an engine seizure is, we need to take a look inside an internal combustion engine.


All engines of this type have moving parts, whether it’s a four-cylinder inline, a V-Twin, or another engine type entirely. 


Some are smaller than others, but the bottom line is that these internal parts are designed to move in and out – from the crankshaft at the bottom of the engine to the camshaft and the piston at or at the very least near the top.


With this in mind, what do you suppose would happen if one or even several parts couldn’t move for some reason? 


Then, the engine can’t run at all – and that’s when you’ve got an engine seizure. 


But what causes the engine to seize? There are many reasons for it, but for this episode, we’re going to look at the 3 most common reasons.


And out of all those common reasons, there is none more common than a lack of engine oil.


Remember all of those moving engine parts we talked about earlier on? One of the main reasons why they can move in and out is because of proper lubrication.


And if there’s not enough engine oil in your engine, or even if there’s no engine oil at all, it increases friction, which, in turn, means that the moving parts will grind against each other.


Some parts, like the piston, might even get stuck inside the combustion chamber if it doesn’t get enough oil.


And if the piston is stuck, it means that your fuel and air mixture won’t get compressed, and certain won’t get ignited by the sparkplug.


In other words, you’re not going anywhere. 


What’s the best way to prevent this? Check your oil regularly, and top up the oil if you need to. Your engine depends on it.


The next common reason for an engine seizure is overheating. 


Because although an internal combustion engine can get very hot, there is such a thing as “too hot.”


Remember that many of the moving parts inside your engine are made from metal. When metal gets hot, it expands – and once this expansion happens, it’s permanent.


Why is this a problem? Well, let’s look at the engine valves. If you remove all the valves from your engine, you’ll notice that the shaft is the same length for all of these.


And there’s a good reason for that – the valve is designed to open and close at certain points – it all depends on how the valve timing is set up. 


But even if the valve timing is set up flawlessly, if the shaft for one of the valves expands permanently because of overheating, it will protrude longer than it should and won’t close properly, even when it should.


And if it’s still open during the compression stroke, the piston will slam into that valve, which will bend, leaving the intake or exhaust port permanently open.


So if you suspect your engine is overheating, it’s best to get to the bottom of it ASAP. And if you’d like to know more about 5 common reasons why an engine would overheat, please check out episode 45 of this podcast.


Anyway, let’s now move on to the third and final reason for an engine seizure – a fuel mixture that’s too lean.


Although “running rich” is something to avoid, it’s not much better to have a fuel/air mixture that’s too lean, since two effects of a lean mixture include reduced power and, for the context of this episode, increased combustion temperatures.


Does that sound familiar? That’s right – it’s just like the overheating problem we just looked at.


But there’s a twist – even if the cooling system works like it’s supposed to, a lean fuel mixture can cause the same problems that overheating can cause i.e. increased wear and tear on internal engine components and metal components expanding beyond their intended limits.


And those are 3 common reasons for an engine seizure. But did you know that there are two types of engine seizures – a soft seizure and a hard seizure?


Before we end this episode, let’s compare the two, starting with the soft engine seizure.


With a soft engine seizure, you might experience a sudden reduction in engine performance, often caused by a lack of lubrication – again, remember to check that you’ve got enough oil in your engine.


Anway, the good news about a soft engine seizure is that if you catch it early on, it’s only temporary. In some cases, it might even be possible to restart the engine again.


Sadly, the same can’t be said about a hard engine seizure – if you have one of those, it’s the result of prolonged overheating, or massive mechanical failure.


Whatever the case might be, with a hard engine seizure, the engine won’t even turn over when you try to start it. 


In other words, fixing this type of seizure requires a lot more than a can of WD-40. Often, the only solution is to do a complete engine overhaul – and if you’re curious to know more about what that is, please check out episode 34 of this podcast.


Either way, that’s the end of this episode about what an engine seizure is, what causes it, and the differences between a soft vs. a hard engine seizure. 


I hope you enjoyed listening and, above all, that you learned something new. 


Until next time, keep your helmet on and your eyes on the road. Bye!