After a few thousand kilometers, your motorcycle’s engine doesn’t run like it used to. In that case, it’s probably due for an engine overhaul. But what is that? And how is it different from an engine replacement? In this blog post, you’ll discover:
- What an engine overhaul is
- Differences between an engine overhaul and an engine replacement
- 3 Common reasons why you’d need to rebuild your engine
- How much an engine overhaul typically costs
Prefer to get this information in podcast form? Listen to the 30 Minute Motorcycling Podcast episode about compression ratios:
What is an Engine Overhaul?
Whether you call it an “engine rebuild,” “engine restoration.” or “engine overhaul,” the purpose is always the same – to revive an old engine by replacing every old worn-out part with brand new ones. And by “every old worn-out part,” I mean every old worn-out part. Every little piece of the old engine must be replaced when you rebuild the engine- from the gaskets to the piston rings. Even the cylinders get a new rebore. If all goes well, you should have a brand new engine that looks and runs like the one the bike had when it left the factory.
Engine overhaul vs. Engine replacement
An engine replacement is just what it sounds like – you remove the old engine and replace it with a brand new one. You might have to remove some parts to loosen the engine, but apart from that, An engine overhaul also requires precision measurement tools, like a micrometer. And above all, overhauling an engine takes time. If you’d like to see what it looks like in real life, here’s a YouTube video of a man in the UK overhauling an old Honda SS50 engine:
Do You Need to Rebuild Your Engine? 3 Common Signs
1. Engine knocking and rumbling noises
Do you hear a lot of knocking sounds coming from your bike? Specifically – from the engine itself? It might mean that the piston’s connecting rod is either bent or broken. The connecting rod attaches the piston head to the crankshaft and controls the movement of the piston itself. It doesn’t matter if you’ve got a two-stroke or a four-stroke engine – if the connecting rod is broken or bent, it means that the compression of the air/fuel mixture is ineffective. And this is the most common reason for engine knocking. Alternatively, the main bearings could be broken.
In a mechanical brake system, there’s no liquid whatsoever.
Instead, power is delivered through a metal cable that tensions as you squeeze the brake lever - similar to how many motorcycle clutches work.
Although not so much on modern motorcycles, these brakes are highly common on bicycles and e-bikes.
2. General engine neglect
Mileage doesn’t necessarily need to be the be-all-end-all determining whether an overhaul is necessary. Even a high-milage engine can run great, provided it has been maintained regularly. Neglect, on the other hand, is a very different story. It doesn’t matter how high or low the mileage for your engine is – if it’s neglected, it will run poorly nonetheless.
3. High oil consumption or excessive smoke
If you’re bike’s running through oil and belching out more smoke than usual, it ould be a sign that the piston rings are worn-out. The piston rings are found on the side of the piston head and are there to:
- Scrape off excessive oil deposits from the cylinder walls
- Provide a seal to prevent oil from entering the combustion chamber
How Much Does an Engine Overhaul Cost?
According to howmuchisit.org, it can cost between $500-$8,000. However, if you need to buy extra equipment and tools, the price can increase even further. But remember – there’s also a time cost as well, which is far greater than the financial one. Rebuilding a motorcycle engine can take as much as 12 hours.