The timing chain in a motorcycle is a small roller chain that is designed to drive the camshaft. That’s why it’s also known as a “cam chain” as well. The camshaft is a little spinning shaft on top of the engine, which is designed to control the valves. Surprisingly, a motorcycle timing chain looks like a regular bicycle chain. Besides metal chains, belts and gears are also used as a camshaft drive in motorcycles.
If you would like to find out more about motorcycle timing chains and their maintenance, you are in the right place.
We at PowerSportsGuide have compiled all you need to know under one roof!
What is the Timing Chain in a Motorcycle?
Motorcycle engines feature valves that control the exchange of gases in the engine’s cylinders.
These valves move continuously when opening and closing the cylinder, which requires some power.
And this power comes from the crankshaft! But how does the crankshaft transmit power to the valves?
This is where the timing chain comes into play.
The timing chain in a motorcycle connects the crankshaft to the camshaft. There’s a smaller sprocket mounted on the crankshaft while the camshaft has a bigger sprocket attached to it. These sprockets are connected by the timing chain. The crankshaft drives the chain, which transmits power to the camshaft, which finally controls the valves.
This means that the camshaft RPM is in harmony with the RPM of the engine, even though it rotates more slowly because of the gearing ratio.
The timing chain is also known as the cam chain, as it actually drives the camshaft. But then where does the name “timing chain” come from?
In a nutshell, this part is often referred to as the timing chain because it ensures that the valves open and close on time.
This role is key, as the valves in the engine have to open and close at a specified time to ensure proper engine operation.
If the valves were not perfectly synchronized with the crankshaft, the valves would move at the wrong time.
In the worst-case scenario, the pistons would hit the valves, causing major engine damage.
Unlike the heavy-duty drive chain (which is also driven by sprockets), the timing chain is a much thinner chain. At first glance, it looks like a simple bicycle chain.
The timing chain is enclosed in the engine, so it’s completely protected from water and dirt.
On top of that, it’s lubricated by the engine oil!
Thanks to this care, timing chains are very durable and many of them virtually last forever.
Here’s a great animation on how a timing chain works in a motorcycle:
Do Motorcycles Have Timing Belts?
Yes, it’s a lesser-known fact that some motorcycles feature timing belts instead of metal roller chains. What’s more, besides toothed belts and chains, gears can also be used as the camshaft drive. The majority of production bikes come with a timing chain, and some of them have belts, but only a few feature gears.
As an example, Ducatis and some big touring bikes feature timing belts.
What is a Cam Chain Tensioner on a Motorcycle?
The cam chain tensioner on a motorcycle is responsible for maintaining the desired tension of the timing chain (cam chain). There are two main types of motorcycle cam chain tensioners. The majority of bikes are manufactured with an automatic cam chain tensioner, which is maintenance-free. Or, at least, as long as it operates properly. In contrast, some bikes feature a manual tensioner that requires the rider to adjust the timing chain manually.
Just like any other chain drive, a motorcycle timing chain also requires some slack to avoid stress on the bearings.
On the other hand, too much slack is undesirable. A loose chain can lead to operating issues and will wear out the chain/sprockets much faster.
To avoid these issues and maintain the proper timing chain tension, every motorcycle is equipped with a tensioner.
The automatic motorcycle cam chain tensioners typically use a spring-driven worm, a spring-loaded arm, or even hydraulic power to keep the chain tight.
Hydraulic tensioners use the oil pressure provided by the engine’s oil pump.
Besides the more common automatic units, some motorcycles come with a manual tensioner.
As the name implies, this unit can only be adjusted manually, which requires some extra attention.
So, the design of timing chain tensioners varies widely, but basically all do the same thing. Let’s see how they work!
How Does the Cam Chain Tensioner Work on a Motorcycle?
Simply put, the tensioner features a wheel or a slider, which is mounted halfway between the two sprockets. The spring or hydraulic pressure forces this small slider/wheel against the chain. It causes the chain to move inwards, which increases the tension and finally eliminates excessive chain slack.
These tensioners typically feature an “anti-return mechanism,” meaning that they can only move in one direction.
Here’s a great video on how a hydraulic cam chain tensioner works:
What is CCT on a Motorcycle?
The abbreviation CCT on a motorcycle simply refers to the Cam Chain Tensioner, which is also known as a TCT (Timing Chain Tensioner).
Motorcycle Pushrod vs. Timing Chain
Besides overhead cam valvetrains, which feature timing chains or belts, pushrod valvetrains are also used on motorcycles. As the name suggests, a pushrod valvetrain uses long metal rods to move the valves. Pushrods were much more prevalent on vintage bikes, but a few modern motorcycle engines feature this design as well. This type of valvetrain typically fits well on larger-displacement, air-cooled engines like the big V-twin cruises.
The cylinders of these bikes are usually pretty large, so pacing them into the frame is tricky.
This is where pushrods come in handy!
The main advantage of a pushrod valvetrain is that it can lower the height of the cylinders. How?
This is because on these bikes the camshaft doesn’t sit on the top of the engine!
Therefore, the cylinders can be lower, and fit into a smaller frame.
Here’s an informative video on how a pushrod motorcycle engine works:
What are the Symptoms of a Bad Timing Chain?
The most common motorcycle timing chain symptoms are as follows:
- Noises from the engine (most common)
- Decreased performance
- Other engine malfunctions
- Engine doesn’t start or stalls
- Too much slack in the timing chain
It’s safe to say that the most frequent problem with timing chains is arguably that they become noisy over time.
Motorcycle Timing Chain Noises
When it comes to motorcycle timing chain noises, they typically vary depending on the model and its engine design. However, a bad timing chain often produces one of the following noises:
- Buzzing or squealing engine sound
- Rattling noises (like having a bunch of rocks in the engine)
- Rhythmical “tick, tick, tick” sounds
These noises are typically noticeable at idle or lower RPMs and always come from the cam chain tunnel.
But to be more precise, in most cases it’s not the timing chain that goes wrong, but the tensioner.
If they are fully extended or fail, they can’t tighten the chain anymore.
This usually means a loose chain!
An increased chain always results in various noises or even engine malfunctions.
So, if you notice any noises or other issues with your timing chain, you may want to first inspect the tensioner!
It’s also good to know that tension failure is a common issue on certain motorcycle models.
On these bikes, it makes sense to replace the automatic tensioner with a manual one.
Before you dig deeper, don’t forget that the noises may come from somewhere else.
For instance, it could be a clutch basket rattle, which is a common issue on Kawasakis.
If pulling the clutch lever makes quiets the noise, it’s a clue that your bike has a clutch issue.
Let’s move on and take a closer look at the chain as well!
When Should a Motorcycle Timing Chain Be Replaced?
How Long Does a Motorcycle Timing Chain Last?
Unlike the drive chain, the timing chain doesn’t have to tolerate a lot of engine power.
Since it’s designed to only drive the camshaft, the time chain takes only a little power from the crankshaft.
Consequently, timing chain replacements on motorcycles are very rare.
It’s safe to say that with proper maintenance, timing chains can even last as long as the engine. That’s why you can find bikes with original timing chains, which have over 150,000-200,000 miles on them! In contrast, some owners prefer to replace their chain after a certain mileage. For instance, 50,000 miles is a typical milestone when more cautious owners consider a replacement.
As they say, replacing the timing chain is like having extra insurance on their bike.
Since a broken timing chain can lead to serious engine damage, it makes sense to replace it to avoid these issues.
But as a rule of thumb, the sprockets and the timing chain should be replaced if they are damaged or worn out.
And this is independent of the mileage!
Let’s move on and see when a motorcycle timing chain should be replaced.
When Should a Motorcycle Timing Chain Be Replaced?
In most cases, there’s no scheduled replacement interval for a motorcycle timing chain. Since these chains are very durable, they are typically considered lifetime parts. Therefore, most owners don’t replace it as long as it’s in good condition. On the other hand, a timing chain must be replaced if it’s worn out or gets damaged. But how do you know when your timing chain is worn out? Keep reading!
Before we drill into the details, something important needs to be clarified.
Contrary to popular belief, motorcycle timing chains don’t actually stretch! Instead, the slack is caused by the chain wearing out.
When the chain wears its pins get smaller while the holes start to grow, which results in a longer chain.
Although it looks like it’s stretched, the plates virtually remain the same length.
To inspect a motorcycle timing chain, you have to remove the cover and the engine oil may also need to be drained. Once you get access to the chain, you can measure its slack and the distance between two pins with a vernier caliper. Then you should check your service manual, as it will tell you if the chain is worn out and needs to be replaced. Rather than mileage, the time of replacement is typically determined by the wear of the chain.
How do You Adjust a Motorcycle Timing Chain?
If your bike has an automatic chain tensioner this means you don’t have to deal with adjusting. However, on some bikes you have to unscrew a bolt or a nut to activate this automatic tensioner. If the bike features a manual tensioner, you have to adjust the chain manually every time it’s needed. The exact procedure is clearly stated in your bike’s service manual. Make sure to check it carefully before you do any maintenance on your bike!
If your bike has an automatic tensioner but it doesn’t eliminate the chain noises, this is a clue that the tensioner is bad/reached its limit or the chain is worn out.
Don’t forget that too much slack in the chain can wear out the sprocket faster, or in the worst-case scenario it can jump (skip a tooth), which may end in engine damage!
Therefore, you always have to be sure that the timing chain on your bike is properly tightened.
Here’s a great video on how to adjust a motorcycle timing chain:
How do You Install a Timing Chain on a Motorcycle?
Unlike adjusting its tension, installing a timing chain on a motorcycle can be enormous work. This is because to replace the chain, in many cases the sprockets have to come off as well. Ideally, the chain is located on the side of the engine and the sprockets are removable. But if the chain sits between the cylinders, this probably means that you have to pull out the whole crankshaft to install the new timing chain.
As you might assume, it’s not a five-minute job!
While chain replacement is usually much easier on a single-cylinder engine, on a bigger bike it takes a lot more work.
Finally, it always depends on the design of the engine.
Besides, if you have to install a new timing chain in your bike, experts recommend replacing the cam sprockets too.
On some bikes, this can be tricky! Why?
This is because sprocket replacement is only simple if they are removable.
But in some engines the cam sprocket is fitted tightly to the crankshaft, which can cause a lot of headaches to remove.
What’s more, on a few bikes the cam sprocket is not replaceable at all, as it is permanently mounted on the crankshaft.
This means if you want to replace the cam sprocket, you actually have to replace the entire crankshaft.
It sounds crazy, but this is the truth!
It’s a clue that timing sprockets are designed to last as long as the entire engine. If you are lucky, yours will. If not, you’ll probably face a costly repair.
Back to the time chain replacement, the other thing that makes it difficult is that the cam timing mustn’t be changed.
In other words, the timing with the new chain has to be the same as it was with the old chain.
Messed up timing can lead to an uneven engine operation, or even engine damage!
As you can see, replacing a timing chain and the sprockets is not for beginner riders.
If you’re not familiar with valve settings and engine repairs in general, it’s recommended that you leave this replacement to a professional.
But if you want to install a timing chain on your bike yourself, make sure that you carefully read the service manual and follow the manufacturer’s recommendations.
For more info, here’s a great step-by-step tutorial on how to replace a motorcycle timing chain.
Are you wondering how much it costs to repair a motorcycle timing chain? Keep reading!
How Much Does It Cost to Repair a Motorcycle Timing Chain?
Depending on the source of the problem, fixing a motorcycle timing chain can be a cheap or even a pretty expensive repair. If the tensioner is all that has to be replaced, it would be about $50-$150 plus labor. But don’t worry as this service can typically be done in less than an hour! But if the chain needs to be replaced too, you have to be prepared for a hefty repair bill. Depending on the design of your engine, replacing the timing chain may cost you many hundreds or even thousands of dollars!
When it comes to motorcycle timing chain prices, they typically range from $50 up to $100. However, this is typically not the biggest cost, it’s the labor.
It’s hard to give even a ballpark figure for the complete repair as it depends on countless factors.
If the cam drive sits between the cylinders, the crankshaft has to be removed to install the new chain.
As you might assume, this can result in a lot of labor.
Besides the chain, it’s wise to replace the sprockets in many cases which would add to the cost.
What’s more, once the engine is taken apart, the repair usually involves replacing some other parts like bearings, gaskets, and so on.
Because of this, replacing the timing chain on your bike may cost you far more than you expect!
Conclusion
Motorcycles feature three different types of camshaft drives.
Most bikes use a metal timing chain to drive their camshaft, while other bikes have a rubber belt or gears for the same purpose.
This chain connects the two cam sprockets, one of them is mounted on the crankshaft while the other is attached to the camshaft.
The timing chain on a motorcycle is used to transmit power from the crankshaft to the camshaft.
Timing chains are typically pretty durable, so they are usually considered to be a lifetime part.
However, some manufacturers may have a recommended replacement schedule for the chain.
In most cases, it depends on the wear on the chain rather that the mileage.
Keeping safety in mind, some owners replace it periodically regardless of its condition.
Unlike chains, tensioners are prone to breaking, which may end in slack in the chain. This slack typically results in a noisy engine, lack of power, or other engine malfunctions.
Disclaimer: This post is for general informational purposes only. Before you do any maintenance on your bike, always read its service manual and follow the manufacturer’s recommendations!
References:
https://www.diymotofix.com/blog/cam-chain-wear-and-replacement-tips1
http://www.dansmc.com/camchain_adjust.htm
