How Do You Know When a Dirt Bike Needs a New Top End? - Risk Racing

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How Do You Know When a Dirt Bike Needs a New Top End?

December 02, 2021

How Do You Know When a Dirt Bike Needs a New Top End?

Your dirt bike is your pride and joy. It isn’t a toy, it’s a versatile machine, don’t let anyone tell you otherwise. Dirt bikes are powerful, strong, and can tackle the toughest terrains, but they won’t last an eternity. A bike can take a lot of wear and tear over the years and repairs will be needed eventually. It isn’t just down to how you treat the bike, but how well it’s been maintained. If you spot the signs quick enough, you can prevent engine troubles from getting any worse and keep repair costs relatively low. 

So,what does it mean when a dirt bike needs a new top end? I’m often asked this question and we see a lot of newbies push their bikes too far. If you’re an experienced dirt bike owner, you’ll know what a top-end is – hopefully you do anyway, and if not you’ve come to the right place. Fortunately, we know and can help you spot the signs that your bike needs a new top end. So, what are the signs that a new top-end is necessary?

Motocross Engine

What Does It Mean When a Dirt Bike Needs a New Top End?

This is a process that involves the inspection of and full removal of the cylinder and cylinder head. The piston rings and piston must be checked for any signs of damage or wear. When there are signs of damage, the parts must be fully replaced to ensure the bike runs smoothly and is track or trail worthy. Fortunately, you do not need to repair or replace every part of the top end of the bike. For example, if the cylinder is in tip-top condition, but the piston rings show signs of significant wear. You would just need to replace those piston rings and most likely the piston rather than replacing the cylinder, valve springs, and cam chain (only four a four stroke). 

Dirt Bike Valve Train

How Much Does It Cost to Rebuild a Top End on a Dirt Bike?

It's important to note that you don’t always need to fully replace or repair the entire top end of the dirt bike. As said previously, you could just need minor work done to one section, such as the cylinder. So,how much does it cost to rebuild a top-end, or what should you expect to pay? It is a tough question to answer as it depends on the extent of the rebuild. For example, changing the bike’s gaskets could cost you less than $50. Installing a new cylinder, however, could be $400 or $500 – and that, of course, doesn’t include labor costs (if you're not doing it yourself)! 

A total rebuild, however, could cost you more than $1,000. Again, it depends on the age of the dirt bike, its condition, and the extent of the problem. It’s quite difficult to put a precise number on a top-end rebuild until a trained mechanic examines it in full. In most cases, minor repairs should be enough to patch the problem; unfortunately, this isn’t always the case and a full rebuild is necessary. 

Signs You Need a New Top End

When do you need a new top end? People continually ask the question, even when they’ve had top-end trouble before. It’s about making simple but necessary repairs to the dirt bike. Fortunately, there are several major signs to spot the bike needs a new top end.

Here are some of the signs that you may be in need of a new top-end on your dirt bike. If you can relate, it’s at least time for an inspection if not some wrench time.

A Weak Feeling

One major indication is when the bike feels as though it’s losing power. When the engine feels weak and there is a lack of power behind it, even when on wide-open throttle. 

Essentially, the bike is gutless – suffers from a lack of power – and it usually is down to a worn piston or piston ring. When the bike has had too many hours on it, it wears the top end down and needs to be repaired or replaced. Remember, the problem will only get worse as time progresses or as you continue to ride the dirt bike. 

Motocross Riding

The Bike Is Hard To Start!

Regardless of whether you have a 4 or 2-strike dirt bike, it shouldn’t take 20 or 30 kicks to start the engine. Most engines should be up and running within 3 or 4 kicks, anything more and it’s a good indication there is something wrong. When the bike takes a dozen or so kicks to start, it’s a sure-fire sign there is an issue with the bike. Of course, it can take a little longer to start a bike in extreme climates, especially when it isn’t properly jetted. Some bikes also need additional kicks – and more muscle – to get going. 

While a dirt bike may have an issue with the top end, it might just be a sign the top end is worn away. There are several factors that could contribute to the dirt bike taking a long time to start, however, it’s often associated with top-end repairs. 

Starting a Dirt Bike

A Noisy Engine

Rattles, taps, and knocking noises could be an indication the parts are worn out. When the cam chains or tensions wear out, it’ll begin to rattle. The piston and cylinder might need replacing when knocking noises begin. However these noises can also be associated with issues in your bottom end.

Wonky Performance

When a bike’s engine is stop-start or is inconsistent, it could be a sign of a major issue. It doesn’t automatically mean; however, the bike is a total write-off. It doesn’t also mean you’ll have to rebuild the top end either. It does indicate, though, serious repairs are necessary, nonetheless. The biggest issue could be down to the gaskets or engine seals. If these are worn away, they can create an inconsistent performance. Gaskets worn away can cause fluids to get where they aren't supposed to be or cause oil and coolant to mix causing significant issues.

Smoke Billowing from the Engine After Warm-Up

It’s not uncommon to see smoke coming from a dirt bike; however, excessive smoke from the tailpipe could spell disaster. If you see blue smoke, it could be down to the gearbox oil burning in the combustion chamber. White smoke could indicate the coolant is burning in the chamber. Usually, the issue lies in a leaking cylinder or the gaskets. When this occurs, you’ll need to replace the cylinder, and gaskets otherwise a blowout could occur. You want to avoid this, as it’ll add a lot of money to the repair bill. 

Smoking Dirt Bike

Dirt Bikes Vary

While we’ve talked about signs that indicate you need a new top end, you never know what is wrong with the bike until you get it checked out. Your bike might be difficult to start but that doesn’t always signal it needs a new top end. It could be something with the fuel delivery system or the spark plug. If the bike hasn’t been used for a prolonged period, that could be the cause of the bike not starting properly. Remember, not all dirt bikes are the same; they don’t all work the same and have different problems. You cannot be sure what issues the dirt bike has until you crack it open or get a professional to inspect it. 

Take Care of Your Dirt Bike

Your dirt bike is a treasured possession, but you need to know how to spot the signs of a potential issue. The top-end can be troublesome and expensive, especially when you leave the issue to get worse. It is essential to take your bike into a repair shop the second you notice something is wrong. For instance, when the engine starts to rattle or there is smoke billowing from the engine after warming up, take it in for an inspection. Sometimes, it’ll be a minor fault that needs repairing; however, not always. Fixing the issue quickly could prevent a total rebuild of the top end.

If you are just starting to tackle the maintenance of your dirt bike, make sure you have a good dirt bike stand to put it on. Our ATS MX Stand comes with magnetic parts trays built into the sides making a great place to store small nuts and bolts as you go.

Motocross Stand

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