What Can Cause a Dirt Bike Not to Start? - Risk Racing

What Can Cause a Dirt Bike Not to Start?

February 03, 2022 6 min read

What Can Cause a Dirt Bike Not to Start?

Your ride can’t start if your dirt bike doesn’t start. The last thing you need when getting ready for a ride, for practice, or a race is for your dirt bike not to start. As a dirt bike rider or racer, like me, you probably like going fast. Don’t get left behind because your dirt bike won’t start. 

There are multiple reasons as to why your dirt bike might not be starting. Air, compression, fuel, and spark are the four foundations needed for a bike to start. Before taking your bike to a mechanic, check the four basics to determine why your dirk bike might not be starting. 

Being stationary is not an option in dirt bike riding, unless you’re completing a routine maintenance checkup. Being an athlete in what’s considered one of the toughest sports is thrilling, but it’s mostly distressing if you can’t get your bike to start. Read on to find out why your dirt bike isn’t starting and let’s get you back on that fast track asap. 

Why Will My Bike Not Start?

Dirt bike won’t start, or it starts but doesn’t stay running? There are numerous reasons as to why your dirt bike possibly isn’t starting. From something as simple as there’s no gas in the tank to slightly more complicated issues that need a mechanics touch. 

Not to sound like that IT guy who asks if you’ve checked the switch is on at the wall, but have you checked all your basics first? Before taking your dirt bike to the mechanic, there’s a few simple components you can look into first. 

Check the fuel. 

An empty gas tank won’t get you very far my friend. Maybe you thought you filled up recently, check again and make sure you have gas in the tank before you head out for your ride. Save yourself the unpleasant embarrassment of getting to the course and trying to start your dirt bike without any gas. 

Though I don’t like to admit this, I’m fairly sure we’ve all overlooked this at some stage in our dirt bike careers. 

Is your carburetor in good condition? 

If you’ve checked the gas and can see or hear that there’s plenty in there, you’ll want to check the carburetor is getting fuel. The carburetor’s job is to help get the fuel to the engine.

Make sure your dirt bike engine is cold before opening the overflow to check if any liquid comes out. If liquid comes out, the carburetor isn’t the issue. The pet cock or fuel line might be blocked so you’ll need to have the fuel line unclogged and cleaned up. 

Keep in mind that if there’s too much excessive gas in the carburetor it might mean you have a flooded engine. 

Charge your battery. 

This step isn’t for everyone as many of us know a battery doesn’t always power the engine of a dirt bike. For those of you that do, however, have a battery for a more stable ignition, if you haven’t yet, check that your battery has charge. 

Electric starts are becoming more popular every year so this one will probably be a more frequent issue in the future. Storing your bike somewhere that won’t let the cold affect it too much could help to preserve your battery. 

Bad spark plugs. 

We need a spark to ignite the engine. That glorious roar when the engine starts is all thanks to our spark plug making it possible. Another simple fix is to check the spark plugs and replace them if necessary. 

Other than the fact your dirt bike isn’t starting, some other common signs that might indicate the spark plug is at fault is:

  • Corrosion 
  • Rust
  • Burn marks
  • Broken tips
  • Misfiring
  • Backfiring
  • Frequent flooding of the engine

You can check if the issue is the spark plug by following these easy steps:

  1. Remove the spark plug from the ‘head’, leaving it in the boot. 
  2. Hold the spark plug from the boot end and do not hold or touch the metal or you’ll risk shocking yourself. 
  3. Place the spark plug against metal and try the kick starter a few times. 

If there’s no spark, you need a new spark plug. If there is spark and you’ve tried the above solutions, your spark plugs might need a good cleaning. I’d recommend replacing them anyway, it’s quick and cheap enough to justify getting new ones. 

Spark plugs don’t last forever and the more you ride your dirt bike the more often they will need to be replaced. Faulty spark plugs are a common issue so the fact they’re so cheap and easy to fix doesn’t go unnoticed. You might even benefit from having a few spares on hand. 

It’s recommended that you change your spark plugs every 5 years but that doesn’t mean it will always take 5 years for your plugs to wear out or go bad. The more we ride, the sooner we need to replace parts. It’s common to have to replace spark plugs yearly. 

Why won't my bike start

Low compression.

Low compression might be the culprit at hand. If the piston rings and the piston itself are warn it will cause low compression.

Common signs of low compression are:

  • Low power
  • Kick starter kicks over very easily
  • Spark plug fouling
  • The bike won’t start

The manual for your dirt bike will have the PSI guidelines (Pounds per square inch). This means not all dirt bikes will have the same specifications. Check your manual and complete a compression test on your dirt bike to find out if low compression is the problem. 

Here’s a quick guide on how to check the compression:

  1. Switch off the engine
  2. Remove the spark plug from the head so it’s not touching any metal
  3. Remove the seat and gas tank (hopefully, there’s enough room under the tank so you don’t have to remove the gas tank)
  4. Hold the throttle open
  5. Insert the cylinder compression gauge
  6. Kick or turnover your engine until the compression gauge stops moving

If the pressure doesn’t reach the desired amount, you officially have low compression, and this could mean any number of issues under the top end. Check for leaks in valves, cylinders and the gasket and also for worn pistons or piston rings. 

What causes low compression

Dirty air filter.

I can’t stress this enough, clean your air filter. Remove the seat and side panel of the air covers so you can check the filter’s air intake is clear. Take the air filter out, clean it if needed, and then check further down the air intake to make sure it’s clear and nothing is blocking it. 

Think of this like it’s your own airways. Clear airways mean a higher level of functioning.  

If your air filter isn’t well maintained, it’ll cause further issues with the bike including fouled spark plugs. A fouled spark plug is when your plug becomes covered in unwanted substances like oil and fuel. A fouled spark plug will fail to ignite the spark that fires up your engine. 

Can You Start a Dirt Bike in Gear?

Before starting your dirt bike check that you’re in neutral. If your bike isn’t starting because you’ve been trying to kick start your bike while it’s in gear, I sincerely hope no one else noticed. I really hope that the bike didn’t actually start ‘in gear’ as it would just take off unexpectedly and most likely cause an accident. 

You can start a dirt bike while it’s in gear but just like a car, you’d need to have the clutch pulled in. If you’re new to dirt bike riding, I suggest always starting in neutral as the take-off can be tricky if you’re starting in gear.

Experienced riders sometimes start their bike while it’s in gear for a stronger chance of a faster holeshot in Hare Scramble and GNCC style races. 

Hare scramble racing

How Do You Unflood a Dirt Bike?

First, you need to know how to tell if your dirt bike is flooded. How can you tell if your dirt bike is flooded you ask? If you’re finding it difficult to kick over and you can smell fresh fuel in the air, you probably have a flooded dirt bike. 

Flooding can happen if you’ve tried to kick start your bike too many times without it starting. There’s an uneven amount of air and fuel in the engine so now it won’t kick over because there’s too much gas in the cylinder.

To fix a flooded engine you can do a couple things: take the spark plug out and kick or turnover your engine to spray out excess fuel, or let the bike sit for awhile the gas will natural evaporate and flow back into the carburetor. 

If you do have a flooded engine because you’ve tried to kick start your bike too many times without it starting, you’ll want to examine why it’s not starting properly in the first place. 


What Makes a Dirt Bike Hard to Start?

Bikes aren’t easy to maintain due to the extreme riding conditions. There are common issues linked to one another that cause problems with starting your dirt bike. Dirt bikes are hard to start if parts are worn out and elements like the cold and sitting stored for too long can make it hard to get your bike started. 

Keep your dirt bike well maintained to avoid unnecessary and frustrating issues. Regularly replace and maintain the four basics (air, compression, fuel, and spark) for best results and to keep yourself on the track and in the fast lane longer. 

If the bike needs worked on, then an MX Stand would really come in handy. Check out the options we recommend atRisk Racing.

ATS MX stand: 

https://riskracing.com/pages/ats-adjustable-top-magnetic-moto-stand

Moto stand

MX Ride-on Stand: 

https://riskracing.com/pages/rr1-ride-on-lift

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