If you’re reading this article, you’ve probably found yourself in a frustrating situation with your motorcycle. I have restored over a dozen motorcycles, several of which had seized engines. Through my experience, I’ve been able to easily recognize the symptoms of a seized engine.
So, how do you tell if your motorcycle engine is seized? If you are sure your motorcycle battery and starter are in good shape, an electric starter engine will click but will not rotate if it is seized. On a kick starter engine, the kick pedal will not move at all as it will be stuck in place due to the piston seizure.
Having to deal with a seized engine is incredibly discouraging. You may feel overwhelmed or that this is over your head. There’s a lot to consider when it comes to seized motorcycle engines, and it may be possible for you to fix it yourself.
What Causes a Motorcycle Engine to Seize
There are several ways a motorcycle engine seizes. Unfortunately, it happens more frequently than you’d expect. If you suspect this is what has happened with your bike, you’re not alone. Depending on the cause, you may or may not be able to fix it.
The first and most common reason a motorcycle engine seizes is because of lack of lubrication. If you have failed to add or top off the oil in your engine, it’s likely there is an engine seizure. If you suspect this to be the reason your engine has seized, the damage may be too severe for you to fix yourself.
The oil’s job is to lubricate and transfer heat away from the moving parts of the engine. Friction is created when the metal parts are moving against each other thousands of times a minute. If there isn’t oil separating the metal parts during movement, the friction increases significantly as well as the heat, making the up and down motions almost impossible.
The increased temperature and friction ultimately cause the engine parts to wear heavily. Parts will want to seize together, but are forced to continue movement which will cause internal damage including bent valves, broken pistons, cylinder wall scratches, burnt piston rings, etc.
The second reason a motorcycle engine seizes is due to old or dirty oil. Sure, it’s nice on the wallet to change your oil sparingly, but your motorcycle won’t appreciate it and you eventually won’t either. Oil thins out and degrades over time and will ultimately have minimal cooking and lubricating effects on your engine.
Again, if the lubrication is not doing it’s job, or doing a poor job, the expansion of the mechanics inside your engine will become too much and cause the pistons to stop moving.
The third biggest reason a motorcycle engine seizes is due to rust and grime build-up from sitting for long periods of time. If you let your motorcycle sit for too long, water and condensation can find it’s way into your carbs and engine which will expedite the formation of rust.
Rust in the engine acts like a weld, fusing your piston to the cylinder wall. Once there’s a small bit of rust, that spot of rust will propagate around the entire piston, and soon enough the entire piston is rusted to the cylinder wall. Check out this article I wrote to find out more about what happens when you let your motorcycle sit.
How to Fix a Seized Motorcycle Engine
There are several ways you can try to free up your engine and get it started again. Be mindful that these results are not guaranteed. Always be careful when you are working on your motorcycle. Be sure to wear protective eye gear and gloves.
The first method you should always try is lubricating your pistons and combustion chamber. You can do this by taking out all of the spark plugs and pouring a lubricant down the spark plug holes. Your spark plug holes lead directly to the top of each piston. Even if you are suspicious of only one part of the engine that’s seized, pour lubrication down every spark plug hole anyway to ensure you get the problem cylinder. Unless you’re in the worst case scenario where every piston is seized.
There are several lubricants you can try. It’s important you choose a lubricant that also has penetrating factors to break down any grime that’s seizing the pistons.
WD-40 works great; you may already have it laying around in your garage. You can also try using diesel fuel. Though this gives off a strong odor, it works great for lubrication. The Marvel Mystery Oil is my highest recommendation. It not only provides top notch penetration but it’s also a first class lubricant that mixes well as a fuel additive
Once you’ve added the lubricant, wait several hours for it to soak. After you’ve waited at least several hours, put the motorcycle in first gear (without attempting to start it) and rock the motorcycle forward and backwards slightly, perhaps a couple of inches if possible.
This puts upwards and downwards force on the piston and can break it free. Don’t push too hard though, you don’t want to force something that’s still stuck and cause further damage.
Another method to try is manually turning the flywheel. You can do this by removing the crankcase cover on the side of your engine (every motorcycle is a little different). Have an oil pan underneath as oil will spill out of it (it also might be easier to completely drain the oil before you take off the case). You should be able to easily see a bolt sticking out in the middle.
With a socket, try to rotate the nut or bolt back and forth. Again, do not use a lot of force as this could cause further internal engine damage. You’re just trying to get the pistons loose.
If your engine is seized due to sitting for a long time, these methods should work great for you. However, if you ran out of oil/used low quality oil and these methods don’t work, there may be significant damage inside. You will probably need a top end engine rebuild. Only attempt to do this yourself if you have enough mechanical experience. It’s not a job for a beginner.
How to Prevent a Motorcycle Engine From Seizing
It’s best to take measures to prevent any motorcycle engine from seizing. If you plan on owning a motorcycle, then plan on giving it the proper care it deserves. This will save you a lot of time and money in the future.
Always make sure your motorcycle has oil in it. You should change your oil about every 3,500 miles or at least once a year. Be sure to check your owner’s manual about how often and what kind of oil to use if you plan to change the oil yourself. For information about the right oil to use in a motorcycle, see my article here.
Never go longer than a year without changing your oil, even if you don’t ride your motorcycle that often. Your oil will collect dirt and grime over time that makes it less effective. I’m sure we’ve all heard horror stories of some guy who didn’t change his oil for years. Don’t be that guy.
If you’re unable to use your motorcycle as often as you’d like, make sure your motorcycle doesn’t just sit for long periods of time. It’s important to at least turn it on and let it idle to let the fluids circulate and get the oil up to full operating temperature. This will also greatly prevent any possible rusting. Don’t just start the motorcycle for two minutes and then shut it off. You need to get it hot enough that it can burn off any built up condensation from sitting.
It’s not often, but some motorcycles require coolant. If you have a newer motorcycle, make sure you are aware of whether or not your motorcycle requires coolant. If it does, be sure to top it off every once in a while to keep your engine temperature in check. Click here to see my guide about motorcycles overheating.
What Happens If The Engine Seizes While I’m Riding My Motorcycle?
If you’re like me, maybe you’ve wondered what would happen if your motorcycle engine seized while you were riding it. If you’re taking good care of your motorcycle, you won’t have to worry about it. It’s also a good rule of thumb to not ride your motorcycle if it seems to be acting up.
Engine seizure while riding can be extremely dangerous. It might even lock up so hard that it could try to buck you off the front of the motorcycle. If you’re riding at 60 mph and your engine and back tire immediately lock up, your bike will want to slow down but inertia will want to make your body keep moving forward at 60 mph, this is a bad combo.
If your engine starts knocking or screeching, immediately pull over. You’ll either need to limp it home (like 15 mph) and hope that it doesn’t seize or get it towed. Click here to see my list of creative ways to tow a motorcycle.
Having an engine seize while you’re riding does present another issue though. Because the back tire is locked, it is difficult to push it somewhere. When riding, always have a cell phone with you so you can call for help in case you break down.
What happens if you add too much oil to your motorcycle engine? If you pour in a little too much just undo the oil drain bolt and take a little out. If you put in excessive amounts of oil, there will be too much pressure, making the oil leak from various parts of the engine. This may also cause unwanted smoke from your engine or even engine detonation, this once happened to me in an old truck.
How much does a motorcycle engine rebuild cost? It varies, ranging between $500 to $8,000 for a professional to complete the task. It’s difficult to set a specific price on an engine rebuild because a lot of it depends on the make and model, the extent of the rebuild, and the shop that is performing the rebuild.