How to Put a Lawnmower Engine on a Bicycle


Everyone knows how steeper it becomes to climb up a hill as you grow older. But if you can install a little engine with your bicycle, you will easily overcome the hills.

I am not telling you to buy a new motorcycle for this task. Instead, you can simply make the job done with your old bicycle, simply adding a petrol power motor with it. In fact, a lawnmower engine can do the work. But do you know how to put a lawnmower engine on a bicycle? Don’t worry; I am going to show you how in this article.

How to Put a Lawnmower Engine on a Bicycle

Required Materials:

  1. Bicycle frame that can accommodate wheels and a drive train.
  2. Engine with transmissions, such as from an old lawnmower or chainsaw.
  3. Chain for the drivetrain.
  4. Hand grips on either side of the handlebars to hold onto while riding.
  5. Seat attachment.

Processes on How To Put A Lawnmower Engine On A Bicycle

Process One:

Step One: Acquire Lawnmower Engine

You can usually find these at your local flea market or on Craigslist for as little as USD 100. This is a good place to start because you will likely need some other items that are easier to come by there than elsewhere (though not always).

Step Two: Scope Out The Bike

Keep in mind what type of bike it will be put onto when looking for an engine and the size of the front wheel hub diameter. For example, if I were putting my lawnmower engine on this bicycle, I would want one with a 20-inch front wheel and large enough exhaust pipe to hit against the frame.

Step Three: Take Apart  Bike

I recommend taking the bike down to just its frame so you can measure and make sure everything will line up right before mounting anything on it.

Step Four: Make A Plate For the Exhaust Pipe To Pass-Through

This is needed because a lawnmower engine has an exhaust pipe larger in diameter than most bicycle front wheels. This means that they won’t fit side by side as designed and rub against each other when turning corners or at high speeds, which could cause serious damage like blowing out your tire.Exhaust Pipe To Pass-Through

If the pipe does hit your wheel while riding, then be prepared for one of two things – either wrapping tape around the exhaust pipe to act as a shield or just replacing your front wheel with one that will fit.

Step Five:

Mount the transmission and cut off pegs final touches and test ride!

Process Two

For this project, I took out the engine of my lawnmower and installed it inside the rear triangle part of my bicycle. The engine is going to require quite a big place, and as it will be the main power source, I have removed the center sprocket for the installation.

My bike is small, so I had to remove the bottom rod from it too. Next, I have set the engine in the center and determined the exact distance measurement. I have created a CAD model based on the measurement and then cut out a steel mounting bracket according to that model.

After mounting the engine and its parts, I removed the old sprocket and used shims for the new sprocket. Then I have made a jackshaft with my design and cut out some slots for tightening the chains. Next, I have made the center rod, which is quite necessary for holding my weight.

Removed Old Sprocket

So, I have cut that out and bent it a bit to match the frame. For finishing up the process, I have put the chains and then belts. That’s it; the process is completed.


  • Wear safety goggles when working on your engine.
  • Keep kids and pets away from the area where you are working with heavy equipment.
  • Always wear a protective face mask to avoid inhaling any chemicals that may be in use during the process or as an emergency measure if something goes wrong (like gasoline fumes). If possible, work outdoors so bystanders can quickly clear out of range should anything happen.

Final Thoughts:

In this article, we’ve seen how to put a lawnmower engine on a bicycle. It’s not difficult and is actually pretty straightforward with the right tools. The most important part of putting in an engine is ensuring that you have enough clearance for the valves because they will determine whether or not it runs well!

It would help if you made sure that your front wheel hub has at least five inches from where the crankshaft meets the tire’s rim up until where it connects to the frame. You’ll also want around two inches between your valve covers and any other parts like brake pads or levers, so adjust accordingly as needed when installing everything.

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