Homemade Motorized Bicycle
Hey everyone, I just wanted to share this homebuilt motorbike I made a couple years ago. I call it the Harley Jacobson because reasons. Its powered a 4 HP 2 stroke engine from a Homelite-Jacobson Snowblower. In the past I have gotten it to around 80 km/h (around 50 mph) but I have since changed the gear ratio to slow it down but improve ease of starting from a stop. Now its limited to around 55 km/h (34 mph). Here is a video of it running https://www.youtube.com/watch?v=J1a7SBU3iAs
This bike is made almost entirely out of crap I found or had lying around.
Yes, I am aware that the engine is quite close to the seat, Yes I have suffered the consequences, Yes I raised the seat.
The original muffler (pictured) has rusted and fallen apart. I made a new one out of an aluminum baseball bat, and added baffles inside, It's still quite loud and I need to figure out how to quiet it down more
The fuel tank came from a snowblower, and is mounted to the frame of the bike with some metal coat rack hooks I found in the shed.
This picture was taken when it was still being built. Here you can see how the power is transferred from the engine to the wheel. The rim actually has a second rim riveted to it, all the spokes were cut off, and its just the circular ring, the grove the tube once sat it is now the perfect place for a V-Belt to sit =}
The belt I had was too long, so that fixed tensioner at the 10 O'clock position of the back wheel was added to keep the belt taught. The moving tensioner near the engine pulley was connected to a brake lever via a cable, this was my clutch, and it worked by tightening and loosening the belt. This tensioner has been revised since then, and now its connected to a foot operated pedal, as it was too heavy to be hand operated for long periods of time. The original belt I used was only meant for fractional horsepower applications, and wasn't meant to slip. It had to be replaced every 100 or so km (62 miles). I've since bought a kevlar wrapped clutch belt which can be slipped all day long if necessary. I also made sure to buy the correct size so I could delete that extra tensioner. The new belt has gone well over 100 km without fail or even signs of wear. At one point I switched to a centrifugal clutch, But I didnt like how it always engaged at a set rpm, not to mention mine was set to engage well below the engine's power curve. it had to slip for so long that it was hot enough to cook bacon on, so I went back to the classic belt clutch.
The engine is of an unknown size, Not much info was really documented on the engines of that particular brand. I know it shares certain parts with Tecumseh engines. All I know is that its a 4 HP engine. Its between 80-140cc's. It revs to around 6800 rpm unloaded, and when under load usually goes no higher than 5500. It makes very little torque down low until it hits its power curve. Its like vtec kicking in, but with no valves to speak of. I have been very happy with its reliability. It always used to get me to work and started on the 3rd pull.
This is the fourth motorized bicycle I've made. The first two used weed wacker engines. The first one specifically, I made in the 10th grade with a couple friends, we had no idea what we were doing. We used a worn out, rod knocking 18cc 2 stroke engine, which was coupled to the rear wheel with a friction drive system. Just pedal to start. The thing could barley stay moving on a flat road carrying a 120 lbs high schooler, but you gotta start somewhere, right?
One of my friends who helped me build the first one, decided to build his own, out of a 20 cc weed wacker engine, this started a friendly competition which would spawn an additional 3 bikes from me and a go kart from him.
The second bicycle was pretty much the same, except with a 25cc engine (fun fact: Betzi's orignal owner also gave me this engine for free), which was not worn out, But it did have a faulty carburetor. Sometimes the bike would be able to go up to 25 km/h (15 mph) while other times, the engine would just stall when the throttle was opened. Due to a poorly thought out engine mount, which was made by my friend who built his own bike, the engine block cracked and that was the end of this
The third was a piece of crap, Aimed for the moon, shot too high, hit the sun, got burnt and lesson learnt. It used a 170cc 4 stroke Tecumseh engine, Had way too many misaligned moving parts, gear ratio was not at all correct for the engine, and as a result, it barley went faster than the 25cc one. poorly thought out engine mounts which eventually lead to the bicycle frame splitting in half. Have I mentioned that I can't weld, and these things have exclusively been held together by bolts? Here is a picture of the bike when it was still in one piece
I loved building these things, But sadly my friends are now all obsessed with video games or busy with university life. I've been wanting to build one last one, just for the hell of it, before I go back to continue my own education.
But instead of just winging it like with the other 4 bikes, I was thinking of actually planning this one out properly, If anyone is interested, maybe I can post some ideas and poorly drawn out plans, and anyone who has any input can chime in maybe?
Anyways that was a long ramble, tune in next time when I show you my crappy dangerous homemade stick welder
This bike is made almost entirely out of crap I found or had lying around.
Yes, I am aware that the engine is quite close to the seat, Yes I have suffered the consequences, Yes I raised the seat.
The original muffler (pictured) has rusted and fallen apart. I made a new one out of an aluminum baseball bat, and added baffles inside, It's still quite loud and I need to figure out how to quiet it down more
The fuel tank came from a snowblower, and is mounted to the frame of the bike with some metal coat rack hooks I found in the shed.
This picture was taken when it was still being built. Here you can see how the power is transferred from the engine to the wheel. The rim actually has a second rim riveted to it, all the spokes were cut off, and its just the circular ring, the grove the tube once sat it is now the perfect place for a V-Belt to sit =}
The belt I had was too long, so that fixed tensioner at the 10 O'clock position of the back wheel was added to keep the belt taught. The moving tensioner near the engine pulley was connected to a brake lever via a cable, this was my clutch, and it worked by tightening and loosening the belt. This tensioner has been revised since then, and now its connected to a foot operated pedal, as it was too heavy to be hand operated for long periods of time. The original belt I used was only meant for fractional horsepower applications, and wasn't meant to slip. It had to be replaced every 100 or so km (62 miles). I've since bought a kevlar wrapped clutch belt which can be slipped all day long if necessary. I also made sure to buy the correct size so I could delete that extra tensioner. The new belt has gone well over 100 km without fail or even signs of wear. At one point I switched to a centrifugal clutch, But I didnt like how it always engaged at a set rpm, not to mention mine was set to engage well below the engine's power curve. it had to slip for so long that it was hot enough to cook bacon on, so I went back to the classic belt clutch.
The engine is of an unknown size, Not much info was really documented on the engines of that particular brand. I know it shares certain parts with Tecumseh engines. All I know is that its a 4 HP engine. Its between 80-140cc's. It revs to around 6800 rpm unloaded, and when under load usually goes no higher than 5500. It makes very little torque down low until it hits its power curve. Its like vtec kicking in, but with no valves to speak of. I have been very happy with its reliability. It always used to get me to work and started on the 3rd pull.
This is the fourth motorized bicycle I've made. The first two used weed wacker engines. The first one specifically, I made in the 10th grade with a couple friends, we had no idea what we were doing. We used a worn out, rod knocking 18cc 2 stroke engine, which was coupled to the rear wheel with a friction drive system. Just pedal to start. The thing could barley stay moving on a flat road carrying a 120 lbs high schooler, but you gotta start somewhere, right?
One of my friends who helped me build the first one, decided to build his own, out of a 20 cc weed wacker engine, this started a friendly competition which would spawn an additional 3 bikes from me and a go kart from him.
The second bicycle was pretty much the same, except with a 25cc engine (fun fact: Betzi's orignal owner also gave me this engine for free), which was not worn out, But it did have a faulty carburetor. Sometimes the bike would be able to go up to 25 km/h (15 mph) while other times, the engine would just stall when the throttle was opened. Due to a poorly thought out engine mount, which was made by my friend who built his own bike, the engine block cracked and that was the end of this
The third was a piece of crap, Aimed for the moon, shot too high, hit the sun, got burnt and lesson learnt. It used a 170cc 4 stroke Tecumseh engine, Had way too many misaligned moving parts, gear ratio was not at all correct for the engine, and as a result, it barley went faster than the 25cc one. poorly thought out engine mounts which eventually lead to the bicycle frame splitting in half. Have I mentioned that I can't weld, and these things have exclusively been held together by bolts? Here is a picture of the bike when it was still in one piece
I loved building these things, But sadly my friends are now all obsessed with video games or busy with university life. I've been wanting to build one last one, just for the hell of it, before I go back to continue my own education.
But instead of just winging it like with the other 4 bikes, I was thinking of actually planning this one out properly, If anyone is interested, maybe I can post some ideas and poorly drawn out plans, and anyone who has any input can chime in maybe?
Anyways that was a long ramble, tune in next time when I show you my crappy dangerous homemade stick welder
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