My first motor bicycle (project)! Help needed.

A

aaronmorg

New Member
Hello all,

I am new to the forums and to building these types of things as well.

My father recently bought a shiny new Echo weedeater and said I could have his old one. So I got to thinking that it would be cool to put the engine on my bicycle. Little did I know that many people have already done this and it is quite common.

I have taken apart the weed eater and put the shaft in the shed. I have the engine by itself and am not sure where to go next.

I know I need a place to put the engine on my bike, such as a rack or something. I know I need a clutch because having the engine direct-drive to the wheel would cause it to lock up and die (I think).

But, other than some basic knowledge and common sense, I have no idea where to start.

I think the first thing I should get is some kind of shaft from the square slot where the old shaft was. I'm not sure but I think you put a small gear there.

I am the most basic of beginners and any help would be GREATLY appreciated.

Thank you for taking the time to help me :D.
~ Aaron ~
 
easiest way to do a weedeater engine is to remove the flywheel cover/ pull start, then mount a bike peg on the shaft, where the flywheel is.. mount it on a rack so the peg turns on the tire.. you could also make the engine lift off on a hinge sort of thing.. but just pedeling fast from a standing start will start it up, couple pumps on the primer ball and it'll start, shouldn't need choke.. weed eater engines are not versitile enough to use clutches.
 
Is the setup you are talking about like the one on this site:
(changed due to spam filter) "bikemotorparts(dot)com"

If so, I was trying to go for more of a chain setup because the ratio of power doesn't look too great on that setup.

I was wondering if you could use a clutch because you could just start it up with the clutch depressed and then slowly let off the clutch until your bike was at speed.

EDIT: I am going to try and get some pictures of the engine and bike I am using.
 
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a weed wacker engine makes less than 2hp.. the scrub wheel riding on the tire makes a good ratio for the engine.. a clutch is possible, but it would be easiest if it was a friction drive, with a scrub wheel.. clutch would just attach from the engine and the clutch to the scrub wheel.. centrifigul clutch would work... theres no way to make a manual clutch work on a weedwacker, it would be to complex to make it practical..

how many CC is the engine?
 
The engine is a Homelite ST-275. Not sure about the CC.

Here is the bike I am using along with a left/right view of my engine.
 

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Look at some of the videos on you tube..
There are some cool weed eater builds and you can see them in action.
I will help you see what needs to be done...
go to youtube and type moterized bikes...
 
The engine, being a bit older, may be a bit larger in displacement.. probably somewhere around 40cc.. it is probably too old for an EPA sticker which would list the engine displacememt.. I really don't know how you would do a manual clutch.. in all reality, chain drive is impractical for a weedeater engine..
 
There are a ton of ways to use a wacker engine. This is how the rc folks do it.

Wackerengines

Strip the engine of most EVERYTHING. Remove the bolt that hold the flywheel in place and put on a prpo adaptor or in your case a Foot Peg.

Good Motoring

DeadEye
 
I have come to the conclusion that instead of being stubborn and insisting on using an out-dated motor. I will purchase a kit.
Kit = Motorized Bicycle Engine Kits

But there is a small catch:

The only bike I would want to put this kit on has a 20-22" diameter. The kit is made for 24-26" Diameter.

How much trouble would it be to make the engine able to run on this smaller wheel size?
 
it will not fit in the bike you have a picture of. 20-22" frames are not big enough in the center V to fit the engine and deffinetly not the BMX you have a pic of.. it could fit in some 20-22" bikes but not that 1... I have a 20" chopper bike I built years ago out of a 20" Huffy BMX from circa 1990.. nothing special but has 26" roadbike forks and a 12" front tire.. original forks were cut into a sissy bar and welded behind the seat.. my engine would almost fit in my chopper.. close but it's too tall.... it would work if I cut a section out of a girls bike top bar and welded it in upside down..
 
yeah im wondering the same thing how much can i take off and how can i get it to start without the pull start ... like a coast start or what ... help
 
Like how you can start a manual transmission while it is rolling?

We do that with my friend's mustang because it's old and he needs a new starter.

If that's the case then that's not a big deal. If I understand this correctly, I'll just have the engine live and hold the clutch. Pedal once or twice to get some speed then let go of the clutch?

It should start right?
 
matt167 said:
it will not fit in the bike you have a picture of. 20-22" frames are not big enough in the center V to fit the engine and deffinetly not the BMX you have a pic of.. it could fit in some 20-22" bikes but not that 1...
Click to expand...

Could someone post a picture of how a motor like this would be mounted on a bike?

I'm confused as to where it is mounted.
 
this is my old beater bike.. messed up rear wheel b4 it was running.. now the kit is in a 26" roadmaster mountain bike..


to start.. lock the clutch in with the button.. pedal up some speed, grab the clutch handle and unlock it ( just pull it a tiny bit and it'll release ).. let the clutch out, crack the throttle, keep pedaling until it starts.. could probably use some choke to start too..
 

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