Motorized Bicycle - Winter Project 1 from Spike Category: On-Road Fabrication

[greygizmo]

Looks great! It looks like it would take quite a bit of skill and patience to Fab a tank like that. I wouldn't even know where to begin.


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[Spike]

Looks great! It looks like it would take quite a bit of skill and patience to Fab a tank like that. I wouldn't even know where to begin.


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Thanks!
I think it took me about a day and a half to make the tank, maybe two days. including mounting and pressure testing. I could probably do it in a day if i was working hard. When i get my new power hammer going i could probably hammer out 4 tank shells at one time and get 3 or 4 done in the same amount of time.

[Spike]

Springer and Front Wheel

Next up is getting the springer onto the bike. I started with a standard Schwinn style springer front end for 26" wheels. To make the springer fit the bike, i ended up having to add about an inch and a half of length to the steering stem... not a big deal on a bicycle, i just put a slug inside the tube and extension and some plug welds to add extra strength to the stem. This also changed the angle that the spring mounted to the front end, so i had to re-forge/reshape the spring perch to fit the new geometry made by extending the steering tube.
Here's a picture after the springer was fit onto the bike.

This is the thing that makes the bike so much better. Without the springer and the brake, it's a little scary. With just a solid front fork there is a definite feeling that the front end is going to fold up and collapse on you every time you hit a bump.


I made a quick little mounting tab, and welded it right to the springer's leg to mount the little brake caliper. Since i had to remove the chrome to weld to the springer's leg i just repainted that part semi-gloss black to match the brake caliper.


I swapped the rims out for a heavy duty double wall rimset and put on the whitewalls once i got it to this point.

[Jason]

The more I see this, the more I want to build one. If you added gears, do you think it would be able to take off from a stop?

[agent4573]

Instead of gears it would be better to just add a centrifugal clutch from a small go-cart or spend the money and get a constant velocity drive system for it. All those little crappy 2 horsepower go carts get going from a standstill, then this bike can too. It'll add a bit of weight and some noise, but it should be able to get you going from a standstill.

[Rambozo]

Instead of gears it would be better to just add a centrifugal clutch from a small go-cart or spend the money and get a constant velocity drive system for it. All those little crappy 2 horsepower go carts get going from a standstill, then this bike can too. It'll add a bit of weight and some noise, but it should be able to get you going from a standstill.

But without a positive clutch, you would need another method to start it. I'm sure with a few tweaks you can get enough power to have a standing start. I see some of those are tweaked to go 50+ MPH.

[Spike]

Its not like you have to pedal up to speed and then the engine takes over, I usually pedal 2 or 3 pedal strokes before I start letting out the clutch.
When I start out from an intersection, i'm letting out the clutch about halfway across the first intersection and under engine power again before i'm halfway through the second lane. If I weren't 250 lbs it would be faster.

[Spike]

Instead of gears it would be better to just add a centrifugal clutch from a small go-cart or spend the money and get a constant velocity drive system for it. All those little crappy 2 horsepower go carts get going from a standstill, then this bike can too. It'll add a bit of weight and some noise, but it should be able to get you going from a standstill.

But without a positive clutch, you would need another method to start it. I'm sure with a few tweaks you can get enough power to have a standing start. I see some of those are tweaked to go 50+ MPH.

The more I see this, the more I want to build one. If you added gears, do you think it would be able to take off from a stop?

Absolutely. You can buy a jackshaft kit, which replaces the bicycle's front crank and runs the engine's power through the bicycle's existing gears.
I've seen people getting up to 55-60mph with gear kits like this, and they start from a stand-still using the engine's regular clutch... so they still start the same.

Another option for adding some fuel economy, get up and go, and top speed, is to use an engine out of a little dirtbike with a CVT transmission (and a kickstart). I plan on building myself one of these with a 50cc 4 stroke engine from a dirtbike with a CVT transmission and an auto-clutch. with the CVT the engine can be even smaller and ends up working better.

[agent4573]

I completely forgot the only way to start it was to pop the clutch. Forget my idea about the centrifugal clutch. I think if you go with a kickstart motor it falls under dirtbike/moped and has to be registered differently than if you just use the bicycle pedals to get going. A few pedals really isn't a big deal if the motor is doing the work 99% of the time.

[Spike]

Break In, Break Down, and Final Touches

Whenever i sell a motorbike, i put at least 20 miles on the engine to get the break-in period over with and work out any would-be problems before it gets shipped out.
This particular engine had a problem, and not a common one. Aside from having a terrible intake leak problem, there was a bunch of crud in the engine case from manufacturing that got sucked into the cylinder and scarred up the piston and rings. Like i've said before, it's good to buy a local engine if you can. All i had to do was take it out and do a warranty exchange it for a good engine.

This picture also shows one of the upgrades i put on the engine. I throw out the junk spark plug that comes in the kit, and replace it with an E3 spark plug. Works great, and i've never fouled one yet!

During the second 20 mile break-in i realized i needed a place to put my drink, so i made a quick little cup-holder for the handlebars.


After the break-in it was all ready to hand over to the customers.

[Spike]

All Finished

[DVA]

During the second 20 mile break-in i realized i needed a place to put my drink.

Road Pop???

[Spike]

Road Pop???

:: facepalm ::
no... not booze. Coffee, soda, or usually just water.

By the way, drinking alcohol while riding a bicycle still gets you a DUI in most places.

[Jason]

The 50cc idea would be pretty sweet. Are you making your own front ends?

[Spike]

The 50cc idea would be pretty sweet. Are you making your own front ends?

I didn't make this front end, only modified an existing one. Though i could easily make one, and it would be a far cry better than the one i bought. Isn't that usually how it goes?