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

[Spike]

Custom Motorized Bicycle
Been awhile since i've posted a new project on the forums, and i figure this is a good one for the Winter Contest. I've been putting together some custom motorized bicycles here and there over the last 6 months or so, and this is one my favorite so far!



Here's a preview picture of the overall build to mewl over until i get the rest of the pictures ready and the write up finished.

[ShaneJackson]

That is really nice looking. What kind of speed can you get on it? Since it has a motor do you not have to have a plate if you were on a road?

[Spike]

That is really nice looking. What kind of speed can you get on it? Since it has a motor do you not have to have a plate if you were on a road?

Thanks!
it's 100% street legal, even here in CA where nothing is legal. It's only 66cc, and the pedals are still functional so it's just a bicycle with a motor in it, and not considered a scooter or moped. You can ride in the bike lane, but not on sidewalks or pedestrian bike-paths,you have to wear a DOT helmet, and you have to obey traffic laws, just like you were on a bicycle.
At full throttle i can get to 35mph, but i usually cruise at around 17-20 mph. Faster than 20 mph on a bicycle is a little more 'excitment' than i care for!

[youngnstudly]

Wow! That turned out very nice! I'm also curious about the motor. How is fuel economy and what is the distance you can travel on one tank? Is it 2 cycle or 4 cycle? I have been thinking about doing a motorized bicycle for awhile now after seeing them used on Wine tours (I live in the wine country). I thought some cool looking "mini" saddle bags (like the ones that come on the late model Electra Glide Harleys) would make grocery getting a lot more cost effective and fun, but I'd follow your overall theme by leaving it "stripped down" and plain. I'd like to start with a boys cruiser and mold the gas tank into the top bars though. Do these motorized bikes need lights to be street legal? What about helmet laws? Sorry for playing 20 questions, your creation peaked my interest. Keep up the good work!

Edit: Oops, I walked away from my computer to eat and you snuck in and posted before I finished posting. How loud is the engine while cruising?

[Spike]

Wow! That turned out very nice! I'm also curious about the motor. How is fuel economy and what is the distance you can travel on one tank? Is it 2 cycle or 4 cycle? I have been thinking about doing a motorized bicycle for awhile now after seeing them used on Wine tours (I live in the wine country). I thought some cool looking "mini" saddle bags (like the ones that come on the late model Electra Glide Harleys) would make grocery getting a lot more cost effective and fun, but I'd follow your overall theme by leaving it "stripped down" and plain. I'd like to start with a boys cruiser and mold the gas tank into the top bars though. Do these motorized bikes need lights to be street legal? What about helmet laws? Sorry for playing 20 questions, your creation peaked my interest. Keep up the good work!

Fuel economy is one of the selling points here in CA! it gets about 100mpg... if one were lighter than my large self it would get better, i think. My tank holds about 3/4 gallon, so i get about 80 miles. It doesn't need lights to be street legal, but i have to recommend them for street safety. headlight and strobing tail light.

I use the 2 stroke engines, because they actually look like little motorcycle engines, rather than the 4 strokes that look more like a lawnmower engine.

[DVA]

That is a nice bike, 35 MPH is getting with it.

[DaveO]

Very nice! Is this your frame design? It has a very retro look but I spy some updated components, like the disk brake in front, and the way the gas tank tucks under the top tube makes it look like a custom job. What is the extra "fork", that start just fore of the head tube?

[performance]

What brand engine is that? Looks like a weed whacker.

[Rambozo]

Very nice! Is this your frame design? It has a very retro look but I spy some updated components, like the disk brake in front, and the way the gas tank tucks under the top tube makes it look like a custom job. What is the extra "fork", that start just fore of the head tube?

That's a springer fork, a kind of suspension. The frame reminds me of an Electra, but slightly different.

What brand engine is that? Looks like a weed whacker.

Looks like a MotoVelo to me.

[cbmkr]

Is that a Micargi front springer added to the Airwalk Cardiff frame. Looks pretty cool

[Spike]

Yep. Well,.it's a Schwinn style springer. It takes some work to fit the springer to that frame, the neck tube is a lot longer than normal so I had to make a new steering stem, and forge out a new spring perch.

[Spike]

What brand engine is that? Looks like a weed whacker.

It's just the generic imported motor. I get them local, I think "black stallion"is the importer brand... But they are all almost exactly the same.

[Spike]

So, one day while mindlessly roaming through motorcycle blogs and youtube videos when i stumbled across motorized bicycles. I'm in california, and gas at the time was at $5 a gallon and i decided "hey... i could do that... just cooler." Building custom motorcycles is a nice practice run for these extremely difficult and complicated bicycle builds.

I picked a bike with some classy looking lines, and with this one, the configuration of the top tube lets me have enough space to build a very nice gas tank in between the two top tubes. After initial assembly the bike looks like this.


The engine kits are fairly straight-forward. the vague chinesse instructions that come with most kits are fairly useless, but i know there's a whole horde of install videos on youtube. I picked the 2 stroke motor because it looks like a motorcycle motor, and the 4-stroke versions look more like lawn-mower engines. The 2-strokes are also FAR simpler machines. no cam, lifters, valves, timing bits, and since these things are cheap and made in china, i'm banking on simplicity being an important factor in longevity!

I found a local guy here that sells kits, and i HIGHLY recommend buying these things local if at all possible. These kits are made and assembled in china, and not in exactly a 'high quality control' fashion. Having someone that you can take broken or defective bits and bolts to is a huge stress reliever.

Mocking up the motor is interesting, on these frames, the motor has to be in just right to keep the chain from rubbing on the rear chainstays when it's finished. You can see in the picture that there's inches and inches of clearance between the front clamp and the frame when you just use the regular clamp setup, also, the carburetor doesn't fit like this.

I have made extension blocks and new clamps on a couple of the first ones that i did, but i don't like that way of doing it. Now i make my own motor mounts from some chromoly tube and TiG weld them in so that the motor is solid mounted. This makes the whole thing much more 'solid' feeling. the engine is quieter, the clutch is smoother, and it runs smoother. And there's no slipping clamps that can come out of alignment if they get loose.


Alright, that's all i've got time to write tonight. I'll get some more pics when i have more time at the computer.

[agent4573]

Between the bike and the motor how much $$$ do you have in the project? Do you have a link for the motor? I bought the girlfriend a new mountain bike for her birthday this year and now we have an extra schwinn beach cruiser sitting around doing nothing.

[Jason]

Between the bike and the motor how much $$$ do you have in the project? Do you have a link for the motor? I bought the girlfriend a new mountain bike for her birthday this year and now we have an extra schwinn beach cruiser sitting around doing nothing.

I am also interested in this bit of information. I am not really the type to ride a motorized bike around but you never know what the future might bring. I rode bikes a lot growing up and have considered getting a new one recently.

[sportbike]

Looks good. That frame style definitely gives a place for the fuel tank to fit nicely.

Are they pedal start like a moped?

[ShaneJackson]

Damn this forum! You guys keep posting these great projects and it just adds to the list of stuff I want to do.

I love this project for so many reasons... cant wait to see more.

I wonder how far towards a motorcycle you could get away with before the law started looking for a tag?

[Spike]

Between the bike and the motor how much $$$ do you have in the project? Do you have a link for the motor? I bought the girlfriend a new mountain bike for her birthday this year and now we have an extra schwinn beach cruiser sitting around doing nothing.

The motors you can usually pick up for between $200 and $250, and then it's just the cost of the bicycle and some odds and ends nuts and bolts; Don't use the chinese bolts and hardware in the kit. I went to Fastenall and picked up a big bag of 8mm nyloc hex bolts that set me back about 11$.
I've got a bit more into this bike, because of the springer, the gastank hardware, the disc brake, and the new wheels.

I don't have a link to the motor, because i buy mine locally, but they are all over the place online. I recommend getting one that is as close to you as you can, so it will make any warranty/return prolblems that you have an easy chore to deal with.

[Spike]

Looks good. That frame style definitely gives a place for the fuel tank to fit nicely.

Are they pedal start like a moped?

You hold in the clutch, and start riding like a bicycle then pop the clutch and the motor starts. Same way you'd push start a dirtbike, only there's pedals to get you going. Once you're on the go, you still have to pedal to start from a stop. The motor doesn't have gears and the little motor and gears just don't have enough 'umpf' to get you going from a stop.

Damn this forum! You guys keep posting these great projects and it just adds to the list of stuff I want to do.

I love this project for so many reasons... cant wait to see more.

I wonder how far towards a motorcycle you could get away with before the law started looking for a tag?

It varies from state to state, and CA seems to be the worst about it. The letter of the saw say that if it's over 50cc or goes over 20mph, or has an automatic transmission then you have to get a "moped" tag... it's a little sticker tag rather than a real motorcycle tag. But you can't tell 50cc from 66 or 110cc, since they all look pretty much the same on the outside, and even a bicycle can go over 20mph without a motor... so how it works is "as long as your not being stupid" you won't get a ticket. If you're cutting in and out of traffic, or flying down a sidewalk they'll bust you, but they'd just go for the moving violation rather than a vehicle violation unless you were being an extreme nuissance. Since it's obviously a fully functioning bicycle with a little motor kit added onto it, you get a lot of leeway, because there's no serial number or vin stamp to register for a 'moped' tag with. I havn't heard of anyone getting a ticket who wasn't doing something stupid at the time (wheelies on the roadways, riding through pedestrian walkways, running red lights, etc).

[Spike]

Gas Tank Fabrication

Now there is a goofy little gas tank that comes with these motor kits. It has a lot in common with a soda can, and i dented mine with my fingers when i grabbed it out of the box. it uses these little clamps that break off and leak... just junk. I was already planning on making my own tank, so i chucked mine in the recycle bin as soon as i got it out of the box.

I made mine out of aluminum. It ended up being about the same weight as the paper-thin tin-can that came in the kit... held more gas, and looked better to boot.
My tank bolts in like a motorcycle gastank, i made some threaded aluminum bungs and i drilled holes through the two smaller frame top tubes for the mount bolts to go through. With aluminum, it's important to get a lot of support contact area on the weight bearing surface of the tanks, so it works out well that the whole bottom of the tank makes contact with the frame rails for the mounts.


The bungs are a 'blind-tap' type, which means the threaded hole does not go all the way through the back of the bung. Great for tanks and other things that need to be sealed.

The shape of the tank is very similar to a style of motorcycle gas-tank that i make, and the whole shell is only 3 pieces (top, bottom, and the sides are 1 piece). Using the english wheel, plannishing hammer, and a myriad of hand hammers and dollies all the panels have compound curves in them. Here's a picture of some tuck shrinking on the top panel.


Shrinking is an essential step to making a deliberate curve like this.



With any aluminum project fitup is very important. Steel is very forgiving, but aluminum is not. Steel is your buddy, steel is your pal... aluminum pretty much hates you and doesn't like it when you come over to play, and if you don't play exactly right, there's a big falling out and it takes a lot of work to get everyone back together. It's worth the extra time spent in fitup to get it as close as possible. The alloy of the filler rod is much weaker than the base metals, so you want your seams to be small to minimize the stress on the weaker filler metal.



I didn't get a picture of it before i welded it up, but the sharpie line at the bottom of the tank is a 'flange'. After the top and sides were welded up i flanged the bottom edge in, so that the face of the flange sits on the tank's base, and there's more material on the load bearing edge, rather than just a 90 degree butt weld. Not sure if you can tell the radiused lower edge in this pic.


After the shell was all put together, i welded in an aluminum gas-cap bung for a harley style gas cap, and threaded and welded in the fuel petcock bung.