Tuesday, July 30, 2019

guest article, article 2 of 2 today

article 2 of 2 today

Post apocalypse motorized bicycle project

As the title implies, I was looking for a simple alternative to hard times transportation. At my age (55) I do expect to see a mad max style collapse. I do however expect to see hard times. The idea was something that was very simple and easy to work on, sipped petrol, and if necessary, could be replaced very cheaply. Worst case scenario, it reverts back to a pedal bike. Well, it doesn’t get any cheaper than this option, and in the description of one poster, these motors are about as complicated as a propane barbecue. I’m also the minion that had been wanting to get a motorcycle forever. Motorcycles to me are the perfect low income alternative to transportation, but I could never get myself to commit to the concept however, and the reason of course might be obvious: The frigging things are dangerous! Still, the desire would not go away. After much research, I decided that a compromise was in order, and I decided to motorize my existing 29” bicycle. This was appealing for a few reasons, and cost was one of them. In my state there is a one time mail in $22 fee, and you will receive a permanent moped plate. There is no insurance required, but in my state, you do need a motorcycle license. However in many states you do not. It was a good low cost entry into the world of motorcycles, and due to the lower than average speed of these bikes, much safer in my opinion (You don’t often hear of bicyclists being injured or killed, but you cannot say the same about motorcyclists).

I purchased a 66cc (The Chinese market them as 80cc) 2 stroke frame mount motor kit for $100 off of ebay. These kits mount in the space below the top bar, and forward of the seat. There is an additional sprocket in the kit that mounts through the spokes and on the side opposite of the gear that the bike’s pedals use, and that has its own chain. Regardless of how many gears the bike has, you only have one speed with the motor. I had already chose a single speed beach cruiser long before I decided to motorize a bicycle, because to me, the more simple something is, the better. You will need a men’s bike, and really, in all likelihood, a beach cruiser, as this style offers the most space in the area where the motor mounts. However, when all is said and done, you need anywhere from 9” to 11” to mount the motor. Yes, they are cheap Chinese motors, and high RPM’s are not their friend. But if you run them rich, do not over rev them, and do not overheat them, they will usually last long enough that you will get more than your $100 investment out of them. I did not know this until later, but you can buy higher quality kits with upgraded components, that last much longer. Here is one such kit:

I should mention that while I consider myself a capable enough person to do most anything that I put my mind to, mechanical aptitude is not my strong suit, and projects of this nature do not come naturally for me. As a result, I enlisted the aid of my brash, alcoholic brother, who is a natural at such projects. Of course the help was appreciated, but as always, I paid the price for it in the loss of dignity and self respect. Bottom line: Try to avoid enlisting the help of alcoholic family members, whenever possible :D The project was not over the top difficult, but it also was not real easy, at least not to me.

Other considerations

Of important note is the bike that you pick. If you’re starting out new, without a bike, try to pick the motor kit that you want, and then decide on the most appropriate bike for the kit. Also, unless you’re Paul Bunyan, stay away from unconventional sized bikes, such as the 29” or larger bikes. The tires and tubes are expensive, and generally have to be custom ordered. Also of note is that practically all of these motor kits are designed for the standard 26” bikes. If you have a little more in your budget to spend than did I, the easiest option would be an electric wheel hub, which is as easy as simply switching out either your front or rear wheel (The front being the easiest) with an electrified replacement. Very easy to install, but it is roughly anywhere from 2 to 10 times the cost, depending on the performance option that you choose.


I got pretty lucky, and ran into few problems. However my clutch would not release, so I could not go into freewheel mode. It turned out to be a simple adjustment, and the video below explains the problem in more depth, and was able to help me out. With these poor Q/C motors, you can expect to run into little problems such as this one.

There are often no instructions with these kits, but fortunately, there are plenty of videos on them. And yes, I did get it mounted and running, and it’s currently in the breaking in stage. Initially, I couldn’t see a spark when I held the spark plug to the engine case, and turned over the wheel, and thought for sure that I had a bad electrical component. But sure enough it fired right up, and for a 2 stroke, it’s surprisingly quiet. Another issue is that it spits a good deal of the oil/gas mixture out of the exhaust. The following morning when I got up, there was a puddle of oil/gas on the ground (And yes, I shut the fuel petcock off, and ran it until the motor died, but it still had enough left over fuel in the crankcase to leak). You will want to place a small bucket under the exhaust pipe when you park it. And don’t park it or drive it on your yuppie father in law’s custom, exposed aggregate driveway (Not a problem for me, but I know that it is for some of you :D )

What I’d do differently.

Well, no matter how much research you do, it seems that you always discover an easier option after the fact. What would I have done, knowing what I know now? I probably would have got a friction drive rear engine mount. Yes, they cost about twice as much (Still much cheaper than electric on average though) but they are super simple, and contain only a handful of the parts that the frame mount that I chose had, and I probably could have installed it easily by myself in about an hours time. They may not be the best for hill climbing, but you can always pedal assist to help get up hills. They are also said to wear out tires a little quicker, but I can also live with that, and the 26” tires are common, and are not expensive to begin with.

All in all, I’m pleased with the end result, but if I ever do it again, I’ll likely go with the friction drive mount on a standard 26” bike. On a difficulty level of 1 through 5, I’d rate the frame mount that I chose a 4, and the friction mount a 1 or 2. Way, way, easier, and if you’re anything like me, save yourself the grief and look into this option first.

The bike (Yes, I forgot to re-install the rear fender). I do not recommend the unconventional sized bikes, but I will say this: It’s a great looking bike, and reminds me a lot of the early motorcycles, when bicycles were first being motorized, and were a moped hybrid of sorts, which still included the pedals.

A close up of the motor

A close up of the rear motor gear assembly. The gear for the bike’s pedals is on the opposite side.


  1. Correction: Meant to say: At my age (55) I do “not” expect to see a mad max style collapse. Sorry folks. Little typo’s like that annoy me, as well as confuse readers. And I thought that I had thoroughly proofread it too.

    Also, an update: The fuel leak was coming from two areas. Some did leak from the exhaust as I had previously mentioned, but I had forgotten to use the small washer between the petcock and the fuel tank, and fuel was leaking from there as well.

    1. Yeah, my bad. I could have sworn I read "not" myself. This is why I'm not an editor.

  2. I would dig something like this in diesel.

    Or electric towing a trailer roofed with photovoltaic panels. 'Free fuel from the sky'.

    Say, Comet, how long do brakes last? I'm thinking extra weight and speed...

    1. If this is a single speed, are there brakes, per se? Or is the wheel just being locked from turning? Not sure about the mechanics of this. Any of you pointy head dudes know?

    2. My bike has a foot coaster brake Jim, and I was able to keep it without the motor gear interfering with it. However, if you look at the close up pic of the gear, you will see that I used tapered head screws, because the bolt head style that they sent me in the kit did prevent the coaster arm from mounting. It’s probably also not a bad idea to install an auxiliary front brake at some point, and I just might do that someday. Though I do not see myself ever driving this thing much beyond 15mph, and perhaps 20mph max. After all, it is still a bicycle, and not designed for such speeds. Worse yet, it’s a Chinese bicycle.

    3. Even American bicycles are Chinese, assembled here. And twice/thrice the price-not nice.

    4. “Say, Comet, how long do brakes last? I'm thinking extra weight and speed...”

      I’m not sure LM, with the motor, but it looks like Stevelo answered the question below. Since I do not plan on riding this thing furiously, I suspect that I will get more use out of the brakes and the motor than will most people. And if it doesn’t last, then I’ll go with the friction drive next time. If brake wear does become an issue, then I’ll consider switching over to hand brakes. At least they are easy to replace.

  3. Sad thing is where I live bicycling and walking are the most dangerous modes of transportation. Motorcycles are much safer around here, the wrecks on those come from not paying attention and wildlife

  4. Well done! Sort of... Them 2 smokes are some shakers! I had one with a jack-shaft kit - that powered through the gears - and could pull two full 5g buckets of water up a steep hill!

    They require a lot of motor mount tightening or they will rattle off the bike long term! I used sparkly nail polish.

    The quality of the bike is important and DO NOT USE THE REAR FENDER! It may loosen up and cause a crash at speed!

    I learned how to do it at motorbicycling.com and motorizedbikes.com (forums). The engine quality is also important. Engine kits from eBay is not the way to go for a long lasting engine. But many folks like them for their low cost.

    Use a fairing to get more than 100mpg! And 3mph faster speed. Sun recumbents has on on Amazon. You'll need a front rack to attach it.

    On mine the jack shaft bearing EXPLODED under load pulling about 75 pounds! I had to push it up hills because of the weight :( always get the best bearings you can afford. Also I had chain stretch problems.

    These days I'm a 4 stroke friction man. It costs a lot at first but the maintenance is non existent! Put the roller on the wheel and your good. It's quiet too! I got mine from staton-inc.com/store/ .

    Friction drive sucks in the rain with high pressure slick tires! (Lower rolling resistance;;) but many folks use regular tires and say it's fine. I prefer the extra speed because of my distance to buy food. Apx 40 miles round trip. Currently less than a half gallon of go juice. Fairings baby!

    On friction drive, big hills require a high rpm and fast throttle or they won't pull! Keep your rpm as fish as you can and pedal furiously! I can go uphill about 12-15 mph with a 50# load. The trick is to rev up before you get to the hill.

    The 2 strokes are loud but they pull hard!

    About the brake wear question. They only last a few years instead of many years. The whole thing weighs about 80#'s!

    It's a option for old dudes one me, 56. I was going to write a guest article but it read like "American psycho" with too much information about tiny details. So I quit. Sorry Jim :( I might try again.


    1. You ain't kidding on the cost-$400. But, Honda engine, so...I'd say it would be worth it. And, under 50cc, so it shouldn't need a motorcycle licence. Not any worse than the e-powered front wheel cost wise. Well, if you don't write any more, it was still a lot more than I knew. Thanks.

    2. Good input, thanks. Yes, I’m firmly convinced now that the friction set up is the way to go. I’m told that you should pedal to get started (As opposed to throttling them from a start) and pedal when going up the bigger hills, but no biggie, and they sure seem like the ticket. I also read about the tire slippage in the rain, but this is also not a big deal to me, as I do not plan on riding when it is wet out.

      On the 2 stroke, I’ve been reading that the high performance exhaust pipe with the expansion chamber greatly reduces the vibrations. Yes, they are shakers, but I will go real easy with it, and never take it near full RPM’s. But next time, I will in all likelihood go with the friction set up.

  5. Nicely done on the guest article. Thanks. That and comments doubled my motorized bike knowledge.
    The Bison World Publishing Empire Field Agents always deliver the hard won facts of frugal survivalism.

    1. They are a bunch of Good Eggs, eh?

    2. Thanks 4:05, much appreciated. It’s better to learn through the mistakes of others such as myself if at all possible. Knowing what I know now, I’d of splurged and got the friction set up similar to the one that Stevelo linked above.

  6. Lord Bison, may your raven locks shimmer eternally. Cheap two cycle engines need a good oil. Amsoil Sabre is the best IMO and can be mixed as lean as 100 to 1. I have always used Amsoil at 50 to 1 in everything from weedwhackers to chainsaws. I recently gave away my cheapo weedwhacker after 16 years. It still ran great, I just bought a better one. Amsoil is pricey but works well.

    1. Good reference. Minions, here is the link

    2. Thanks for the tip HD. I wish listed it, and will look into getting some once I’m through the break in process (What I mean by that in case anyone wants know, is that you’re supposed to avoid the slicker synthetics during the break in process)