Which engine?

M

Motorvator

New Member
Hello everyone, my name is Chad and I come from the bicycle industry. I actually still work in the industry. I am very interested in creating my version of what a motorized bicycle should be, and hope to change some of your minds about your bicycle set ups. Inversely, I need to know about motors. It seems to me there is not a whole lot of difference from one motor to the next, and am trying to decide which to get. I definately want a chain drive as I will be using a disc brake hub to bolt a king cog to, so the simplicity of the cheap 2 stroke motors is very appealing. I don't want to spend more than 200.00 on a motor, but am very open to a four stroke motor that installs the same way as the 2 strokes do. I definately DO NOT want a friction drive, as I believe from my experience in loaded touring, that is way too much weight on the back of the bicycle and I do plan on laying this thing over through the turns flat track style. So, which engine for around 200?
 
Welcome to the forum Chad, glad you joined us.

If cost is a issue, I think the 2-stroke engine kit is going to be the cheaper route. Never built or used a four-stroke so hopefully some who have can add the cost of building one and prove me wrong.
 
Hi Chad, welcome! Nice to see some real bicycle guys here!

Building a 4-stroke definitely costs more up front, but in the long-term, I feel it proves cheaper - especially if you intend to use it for daily transportation.
The 4-stroke is simply smoother, more reliable (most are industrial-rated engines), and you don't need to mix oil in the fuel. Most use less oil than 2-strokes.
$200 can easily buy you a chinese Honda clone motor. You need everything else tho lol

The china 2-stroke is more compact, cheaper initially, makes more power per cc, but it's like playing the chinese lottery when you get one. To start with, they are generally not balanced well and have "dirty" castings. Second, they usually have mediocre bearings. Third, the cylinder jug is the biggest glaring weakness of them. No matter what mods you do, you still have that 1930's era Russian-designed cylinder. The chinese 2-stroke is not designed for sustained operation. Older instructions say to shut them off every half hour and let cool.

Don't get me wrong, I'm not hating on the chinagirl. There are many here who are successful with them. I spent 4 years riding bikes powered by them. If you like to tinker and tinker often, they fit the bill. I'll probably get another one for a really fun toy bike or something. I will never use one for a dependable daily rider again, however. 1 year with a 4-stroke Huasheng is enough to change my mind.

No matter which way you go, you must eventually get a chinese 2-stroke for the experience tho! :D
 
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I built this kit for about 200 bux. It is a 4 stroke fricton drive that excells all others in efficency and speed of 40 mph if I want, and it has no added weight high over the rear wheel.
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Good looking bike, Wayne. I especially like the seat post and that handlebar mounted rain gage. :)

Tom
 
The handle bar mounted rain gauge seams to be a special feature do tell.:D

This is the neatest looking friction drive set up I have seen yet!
 
wayne z said:
Thanks, The seatpost is made from the footlever off a Honda centerstand.
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It took me a while to figure out what you were talking about here.

That's really cool. Genius actually, it takes one to know one don't you know lol.
 
2 stroke China Girl is definitely the way to go on a motor bicycle with these conditions,

1. You have blue print your motor before installation in the frame

2. or, you need to plan on buying about 5 motors on average it get 1 good one out of the box. Still not as bad a deal as it might seem, because you'll have spare parts to keep you going for years.

The advantage of a China Girl as I've described is, it will be faster and lighter, plus just as smooth, and dependable as a 4 stroke of equal size. Even if it's not faster it will still be a lot lighter. China Girl motors are easier to work on, and less maintenance intensive. There's a better aftermarket for China Girl parts, and performance.

When all these considerations are taken into account, the China Girl advantage is pretty much insurmountable. Here's two China Girls to prove my point, that also happen to be my own.

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I must be right because my wife said something about me knowing it, and it all lol.
 
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biknut said:
2 stroke China Girl is definitely the way to go on a motor bicycle with these conditions,

1. You have blue print your motor before installation in the frame

2. or, you need to plan on buying about 5 motors on average it get 1 good one out of the box. Still not as bad a deal as it might seem, because you'll have spare parts to keep you going for years.

The advantage of a China Girl as I've described is, it will be faster and lighter, plus just as smooth, and dependable as a 4 stroke of equal size. Even if it's not faster it will still be a lot lighter. China Girl motors are easier to work on, and less maintenance intensive. There's a better aftermarket for China Girl parts, and performance.

When all these considerations are taken into account, the China Girl advantage is pretty much insurmountable.
I must be right because my wife said something about me knowing it, and it all lol.
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Another problem with 4 strokes, and this is a deal breaker for me, is most of the common 4 stroke MB kits only have a centrifugal clutch. That may not be as much of a problem if you come from a non motorcycle, or non riding background though.
 
Did you say get 5 motors and you might get a good one? you got to be kidding me, save your money and time and get a quality 4 stroke engine and never have to worry about a thing, add reg gas and go, Half of this forum is about problems with these cheap 2 stroke engines. People get em to work but for how long before they take a s#@t
there is nothing wrong with a centrifugal clutch and I have hundreds of hours riding motocross and racing downhill mtb bikes. china = crap USA ALL THE WAY !!!!
 
Lance Portnoff said:
Did you say get 5 motors and you might get a good one? you got to be kidding me, save your money and time and get a quality 4 stroke engine and never have to worry about a thing, add reg gas and go, Half of this forum is about problems with these cheap 2 stroke engines. People get em to work but for how long before they take a s#@t
there is nothing wrong with a centrifugal clutch and I have hundreds of hours riding motocross and racing downhill mtb bikes. china = crap USA ALL THE WAY !!!!
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For a beginner with limited mechanical experience, there's a lot of wisdom to what you're saying , that's for sure.

OTOH someone with skill can have a well built China Girl motor for about $335 or less. This assumes $185 for 1 motor kit, plus 4 extra cranks, which are about $25 each. The rest of the $335 is gaskets and shipping. Add another $30 if you upgraqde all the bearings.

That sounds like a lot of trouble, but imo you end up with a better motor for a motor bicycle for your trouble.
 
Biknut, have you even built a 4-stroke MaB yet? You're talking crazy over there, saying a chinagirl is just as reliable as a 4-stroke.

I spent 4 years with 66cc chinagirls. I've spent 18 months with my 49cc Huasheng. From my experience, a chinagirl needs more work in one month than a Huasheng in one year. In fact, all I've had to do to my Huasheng in 18 months is a valve adjustment and 4 oil changes. I haven't had to adjust anything else on the engine. I haven't even had to tighten a loose bolt on the bike. Even with the bugs I had with my shifter 4G in the beginning, it was much less work overall than any single chinagirl I've had, and I've had 5 of em. Also, when you get a Huasheng (or any 4-stroke), you already know it's not going to need any work to make it reliable :-{

You want to look at cost, you aren't taking into account running costs, either. A 49cc 4-stroke uses >25% less fuel and arguably less oil than any chinagirl, mile for mile. A chinagirl costs more in a year than a Huasheng just to get around, and we aren't talking "spare parts" yet.

Commie copy of a 1930's commie engine vs a commie copy of a modern Japanese industrial engine. Technology wins again.
 
I think the difficulty here stems not from the classic 2 vs 4 stroke debate, definitely not country of origin, nor even the dubious quality control inherent with the in frame two stroke kits, but again & perhaps unsurprisingly - initial cost. The OP made their desires quite clear & unfortunately within those parameters there is to my knowledge only one kit that comes close to meeting all of them;

"I definately want a chain drive as I will be using a disc brake hub to bolt a king cog to, so the simplicity of the cheap 2 stroke motors is very appealing."

"I don't want to spend more than 200.00 on a motor, but am very open to a four stroke motor that installs the same way as the 2 strokes do."

"I definately DO NOT want a friction drive, as I believe from my experience in loaded touring, that is way too much weight on the back of the bicycle"

"So, which engine for around 200?"

As far as I'm aware, while you can get a cloned four stroke engine for around $200 - this would be an "engine only" sale, which while the OP stated that's what they wanted to spend on an engine, I'm going to assume they weren't considering a gear box, mounting plate, fuel tank, wide crank kit, sprocket, exhaust system, throttle kit & cables, chain & tensioner as separate purchases - which once included with the engine cost appears to be more than double the price they were willing to spend (if I am mistaken, please forgive the assumption).

Even setting aside personal mechanical experience & luck, yes - much can be said regarding the longevity and overall, long term cost savings of even the cloned four strokes over the least expensive two stroke kit money can buy. There is also much that can be done to reduce the cost of an in frame four stroke build, depending on your ability to fabricate, scrounge & repurpose components both new and used. Yet no mention of fabrication was made nor long term expectations and the fact remains that if the budget limitations dictate no more than $200 towards the cost of motorizing a bicycle and including the above stated parameters - there is only one choice I'm aware of, the in frame two stroke kit.

Everyone here has brought up valid points regarding the strengths and weaknesses of their favored engine type, yet I must advise caution regarding quoted costs. While you may indeed end up repairing or replacing components of the two stroke kit and it's important to mention that potential, the cost of all the components of a four stroke build must be included to accurately depict the initial expenditure, enabling them to make the most informed decision based on what they want and can afford. Neglecting to state the cumulative costs of all components needed does everyone a disservice.

If I am misinformed and you can get a complete four stroke kit that includes everything needed to motorize a bicycle for $200 - please do correct me, providing a source for such ofc. Were one to exist however, I would have to question it's overall quality & reliability as well as I believe what the bottom line is truly about is deceptively simple...

...what can you really expect from $200?
 
The_Aleman said:
Biknut, have you even built a 4-stroke MaB yet? You're talking crazy over there, saying a chinagirl is just as reliable as a 4-stroke.

I spent 4 years with 66cc chinagirls. I've spent 18 months with my 49cc Huasheng. From my experience, a chinagirl needs more work in one month than a Huasheng in one year. In fact, all I've had to do to my Huasheng in 18 months is a valve adjustment and 4 oil changes. I haven't had to adjust anything else on the engine. I haven't even had to tighten a loose bolt on the bike. Even with the bugs I had with my shifter 4G in the beginning, it was much less work overall than any single chinagirl I've had, and I've had 5 of em. Also, when you get a Huasheng (or any 4-stroke), you already know it's not going to need any work to make it reliable :-{

You want to look at cost, you aren't taking into account running costs, either. A 49cc 4-stroke uses >25% less fuel and arguably less oil than any chinagirl, mile for mile. A chinagirl costs more in a year than a Huasheng just to get around, and we aren't talking "spare parts" yet.

Commie copy of a 1930's commie engine vs a commie copy of a modern Japanese industrial engine. Technology wins again.
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I admit that although I have a lot of experience with 4 stroke motors, I have zero experience with 4 stroke MB motors other than what I've read on this site. I don't think that matters much though, because the principal is the same.

I accept your representation of your 4 strokes quality and performance as true and accurate. And if we're talking about a typical China Girl motor out of the box, then you're pretty much right on about that too.

But my comments are about an accurately assembled China Girl, and your description of a China Girl, compared to the reality of my motor is badly off the mark.

I'm fairly confident that in a side by side comparison between the 4 stroke motor you've described, and my China Girl motor, mine is equal, or superior in almost every area. Weight, performance, cost, longevity, I just don't see any advantage you have. If you're getting better than 120 mpg, then that has to be because your motor has lower performance.

I know you can argue that I had to go to a lot of trouble to make a motor of this quality, and stock motors are not going to be nearly as dependable as mine, but all the parts are readily available, and the skill it takes to make one is relatively low level by most motor building standards imo.

After reading all this you'll probably get the impression that I'm some kind of 2 stroke lover, but I promise that's not the case. I've been just as biased against 2 strokes all my life as most people are. As a matter of fact I think was born with a bias against 2 strokes.

In junior high school I bragged to a kid that my souped up Honda 90 would destroy his stock Yamaha Twin Jet 100 in a drag race. The only thing I knew about a Twin Jet 100 at the time was it was a crappy pos 2 stroke. The only thing that got destroyed that day was my appetite, after having to eat a gigantic piece of humble pie when he showed me his a## about 5 times in a row lol.
 
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