Totally pointless- adding power and efficency to a 66cc chinese bicycle moped...
 

OK, so I have a partially finished bicycle moped (one of those 66cc happy time motors) in my garage. Engine is attached, not much else.

So, mostly for fun, I want to add power and efficiency to this thing.

Currently I am working on placing the carb/ air intake off to the side to get cold air (and because my frame is too small for it to fit normally.

I was reading about a "wicking" carburetor in the experements section from what I gathered it basically consisted of a metal box with holes in either side of it, a pool of gasoline, and special oil clean up rags hung from it to wick the fuel up and have it evaporate into the air.

Reading this, it looked simple enough, I just have a few questions:

1. On an air cooled engine, would this overheat it? I assume this would create a lean burn that would make it burn hotter.

2. how well does 2 stroke engine oil evaporate? would I be getting the proper amount of oil to my engine?

3. I know this would help eficenct, but would it hurt power? I only have 2-3 horsepower, so this is a biggy.


Other things I'm considering:

-smooth, not knobby tires.
-Water/Methanol Injection to help reduce engine heat
-small fan, battery powered, next to the engine, to cool it faster (or just build arger fins)
-Nitrous. I'm a 19 year old guy...who dosn't want nitrous?

Another, sort of unrelated question. HHO- I know it's hard to get it right as an integrated system, but how difficult would it set up an electrolisis machine off power at home, hook it up to a compressor, and get a fitting to fill up a propane tank with HHO and adding it to the fuel mix? Also how would just adding strait propane, oxygen, or any other gas that can be bought in a small cylender effect efficency, power, and heat?

P.S. I know that compressing your own HHO at home would be dangerous and crazy, and that adding a front hub motor and charging a battery at home would be much simpler and easier.

I like your thinking about nitrous and such on a 66cc. haha BUT I have to warn against this. It isn't just dangerous, it's deadly. HHO is H2 and O2 in a perfect stoich ratio. If you were to compress it into a cylinder and one little spark lights it up into the tank it's no longer a storage tank but a bomb. If you were to store them separately that is another story, but together is a huge no no.

Unfortunately 66cc is too small for any real performance improvements but what you could do is measure your head temperature and block off the air intake for the cooling of the engine to raise the engine temps. The hotter an internal combustion engine runs the more efficient it is to a point. I don't know how much you'll get out of it since I don't know what your engine normally runs. Normally they hover around 350 under load.

Since it is a 2 stroke all you can do is get the spent fuel out of it as fast as possible. Exhaust is your only bet here.

And finally, I don't think the wicking carb will work because 2 stroke oil doesn't evaporate.

thank you. You just saved me an engine.

Now, there are some various expansion chamber exausts availible that are much better than the stock one.

What about adding pure oxygen and adjusting it to run as richer mixture? This probably wont help with economy, but it should help with power.

BTW, I wasn't expecting to do much with the 2 stroke. When I complete this I'm going to try getting a 4 stroke and massing with that. I'm hoping that by using very small engines I can take some more risks and try more exotic solutions that would be too costly on larger machines.

FWIW, I've run a lot of nitrous in the past few decades. However I can only advise you that it is a COMPLETE waste of time and money for this project. Even if you can get a 50% power gain, do you really think that will be worth it? No way! Remember that your top speed won't go up, only your acceleration. And who really cares if you go 0 to 25 in one second less. It's been done, but mostly as a science project by someone with extra money to throw around.

I love HP (and torque) as much as the next guy, but you're wasting your time (and especially money) on that one.

-Bob C.

Good idea. Counterintuitively, wider is better. For automotive tubeless radials with their stiff well-defined squared-off profiles there is some question, but for common bicycle tires it's a sure thing. What you want is wide tires that can accept high pressure.

The old myth that road bikes use narrow tires for rolling resistance is wrong; they use narrow tires because they have less aerodynamic drag, a very important concern for road bicyclists. The higher pressure that they can handle mitigates the increased rolling resistance.

Yes, I do know to get fat ones, I have a road bike as my main bike, and I have all too many scraped elbows and knees to know that skinny ties suck for cornering. Or for potholes. Or sand. Or water.

Mmmk, just checking. The thing is, for every increase in horsepower I can add a larger rear sprocket to take advantage of it as speed.

Nitrous will gain you power for about 10 - 15 seconds, then your sprocket will be sized incorrectly for the other 29:50 of your ride...

-BC

ahhh...thanks for the info.

I'm still looking into ways to soup it up. it's a $125 engine, and I'm not afraid to experiment with it. I have some personal desire to get some first hand knowledge about experemental ways of souping up scooter engines, mainely the fact that you can park a 50cc (or something that looks like a 50cc) on the sidewalks in the city.

I don't know if your engine is one of them, but they do make kits to go to 80cc from 50cc. I think it is just a big bore kit.

I think that's on one of the Yamaha scooters. All those "80cc" bicycle moped kits on ebay are actually 66cc, it's just that they are in the 60-80cc "class" that they get labled as such.

chinese engine= blow up soon enough without trying to do so.

Having had a number of 2 strokes, in stock configuration they are made to go through every kind of weather and traffic conditions without hassle. Also the economics of factory assembly, the cheaper the scoot, the more cost savings went into its production.

In the 80's I had an RD250 Yamaha twin 2 stroke. I replaced the cylinders and pistons with 350 units, added a DG head that raised the stock compression from 7.4 to 9.5 to 1, added Bassani expansion chambers for exhaust, swapped the 28 mm carbs for 34 mm carbs. In the end it had the power of a 900 cc bike. The trade off was I went from 42 mpg to 18 mpg !!! With help from my local Yamaha dealer, he showed me how to jet it leaner, play with needle sizes in the carburators to get the bike back some MPG. After that I got between 28 to 34 MPG, that was liveable.

With allot of the scoots out there especially the 50 cc class, a pipe and carb will will raise your upper RPM and that way increase your speed, because you can't change your final drive ratio. If you check out Mopedarmy.com, they have dozen of stories. Youtube more than likely has your scoot modified, and you can follow the trail to see what they did.

With your bike, if you can get a Mikuni carb kit for it, that may be better than the stock carb by providing better atomization of the fuel. If you do add an expansion chamber, limit if you can the exhaust outlet size. An expansion chamber works like a reverse supercharger, the chamber creates a vacuum effect, making the exhaust pressure lower, drawing in a larger volume of fuel. If you have ever added an expansion chamber to a stock bike, its a rush, once up in the RPM band, the expansion chamber goes into action and the bike leaps away. To cover all this extra power, you have to add fuel, therby making your MPG go down.

Defentely go out and play, tear it appart, its a tone of fun. I don't know if there is an 80cc kit for it, it would be interesting to see how many after market perormance parts would make better MPG. Little things like advancing the spark a degree or two might make better MPG, advance it too much and you'll overheat, overheating a 2 stroke means seazing the piston.

Taking the cylinder head and milling it down a millimeter could give you a bump on compression, there is some more MPG. Going to a Bosch platinum can help. A pile of little things can add up to a big thing. Enjoy.

Oh yeah I forgot, if your scoot has a variator, or variable transmission, you can remove or sand down the limiting washer on the engine side of the drive pulley, with this it will make the cones come closer together and raise your final drive ratio, making your gears taller by 1 or 2 percent.

A medium/low ported 2 stroke will give more pull down low and allow a lower rpm for normal cruising.